Targeting metalloptosis in tumor therapy: from molecular mechanisms to application of metal nanoparticles.

Advances in nanotechnology have enabled the development of novel nanoparticle-based therapeutics for cancer treatment [ 499 ]. Several nanomedicine formulations incorporating conventional chemotherapeutic agents have demonstrated significant antitumor efficacy and have progressed to various stages of clinical evaluation [ 500 ], showing particular potential for the treatment of bladder, breast, and renal cell carcinoma. Nanoparticles can be broadly categorized into four main classes: lipid-based nanoparticles, polymeric nanoparticles, carbon-based nanomaterials, and MNPs, each with distinct physicochemical properties and therapeutic applications. MNPs have emerged as promising nanoplatforms owing to their multifunctional therapeutic potential. MNPs offer several unique advantages for biomedical applications, including target specificity through surface conjugation with tumor-targeting ligands, multifunctional capacity as both a drug carrier and imaging contrast agent, enhanced biocompatibility and controlled biodegradability to minimize systemic toxicity, and tunable physicochemical properties, enabling precise engineering for specific therapeutic needs [ 501 ]. These nanomaterials are typically classified into noble (e.g., Au and Ag) and non-noble (e.g., Fe/FeOx, ZnO, and Cu) metal categories, each offering distinct advantages for oncological applications. Noble MNPs exhibit exceptional oxidation resistance and plasmonic properties, whereas non-noble MNPs provide cost-effective alternatives with unique magnetic, catalytic, and semiconductor characteristics, despite their greater oxidative susceptibility [ 501 ]. The current biomedical applications of MNPs include cancer theranostics, photothermal ablation augmentation, radiosensitization, and targeted drug delivery. Overall, MNPs present significant potential as next-generation therapeutic agents for clinical applications [ 502 ]. Although the therapeutic potential of ferroptosis in oncology has been extensively reviewed, the distinct advantages of MNP-mediatedferroptotic cancer therapy remain largely unexplored. The strategic application of MNPs to induce ferroptosis has emerged as a promising approach for selective cancer-targeting therapy [ 503 ]. Initial investigations have demonstrated that iron oxide nanoparticles (IONPs) can exploit this vulnerability by delivering cytotoxic iron overload, which overwhelms cellular antioxidant capacity, thereby triggering ferroptosis [ 504 ]. The application of iron-based nanoparticles (IONPs) in cancer therapy has been extensively explored for their potential to induce ferroptosis. Recent research has focused on the synthesis, functionalization, and application of IONPs to enhance their therapeutic efficacy, while ensuring biocompatibility. For instance, the use of magnetic iron oxide nanoparticles (MIONs) has been investigated for their capacity to induce ferroptosis through the accumulation of iron in cancer cells, which catalyzes lipid peroxidation [ 505 , 506 ]. The integration of IONPs with other therapeutic modalities, such as chemotherapy or immunotherapy, has shown synergistic effects, potentially overcoming resistance mechanisms in cancer cells [ 507 ]. IONPs have been employed for magnetic hyperthermia, where they generate heat upon exposure to an alternating magnetic field, leading to the induction of ferroptosis. Studies have demonstrated that this approach can significantly reduce tumor growth in various cancer models, including breast, liver, and ovarian cancer [ 506 , 508 ]. Functionalized IONPs have been developed to deliver ferroptosis inducers, such as RSL3 or erastin, directly to cancer cells. For example, nanoparticles coated with tumor-targeting ligands, such as folate or peptides, have been used to selectively induce ferroptosis in ovarian cancer cells [ 509 ]. IONPs have been combined with other treatment strategies to enhance their therapeutic outcomes. For instance, the use of IONPs loaded with chemotherapy drugs, such as doxorubicin, has been explored to induce ferroptosis alongside conventional chemotherapy effects [ 510 ]. IONPs induce ferroptosis primarily through three mechanisms. IONPs increase the labile iron pool within cancer cells, promoting lipid peroxidation via Fenton chemistry and generating reactive oxygen species (ROS) [ 511 ]. By releasing iron or delivering ferroptosis inducers, IONPs can inhibit GPX4, facilitating ferroptosis [ 512 ]. Iron accumulation catalyzes the formation of lipid peroxides, which are toxic to cells and lead to membrane damage and cell death. The future of IONPs in cancer therapy appears promising, with potential applications in precision medicine, theranostics, and combination therapies. Precision medicine, tailoring IONP treatments to specific tumor types or genetic profiles, could maximize therapeutic efficacy while minimizing toxicity. The utilization of iron sulfide nanoparticles (ISNPs) in cancer therapy has garnered significant attention because of their unique physicochemical properties, particularly their ability to induce ferroptosis, an iron-dependent form of RCD. Recent studies have explored the potential of ISNPs in various cancer models, highlighting their efficacy, molecular mechanisms, and future applications. ISNPs have been investigated for their ability to promote ferroptosis through iron overload and subsequent lipid peroxidation. Studies have demonstrated that these nanoparticles can effectively increase intracellular iron levels, which is crucial for initiating ferroptosis. The synthesis methods for ISNPs have been refined to enhance their stability, biocompatibility, and targeting capabilities, enabling their effective use in vivo [ 513 ]. In preclinical models, ISNPs have shown the ability to reduce tumor growth in cancers such as breast and pancreatic cancer. For instance, FeS@BSA nanoparticles have been reported to effectively inhibit tumor growth in breast cancer models by inducing ferroptosis [ 514 ]. ISNPs have been combined with other therapeutic agents to enhance cancer cell death. The co-delivery of ISNPs with chemotherapy drugs, such as doxorubicin has been explored, leveraging both the ferroptosis-inducing properties of ISNPs and the cytotoxic effects of the drug [ 515 ]. Meng et al. reported a multifunctional FeS2 nanoparticles for magnetic resonance and near-infrared imaging-guided photothermal therapy in a triple-negative breast cancer mouse model [ 516 ]. Iron sulfide nanoparticles are a promising platform for inducing ferroptosis in cancer therapy. Their ability to increase iron levels within cancer cells, combined with their potential for targeted delivery and theranostic applications, positions them as valuable tools in the evolving landscape of cancer treatment. Nonetheless, further research is essential to optimize their design, enhance their specificity, and ensure safety for clinical applications. Gold nanoparticles (AuNPs) have emerged as promising agents in this field because of their unique physicochemical properties, which facilitate targeted drug delivery, photothermal effects, and the ability to modulate cellular redox states [ 517 ]. Two-dimensional metal–organic frameworks (MOFs) are a class of coordination polymers formed through the self-assembly of metal ions with multifunctional organic ligands. These nanostructures demonstrate exceptional protein-encapsulation capacity and pH-responsive sensitivity [ 518 ], establishing them as highly effective lysosome-targeted delivery platforms. A study demonstrated the use of AuNPs integrated into MOFs to enhance the accumulation of hydroxyl radicals and thermal sensitivity, thereby promoting ferroptosis in triple-negative breast cancer in conjunction with mild radiotherapy [ 519 ]. Xiao et al. presented a unique multi-center bonding in hypercarbon-centered gold clusters that acted as ferroptosis inducers in cancer therapy, demonstrating a novel approach to metallodrug design with significant antitumor efficacy [ 520 ]. Rojas-Cessa et al. recently demonstrated that phytosynthesized gold nanoparticles (PAuNPs) induce multimodal cytotoxicity in gastric cancer cells through three distinct mechanisms: promoting mitochondrial dysfunction, nuclear fragmentation, and activation of the ferroptosis pathway [ 521 ]. For example, Mi et al. demonstrated that cirsium japonicum-synthesized gold nanoparticles (CJ-AuNPs) induce oxidative stress and ferroptosis in AGS gastric cancer cells through complex mechanisms [ 522 ]. CJ-AuNPs triggered cytosolic ROS accumulation and promoted lipid peroxidation, as evidenced by increased levels of malondialdehyde (MDA). Ultrastructural analysis revealed mitochondrial impairment characterized by cristae fusion and organelle shrinkage. The ferroptosis inhibitor ferrostatin-1 significantly attenuated MDA production, thereby confirming ferroptotic cell death. Mechanistically, CJ-AuNPs downregulated key ferroptosis regulators (SLC7A11 and GPX4) and upregulated heme oxygenase-1 expression. AuNPs present a novel and potent approach for inducing ferroptosis in cancer cells, offering advantages in terms of targeted delivery, minimal toxicity, and the ability to leverage the unique tumor microenvironment for enhanced therapeutic outcomes. Future research should focus on refining these systems for clinical applications, understanding the full scope of their biological interactions, and exploring their potential in combination with other therapeutic strategies. Copper nanoparticles (CuNPs) have shown significant potential for delivering copper ions or copper-based compounds to induce cuproptosis in cancer cells. Copper-loaded nanoparticles can be engineered to deliver copper specifically to tumors, releasing copper ions to disrupt copper homeostasis and induce cell death. The use of nanoparticles allows for controlled release, enhanced bioavailability, and reduced systemic toxicity, making them an attractive option for cuproptosis-based therapies. Recently, several nanomaterials have been implicated in the regulation of cuproptosis, facilitating the discovery of more cuproptosis drugs [ 523 – 525 ]. CuNPs predominantly induce cuproptosis by increasing intracellular copper ion accumulation. A representative example is the GSH/ROS-responsive nanoplatform PCD@Cu developed by Wang et al., which co-delivers camptothecin (CPT) and doxorubicin (DOX) using stimulus-cleavable linkers to achieve this. In the tumor microenvironment, PCD@Cu triggers the release of CPT and DOX, causing DNA damage and apoptosis, and Cu 2 ⁺, which is reduced to Cu⁺ to initiate cuproptosis. The resulting dual cytotoxicity and GSH depletion further promoted immunogenic cell death and enhanced T-cell infiltration, demonstrating potent antitumor activity against triple-negative breast cancer through synergistic apoptosis-cuproptosis-immunotherapy crosstalk [ 18 ]. CuNPs can be classified into four types: components containing copper-based metal–organic frameworks (Cu-MOFs), Cu 2 O, Cu + loading or coordination, and Cu 2+ loading or coordination of nanomaterials. For example, Song et al. developed a nanosystem known as near-infrared (NIR) light-driven nanomotors (CuSiO 3 @Au–Pd NMs) to induce a Fenton-like reaction, generate hydroxyl radicals (·OH), and stimulate cuproptosis in cancer cells. The nanodrug CuSiO 3 @Au–Pd NMs efficiently targeted breast cancer, intensified oxidative stress and cellular apoptosis, and primarily suppressed MCF-7 cell growth [ 526 ]. Ning et al. synthesized platelet vesicle (PV)- coated cuprous oxide nanoparticles to release copper ions under acidic conditions and hydrogen peroxides(·OH) in tumor cells, causing lipoylated protein aggregation, iron-sulfur protein loss, and inducing breast cancer cell cuproptosis, as well as suppressing lung metastasis [ 527 ]. Chen et al. prepared a nanoenzyme in which Cu 2 O was substantially preserved in Cu 2 O@Mn 3 Cu 3 O 8 (CMCO) [ 528 ]. The CMCO nanospheres generate hydroxyl radicals (•OH) by degrading H 2 O 2 to induce efficient ferroptosis and cuproptosis in colorectal cancer cells. Xu et al. constructed a nanoplatform, known as GOx@[Cu(tz)], for starvation-augmented cuproptosis therapy in athymic mice bearing 5637 bladder cancer cells [ 529 ]. The GOx@[Cu(tz)] NPs, with a particle size of 234 nm, could release a large amount of Cu(I) ions to promote • OH generation and aggregation of lipoylated proteins under 808 nm laser light illumination. Zhong et al. successfully developed a novel nanoplatform composed of Cu 2 O nanocubes and CuBTC metal–organic frameworks (MOFs), namely Cu 2 O@CuBTC-DSF@HA nanocomposites (CCDHs) [ 530 ]. CCDHs represent a promising antitumor strategy that selectively induces cuproptosis via intracellular Cu + accumulation. Notably, tetraethylthiuram disulfide-loaded CCDHs synergistically enhanced cuproptotic cell deathwithout triggering apoptosis. A comprehensive evaluation at both cellular and organismal levels confirmed their potent therapeutic efficacy and favorable biosafety profiles. In another study, researchers used E. coli @Cu 2 O nanomedicine to induce cuproptosis. By encapsulating E. coli and Cu 2 O complexes within irregular nanospheres, resulting E. coli @Cu 2 O achieved near-infrared II (NIR-II) -guided synergistic therapy by combining ferroptosis/cuproptosis and immunotherapy treatment. Engineered E. coli @Cu 2 O can release Cu 2 O nanoparticles, consume GSH, generate •OH, and stimulate DLAT aggregation, resulting in cuproptosis to boost antitumor responses and suppress tumor metastasis in MC38 tumor-bearing mice [ 531 ]. He et al. fabricated a CuO 2 silica nanosystem (CuO 2 /DDP@SiO 2 ) [ 532 ], integrating the copper peroxide-induced DLAT oligomerization and FDX1 destabilization ability and the chemotherapeutic effect of cisplatin (DDP). In vitro and in vivo results showed that this CuO 2 /DDP@SiO 2 nanoagent holds great promise for acquiring a synergistically enhanced cuproptosis/chemo/chemodynamic therapy therapeutic effect. Additionally, combining copper-loaded nanoparticles with other treatment modalities, such as photothermal therapy or chemotherapy, could further enhance their therapeutic efficacy. For example, Yu et al. reported a DNAzyme-mediated cascade nanoreactor (ZIF-8-Cu 2 O-DNA) to generate a large number of DNA, zinc ions, and Cu + , which can trigger cuproptosis and chemodynamic therapy (CDT) simultaneously [ 533 ]. ZIF-8-Cu 2 O-DNA triggers CDT and cuproptosis, enhances combination therapy efficiency, effectively kills tumor cells, and suppresses tumor growth in PANC-1-tumor-bearing nude mice. In addition to nanosystems containing Cu 2 O, alternative NMs such as Cu-MOFs can also induce cuproptosis. For example, recent studies by several research groups have found that many s Cu-MOF NPs, including F127 MOF-199, CS/MTO-Cu@AMI, and RCL@Pd@CuZ, can consume GSH and promote cuproptosis [ 534 – 536 ]. Similarly, Chen et al. constructed an intelligent cell-derived nanorobot (SonoCu) to promote reactive oxygen species accumulation, proteotoxic stress, and sensitize cancer cell cuproptosis [ 537 ]. This nanoassembly was composed of macrophage-membrane-camouflaged nanocarriers encapsulating copper-doped zeolitic imidazolate framework-8 (ZIF-8), perfluorocarbon, and sonosensitizer Ce6, which were synthesized using an integrative self-assembly strategy, and can suppress tumor growth in 4T1 tumor-bearing mice. Huang et al. developed a metal–organic framework nanoagent known as BSO-CAT@MOF-199 @DDM (BCMD) to induce cuproptosis [ 538 ]. The nanodrug BCMD can release Cu 2+ , impede GSH synthesis, promote DLAT aggregation, trigger immunogenic cell death (ICD), and enhance the antitumor effect in glioblastoma. In addition, a syphilis mimetic TP0751-peptide decorated stem cell membrane-coated copper-based metal–organic framework (Cu-MOF), known as TP-M-Cu-MOF/siATP7A, was reported to induce cuproptosis and suppress small cell lung cancer (SCLC) brain metastasis [ 539 ]. The TP-M-Cu-MOF/siATP7A NPs, with an average size of 92.6 ± 3.46 nm, exhibited outstanding biocompatibility, high blood–brain barrier (BBB) transcytosis, and improved therapeutic efficacy in SCLC brain metastasis tumor-bearing mice. With the similar effect of TP-M-Cu-MOF/siATP7a, Xu et al. constructed an amorphous metal–organic frameworks (aMOFs) nanoreactor coupled with Dox for cellular cuproptosis induction [ 540 ]. The nanosystem known as DOX@Fe/CuTH HaMOF was able to effectively decrease the expressions of copper transporter ATP7A, increase copper/iron ions concentration in cytoplasm, and synergize with cuproptosis and DOX-mediated apoptosis to kill 4T1 cells. Some inorganic NPs including D-/L-CuxOS@Fe-MOFs [ 541 ], CSTD-Cu(II)@DSF [ 542 ], T-HCN@CuMS [ 543 ], CJS-Cu [ 544 ], Cu(I) NP [ 545 ], CBS [ 546 ], and CuMoO 4 [ 547 ] can also effectively deliver copper into cells, and increase intracellular Cu + /Cu 2+ concentration, leading to cuproptosis. In addition, Ding et al. developed a nanosystem known as Cu 2+ -Anchored Carbon Nano-Photocatalysts (Cu@CDCN) to induce intracellular redox homeostasis destruction and trigger cuproptosis, resulting in the suppression of cancer cell growth [ 548 ]. Moreover, Zhao et al. constructed a metal-phenolic network nanoparticle composed of copper ions and gallic acid, known as Cu-GA NPs [ 549 ]. The Cu-GA NPs with a diameter of 120 nm exhibited excellent biosafety, releasing copper ions and gallic acid, disruotingredox homeostasis, and activating cuproptosis, efficiently inhibiting the growth of 4T1 cells. Similarly, Wang et al. elaborately designed an AuPt-loaded Cu-doped polydopamine nanocomposite, AuPt@Cu-PDA, for combinational photothermal therapy (PTT) in a 4T1 tumor-bearing mouse model by triggering GSH depletion-induced cuproptosis [ 550 ]. The nanoflower-like structure of AuPt@Cu-PDA nanoparticles was synthesized by freeze-drying, with diameters of approximately 206.0 ± 2.7 nm. AuPt@Cu-PDA exhibited low cytotoxicity and good biosafety, as 4T1 and HeLa cells maintained a cell viability of more than 70% at an incubation concentration of 150 μg/mL. Recently, Tian et al. designed an intelligent cupreous nanoreactor, CuO 2 -MSN@TA-Cu 2+ , for selective cuproptosis therapy in tumors [ 551 ]. The nanoplatform can produce Cu 2+ and H 2 O 2 , induce potent cellular cuproptosis, and enhance chemodynamic therapy (CDT). CuO 2 -MSN@TA-Cu 2+  decreased FDX1 expression levels and promoted the aberrant oligomerization of DLAT, resulting in cuproptosis and 93.42% tumor growth inhibition. Additionally, copper nanoparticle (CuNP)-based hydrogels are promising platforms for combating wound infection. Lv et al. developed a multifunctional hydrogel (AuNPs-CuCCDs@Gel) by integrating copper carbon dots (CuCCDs) and gold nanoparticles (AuNPs) into a gelatin-chitosan matrix, endowing the material with photothermal and photodynamic properties [ 552 ]. The hydrogel demonstrated exceptional antibacterial activity, achieving a singlet oxygen quantum yield of 0.70, which surpassed that of methylene blue (0.52). Under 808 nm laser irradiation for 6 min, AuNPs-CuCCDs@Gel rapidly reached 50 °C from ambient temperature, ensuring effective bacterial eradication while minimizing collateral thermal damage to healthy tissue. The hydrogel exhibited remarkable antibacterial efficacy, eliminating 96.46% of S. aureus and 97.48% of E. coli through the synergistic action of localized hyperthermia and ROS generation. While CuNPs have shown promise in enhancing photothermal therapy (PTT) through cuproptosis induction, their clinical translation remains limited by a lack of systematic clinical trials. Preclinical studies should prioritize the investigation of synergistic PTT combinations that leverage the intrinsic photothermal properties of copper-based nanomaterials. Additionally, a comprehensive evaluation of copper-loaded nanoparticles combined with chemotherapeutics is needed to elucidate the enhanced drug delivery mechanisms and the potential for overcoming multidrug resistance. Such combinatorial strategies could substantially improve therapeutic outcomes and expand the clinical potential of copper-based nanotherapeutics [ 553 ]. Calcium-based nanomaterials designed to induce calcium overload-based cell death have garnered significant interest in interdisciplinary fields, including medicine, chemistry, and materials science in recent year [ 27 ]. Calcium nanoparticles (CaNPs) have emerged as promising agents for inducing calcium overload-based RCD. A variety of calcium-based nanomaterials, including calcium carbonate (CaCO 3 ), calcium silicate (CaSi), and calcium fluoride (CaF2), can significantly increase intracellular calcium levels via various mechanisms [ 27 ]. These nanomaterials function as calcium generators that undergo intracellular chemical reactions to produce ROS or nitric oxide (NO), thereby triggering mitochondrial and endoplasmic reticulum dysfunction. This calcium dyshomeostasis leads to cytotoxic Ca 2 ⁺ accumulation, ultimately driving cell death via calcium-dependent pathways. For example, Shen et al. designed a pH-responsive calcium carbonate nanoplatform loaded with Ir(III) complexes(IrCOOH–CaCO 3 @PEG) based on calcium overload and two-photon photodynamic therapy [ 554 ]. This advanced nanosystem selectively accumulates in the lysosomes, destroying the calcium buffer function of mitochondria, resulting in mitochondrial damage and mitochondrial membrane potential loss, and efficiently suppresses tumor growth in a breast cancer tumor-bearing mouse model. Zheng et al. [ 555 ] developed a novel DOX and erianin-loaded CaCO 3 -based nanoparticles (DECaNPs), for the con-current delivery of DOX and erianin to Hepa1-6 tumor-bearing mouse model. This novel nanoagent efficiently induced hybrid cell death pathways, including apoptosis, immunogenic cell death, and ferroptosis. These dual-drug smart drug delivery systems suppressed Hepa1-6 cell growth and significantly enhanced the antitumor effects of αPD-L1. In vivo investigations revealed that DECaNPs promoted the maturation of DCs, activation of T and NK cells, secretion of antitumor cytokines, and triggered hybrid cell death pathways, thereby accelerating coordinated calcium overload, acid neutralization, and immune activation, and amplifying chemotherapy cytotoxicity. Similarly, He et al. [ 556 ] constructed a pH-responsive conjugated polymer–calcium composite nanoparticle (PFV/CaCO 3 /PDA@PEG) for antimetastasis, reactive oxygen species (ROS)-triggered calcium overload, and photodynamic therapy (PDT). The PFV/CaCO 3 /PDA@PEG nanoparticles disintegrated in a weakly acidic tumor microenvironment and simultaneously released the conjugated polymer PFV-COOH and Ca 2+ . A high extracellular Ca 2+ concentration promotes the formation of adhesion dimers between two adjacent cadherin extracellular domains, significantly enhancing intercellular adhesion and inhibiting tumor metastasis. PFV/CaCO 3 /PDA@PEG nanoparticles enter tumor cells through endocytosis, break down in lysosomes (pH 5.5), and escape. PFV-COOH is activated under light and produces many ROS, thereby destroying the mitochondrial Ca 2+ buffering capacity and causing intercellular Ca 2+ overload through ROS-induced mitochondrial dysfunction. PFV/CaCO3/PDA@PEG nanoparticles contribute to realizing PDT, mitochondrial dysfunction, and ROS-triggered Ca 2+ overload, which play a synergistic role in cancer therapy.The PFV/CaCO3/PDA@PEG nanoparticles exhibited excellent biocompatibility, enhanced antitumor efficiency, and excellent tumor migration inhibition, providing a promising strategy for multifunctional cancer therapy with anti-metastatic effects. Yan et al. [ 557 ] developed an innovative nanoparticle system (CCPCR NPs) comprising CuS-α-CHA&penthiopyrad@CaCO3-RGD for synergistic Cu + /Ca 2+ double-overload therapy coupled with metabolic symbiotic disruption. This sophisticated design employs penthiopyrad, a mitochondrial TCA cycle disruptor that can shift tumor metabolism toward lactate production and α-Cyano-4-hydroxycinnamic acid (α-CHA), a monocarboxylate transporter 4 (MCT4) inhibitor that can block lactate efflux. CCPCR NPs undergo tumor-selective endocytosis, where acidic conditions trigger CaCO 3 decomposition and penthiopyrad and α-CHA release. The combined action of penthiopyrad-induced TCA cycle blockade and α-CHA-mediated lactate accumulation creates a self-amplifying cycle that causes intracellular acidification, enhanced Cu + -based Fenton-like reactions, and mitochondrial dysfunction. This metabolic rewiring synergizes with Cu + -mediated cuproptosis via protein lipoylation disruption, Ca 2+ overload-induced mitochondrial permeability transition, and ROS-triggered immunogenic cell death. The resulting cascade activates DAMPs release, tumor-associated antigen presentation, and immune cell infiltration, ultimately achieving potent antitumor efficacy through metabolic,ionic,and immunological coordination. Moreover, Liu et al. [ 558 ] synthesized a hybrid theranostic nanosystem, CaCO 3 @CQ@pDB NPs(CCD NPs), composed of a second near-infrared (NIR-II) absorbed conjugated polymer DTP-BBT (pDB), CaCO 3 , and an autophagy inhibitor (chloroquine, CQ) to induce calcium overload and promote apoptosis. CaCO3 in this nanosystem can decompose into a large amount of Ca 2+ in the mildly acidic tumor microenvironment and enter the mitochondria, thus breaking the balance of Ca 2+ concentration in the mitochondria and thereby activating mitochondrial apoptosis through Ca 2+ overload. The autophagy inhibitor chloroquine (CQ) was added to the nanosystem to interfere with the fusion of lysosomes and autophagosomes, resulting in the inability to produce autolysosomes, thereby blocking the autophagy pathway and promoting apoptosis of tumor cells. Under IR-II laser irradiation, pDB-mediated photothermal therapy can kill the tumor cells. Furthermore, Hu et al. [ 559 ] developed a nanosystem, I/B@MSN-T@HA, which can trigger Ca 2+ overload, generate NO, produce ROS, cause mitochondrial dysfunction and consequent apoptosis, and inhibit tumor growth in 4T1 tumor-bearing mice. Although intracellular Ca 2+ nanogenerators, including CaCO 3 , have shown effects in cancer therapy. However, the therapeutic efficacy of these agents is often compromised by inadequate targeting and restricted penetration into tumor tissue, resulting in suboptimal treatment outcomes. Zhang et al. [ 560 ] synthesized a novel nanosystem known as mitochondrial N770-conjugated mesoporous silica nanoparticles loaded with CaO 2 (CaO 2 -N770@MSNs) for orthotopic and distant colorectal tumors therapy that specifically contributes endoplasmic reticulum stress and mitochondrial damage and induces ICD. With the combination of O 2 generated from CaO 2 and hyperthermia under near-infrared irradiation, CaO 2 -N770@MSNs selectively accumulated at the tumor site in mice with colorectal cancer, were effectively taken up by cancer cells, and suppressed tumor cell growth. CaO 2 -N770@MSNs induced calcium overload-phototherapy synergistic treatment strategy showed a good ability to eradicate orthotopic and distant tumors and enhanced the antitumor immune response. This safe and effective treatment offers newpossibilities for the synergistic treatment of colorectal cancer. Similar in breast cancer, Lu et al. [ 561 ]designed and synthesized a novel nanomotor, CaO 2 /DOX@HPS-IR-1061-AS1411, which releases O 2 and ROS, induces calcium overload under acidic conditions, and effectively inhibits breast cancer growth. Both in vitro and in vivo investigations revealed that CaO 2 /DOX@HPS-IR-1061-AS1411 demonstrated superior therapeutic effects in 4T1 tumor-bearing mice, exhibited negligible cytotoxicity, and selectively induced oxidative stress and apoptosis in breast cancer cells. Recent advances in calcium-based nanotherapeutics have demonstrated their remarkable potential for synergistic cancer treatment. Xie et al. [ 562 ] engineered an innovative Ca 2 ⁺ nanogenerator (CaPCAV) that effectively couples calcium overload with immunotherapy. Mechanistic studies revealed that CaPCAV reprograms tumor-associated macrophages from the immunosuppressive M2 phenotype to antitumor M1 macrophages, while simultaneously enhancing cytotoxic T cell infiltration within the tumor microenvironment. Guo et al. developed a multifunctional BPQD@CaO₂-PEG-GPC3Ab nanoplatform that integrates calcium overload-mediated therapy (COMT) with photodynamic therapy (PDT) for HCC treatment [ 563 ]. This smart nanosystem undergoes tumor-specific disassembly to form CaO₂ and black phosphorus quantum dots (BPQDs). The CaO₂ component generates both Ca 2 ⁺ ions and H₂O₂ in the acidic tumor microenvironment, where H₂O₂ is subsequently converted to O₂ to alleviate hypoxia and potentiate PDT. Concurrently, the BPQDs efficiently converted the generated O₂ into cytotoxic singlet oxygen ( 1 O₂) under NIR irradiation. Mechanistic investigations demonstrated that this multimodal therapy significantly upregulated pro-apoptotic markers (cleaved caspase-3/9/12 and Bax) while downregulating anti-apoptotic Bcl-2, ultimately inducing robust apoptosis in Huh-7 cells. This innovative multimodal therapeutic strategy synergistically combines COMT, PDT, and targeted apoptosis induction, demonstrating its compelling potential for clinical translation in the treatment of HCC. This integrated approach capitalizes on distinct yet complementary mechanisms to overcome TME barriers and enhance therapeutic efficacy, offering a promising paradigm in precision oncology. Recently, many studies have revealed that various zinc oxide nanoparticles (ZnONPs) can induce different types of cell death [ 28 ]. Zhang et al. synthesized ZnONPs that triggered oxidative stress-dependent ferroptosis. Mechanistic investigations revealed that the NPs increased Bach1 and MZF1 mRNA levels, induced GSH depletion and lipid peroxidation, and increased Fe 2+ levels in HUVECs. Similarly, Pan et al. [ 564 ] developed a nanoplatform that responds to H 2 S, utilizing zinc oxide-coated virus-like silica nanoparticles (VZnO) for ferroptosis treatment in colorectal cancer. The superior H 2 S scavenging capability of VZnO significantly decreases H 2 S levels in colorectal cancer, thereby inhibiting the proliferation of CT26 and HCT116 colorectal cancer cells. Additionally, the reduction of H 2 S levels in colorectal cancer contributes to tumor inhibition by initiating ferroptosis. VZnO, an H 2 S-sensitive nanosystem, appears to have no therapeutic impact on cancers that do not have high H 2 S levels. Chen et al. [ 92 ] reported that ZIP7 is indispensable for ferroptosis and is involved in regulating zinc transport from the endoplasmic reticulum to the cytosol. Mechanistic investigations revealed that genetic and chemical inhibition of ZIP7 led to ER stress, involving the induction of HERPUD1 and ATF3 expression. This evidence confirmed that Zn 2+ and ZnO nanoparticles can lead to ferroptosis, suggesting that zinc could be used as a potential strategy to enhance cancer cell death. ROS play a key role in numerous signaling pathways that finely coordinate physiological and pathological functions in the mitochondria and peroxisomes. In cancer tissues, ROS are closely related to tumorigenesis and promote tumor development. However, many studies have shown that excessive ROS levels can produce cytotoxic effects, leading to tumor cell death. Sensi et al. [ 565 , 566 ] found that zinc overload can induce mitochondrial damage, trigger Zn 2+ -dependent ROS production, and coordinate Ca 2+ -induced damage to disrupt calcium homeostasis leading to cell death. Various studies have shown that ZnO NPs can induce apoptosis in various tumor cells through different mechanisms [ 567 ], including lung carcinoma cells [ 26 , 568 ], B16F10 melanoma cells [ 569 ], cervical carcinoma [ 570 ], and human gingival squamous cell carcinoma [ 571 ]. Dong et al. developed a ZnO nanosystem, Au@ZnO@GQDs/HA NPs (AZGH), to promote ROS production [ 572 ], enhance photothermal therapy (PTT) and PDT, and induce apoptosis in triple-negative breast cancer cellss . Both in vitro and in vivo experiments revealed that AZGH increased intracellular ROS levels, decreased 4T1 cell viability, induced cell apoptosis under NIR irradiation, and exhibited an excellent tumor growth inhibitory effect in 4T1 tumor-bearing mice. Zhou et al. [ 573 ] constructed a nanoagent known as TME-responsive manganese-enriched zinc peroxide nanoparticles (MONPs), which can enhance anti-PD-1 therapy effect and induce ICD. Mechanistic investigations revealed that MONPs dissociated to produce . OH and induced ICD in the acidic tumor tissue microenvironment. Mn 2+ activates the STING pathway and synergistically induces the secretion of type I interferon and inflammatory cytokines, thereby exerting specific T cell functions. Simultaneously, MONPs deactivate cascade immunosuppression by reducing Tregs and polarizing M2 macrophages to type M1, releasing a cascade adaptive immune response. Similarly, Sun et al. [ 574 ]constructed an H 2 O 2 self-supplying nanozyme known as ZnO 2 @Pt,which can selectively induce ROS generation at tumor sites. In vitro experiments revealed that ZnO 2 @Pt induced oxidative stress damage by increasing Zn 2+ release and downregulating ATP and NAD + levels. In vivo experiments showed that ZnO 2 @Pt could produce ROS at the tumor site, induce apoptosis, and downregulate the energy supply pathway related to glycolysis, resulting in an 89.7% decrease in tumor cell growth. Mechanistic studies revealed that Zn 2+ released by ZnO 2 @Pt can inhibit the activities of key glycolytic enzymes, such as hexokinase II (HK2) and lactate dehydrogenase A (LDHA), disrupt REDOX metabolism, induce tumor cell apoptosis, and inhibit tumor cell proliferation. Yang et al. [ 575 ]developed a novel nanoplatform, ZnFe 2 O 4 -PTX@CCM, composed of paclitaxel (PTX) and ZnFe 2 O 4 , for tumor immunotherapy. Both in vitro and in vivo experiments demonstrated that ZnFe 2 O 4 -PTX@CCM enhanced cGAS/STING activity, facilitated dendritic cell maturation, boosted the infiltration of cytotoxic T lymphocytes and natural killer cells, and ultimately surrpessed tumor progression. In another study, Deng et al. [ 576 ] synthesized a smart drug delivery nanosystem known as ZnO@CuS nanoparticles composed of doxorubicin (DOX) and pirfenidone (PFD). The nanostructure ZnO@CuS can activate a cascade that increases ROS production, which decreases GPX4 and GSH levels, induces tumor cell death, and reduces tumor growth (89.7%) and lung metastasis in 4T1 tumor-bearing mice. In summary, the current research demonstrates that zinc nanoparticles (ZnNPs)-mediated cell death primarily occurs through established RCD pathways, with no novel zinc-specific mechanisms identified yet. While zinc-based nanomedicines, particularly ZnO nanoparticles, show anticancer potential, their precise mechanisms remain incompletely characterized. A critical unmet need is the elucidation of a universal mechanism that governs zinc ion-mediated cytotoxicity in cancer cells. Nevertheless, the targeted disruption of zinc homeostasis via ZnNPs represents a promising therapeutic strategy that requires further exploration. Manganese-based nanoparticles (MnNPs) induce ferroptosis in tumors through multiple mechanisms, including GSH depletion, elevated ROS generation, and enhanced LPO [ 577 ]. For instance, MnO₂ nanoflowers under near-infrared irradiation triggered ferroptosis in Cal-27 cells by increasing intracellular Fe 2 ⁺ levels, accumulating LPO, and decreasing GPX4 [ 578 ]. Similarly, manganese silicate nanobubbles effectively induce ferroptosis via GPX4 inactivation and GSH depletion [ 577 ]. Zhao et al. developed a multifunctional nanotherapeutic platform (brusatol/silica@MnO2/Ce6@PDA-PEG-FA, BSMCPF) that exploits the acidic tumor microenvironment for pH-responsive drug release. This innovative design achieves dual therapeutic effects through NRF2 pathway inhibition via brusatol-mediated suppression of the antioxidant response, effectively overcoming tumor thermoresistance, and synergistically inducing ferroptosis through coordinated downregulation of both ferritin heavy chain 1 (FTH1) and GPX4 [ 579 ].The tumor-selective activation and multimodal action mechanisms of this nanoplatform represent a significant advancement in precision cancer therapy. In addition, Mn-MC NPs demonstrate exceptional therapeutic potential, exhibiting a high drug-loading capacity (63.42%) that enables direct tumor ablation while simultaneously potentiating both innate and adaptive immune responses [ 580 ]. In subcutaneous tumor models, Mn-MC NPs exhibited dual therapeutic efficacy, completely eradicating primary tumors, and significantly suppressing distal and metastatic tumor progression through synergistic immunomodulation. Furthermore, these nanoparticles induced ICD, providing sustained protection against tumor recurrence. Moreover, MnNPs potently activate both innate and adaptive immune responses via the cGAS-STING signaling pathway, establishing their significant therapeutic potential in cancer immunotherapy [ 581 ]. For example, Mn-HSP NPs have demonstrated dual therapeutic efficacy against breast cancer, effectively inhibiting primary tumor growth and suppressing pulmonary metastasis in vivo [ 582 ]. Mechanistically, these MnNPs activate the STING pathway to potentiate innate immune responses while simultaneously inducing pyroptosis, establishing a novel combinatorial approach for enhanced cancer immunotherapy. MnNPs exhibit excellent biocompatibility and broad therapeutic potential in nanomedicine, particularly in cancer immunotherapy, through four key mechanisms [ 583 ]: functioning as versatile nanocarriers for the targeted delivery of immunotherapeutic agents; serving as potent immune adjuvants to remodel the tumor microenvironment; activating systemic antitumor immunity via cGAS-STING pathway stimulation; and enabling real-time therapeutic monitoring through Mn 2 ⁺-enhanced T1-weighted magnetic resonance imaging (MRI), as paramagnetic Mn 2 ⁺ ions significantly improve contrast upon protein binding. Magnesium oxide nanoparticles (MgO NPs) exhibit potent anticancer activity primarily through ROS generation mediated by the release of Mg 2+ ions, ligands, and reaction byproducts [ 584 ]. The resulting oxidative stress induces DNA damage, protein denaturation, and lipid peroxidation, culminating in cancer cell death. However, the precise molecular mechanisms underlying Mg 2 ⁺-mediated cytotoxicity remain unclear [ 585 ]. Although promising, the clinical translation of MgO NPs faces challenges in terms of biocompatibility and cytotoxicity [ 586 ]. Green synthesis approaches may address these limitations, as biofabricated MgO NPs demonstrate superior biosafety profiles and enhanced bioavailability compared with conventional metal oxide nanoparticles (e.g., cobalt oxide) [ 585 ] [ 169 , 171 , 172 ]. Notably, recent advances have revealed that Mg 2 ⁺ incorporation into nanomaterials can potentiate the rolling circle amplification of therapeutic DNA, enabling the development of novel antitumor strategies. Palladium nanoparticles (PdNPs) exhibit unique biocompatibility, enabling favorable interactions with intracellular and extracellular biomolecules. In addition to their inherent metallic properties, PdNPs possess exceptional physicochemical characteristics, including remarkable thermal and chemical stability, potent photocatalytic activity, tunable optical/electrical properties, and cost effectiveness. These attributes underpin their demonstrated antimicrobial, antitumor, and antifungal activities, positioning them as versatile platforms for developing advanced photothermal and photoacoustic agents, efficient gene/drug delivery systems, targeted antimicrobial/antitumor therapeutics, prodrug activators, and sensitive biosensors for various applications. Although PdNP-based nanotherapeutics represent a relatively nascent field, their distinctive biological properties coupled with significantly reduced cytotoxicity suggest their tremendous potential for transformative applications in nanomedicine [ 587 ]. Recently, Choudhary et al. developed an eco-friendly synthesis of PdNPs using Asterarcys algal extract, yielding biocompatible and renewable nanostructures with potent catalytic activity [ 588 ]. Althoughthese PdNPs demonstrated efficient substrate conversion, further validation through MTT assays is required to fully evaluate their potential anticancer applications. Silver nanoparticles (AgNPs) have emerged as versatile nanomaterials with broad applications in biomedicine, electronics, and environmental science [ 589 ]. In the medical field, AgNPs demonstrate remarkable therapeutic potential, including enhancing wound healing and bone regeneration, serving as effective vaccine adjuvants, functioning as antidiabetic agents, enabling sensitive biosensing platforms, and exhibiting potent antimicrobial and anticancer activities [ 590 ]. Plant-mediated synthesis of AgNPs represents an eco-friendly advancement in nanomaterial production, leveraging phytochemicals to simultaneously reduce metal precursors and enhance antibacterial efficacy [ 591 ]. This green synthesis approach improves nanoparticle stability while expanding their functional applications, positioning plant-derived AgNPs as promising tools for technological and biomedical innovations. Recent work by Bhavi et al. demonstrated that simarouba glauca-synthesized silver nanoparticles (SG-AgNPs; mean diameter: 12.45 nm) exert dose-dependent cytotoxicity in A549 lung cancer cells through three distinct mechanisms: induction of oxidative stress, activation of apoptotic pathways, and initiation of DNA damage [ 592 ]. Notably, SG-AgNPs significantly improved the survival rates of bacteria-infected C. elegans, consistent with established findings on nanoparticle-mediated antimicrobial activity and toxicity in model organisms, which demonstrated that SG-AgNPs confer potent protection against infection-induced mortality, with increased efficacy at higher concentrations. These findings highlight the therapeutic potential of SG-AgNPs as antimicrobial agents. Additionally, Shaaban et al. demonstrated that AgNPs exhibit potent antimicrobial activity against multiple pathogenic strains [ 593 ]. Treatment of preformed biofilms (Pseudomonas aeruginosa ATCC 9027, Salmonella typhi ATCC 12023, Escherichia coli ATCC 8739, and Staphylococcus aureus ATCC 6598) with 50 mg/mL AgNPs for 24 h reduced the biofilm biomass by 10.7%, 34.6%, 34.75%, and 39.08%, respectively. Notably, AgNPs displayed selective cytotoxicity against human cancer cell lines, with IC 50 values of 0.160 mg/mL (MCF-7 breast cancer) and 0.156 mg/mL (Caco-2 colon cancer). These findings validate the efficient actinomycete-mediated synthesis of AgNPs and their dual therapeutic potential as antimicrobial and anticancer agents. Moreover, emerging evidence suggests that AgNPs exhibit synergistic anticancer effects when combined with conventional chemotherapeutic agents [ 594 ]. Multiple studies have demonstrated that AgNPs can potentiate the efficacy of clinically approved drugs by simultaneously targeting key cancer hallmarks, including oxidative stress dysregulation and drug resistance [ 595 ]. These combinatorial approaches show promise in overcoming therapeutic resistance in aggressive malignancies. Additionally, Abbigeri et al. demonstrated that AgNPs synthesized using M. annua root extract (R-AgNPs) displayed potent antioxidant activity and effectively inhibited α-amylase, a key enzyme in carbohydrate metabolism [ 596 ]. These findings suggest that R-AgNPs are promisingantidiabetic agents. Further studies are needed to elucidate the precise mechanisms of action and evaluatethe clinical potential of these compounds for diabetes management. Nickel oxide nanoparticles (NiONPs) possess unique magnetic and electrical properties that render them valuable for electronic and magnetic device applications. In addition to their physical characteristics, NiONPs exhibit catalytic capabilities for organic transformations, including alcohol oxidation and nitroaromatic hydrogenation. Notably, several studies have revealed their potential pharmacological activities, suggesting their broader biomedical relevance [ 597 ]. Emerging evidence has demonstrated that NiONPs exhibit promising anticancer properties, with the capacity to suppress proliferation in multiple cancer types [ 598 ]. For example, Deng et al. developed Marsdenia tenacissima extract-functionalized nickel oxide nanoparticles (MTE@NiO-NPs) that effectively induced apoptosis in A549 and H1299 lung cancer cells [ 599 ]. MTE@NiO-NPs triggered cytotoxic effects by elevating intracellular ROS levels and reducing the mitochondrial membrane potential, collectively driving programmed cell death. Moreover, Mani et al. demonstrated that Abutilon indicum leaf-mediated NiONPs display potent cytotoxic activity against cervical cancer cells and effectively inhibit HeLa cell proliferation [ 600 ]. These NiONPs show promise as anticancer agents because of their selective tumoricidal effect.

Nickel (Ni 2 ⁺) is an essential micronutrient that supports diverse physiological processes, including hormonal regulation, lipid metabolism, immune function, enzymatic activity, and DNA repair [ 212 – 214 ]. However, excessive nickel exposure induces multifaceted toxicity, including genotoxic, hematotoxic, and carcinogenic effects. Mechanistically, nickel disrupts cellular Ca 2 ⁺ homeostasis through multiple pathways. NiO nanoparticles elevate cytosolic Ca 2 ⁺ via TRPV4 channel activation in pulmonary artery endothelial cells [ 215 ], and various nickel forms (NiO, NiNPs, and NiCl 2 ) induce cytotoxicity in bronchial epithelial cells, which is preventable by Ca 2+ chelation [ 216 ]. NiCl₂ triggers Ca 2 ⁺-dependent eryptosis in erythrocytes by enhancing Ca 2+ influx [ 217 ]. Collectively, these findings demonstrate that nickel perturbs Ca 2 ⁺ signaling through both extracellular influx and intracellular release, culminating in mitochondrial dysfunction and cell death. Nickel-induced Ca 2+ elevation promoted ROS generation and triggered mitochondrial caspase-dependent apoptosis (Fig.  8 ). Mechanistic studies have revealed that NiO NPs disrupt Ca 2 ⁺ homeostasis, increasing intracellular ROS and mitochondrial Ca 2 ⁺ levels, ultimately inducing mitochondrial dysfunction and apoptosis in pulmonary artery endothelial cells [ 215 ]. Nickel-refining fumes cause oxidative stress-mediated DNA damage and apoptosis in NIH/3T3 cells [ 218 ], and Ni 2 ⁺ exposure induces G2/M arrest and p53-dependent apoptosis in nasal epithelial cells, which is reversed by N-acetylcysteine (NAC) treatment [ 219 ]. Notably, in bronchial epithelial cells (BEAS-2B), nickel compounds activated the ASK1/p38 pathway and induced apoptosis [ 220 ], which was similarly inhibited by NAC. While these studies established ROS as central to nickel-based apoptosis, the precise sources of ROS generation and the effects of nickel-based apoptosis remain to be elucidated. Additionally, Ni 2 ⁺ overload can trigger necroptosis, autophagy, and pyroptosis by regulating various pathways. Zhang et al. demonstrated that NiCl 2 induces robust ROS production and triggers necroptosis by upregulating the mRNA and protein expression of key necroptotic mediators RIP1, RIP3, and MLKL [ 221 ] (Fig.  8 A). Moreover, NiCl₂ induced renal damage and increased autophagy via elevated expression of Beclin1, Atg5, LC3-II, p-AMPK, and p-ULK1 [ 222 ]. Nickel-refining fumes (NiRFs) can induce cell pyroptosis by stimulating NLRP3, caspase-1, and N-GSDMD expression [ 223 ], thereby improving AMPK/CREB/NRF2 expression(Fig.  8 A). Fig. 8 The Ni 2 ⁺/Cd 2 ⁺/Pb 2 ⁺-based RCD pathways schematics. A . Nickel-induced Ca 2 ⁺ elevation promoted ROS generation and triggered mitochondrial caspase-dependent apoptosis, Ni 2+ -based apoptosis pathways manly including Ca 2 ⁺/caspase3/DNA damage; The Ni 2+ /ROS/RIP1/RIP3/MLKL axis regulate Ni 2+ -based necroptosis pathways; Ni 2+ also induce autophagy by ATG5 and LC3-II expression and increasing Beclin1/P-PI3K/P-AMPK axis. Ni 2+ -based pyroptosis pathways including NLRP3/Caspase1/N-GSDMD/NRF2/CREB/AMPK axis. B . Free Cd 2 ⁺ enters cells via metal transporters (ZIP14, TRPV6); Pb 2 ⁺ transport is mediated by ZIP8 and ATP7A. Cd 2+ -based ferroptosis pathways mainly include Fe 2+ overload and lipid peroxidation and Cd 2+ -based apoptosis is accompanied by ROS production, p38, and caspase 3 activation. Pb 2 ⁺ can induce Ca 2 ⁺, Fe 2 ⁺, Cu 2 ⁺, and Zn 2 ⁺ dysregulation triggers apoptosis. Cd 2+ -based apoptosis pathway main including Ca 2+ /IP3R/P38/Caspase3 axis The Ni 2 ⁺/Cd 2 ⁺/Pb 2 ⁺-based RCD pathways schematics. A . Nickel-induced Ca 2 ⁺ elevation promoted ROS generation and triggered mitochondrial caspase-dependent apoptosis, Ni 2+ -based apoptosis pathways manly including Ca 2 ⁺/caspase3/DNA damage; The Ni 2+ /ROS/RIP1/RIP3/MLKL axis regulate Ni 2+ -based necroptosis pathways; Ni 2+ also induce autophagy by ATG5 and LC3-II expression and increasing Beclin1/P-PI3K/P-AMPK axis. Ni 2+ -based pyroptosis pathways including NLRP3/Caspase1/N-GSDMD/NRF2/CREB/AMPK axis. B . Free Cd 2 ⁺ enters cells via metal transporters (ZIP14, TRPV6); Pb 2 ⁺ transport is mediated by ZIP8 and ATP7A. Cd 2+ -based ferroptosis pathways mainly include Fe 2+ overload and lipid peroxidation and Cd 2+ -based apoptosis is accompanied by ROS production, p38, and caspase 3 activation. Pb 2 ⁺ can induce Ca 2 ⁺, Fe 2 ⁺, Cu 2 ⁺, and Zn 2 ⁺ dysregulation triggers apoptosis. Cd 2+ -based apoptosis pathway main including Ca 2+ /IP3R/P38/Caspase3 axis Cd 2 ⁺ and Pb 2 ⁺ overload accumulates in tissues and disrupts essential metal homeostasis (Zn 2 ⁺, Fe 2 ⁺, Cu 2 ⁺, and Ca 2 ⁺), contributing to tissue damage and disease pathogenesis. Free Cd 2 ⁺ enters cells via metal transporters (ZIP14, TRPV6), whereas the bound forms (Cd-MT, Cd-GSH, Cd-Cys) are internalized through receptor-mediated endocytosis [ 47 ]. Similarly, Pb 2 ⁺ transport is mediated by ZIP8 and ATP7A [ 48 – 50 ]. These findings establish that Cd 2 ⁺ and Pb 2 ⁺ toxicity directly interferes with physiological metal ion homeostasis. Cd 2 ⁺ competitively displaces Fe 2 ⁺ from cellular biomolecules, inducing oxidative stress and cell apoptosis (Fig.  8 B). Nevertheless, Cd 2 ⁺ exposure differentially alters intracellular Fe 2 ⁺ homeostasis depending on the cell type. In mouse collecting duct cells (mIMCD3), elevated Fe 2 ⁺ protects against Cd 2 ⁺ toxicity by reducing ROS and preserving catalase activity, whereas Fe 2 ⁺ chelation (DFO) exacerbates cell death [ 224 ]. Human BJAB cells show Cd 2 ⁺/Cu 2 ⁺ accumulation with concomitant Zn 2 ⁺/Fe 2 ⁺ depletion [ 225 ]. Duck brains exhibit increased Mo 2 ⁺/Cd 2 ⁺ but decreased Fe 2 ⁺/Cu 2 ⁺/Zn 2 ⁺ [ 226 ]. Sertoli cells demonstrate cytoplasmic Fe 2 ⁺ accumulation alongside Zn 2 ⁺ loss [ 227 ]. Notably, Cd 2 ⁺ induces iron overload and ferroptosis in renal epithelia [ 228 ], PC12 cells [ 229 ], and pancreatic β -cells [ 230 ] (Fig.  8 B), contributing to hepatic, renal, and testicular dysfunction [ 231 – 233 ]. While Pb 2 ⁺-induced ferroptosis remains unexplored, Pb 2 ⁺ competes with iron, elevating free Fe 2 ⁺ levels and triggering oxidative oxidative stress-dependent apoptosis in neural and renal tissues [ 234 – 236 ]. Cd 2 ⁺ and Pb 2 ⁺ exposure disrupts intracellular Ca 2 ⁺ homeostasis, with multifaceted consequences across cell types: TRPV5/6 channels mediate Cd 2 ⁺ permeation in HEK293 cells [ 237 ]; Cd 2 ⁺-induced Ca 2 ⁺ dysregulation triggers apoptosis in B cells and renal tubules [ 238 , 239 ], linking to autophagy and tumorigenesis [ 240 ]; Cd 2 ⁺ and Pb 2 ⁺ activate IP3R/Ca 2 ⁺/p38 signaling, inducing apoptosis in renal and neural cells [ 238 , 241 ]; pharmacological inhibition (2-APB, verapamil) attenuates Cd 2 ⁺ and Pb 2 ⁺ induced apoptosis and DNA fragmentation [ 238 , 242 , 243 ]; Cd 2 ⁺ elevates cytosolic Ca 2 ⁺ by impairing SERCA-mediated ER Ca 2 ⁺ reuptake [ 244 , 245 ]. These findings establish that Ca 2 ⁺ dyshomeostasis is central to Cd 2 ⁺/Pb 2 ⁺ cytotoxicity and RCD. Magnesium (Mg 2+ ) contributes to maintaining cell membrane stability, whereas Ca 2+ has a distinct function in transmitting information. Additionally, metalloenzymes rely on Mg 2+ and Zn 2+ for their catalytic functions, whereas metal centers such as Fe 2+/3+ , Mn 2+ , and Co 2+/3+ facilitate electron transfer through specific ligand interactions [ 184 ]. Manganese (Mn 2 ⁺) competes with iron (Fe 2 ⁺) for binding to transferrin and transport via divalent metal transporter 1 (DMT1). Cobalt shares significant chemical homology with iron and nickel and serves as a critical modulator of cellular iron homeostasis [ 184 ]. Magnesium ions (Mg 2 ⁺), manganese ions (Mn 2 ⁺), and cobalt (Co 2 ⁺/ 3 ⁺), can be toxic or have no significant effect at low doses but can accumulate over time and generate various toxic effects and initiate various forms of RCD (Fig.  9 ). Interestingly, certain intracellular metal ions are crucial for various forms of cell death as they participate in distinct signaling pathways that control RCD [ 99 , 246 ]. This process is further complicated by the presence of numerous subroutines and external factors. Fig. 9 Schematic of Mg 2 ⁺/Mn 2 ⁺/Co 2 ⁺/Cr⁶⁺/Mo 6+ -based RCD Pathways Schematics. A . Mn 2+ -based ferroptosis pathways, including the Mn/cGAS/STING pathway; the Mn/cGAS/STING/IFN-I axis regulates Mn 2+ -based pyroptosis pathways; Mn also induces pyroptosis by promoting ROS production and increasing cleaved-caspase3/GSDME-N. Mn 2+ -based apoptosis pathways including SIRT1/FOXO3A/PUMA/Bim/cleaved-caspase3 axis. B . Mg 2+ -based apoptosis pathways including ATP/p-gp/HIF-1α axis. C . Co 2+ induces -based apoptosis pathways including ROS production, HIF-1α high expression, cytochrome c release, and cleaved-caspase3 increase thereby resulting in apoptosis. CoCl 2 induces autophagy by increasing the expression of LC3-II and cathepsin-B. Co 2+ triggers ferroptosis by inducing Ca 2+ overload, decreasing GPX4 and GSH levels, and promoting lipid peroxidation. D . Cr 6+ overload-based ferroptosis along with SLC7A11, GPX4 and GSH downregulation, 4-HNE and TFR1 elevation, and increased lipid peroxidation. E . The Mo 6+ overload-based ferroptosis pathway including O 2− generation, HMOX1 and lipid peroxidation elevation, and GPX4 downregulation Schematic of Mg 2 ⁺/Mn 2 ⁺/Co 2 ⁺/Cr⁶⁺/Mo 6+ -based RCD Pathways Schematics. A . Mn 2+ -based ferroptosis pathways, including the Mn/cGAS/STING pathway; the Mn/cGAS/STING/IFN-I axis regulates Mn 2+ -based pyroptosis pathways; Mn also induces pyroptosis by promoting ROS production and increasing cleaved-caspase3/GSDME-N. Mn 2+ -based apoptosis pathways including SIRT1/FOXO3A/PUMA/Bim/cleaved-caspase3 axis. B . Mg 2+ -based apoptosis pathways including ATP/p-gp/HIF-1α axis. C . Co 2+ induces -based apoptosis pathways including ROS production, HIF-1α high expression, cytochrome c release, and cleaved-caspase3 increase thereby resulting in apoptosis. CoCl 2 induces autophagy by increasing the expression of LC3-II and cathepsin-B. Co 2+ triggers ferroptosis by inducing Ca 2+ overload, decreasing GPX4 and GSH levels, and promoting lipid peroxidation. D . Cr 6+ overload-based ferroptosis along with SLC7A11, GPX4 and GSH downregulation, 4-HNE and TFR1 elevation, and increased lipid peroxidation. E . The Mo 6+ overload-based ferroptosis pathway including O 2− generation, HMOX1 and lipid peroxidation elevation, and GPX4 downregulation Divalent metal ions (e.g., Mg 2 ⁺, Mn 2 ⁺, and Co 2 ⁺) are essential for tumor growth, progression, and cancer immunotherapy [ 29 , 247 ], demonstrating tremendous their potential to trigger metalloptosis. An increase in intracellular Mn 2+ not only induced feroptosis in breast cancer by activating cGAS-STING pathway, but also induced apoptosis in cervical cancer through a decrease in mitochondrial membrane potential [ 248 , 249 ] (Fig.  9 A). Increased intracellular Mn 2+ can also induce pyroptosis in hepatocellular carcinoma by activating the cGAS-STING pathway and releasing type I interferons [ 250 ]. Mn 2 ⁺ overload triggers neuronal pyroptosis via ROS-dependent activation of the caspase-3/GSDME-N axis(Fig.  9 A) [ 72 ]. Pharmacological inhibition of either caspase-3 or ROS signaling confers significant neuroprotection against Mn 2 ⁺-induced cytotoxicity. Jiang et al. demonstrated that manganese activates the FOXO3a-Bim/PUMA signaling axis, driving cleaved-caspase3-dependent neuronal apoptosis through enhanced SIRT1 protein degradation (Fig.  9 A). Elevated intracellular Mg 2+ levels block intracellular adenosine triphosphate (ATP) production, repress P-gp expression, suppress the TCA cycle, and decrease HIF-1α levels, which has been demonstrated to cause apoptosis in breast cancer (Fig.  9 B). The Mg 2 ⁺ plays a vital role in maintaining mitochondrial function, apoptosis, and drug resistance in cancer cells [ 251 ]. Cobalt mimics hypoxia by stabilizing hypoxia-inducible factor-1α (HIF-1α) and triggering both physiological and pathological responses in neurons. In human neuroglioma H4 cells, CoCl₂ can induce the generation of reactive oxygen species (ROS) and downregulate the m⁶A demethylase FTO, ultimately promoting apoptosis [ 252 ]. Cobalt ions (Co 2 ⁺/Co 3 ⁺) can induce apoptosis in various cancers by enhancing the expression of hypoxia-inducible factor 1-alpha (HIF-1α) and promoting the interaction of Co 3 ⁺ with receptors, which subsequently increases the production of ROS (Fig.  9 C) [ 60 , 253 ]. Cobalt ions (Co 2 ⁺) trigger mitochondrial apoptosis in primary rat hepatocytes by inducing cytochrome c and AIF release concomitant with caspase3/PARP activation [ 254 ]. This apoptotic response is potentiated by Co 2+ mediated elevation of HIF-1α expression. Beyond eliciting mitochondrial apoptosis through ROS generation, Co 2 ⁺ induces autophagic cell death in SK-N-BE(2)c neuroblastoma cells via the upregulation of LC3-II expression and activation of cathepsin B [ 255 ]. Gupta et al. demonstrated that CoCl₂ triggers ferroptosis in neuronal cells through coordinated cytosolic Ca 2 ⁺ elevation, lipid peroxidation accumulation, GSH depletion, and GPX4 suppression [ 256 ]. These findings establish that cobalt neurotoxicity occurs through the ferroptosis pathway. Chromium (Cr) binds transferrin in circulation and enters tissues via receptor-mediated endocytosis [ 257 ], potentially contributing to Cr toxicity by disrupting iron homeostasis. Zhuge et al. recently demonstrated that Cr 6 ⁺ exposure induces testicular damage through the concurrent activation of ferroptosis and autophagy (Fig.  9 D). Mechanistically, Cr 6⁺ increases 4-hydroxynonenal (4-HNE) and transferrin receptor 1 (TFR1) expression and decreases GPX4 and SLC7A11 expression to promote ferroptosis, while upregulating Beclin1 and LC3B-II to stimulate autophagy [ 258 ]. Chromium exposure (Cr 3 ⁺, Cr 5 ⁺, Cr⁶⁺) induces oxidative stress in human bronchial epithelial cells, oxidizing the Fe-S cluster enzyme thioredoxin 2 (TRX2) aconitase, a TCA cycle component [ 259 ]. TRX2 oxidation may represent acuproptosis-like mechanism underlying Cr toxicity. Further investigation may reveal novel Cr-dependent cell death pathways analogous to cuproptosis, thereby expanding our understanding of metal toxicity. Molybdenum (Mo) toxicity, although rare, can occur due to excessive dietary supplement intake or occupational exposure. Cellular Mo 6+ overload disrupts ion homeostasis and exerts toxicity through various mechanisms, such as the generation of reactive oxygen species (ROS), including singlet oxygen [ 1 O₂] and superoxide anion [O₂•⁻] from H 2 O 2 [ 260 ], inducing GPX4 decrease, upregulation HMOX1, lipid peroxidation, and ferroptosis in tumors(Fig.  9 E). The formation of insoluble copper-thiolate-molybdenum complexes induces copper deficiency, potentially exacerbating copper-dependent disorders such as Menkes disease [ 261 ]. Further research is needed to elucidate the molecular mechanisms of Mo-based RCD, particularly during co-exposure to other metals, and to assess the health consequences of excessive Mo exposure.

Some key pathway regulators of iron-triggered RCD include ferroptosis, apoptosis, necroptosis, and pyroptosis. (Table  2 , Fig.  3 ). The intracellular accumulation of labile Fe 2 ⁺, a critical driver of ferroptosis, is tightly regulated by a well-coordinated iron uptake pathway. Extracellular Fe 3 ⁺ is first bound to transferrin (TF) and internalized via transferrin receptor 1 (TFR1)-mediated endocytosis. Within endosomes, Fe 3 ⁺ is reduced to Fe 2 ⁺ by six-transmembrane epithelial antigen of the prostate 3 (STEAP3), followed by its release into the cytosol through divalent metal transporter 1 (DMT1). Fe 2 ⁺ subsequently contributes to lipid peroxidation and ferroptosis. Notably, suppression of TFR1 expression depletes intracellular iron levels, thereby rendering cells resistant to ferroptosis. Elevated labile Fe 2 ⁺ pools drive ferroptotic cell death through Fenton reaction-mediated lipid peroxidation, in which iron-catalyzed ROS generation preferentially targets polyunsaturated fatty acid (PUFA)-rich intracellular membranes (Fig.  3 ). GPX4 inhibition results in the sustained accumulation of phospholipid hydroperoxides (PLOOHs), which initiate iron-catalyzed Fenton reactions that propagate a self-amplifying cycle of lipid peroxidation and ferroptosis [ 144 ]. Table 2 Key RCD regulators by metal ions Element Metal ion Cell death modalities Key pathway regulators Cancer type Ref Iron Fe 2+ Iron-based ferroptosis CTRP6, SOCS2, xCT/GPX4, LOX, POR, Lung cancer, renal carcinoma [ 262 , 263 ] Iron-based autophagy NCOA4, LC3 Fibrosarcoma [ 264 ] Iron-based pyroptosis Tom20, Bax, caspase3/7/9, GSDME, PARP Melanoma, neuroblastoma [ 265 , 266 ] Iron-based apoptosis P53, bax, caspase-3/9, CAMKK2/AKT/mTOR Lung cancer, ovarian cancer [ 61 , 158 ] Calcium Ca 2+ Calcium-based ferroptosis CAMKK2/AMPK/NCOA4, MCU ESCRT-III Ovarian cancer fibrosarcoma [ 61 , 191 ] Calcium-based apoptosis T2R14, SERCA2B, BCL-2, NSE Headneck squamous cell carcinoma, prostate cancer [ 267 , 268 ] Calcium-based pyroptosis TLR4, NLRP3, Tom20, GSDMD, caspase-1 Lung cancer, colorectal cancer [ 269 , 270 ] Calcium-based autophagy-dependent cell death Camk2, MLKL, LC3-II, SQSTM1/p62 Colorectal cancer [ 271 ] Calcium-based necroptosis CaMKII, mPTP, RIP3, MLKL RIPK3/MLKL/PMLKL/ESCRT-III Colorectal cancer [ 272 , 273 ] Copper Cu 2+ Copper-based cuproptosis FDX1, IL-6, TNF-α, IFN-γ Melanoma [ 274 ] Copper-based ferroptosis GSH/GPX4/TAX1BP1 Pancreatic cancer [ 153 ] Copper-based necroptosis ROS Ovarian cancer [ 179 ] Copper-based apoptosis ROS-MAPK, JNK, p38, NF-κB Breast cancer [ 175 ] Copper-based pyroptosis NLRP3/Caspase-1/GSDMD  / [ 275 ] Copper-based Autophagy-dependent cell death ULK1/2, Cu–ULK1/2 interaction Lung cancer [ 276 ] Zinc Zn 2+ Zinc-based apoptosis Frizzled-7, ZnT2 Breast cancer [ 277 , 278 ] Zinc-based lysozincrosis TRPML1 Metastatic melanoma [ 279 ] Zinc-based necroptosis RIPK1, RIPK3, and MLKL Breast cancer [ 280 ] Zinc-based ferroptosis ZIP7, HERPUD1, ATF3 Breast cancer [ 281 ] Zinc-based pyroptosis DAMPS, NLRP3,caspase1, GSDMD Breast cancer [ 282 ] Magnesium Mg 2+ Magnesium-based apoptosis PI3K/AKT/Mtor, ER and mitochondria stress Multiple cancer [ 251 ] Magnesium-based ferroptosis ROS, miR-142-5p, GPX4  / [ 283 ] Manganese Mn 2+ Manganese-based ferroptosis cGAS-STING pathway Breast cancer [ 248 ] Manganese-based apoptosis ROS, CytoC Cervical cancer [ 249 ] Fe 3+ , Mn 2+ Manganese-based pyroptosis GSDME, Caspase3, cGAS-STING pathway Hepatocellular carcinoma [ 250 ] Cobalt Co 2+ Cobalt-based apoptosis HIF-1α, Cytoc, Caspase3  / [ 60 ] Co 3+ Cobalt-based apoptosis ROS Breast cancer, colorectal cancer, lung cancer [ 253 ] Fig. 3 Iron-based ferroptosis and RCD crosstalk. Excess cytoplasmic iron initiates a redox cascade characterized by Fenton reaction-mediated generation of ROS, which orchestrates a range of cell death modalities, including iron-based ferroptosis, apoptosis, autophagy, necroptosis, and pyroptosis. Under oxidative stress, NRF2-mediated transcriptional activation stimulates the expression of HO-1 and increases intracellular Fe 2+ levels. Fe 2+ initiates sideroflexin 1 (SFXN1)-mediated iron translocation across the inner mitochondrial membrane, leading to mitochondrial iron overload and subsequent ferroptosis. In the iron-based pyroptosis pathway, iron induces ROS generation and activates a specific Tom20-Bax-caspase9/3-GSDME-N axis. The iron-based ferroptosis/autophagy pathway mainly includes TMEM164, ATG5, ATG12, ATG16L1, GPX4, and FTH1. The iron-based apoptosis pathway includes ASK1, JNK, P38, cleaved-caspase3, and p53. The iron-based necroptosis pathway mainly involves RIPK1, RIPK3, and P-MLKL. Abbreviations: ASK1, apoptosis signal-regulating kinase 1; Bax, Bcl-2-associated X protein; TF, transferrin; HO-1, Heme Oxygenase-1; JNK,c-Jun N-terminal kinase; DMT1, divalent metal transporter 1; FPN, ferroportin; STEAP3,six-transmembrane epithelial antigen of the prostate3; GR, gluathione reductase; GSH, Glutathione; GSSG,Glutathione Disulfide; MOMP, mitochondrial outer membrane permeabilization; NRF2, P38, p38 Mitogen-Activated Protein Kinase; nuclear factor erythroid 2 related factor 2; RCD, regulated cell death; ROS, reactive oxygen species; SFXN1, sideroflexin 1; STEAP3, six transmembrane epithelial antigen of the prostate 3; MLKL, Mixed Lineage Kinase Domain-Like Pseudokinase; RIPK1, Receptor-Interacting Protein Kinase 1; GSDME,Gasdermin E; GSDME-N, N-terminal domain of Gasdermin E Key RCD regulators by metal ions Iron-based ferroptosis and RCD crosstalk. Excess cytoplasmic iron initiates a redox cascade characterized by Fenton reaction-mediated generation of ROS, which orchestrates a range of cell death modalities, including iron-based ferroptosis, apoptosis, autophagy, necroptosis, and pyroptosis. Under oxidative stress, NRF2-mediated transcriptional activation stimulates the expression of HO-1 and increases intracellular Fe 2+ levels. Fe 2+ initiates sideroflexin 1 (SFXN1)-mediated iron translocation across the inner mitochondrial membrane, leading to mitochondrial iron overload and subsequent ferroptosis. In the iron-based pyroptosis pathway, iron induces ROS generation and activates a specific Tom20-Bax-caspase9/3-GSDME-N axis. The iron-based ferroptosis/autophagy pathway mainly includes TMEM164, ATG5, ATG12, ATG16L1, GPX4, and FTH1. The iron-based apoptosis pathway includes ASK1, JNK, P38, cleaved-caspase3, and p53. The iron-based necroptosis pathway mainly involves RIPK1, RIPK3, and P-MLKL. Abbreviations: ASK1, apoptosis signal-regulating kinase 1; Bax, Bcl-2-associated X protein; TF, transferrin; HO-1, Heme Oxygenase-1; JNK,c-Jun N-terminal kinase; DMT1, divalent metal transporter 1; FPN, ferroportin; STEAP3,six-transmembrane epithelial antigen of the prostate3; GR, gluathione reductase; GSH, Glutathione; GSSG,Glutathione Disulfide; MOMP, mitochondrial outer membrane permeabilization; NRF2, P38, p38 Mitogen-Activated Protein Kinase; nuclear factor erythroid 2 related factor 2; RCD, regulated cell death; ROS, reactive oxygen species; SFXN1, sideroflexin 1; STEAP3, six transmembrane epithelial antigen of the prostate 3; MLKL, Mixed Lineage Kinase Domain-Like Pseudokinase; RIPK1, Receptor-Interacting Protein Kinase 1; GSDME,Gasdermin E; GSDME-N, N-terminal domain of Gasdermin E Ferroptosis engages in intricate crosstalk with other RCD pathways, collectively governing cellular fate decisions in diverse physiological contexts and disease states. The interplay between iron-dependent ferroptosis and RCD mechanisms creates a dynamic regulatory network that fine-tunes the maintenance of tissue homeostasis and stress responses. Ferroptosis and necroptosis frequently co-occur and synergistically drive inflammatory responses. The necroptotic cascade requires the sequential activation of RIPK1, RIPK3, and MLKL, which oligomerize at the plasma membrane to induce lytic cell death. Notably, ultrastructural analyses have revealed concurrent ferroptotic and necroptotic features in neurons following cerebral hemorrhage, suggesting an interplay between these death pathways in neurological pathologies [ 145 ]. Iron plays a well-defined regulatory role in necroptosis by dual modulation of Fas signaling pathways and the generation of ROS [ 146 ]. Membrane-associated NADPH oxidase (NOX) complexes, which contain iron-binding regulatory subunits, physically associate with members of the TNF receptor superfamily to serve as the primary source of ROS that induce necroptosis [ 147 ]. Iron overload may promote osteoblastic necrosis by activating the canonical RIPK1/RIPK3/MLKL necroptosis pathway (Fig.  3 ). Mechanistically, excessive iron induces the opening of the mitochondrial permeability transition pore (mPTP), a critical event in the execution of necroptosis, while simultaneously stimulating the production of ROS, which further amplifies cell death signaling [ 148 ]. Additionally, iron-containing porphyrin heme induces macrophage necroptosis through two complementary pathways: TLR4/MyD88-mediated TNF production and TLR4-independent generation of ROS, which together create a pro-necroptotic microenvironment [ 149 ] (Fig.  3 ). Emerging evidence suggests that the production of iron-dependent ROS activates a specific pyroptosis pathway mediated by the Tom20-Bax-caspase9/3-GSDME-N axis [ 150 ] ( Fig.  3 ). A comprehensive mechanistic analysis of iron-mediated necroptotic and pyroptotic signaling is poised to become a crucial research frontier in the regulation of programmed cell death. Ferroptosis is potentiated by the selective autophagic clearance of key regulatory components, including iron storage proteins (SLC40A1), circadian regulators (ARNTL), antioxidant enzymes, adhesion molecules, and organelles (lipid droplets and mitochondria). This process drives ferroptosis by elevating intracellular iron levels and amplifying the lipid peroxidation cascade. Mechanistically, a dedicated autophagy pathway, distinct from canonical nutrient deprivation responses, is orchestrated by ferroptosis-specific regulators such as TMEM164, HPCAL1, and DCN [ 151 ] (Fig.  3 ). Harnessing selective autophagy-dependent ferroptosis represents a promising strategy for targeting therapy-resistant malignancies. Ferroptosis is an autophagy-dependent cell death modality in which enhanced autophagic flux selectively degrades ferroptosis suppressors (e.g., GPX4, FTH1, and lipid droplets), thereby accelerating iron-mediated lipid peroxidation [ 41 , 152 ] (Fig.  3 ). Notably, some proteins and metal ions exhibit pleiotropic functions, coordinating crosstalk between ferroptosis, apoptosis, pyroptosis, and newly characterized metal-dependent death pathways, such as cuproptosis [ 41 ]. For example, copper ions can trigger cuproptosis and lead to autophagy-dependent ferroptosis by promoting GPX4 ubiquitination and aggregate formation [ 41 , 153 ]. Ferroptosis and apoptosis exhibit intricate mechanistic crosstalk, characterized by mitochondrial ROS accumulation, iron overload, and systemic redox imbalance, which are the key hallmarks that functionally interconnect these distinct cell death pathways. For example, mitochondrial cardiolipin is a unique phospholipid that undergoes selective oxidation during the initiation of apoptosi. This oxidation is mediated by cytochrome c when it is bound to cardiolipin, which acquires peroxidase activity. The oxidized cardiolipin then facilitates the permeabilization of mitochondrial membranes, enabling the critical release of proapoptotic factors [ 154 ]. This iron-redox axis orchestrates oxidative damage to the mitochondrial membranes and enhances the vulnerability of cancer cells to ferroptotic cell death. (Fig.  3 ). Heme oxygenase-1 (HO-1) is a cytoprotective antioxidant enzyme and a vital regulator of intracellular iron homeostasis. Under conditions of cellular damage, NRF2-mediated transcriptional activation stimulates the expression of HO-1 and increases intracellular Fe 2 ⁺ levels [ 155 ] (Fig.  3 ). Moreover, Redox-active labile iron (Fe 2 ⁺) initiates sideroflexin 1 (SFXN1)-mediated iron translocation across the inner mitochondrial membrane, leading to mitochondrial iron overload and ferroptosis [ 156 ]. Fe 2 ⁺ ions can initiate the Fenton reaction, leading to the production of substantial amounts of lipid peroxides and ROS. This reaction ultimately results in the oxidation of the cell membranes and organelles. The accumulation of ROS and subsequent permeabilization of the mitochondrial outer membrane (MOMP) collectively activate multiple apoptotic pathways. Under conditions of oxidative stress, such as ROS stimulation, the mitogen-activated protein kinase kinase kinase (MAPKKK), known as apoptosis signal-regulating kinase 1 (ASK1), can induce apoptosis by activating p38 and c-Jun N-terminal kinase (JNK) [ 157 ]. Notably, iron overload induces p53 phosphorylation, increases ROS and DNA damage, and enhances caspase-3 cleavage, ultimately leading to mitochondrial outer membrane permeabilization (MOMP)-dependent apoptosis [ 158 ]. In addition, the myocardium is significantly affected by iron overload, and cardiac dysfunction is a hallmark of systemic iron dysregulation. Excessive accumulation of labile iron in cardiomyocytes disrupts transferrin function, leading to an increase in ROS and subsequent caspase-3-mediated apoptosis [ 159 ] (Fig.  3 ). Taken together, these findings demonstrate that ferroptosis operates within an integrated cell death network, dynamically interacting with other RCD pathways to determine cellular fate. Determining the molecular crosstalk between these pathways is essential for understanding the delicate balance between cell survival and death. Moreover, these mechanistic insights reveal novel therapeutic opportunities for targeting iron ion-dependent cell death processes, particularly in malignancies and neurodegenerative disorders.

Emerging research has revealed that metal ions exert profound regulatory effects on RCD, offering novel therapeutic opportunities for the treatment of metalloptosis and the development of metalloptosis drugs [ 28 , 99 ]. Essential metal ions, including Cu 2 ⁺, Ca 2 ⁺, Zn 2 ⁺, and Fe 2 ⁺/ 3 ⁺, are critical cofactors in cellular signaling cascades. Dysregulation of these ions has been implicated in the pathogenesis of malignancies and aberrant activation of regulatory cell death pathways [ 100 ]. This review systematically examines the roles of redox-active (Fe 2 ⁺/ 3 ⁺, Cu⁺/ 2 ⁺, Mn 2 ⁺, and Co 2 ⁺) and redox-inert (Zn 2 ⁺, Na⁺, Ca 2 ⁺, and Mg 2 ⁺) metal ions in modulating RCD mechanisms, with particular emphasis on their crosstalk within the signaling networks underlying metalloptosis.

Essential metal ions (Fe 2 ⁺/ 3 ⁺, Zn 2 ⁺, Cu⁺/ 2 ⁺, Mn 2 ⁺, and Ca 2 ⁺) regulate various fundamental cellular processes including DNA biosynthesis, enzyme catalysis, signal transduction, and redox homeostasis. Dysregulated metal ion homeostasis can disrupt fundamental cellular processes whether through excess, deficiency, or aberrant distribution of metal ions, ultimately driving pathological consequences ranging from metabolic dysfunction to programmed cell death. Recent advances in metal ion biology have revealed their critical roles in cancer progression and metal ion cell death pathways [ 287 ]. While ferroptosis continues to dominate therapeutic research, novel metal-ion-dependent regulated death forms, including cuproptosis, lysozincrosis, and calcicoptosis, have emerged as promising frontiers in oncology therapy [ 378 ]. These discoveries, coupled with the established roles of other metal ions in cell death induction, are driving the development of innovative approaches to cancer therapy. Despite decades of development of metal ion-based antitumor agents, only platinum-containing compounds have achieved widespread clinical success [ 379 ]. This limited translation has spurred renewed interest in exploring novel therapeutic applications of metalloptosis in oncology. We discuss the feasibility of targeting metalloptosis for cancer therapy and overcoming drug resistance. The therapeutic induction of ferroptosis in cancer cells represents a promising anticancer strategy that leverages cancer-specific vulnerabilities in iron metabolism, lipid peroxidation, post-translational modification, degradation of proteins [ 380 ], and redox homeostasis [ 381 ]. Malignant cells exhibit increased iron dependence to sustain their proliferative demands, which can be exploited through iron dysregulation and the subsequent accumulation of toxic lipid peroxides , inducing ferroptosis [ 382 ]. Preclinical studies have robustly validated the therapeutic potential of ferroptosis inducers in various cancers [ 383 ]. Garcia-Bermudez et al. recently demonstrated that lipoprotein-mediated delivery of α-tocopherol (α-toc), the predominant vitamin E isoform in human lipoproteins, confers broad ferroptosis resistance across cancer types [ 384 ]. Mechanistic studies have identified sulfated glycosaminoglycans (GAGs) on cell surface proteoglycans as essential mediators of lipoprotein uptake. Genetic or pharmacological disruption of GAG biosynthesis not only attenuated lipoprotein internalization but also restored ferroptosis sensitivity and suppressed tumor growth in vivo, revealing a targetable metabolic vulnerability in malignant cells. Notably, CTSGDP-13 triggers ferroptosis in bladder cancer by modulating the USP7/TRIM25/KEAP1 axis [ 385 ]. Guo et al. demonstrated that dihydroartemisinin triggers ferroptosis in pancreatic cancer cells by modulating survival-associated gene networks [ 386 ]. These findings highlight the diverse molecular pathways through which ferroptosis exerts potent antitumor effects. Xc − system inhibitors are defined as type I FINs, such as erastin [ 125 , 387 ]. Erastin, a small-molecule compound first identified in 2003, was later found to induce ferroptosis by inhibiting system Xc⁻, leading to GSH depletion and inactivation of GPX4 [ 388 ]. Erastin disrupts mitochondrial function by increasing ROS production and reducing ATP synthesis. It binds directly to voltage-dependent anion channel 2 (VDAC2), contributing to mitochondrial membrane permeabilization and selectively triggering ferroptosis in certain tumor cells harboring activating mutations in the RAS-RAF-MEK pathway [ 389 ]. Mounting evidence underscores the therapeutic potential of combinatorial approaches that leverage ferroptosis in cancer treatment. Recent studies have revealed that erastin, a canonical ferroptosis inducer, exhibits significant synergy with various pharmacological agents, resulting in potent antitumor effects across multiple cancer types [ 173 , 390 ]. Biamonte et al. demonstrated that ovarian cancer (OVCA) cells employ CD63 + exosomes to export iron-rich ferritin, thereby evading erastin-induced ferroptosis. These results suggest that synergizing ferroptosis inducers with exosome inhibitors is a promising strategy for reversing ferroptosis resistance in OVCA [ 391 ]. In advanced prostate cancer models, dual targeting of ferroptosis (via erastin or RSL3) and androgen receptor signaling (via enzalutamide) not only suppressed tumor cell proliferation and migration in vitro but also achieved substantial tumor growth inhibition in vivo [ 392 , 393 ]. Mechanistically, this synergy appears to arise from the concurrent disruption of redox homeostasis and androgen-dependent survival pathways. Additionally, in non-small cell lung cancer, the combination of erastin with the natural compound celastrol triggers a profound ferroptotic response characterized by dramatic accumulation of ROS, collapse of mitochondrial membrane potential (ΔΨm), and extensive mitochondrial fission [ 394 ]. These findings position the co-treatment of erastin and celastrol as a promising therapeutic strategy for NSCLC, particularly in tumors resistant to conventional therapy. The dual targeting of both lipid peroxidation and mitochondrial integrity may represent a novel paradigm for overcoming treatment resistance in solid tumors. Erastin has faced challenges in clinical translation due to its poor aqueous solubility and metabolic instability. However, strategic modifications to the aniline ring of erastin have led to the development of chemically stabilized analogs with improved pharmacokinetic properties. Notably, the carbonyl-containing derivative known as imidazole ketone erastin (IKE) exhibits enhanced metabolic stability and solubility while retaining potent ferroptotic activity. In B-cell lymphoma xenograft models, IKE effectively induced tumor-selective ferroptosis and suppressed tumor progression without any observable systemic toxicity, establishing it as a promising clinical candidate for ferroptosis-based therapy. Erastin remains a cornerstone in ferroptosis research, demonstrating significant preclinical promise and emerging clinical potential. Further optimization of delivery systems and combination strategies is crucial for the successful translation of this approach into cancer therapy. PRLX93936, a derivative of erastin, has been evaluated in two phase I/II clinical trials for the treatment of multiple myeloma ( NCT01695590 ) and several advanced cancers ( NCT00528047 ) [ 395 ]. Originally developed for inflammatory bowel disease, sulfasalazine was repurposed as a system Xc − inhibitor that potently induces ferroptosis [ 396 ]. Preclinical studies have demonstrated its efficacy against glioblastoma [ 397 ] and esophageal cancer [ 398 ], and ongoing clinical trials are evaluating its broader anticancer potential [ 399 ]. Mechanistic investigations have revealed that sulfasalazine activates the AMPK/SREBP1 pathway to drive ferroptosis in pancreatic cancer cells [ 400 ], highlighting its capacity to engage multiple ferroptotic cascades. Despite these findings establishing sulfasalazine as a pleiotropic anticancer agent, further studies are needed to optimize its clinical utility across malignancies and validate its safety and efficacy in human trials. RSL3 (RAS-selective lethal 3) is a potent and selective GPX4 inhibitor that irreversibly inactivates the enzyme by covalently modifying the selenocysteine residue in its active site [ 293 ]. Beyond its standalone activity, RSL3 functions as an effective chemosensitizer, synergizing with conventional agents such as cisplatin and doxorubicin to induce ferroptosis in diverse malignancies, including neuroblastoma [ 401 ], osteosarcoma [ 402 ], lung cancer [ 403 ], rhabdomyosarcoma [ 404 ], and breast cancer [ 405 ]. Mechanistically, it potentiates chemotherapy by elevating lipid peroxidation and oxidative stress [ 406 ]. Although clinical studies evaluating survival benefits are lacking [ 407 ], RSL3 shows excellent preclinical tolerability (≤ 400 mg/kg) without significant toxicity [ 408 ], indicating its potential as a candidate for combination therapy. ML162 and RSL3 are first-generation covalent GPX4 inhibitors that directly bind and inactivate GPX4 via reactive alkyl chloride groups; however, their clinical utility is limited by poor selectivity and pharmacokinetics [ 409 ]. To address these limitations, ML210 was developed using masked nitrile-oxide electrophiles, yielding improved selectivity and pharmacokinetic profiles while retaining potent GPX4 inhibition [ 410 ]. However, current GPX4 inhibitors require optimization of in vivo efficacy to achieve therapeutic relevance. Similarly, the ferroptosis inducer FIN56 triggers ferroptosis via GPX4 degradation and CoQ10 depletion. Preclinical studies have demonstrated its efficacy in multiple cancer models, including colorectal [ 411 ] and non-small cell lung cancer [ 412 ]. In gastric cancer, FIN56 exacerbates ferroptosis by dysregulating lipid metabolism and amplifying peroxidative damage [ 413 ]. Curcumin, a bioactive polyphenol derived from Curcuma longa, induces ferroptosis through tumor-specific mechanisms, including SLC1A5 upregulation in breast cancer [ 414 ], GPX4 pathway inhibition in non-small cell lung cancer (NSCLC) [ 415 ], and ACSL4 targeting in HCC [ 416 ]. Sorafenib, a clinically approved multikinase inhibitor for the treatment of certain solid tumors, can induce ferroptosis through various mechanisms, including the promotion of iron accumulation and lipid peroxidation across multiple malignancies [ 417 , 418 ], PVT1/miR-195-5p-mediated GPX4 suppression in HCC [ 419 ], and ACSL4-dependent lipid metabolic disruption. In glioblastoma, it enhances ferroptosis sensitivity by modulating the ROS pathway [ 420 ]. These findings position both compounds as mechanistically distinct and therapeutically effective ferroptosis inducers. Anisomycin, an antibiotic with known pro-apoptotic activity, induces ferroptosis in ovarian cancer by disrupting the redox balance and promoting lipid peroxidation [ 421 ]. 4-Octyl itaconate, a potent inducer of lipid peroxidation, triggers ferroptosis in colorectal cancer by suppressing NRF2 signaling, leading to glutathione depletion and subsequent accumulation of lipid ROS [ 422 ]. In addition, artemisinin and its derivatives (e.g., dihydroartemisinin) exhibit broad ferroptosis-inducing capacity [ 423 ], showing particular efficacy against therapy-resistant glioblastoma [ 424 ] and pancreatic cancer [ 425 ] in preclinical models. While clinical trials are exploring artemisinin-based combination therapies, their specific roles as ferroptosis inducers require further validation [ 426 ]. Simvastatin, a widely used cholesterol-lowering drug, can induce ferroptosis through various mechanisms, such as HMGCR inhibition-mediated suppression of the mevalonate pathway, leading to GPX4 downregulation [ 427 ] and disruption of lipid metabolism to promote lipid peroxidation in gastric cancer models [ 428 ]. These findings reveal the potential of repurposing this compound as an anticancer agent that targets ferroptotic vulnerabilities. Additionally, β -elemene, a natural sesquiterpene from traditional Chinese medicine, demonstrates broad ferroptosis-inducing capacity by overcoming cetuximab resistance in KRAS-mutant colorectal cancer [ 429 ] and activating the lncRNA H19 axis in EGFR-mutant NSCLC [ 430 ]. Its ability to target distinct resistance pathways in different cancer contexts positions β -elemene as a promising adjuvant for precision combination therapies. Substantial evidence demonstrates that cancer therapy resistance arises through multiple interconnected mechanisms, including apoptosis and ferroptosis evasion [ 431 ], activation of compensatory ferroptosis defense pathways that regulate acquired radioresistance [ 432 ], increased drug efflux by ATP-binding cassette (ABC) transporters [ 433 ], cancer stem cells (CSCs) [ 434 ], EMT-mediated cellular plasticity, enhanced DNA Repair [ 435 ], TME-derived protective signals [ 436 ], and epigenetic alterations [ 437 ](e.g., lactylation [ 438 , 439 ]) that modulate drug sensitivity. Chemotherapeutic agents, including cisplatin [ 440 ], ruthenium complexes [ 441 ], and doxorubicin [ 442 ], trigger apoptosis through DNA damage or microtubule disruption [ 443 ], activating cellular stress responses that engage apoptotic cascades. However, tumor cells frequently develop resistance through anti-apoptotic adaptations, such as bcl-2 overexpression [ 444 ] or deubiquitinase overexpression [ 10 ], leading to therapeutic failure of chemotherapeutic agents. Growing evidence demonstrates that ferroptosis induction is a promising therapeutic strategy for overcoming resistance to conventional cancer therapy. This approach offers a multimodal mechanism for reversing drug resistance by triggering ferroptosis through the precise modulation of key molecular pathways, including ubiquitination modification molecules, antioxidant defense systems, lipid peroxidation, and iron metabolism. For example, emerging research have revealed that the targeted disruption of DTX2-mediated NCOA4 and HSD17B4 ubiquitination and degradation represents a promising therapeutic strategy to overcome cancer drug resistance [ 445 , 446 ]. Multiple pharmacological inhibitors of SLC7A11, including withaferin A, fenbendazole, and carnosic acid, show promise in overcoming therapy resistance. These compounds disrupt cystine import, deplete glutathione stores, and render cancer cells vulnerable to ferroptosis. Targeted inhibition of SLC7A11 may be particularly effective against glutathione-dependent resistant malignancies, such as prostate and breast cancer [ 447 ]. Moreover, GPX4 inhibitors (including ginkgetin, DET/DETD-35, and flubendazole) represent a promising class of anticancer agents for overcoming therapy resistance [ 436 ]. These compounds selectively disrupt GPX4 activity, leading to lipid peroxidation and ferroptosis, particularly in malignancies that depend on GPX4 overexpression for survival. Alternatively, modulating iron metabolism to increase the labile iron pool is a potent therapeutic approach for inducing ferroptosis in malignant cells and reversing drug resistance [ 448 ]. Small-molecule compounds, including dihydroartemisinin (DHA) and ursolic acid, exert dual regulatory effects by enhancing iron uptake via transferrin receptor-mediated pathways and promoting ferritinophagy through NCOA4 downregulation [ 449 , 450 ]. Notably, Liu et al. found that DTX2 suppresses NCOA4-mediated ferritinophagy and ferroptosis via ubiquitination-dependent regulation [ 445 ]. Li et al. identified aspartate β -hydroxylase (ASPH) as both a prognostic biomarker and therapeutic target in HCC, where its overexpression correlates with poor clinical outcomes in sorafenib-treated patients. Genetic silencing of ASPH not only restored sorafenib sensitivity but also triggered ferroptosis in resistant tumor cells [ 451 ]. Importantly, the combination of ASPH inhibition and sorafenib treatment synergistically suppressed tumor growth and progression, revealing a promising combinatorial strategy for advanced HCC treatment. Future applications could leverage iron metabolism profiling to guide personalized treatment regimens, potentially enhancing therapeutic efficacy. Although clinical trials exploring ferroptosis inducers as standalone treatments are still in the early stages of development [ 452 , 453 ], their potential as combination agents is highly promising. Ferroptosis inducers have demonstrated significant therapeutic potential when combined with conventional anticancer modalities, including radiotherapy [ 454 ], chemotherapy [ 455 ], and immunotherapy [ 456 ]. These combinations exhibit synergistic effects that enhance treatment efficacy by simultaneously targeting multiple vulnerabilities in cancer cells [ 457 ]. For example, therapeutic synergy emerges when cisplatin is combined with ferroptosis inducers, such as erastin, which collaboratively enhance lipid peroxidation to overcome chemoresistance [ 458 ]. Beyond conventional chemotherapy, ferroptosis induction can potentiate the efficacy of diverse treatment modalities. Targeted agents, such as sorafenib (a multi-kinase inhibitor for hepatocellular carcinoma), directly trigger ferroptosis [ 459 ], and tenapanor synergizes with sorafenib to potently suppress hepatocellular carcinoma organoid growth [ 431 ]. Immunotherapies benefit from ferroptosis-mediated immunogenic cell death, which recruits CD8 + T cells and synergizes with checkpoint inhibitors (anti-PD-1/CTLA-4) [ 460 ]. This multimodal approach capitalizes on ferroptosis to remodel the tumor microenvironment and overcome therapeutic resistance. Preclinical evidence indicates that such multimodal approaches not only potentiate tumor cytotoxicity but also overcome drug resistance [ 461 ], offering a promising avenue for improving therapeutic outcomes. Advancements in nanotechnology have facilitated the emergence of novel methodologies for the targeted delivery of ferroptosis inducers, thereby enhancing the precision and efficacy of therapeutic interventions [ 462 ]. Nanoparticles can be meticulously engineered to exhibit tumor-specific targeting, thereby significantly reducing unintended effects on non-target tissues and concurrently minimizing collateral damage to healthy cellular structures [ 463 , 464 ]. For instance, nanocarriers, such as liposomes or polymer-based nanoparticles, can be employed to encapsulate ferroptosis inducers, such as erastin or RSL3, facilitating their direct delivery to the tumor microenvironment [ 465 ]. Emerging evidence demonstrates that nanoparticle-mediated ferroptosis induction effectively targets therapy-resistant glioblastoma (GBM) [ 466 ]. Nanocarriers engineered to modulate key ferroptosis regulators present novel therapeutic opportunities for the treatment of this aggressive malignancy. Nanoparticle-mediated delivery systems have emerged as powerful tools for targeted induction of ferroptosis. PEGylated liposomal formulations of erastin exploit the enhanced permeability and retention effect to achieve tumor-selective accumulation, enabling localized ferroptosis while sparing healthy tissues [ 467 ]. Alternatively, tumor-specific targeting can be enhanced using ligand-functionalized polymeric micelles, such as folate-conjugated or antibody-directed systems, which actively target cancer cells expressing the corresponding surface markers [ 468 ]. Targeted delivery systems significantly enhance the therapeutic efficacy of ferroptosis inducers, as evidenced by suppressed tumor progression in preclinical models and reduced systemic toxicity [ 469 ]. The TME provides excellent biochemical triggers that enable tumor-specific release of ferroptosis inducers via microenvironment-responsive nanocarriers, simultaneously overcoming drug resistance and reducing systemic toxicity. For example, Yan et al. demonstrated that pH-sensitive polymeric micelles delivering sorafenib potently enhanced ferroptosis under acidic conditions [ 470 ]. Exploiting tumor-selective pH gradients, such nanotherapeutics represent a promising strategy to overcome therapy resistance through ferroptosis induction. The hypoxia-adaptive nanotherapeutic approach specifically targets most therapy-resistant tumors. Recent studies have demonstrated that hypoxia-responsive nanogels can enhance the therapeutic efficacy of ferroptosis and suppress resistant tumor growth [ 471 ]. Additionally, nanoparticle-mediated targeting of lipid peroxidation has emerged as a powerful approach to overcome therapeutic resistance by inducing ferroptosis in tumor cells. Engineered nanocarriers can precisely deliver pro-ferroptotic payloads, including GPX4 inhibitors to disrupt antioxidant defenses, lipid peroxidation catalysts (e.g., lipoxygenase mimetics), and PUFAs as peroxidation substrates. For instance, linoleic acid-loaded liposomes induce ferroptosis in resistant tumors by amplifying lipid peroxidation [ 472 ]. This strategy exploits two synergistic mechanisms: enhanced intracellular PUFA availability and catalyzed lipid peroxidation. By directly manipulating lipid metabolic pathways, such nanoparticle systems selectively target resistant malignancies while minimizing off-target effects [ 473 ]. The precision of nanotherapeutic delivery systems enables the slow controlled release of ferroptosis inducers, exploitation of metabolic vulnerability, and overcoming of conventional chemotherapy resistance. Ferroptosis-driven nanotherapeutics not only enhance therapeutic efficacy but also reduce off-target effects, paving the way for personalized cancer treatments. However, the clinical translation of ferroptosis-driven nanotherapeutics requires further investigation into their biocompatibility, systemic effects, and long-term efficacy to ensure safe integration into existing cancer treatment protocols [ 474 ]. Together, these findings position ferroptosis as a therapeutically exploitable cell death pathway with significant potential for innovative cancer treatments.

Ferroptosis is an iron-dependent RCD characterized by lipid hydroperoxide accumulation, mainly caused by Fe 2+ -mediated Fenton reactions, leading to polyunsaturated fatty acid phospholipid (PUFA-PL) lipid peroxidation (LPO), resulting in cell membrane rupture and triggering cell death [ 34 , 35 ]. Ferroptosis acts as a tumor suppressor in the development of various human cancers, highlighting that ferroptosis induction can be used in cancer therapy as an interventional target [ 22 , 34 , 37 , 101 ]. Mechanistically, ferroptosis is triggered by the collapse of various ferroptosis defense systems and dysregulation of three interconnected metabolic pathways: iron homeostasis, glutathione biosynthesis, and peroxidation of polyunsaturated fatty acids (Fig.  2 ). Fig. 2 Three classical ferroptosis metabolic pathways and their associated defense systems. A . Iron metabolism Pathway: Fe 3+ is transferred from extracellular to intracellular using transferrin receptor 1 (TFR1) as a carrier, and Fe 3+ is reduced to Fe 2+ by six-transmembrane epithelial antigen of the prostate3 (STEAP3). Through the transport of Divalent metal transporter 1 (DMT1), Fe 2+ is left in the cytoplasm. Ferritin initiates iron autophagy mediated by nuclear receptor coactivator 4 (NCOA4) and releases large amounts of Fe 2+ . Heme releases Fe 2+ via the catalysis of HO-1. FPN1 transports iron from cells to the blood. B . GSH metabolism Pathway: Cystine is imported into cells via the heterodimeric transporter System Xc⁻ (composed of SLC7A11 and SLC3A2) embedded in the cell membrane. Inside the cell, cystine is reduced to cysteine, which is subsequently utilized by glutamate-cysteine ligase (GCL) and glutathione synthetase (GSS) to synthesize glutathione(GSH). GPX4 utilizes GSH to convert lipid hydroperoxides (L-OOH) into their corresponding alcohols (L-OH), effectively halting peroxidation. C .Lipid peroxidation metabolic pathway: PUFAs are incorporated into PEs through the catalytic actions of ACSL4 and LPCAT3, resulting in the formation of PUFA-containing phosphatidylethanolamines (PUFA-PEs). These PUFA-PEs subsequently undergo lipid peroxidation mediated by lipoxygenase (ALOX) and hydroxyl radicals, ultimately triggering ferroptosis in cells. The Fenton reaction primarily involves the formation of hydroxyl radicals (HO·) and hydroxide ions (OH·) from hydrogen peroxide (H 2 O 2 ) in the presence of Fe 2+ ions, which deprives polyunsaturated fatty acids (PUFAs) of hydrogen atoms, causing lipid peroxidation. Ferroptosis inhibitor protein 1 (FSP1, encoded by AIFM2) can inhibit ferroptosis induced by lipid peroxidation, independently of GPX4. D . There are six parallel ferroptosis protection systems in cells, namely the GPX4-GSH , FSP1/CoQH 2 , DHODH/CoQH 2 , GCH1/BH4, MBOAT1/2-MUFA, and SC5D/7-DHC system, which precisely defend cellular lipid peroxidation to prevent ferroptosis. Abbreviations: ACAC, acetyl-coenzyme A carboxylase; ACSL4, acyl-CoA synthetase long-chain family member 4; ALOX, Arachidonate lipoxygenases; POR, Cytochrome P450 oxidoreductase; LPCAT3, lysophosphatidylcholine acyltransferase 3; ACC, acetyl-coenzyme A carboxylase; FPN1, Ferroportin 1; CoQ 10 , ubiquinone; FSP1, ferroptosis inhibitor protein 1; PUFAs, Polyunsaturated fatty acids; PEs, phosphatidylethanolamines; HMG-CoA, 3-hydroxy-3-methyl glutaryl coenzyme A; Lipid ROS, Lipid peroxidation Reactive oxygen species Three classical ferroptosis metabolic pathways and their associated defense systems. A . Iron metabolism Pathway: Fe 3+ is transferred from extracellular to intracellular using transferrin receptor 1 (TFR1) as a carrier, and Fe 3+ is reduced to Fe 2+ by six-transmembrane epithelial antigen of the prostate3 (STEAP3). Through the transport of Divalent metal transporter 1 (DMT1), Fe 2+ is left in the cytoplasm. Ferritin initiates iron autophagy mediated by nuclear receptor coactivator 4 (NCOA4) and releases large amounts of Fe 2+ . Heme releases Fe 2+ via the catalysis of HO-1. FPN1 transports iron from cells to the blood. B . GSH metabolism Pathway: Cystine is imported into cells via the heterodimeric transporter System Xc⁻ (composed of SLC7A11 and SLC3A2) embedded in the cell membrane. Inside the cell, cystine is reduced to cysteine, which is subsequently utilized by glutamate-cysteine ligase (GCL) and glutathione synthetase (GSS) to synthesize glutathione(GSH). GPX4 utilizes GSH to convert lipid hydroperoxides (L-OOH) into their corresponding alcohols (L-OH), effectively halting peroxidation. C .Lipid peroxidation metabolic pathway: PUFAs are incorporated into PEs through the catalytic actions of ACSL4 and LPCAT3, resulting in the formation of PUFA-containing phosphatidylethanolamines (PUFA-PEs). These PUFA-PEs subsequently undergo lipid peroxidation mediated by lipoxygenase (ALOX) and hydroxyl radicals, ultimately triggering ferroptosis in cells. The Fenton reaction primarily involves the formation of hydroxyl radicals (HO·) and hydroxide ions (OH·) from hydrogen peroxide (H 2 O 2 ) in the presence of Fe 2+ ions, which deprives polyunsaturated fatty acids (PUFAs) of hydrogen atoms, causing lipid peroxidation. Ferroptosis inhibitor protein 1 (FSP1, encoded by AIFM2) can inhibit ferroptosis induced by lipid peroxidation, independently of GPX4. D . There are six parallel ferroptosis protection systems in cells, namely the GPX4-GSH , FSP1/CoQH 2 , DHODH/CoQH 2 , GCH1/BH4, MBOAT1/2-MUFA, and SC5D/7-DHC system, which precisely defend cellular lipid peroxidation to prevent ferroptosis. Abbreviations: ACAC, acetyl-coenzyme A carboxylase; ACSL4, acyl-CoA synthetase long-chain family member 4; ALOX, Arachidonate lipoxygenases; POR, Cytochrome P450 oxidoreductase; LPCAT3, lysophosphatidylcholine acyltransferase 3; ACC, acetyl-coenzyme A carboxylase; FPN1, Ferroportin 1; CoQ 10 , ubiquinone; FSP1, ferroptosis inhibitor protein 1; PUFAs, Polyunsaturated fatty acids; PEs, phosphatidylethanolamines; HMG-CoA, 3-hydroxy-3-methyl glutaryl coenzyme A; Lipid ROS, Lipid peroxidation Reactive oxygen species Ferroptosis is an iron-dependent cell death process, and an imbalance in iron homeostasis in cells may directly or indirectly affect the sensitivity of ferroptosis. There are two types of iron ions in the cell, Fe 2+ and Fe 3+ , and Fe 2+ is the main one involved in the Fenton reaction [ 41 ]. When GSH is exhausted, the activity of glutathione peroxidase 4 (GPX4) decreases or is inactivated, and toxic lipid peroxides cannot be metabolized into nontoxic lipid alcohols, which can react with Fe 2+ and induce lipid peroxidation, prompting the generation of a large number of hydroxyl radicals and ROS, triggering ferroptosis [ 102 ]. The synthesis of Fe 2+ in cells mainly includes two parts (Fig.  2 A): (1) Fe 3+ is transferred from the extracellular to the intracellular space using transferrin receptor 1 (TFR1) as a carrier, and Fe 3+ is reduced to Fe 2+ by six-transmembrane epithelial antigen of the prostate 3 (STEAP3). Through the transport of divalent metal transporter 1 (DMT1/NRAMP2), Fe 2+ was left in the cytoplasm. When the expression of TFR1 is inhibited, intracellular iron content is lower, and the cell becomes more resistant to ferroptosis [ 103 ]. (2) Ferritin initiates iron autophagy mediated by nuclear receptor coactivator 4 (NCOA4) and releases a large amount of Fe 2+ [ 104 ] (Fig.  2 A). Intracellular ferritin includes the ferritin light chain (FTL) and ferritin heavy chain 1 (FTH1). Fe 3+ is stored in ferritin and can be converted to Fe 2+ , regulating ferroptosis and other cellular physiological processes when necessary [ 104 ]. Intracellular molecules regulate Fe 2+ levels and play essential roles in ferroptosis. For example, iron response element binding protein 2 (IREB2) is mainly involved in the regulatory function of ferroportin (FPN), which can stabilize the transcription of DMT1 and TFR1, increase the iron uptake of cells, and enhance their sensitivity to ferroptosis [ 105 ]. Ferroportin 1 (FPN1) is an iron export protein found in mammals. FPN1 expression is regulated by hepcidin, which binds to FPN1 and induces its degradation. Intracellular poly (RC)-binding protein 2 (PCBP2) interacts with divalent metal transporter 1 (DMT1), and PCBP2 receives iron from DMT1. A central cellular defense mechanism against oxidative stress involves the activation of nuclear factor erythroid 2-related factor 2 (NRF2), a master transcriptional regulator of redox homeostasis. In response to oxidative stress, NRF2 orchestrates the expression of cytoprotective genes, such as heme oxygenase-1 (HO-1), GPX4, and ferritin heavy chain (FTH), which collectively enhance cellular antioxidant defenses and iron metabolism. Zhang et al. revealed that NRF2 regulates ferritin synthesis and degradation to maintain iron homeostasis and prevent ferroptotic cell death [ 91 ]. NRF2 confers ferroptosis resistance in malignant cells through a dual cytoprotective mechanism involving the suppression of phospholipid peroxidation and the chelation of redox-active iron species. This coordinated defense strategy allows cancer cells to evade iron-catalyzed oxidative membrane damage. NRF2 orchestrates iron homeostasis by modulating ferritin dynamics through three key effectors: HERC2, an E3 ubiquitin ligase containing HECT and RLD domains; VAMP8, vesicle-associated membrane protein 8; and NCOA4, nuclear receptor coactivator 4. This regulatory network precisely controls the labile iron pool (LIP), ultimately determining cellular susceptibility to ferroptosis. Notably, tumors exhibiting NRF2 hyperactivation demonstrate marked ferroptosis resistance, whereas pharmacological or genetic NRF2 suppression restores sensitivity to ferroptosis inducers. Any step in the process of iron metabolism disorders may affect ferroptosis sensitivity by altering the level of iron ions in the cytoplasm. Glutathione (GSH) can used as a substrate of GPX4 to catalyze the enzymatic reaction and directly prevent the accumulation of superoxidized lipids. GSH is a scavenger of hydroxyl free radicals and is important for cell defense against oxidative stress. GSH is an essential cofactor for GPX4 activation, which assists GPX4 to reduce peroxides (such as R-OOH) to alcohols (such as R-OH), concomitantly converting two reduced GSH into oxidized glutathione (GSSG) [ 106 ], thereby reducing the generation of toxic free radicals (such as R-O·) and preventing ferroptosis caused by the accumulation of lipid ROS [ 34 ]. Glutathione-disulfide reductase (GSR) catalyzes the NADPH/H + -dependent reduction of GSSG to regenerate reduced GSH. Glucose-6-phosphate dehydrogenase (G6PD) catalyzes the rate-limiting oxidation of glucose-6-phosphate to 6-phosphogluconate in the pentose phosphate pathway [ 107 ], while simultaneously generating NADPH through the reduction of NADP + . As the primary cellular source of reducing equivalents, this reaction provides NADPH to support GSR activity, which is essential for maintaining reduced GSH levels and ensuring cellular redox homeostasis (Fig.  2 B). The ferroptosis defense network is significantly regulated by NRF2 via the transcriptional control of key metabolic effectors. Notably, NRF2 directly upregulates SLC7A11 [ 108 ], which encodes the xCT transporter subunit, critical for cystine uptake, and both the catalytic and regulatory components of glutamate-cysteine ligase. These targets collectively maintain cellular GSH levels, thereby sustaining the activity of GPX4, the central guardian against phospholipid peroxidation in ferroptosis. P53 regulates ferroptosis via two distinct mechanisms: direct binding to the SLC7A11 promoter and interaction with ubiquitin-specific peptidase 7, which collectively reduces histone H2B monoubiquitination at the SLC7A11 promoter, leading to transcriptional repression of SLC7A11 [ 109 ], ultimately impairing GSH biosynthesis and promoting ferroptosis [ 110 , 111 ]. Lipid peroxidation(LPO) is a biochemical process in which cell membranes or membrane organelle lipids are attacked and oxidized by free radicals, including reactive oxygen species (ROS) and •OH [ 112 ]. ROS can be produced by various biochemical processes, including the Fenton reaction [ 102 ], mitochondrial respiratory chain [ 113 ], and enzymatic reactions [ 114 ]. Transition metal iron-mediated Fenton reactions, ROS, and PUFA-PLs play a crucial role in promoting phospholipid peroxidation and ferroptosis [ 34 , 115 ]. PUFA-PLs are generated by acetyl CoA carboxylase9 (ACAC), acyl-CoA synthetase long-chain family member 4 (ACSL4), and lysophosphatidylcholine acyltransferase 3 (LPCAT3) (Fig.  2 C). Lipoxygenase (LOX), NADPH oxidase (NOX) enzymes, NADH-cytochrome b5 reductase (CYB5R1), and cytochrome P450 redox reductase (POR) promote lipid peroxidation through three distinct stages including initiation, propagation, and termination [ 116 , 117 ]. LPO can cause further damage to nearby molecules, resulting in various types of RCD [ 118 , 119 ]. Lipid peroxides and their derivatives, including malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), are indispensable markers [ 112 ]. Regulating certain molecules during lipid peroxidation can affect the occurrence and development of ferroptosis. Wang et al. found that knocking out ACSL4 inhibit ferroptosis and alleviate kidney damage in mice [ 120 ]. Wenzel et al. [ 7 ] discovered that arachidonate 15-lipoxygenase (ALOX15) bounds to phosphatidy lethanolamine-binding protein 1(PEBP1) and forms complexes that produce lipid peroxides and cause GPX4 dysfunction, thus promoting ferroptosis [ 121 ]. This mechanism has been demonstrated in animal models of acute kidney injury and traumatic brain injuries. Ferroptosis suppressor protein 1 (FSP1) functions as an NADPH-dependent oxidoreductase that effectively inhibits lipid peroxidation by reducing coenzyme Q10 (CoQ10) to its hydroquinone form (CoQH2) [ 122 ]. Continuous activation of various antioxidant metabolic pathways catalyzed by enzymatic reactions, can prevent the accumulation of lipid peroxides in the membrane, thereby inhibiting ferroptosis. Lipid peroxidation is a direct executor of ferroptosis. The intracellular antioxidant system, an important component of the ferroptosis defense system, can directly remove lipid peroxides [ 123 ]. Recently, GPX4-dependent and -independent pathways have been identified as potential ferroptosis defense pathways (Fig.  2 D). Recent studies have shown that GPX4 is the only enzyme in the GPX family that reduces membrane lipid peroxides. GPX4 and the cytoplasmic cystine/glutamate antiporter System Xc − (System Xc − ) regulate ferroptosis by affecting lipid and ROS metabolism [ 124 ]. System Xc − consists of solute carrier family 3 member 2 (SLC3A2) and SLC7A11(also called xCT) with an amino acid transport function, which promotes the exchange of extracellular cystine and intracellular glutamate [ 115 ]. Cystine is further converted into cysteine in the cell. Subsequently, cysteine, glutamate, and glycine are combined to generate GSH via enzymatic catalysis [ 125 , 126 ]. Cellular uptake of cystine is a key step in GSH synthesis and a core part of the inhibition of ferroptosis [ 127 ]. Therefore, inhibition of the activity of System Xc − could reduce the synthesis of GSH, eventually resulting in ROS accumulation and triggering ferroptosis. Most studies have shown that the ferroptosis suppressor protein 1 (FSP1)-CoQ10 axis is another important pathway for inhibiting lipid peroxidation and ferroptosis [ 122 , 128 ]. FSP1 is an NADPH-dependent CoQ reductase that reacts with ubiquinone (known as coenzyme Q 10 , CoQ 10 ) or α-tocopherol with the participation of NAD (P) H electrons, thus reducing the generation of intracellular lipid free -radicals, suppressing lipid peroxidation in cellular membranes, and preventing ferroptosis [ 122 , 128 , 129 ]. FSP1 is a GSH-independent inhibitor of ferroptosis, and its mechanism of scavenging lipid hydrogen peroxide is distinct from that of GPX4 [ 130 ] (Fig.  2 D). Bersuker et al. demonstrated that FSP1 can sustain tumor growth upon GPX4 inactivation; however, dual targeting of both GPX4 and FSP1 potently suppresses tumor progression in vivo [ 129 ]. This finding is particularly relevant to hepatocellular carcinoma (HCC), in which cancer cells exhibit a marked dependence on the CoQ10/FSP1 axis for ferroptosis resistance. Pharmacological inhibition of FSP1 not only reduces the HCC tumor burden but also promotes immunogenic remodeling of the tumor microenvironment, as evidenced by the enhanced infiltration of dendritic cells, macrophages, and T lymphocytes [ 131 ]. Zang et al. identified elevated FSP1 expression in gastric cancer (GC) tissues, with strong immunohistochemical staining correlating with aggressive clinicopathological features, including larger tumor size and lymph node metastasis. Notably, FSP1 upregulation was an independent prognostic marker of reduced overall survival in patients with GC. Mechanistically, FSP1-mediated ferroptosis suppression appears to modulate immune cell infiltration within the tumor microenvironment, suggesting a dual role in both tumor progression and immune evasion [ 132 ]. Additionally, Dai et al. revealed that AIFM2 confers resistance to multiple ferroptosis inducers (erastin, sorafenib, RSL3) through a ubiquinol-independent mechanism. Instead, AIFM2 recruits endosomal sorting complexes required for transport (ESCRT)-III to the plasma membrane, activating a membrane repair program that counteracts ferroptosis. Genetic disruption of the AIFM2-ESCRT-III axis significantly enhances the antitumor efficacy of sorafenib in vivo, providing new mechanistic insights into ferroptosis resistance during cancer therapy [ 133 ]. The GCH1-DHFR-BH4 pathway is another key regulator of ferroptosisthat inhibits lipid peroxidation by trapping lipid-free radicals [ 134 ]. Dihydrofolate reductase (DHFR), a newly discovered negative regulator of ferroptosis, catalyzes the reduction of dihydrobiopopterin (BH2) to tetrahydrobiopterin (BH4), specifically decreasing lipid peroxides, thereby inhibiting ferroptosis or reducing the susceptibility of cells to ferroptosis [ 135 ]. GTP cyclohydrolase 1 (GCH1) is a rate-limiting factor in the BH4 biosynthesis pathway, protecting cells from ferroptosis mediated by GCH1metabolites BH4 and BH2 [ 136 ]. BH4 is a cofactor of various enzymes, including aromatic amino acid hydroxylase and nitric oxide synthase (NOS) [ 135 , 136 ]. Speedy/RINGO cell cycle regulator family member A (SPY1) was demonstrated as a new ferroptosis suppressor via reducing LPO generated by the dysregulated GCH1/BH4 axis [ 137 ]. Mao et al. (2021) identified the DHODH-CoQH2 axis as a critical GPX4-independent ferroptosis defense pathway [ 138 ]. Dihydroorotate dehydrogenase (DHODH), an inner mitochondrial membrane enzyme, catalyzes the conversion of dihydroorotate (DHO) to orotate (OA) in pyrimidine biosynthesis and reduces ubiquinone (CoQ10) to ubiquinol (CoQH2) through electron transfer [ 138 ] (Fig.  2 D). Notably, DHODH functions as a key mitochondrial ferroptosis suppressor, effectively scavenging lipid peroxides when GPX4 activity is compromised [ 138 ]. In 2023, Liang et al. discovered novel GPX4- and FSP1-independent ferroptosis suppressors, including membrane-bound O-acyltransferase domain containing 1/2 (MBOAT1/2) [ 139 ]. In this system, MBOAT2 decreases the PUFA content in phospholipids by transferring oleic acid to lysophosphoryl ethanolamine, lysophosphoryl choline, and lysophosphoric phosphate, thereby inhibiting ferroptosis. Endogenous or exogenous monounsaturated fatty acids (MUFA) are indispensable for MBOAT2 to inhibit ferroptosis via phospholipid remodeling. MBOAT1/2 is a member of the membrane-bound O-acyltransferase (MBOAT) family, which catalyzes the transfer of fatty acyl chains to lysophospholipids, contributing to phospholipid remodeling. As lysophospholipid acyltransferases, MBOAT1/2 preferentially catalyze the transfer of monounsaturated fatty acids (MUFAs) to lysophosphatidylethanolamine (lyso-PE), resulting in the formation of MUFA-incorporated phosphatidylethanolamine (PE-MUFAs) while simultaneously reducing the cellular pools of polyunsaturated fatty acid-containing phosphatidylethanolamine (PE-PUFAs). This enzymatic activity has significant implications for ferroptosis regulation. Notably, MBOAT1/2's enzymatic activity influences the balance between saturated and monounsaturated fatty acids and PUFAs in cellular membranes. Although preferentially incorporating less oxidizable fatty acids (e.g., oleic acid, 18:1) into phospholipids, MBOAT2 may reduce the availability of peroxidation-prone PUFAs (e.g., arachidonic acid, 20:4), thereby conferring resistance to ferroptosis. This mechanism parallels the function of ACSL4, which promotes ferroptosis by enriching membranes with PUFA-containing phospholipids [ 140 ]. MBOAT1 and MBOAT2 are transcriptionally regulated by the estrogen receptor (ER) and androgen receptor (AR), respectively. ER or AR antagonists combined with ferroptosis inducers significantly inhibit the growth of ER-positive breast cancer or AR-positive prostate cancer cells [ 139 ]. MBOAT1/2 has emerged as a crucial regulator of ferroptosis, operating through lipid remodeling, hormone interactions, and engagement with essential metabolic enzymes to regulate ferroptosis. Its ability to influence membrane composition and susceptibility to peroxidation highlights its potential as a therapeutic target for cancer and other diseases. Future research should explore the tissue-specific functions of MBOAT1/2, its regulation by additional signaling pathways, and the development of selective modulators for clinical applications. In 2024, two research groups discovered the lathosterol oxidase (SC5D)/7-dehydrocholesterol (7-DHC) axis, another novel ferroptosis defense system [ 141 , 142 ]. These studies demonstrated that 7-DHC is an effective anti-ferroptotic metabolite and that the inhibition of 7-DHC biosynthesis is a potential strategy for cancer treatment. 7-DHC is an intermediate metabolite in the distal cholesterol biosynthesis pathway. Several metabolic enzymes are involved in its synthesis. HMG-CoA is reduced to mevalonate by the rate-limiting enzyme of cholesterol biosynthesis, HMG-CoA reductase. Mevalonate is then phosphorylated by mevalonate kinase to produce mevalonate-5-phosphate. Subsequent decarboxylation of mevalonate-5-phosphate yields isopentenyl pyrophosphate (IPP) through catalysis by phosphomevalonate decarboxylase. IPP undergoes isomerization to dimethylallyl pyrophosphate (DMAPP) through the action of an IPP isomerase. These C5 isoprenoid units are condensed by squalene synthase to form squalene, which is epoxidized by squalene epoxidase to generate 2,3-oxidosqualene. Cyclization of this intermediate by oxidosqualene cyclase (lanosterol synthase) produces lanosterol, the first sterol in this pathway. Lanosterol is progressively converted to lathosterol through a series of reductions catalyzed by lanosterol reductase. In the penultimate step of cholesterol biosynthesis, lathosterol is transformed into 7-dehydrocholesterol (7-DHC) by sterol-C5-desaturase (SC5D). The final conversion to cholesterol is mediated by 7-dehydrocholesterol reductase (DHCR7) [ 143 ]. 7-DHC serves as a potent anti-ferroptotic cholesterol intermediate. Its accumulation in cancer cells exhibits strong pro-tumor survival functions. This protective effect arises from 7-DHC, which can effectively shield the plasma membrane and mitochondrial phospholipids from oxidation and protect the cell membrane from free radical damage, thus suppressing ferroptosis.

Intracellular metal ions play essential roles in intracellular biochemistry and various metabolic processes. However, effectively targeting and regulating the application of metal ions in cancer therapy remains a considerable challenge. This review synthesizes the current developments in RCD, metal homeostasis, and the emerging signaling pathways underlying metalloptosis, with a particular focus on MNP-induced metalloptosis and its potential to overcome drug resistance. Although research on metalloptosis, a form of metal ion-based RCD, has made continuous progress and yielded new findings, several obstacles persist in its clinical application and translation into practice. First, the concentration of intracellular metal ions plays a crucial role in determining their dual functions within the cell, resulting in contradictory clinical outcomes in cancer . This underscores the urgent need for more detailed clinical trials to confirm these findings in the future. The challenges associated with the toxicity and safety of metal ion-based cell death remain significant barriers to clinical application. The relationship between the antitumor concentrations of various metal ions and their biochemical reactivity has not yet been fully elucidated. Moreover, many intracellular metal ions can induce cytotoxicity, ROS production, metabolic disturbances, and inflammatory responses when they reach specific concentrations, potentially harming the normal tissues. The concentration of metal ions varies significantly among intracellular organelles and is regulated by distinct signaling pathways. Consequently, designing chemistries that target specific cell death pathways involving metal ions poses particular challenges because of the complex signaling networks associated with various forms of cell death. The future focus of metalloptosis should be on designing and discovering organ- and cell-specific nanomedicine regulators for the controlled release of intracellular metal ions. Second, several critical questions remain unanswered, including the specific characteristics of the metalloptotic phenotype and the mechanisms that lead to metalloptosis. Furthermore, the development of metal-ion-based cell death chemistries is still ongoing. Investigating the molecular pathways of metalloptosis is essential for advancing metalloptosis in cancer treatment and for developing novel therapeutic strategies. As a newly identified form of RCD, metalloptosis necessitates precise definition, due to the various types of metalloptosis reported thus far, in addition to ferroptosis, cuproptosis, and calcicoptosis, the downstream molecular mechanisms of other types of metal ion (such as Mg 2+ , Zn 2+ , Mn 2+ , and Co 2+ )-induced cell death are still attributed to traditional forms of RCD. Although metalloptosis shows promising anticancer mechanisms across multiple tumor types (Table  2 ), fundamental challenges remain in comprehensively elucidating its molecular pathways and translating these insights into targeted therapies. The field urgently requires innovative approaches to decode the precise regulatory networks governing metalloptosis and develop corresponding therapeutic strategies. In the future, elucidating novel metalloptotic mechanisms triggered by metal overload will require a multidisciplinary approach that integrates in vitro models, animal studies, and clinical specimen analyses (Fig.  10 ). Future investigations should systematically evaluate the dose- and time-dependent effects of various metals across biological systems by assessing morphological alterations, cell viability, oxidative stress, ion dysregulation, and RCD pathway activation. The strategic application of metal-specific inhibitors and chelators is crucial for identifying and characterizing novel metal-dependent cell death modalities. Subsequent validation through orthogonal experimental systems, ranging from advanced drug-resistant cell culture models to preclinical and clinical studies, is essential to confirm these findings. Ultimately, deciphering novel metal-overload-induced cell death mechanisms will require coordinated efforts combining rigorous experimental design, innovative analytical methods and cross-disciplinary collaboration. Fig. 10 Future Directions for Metalloptosis Nanotherapeutics. Left: Metallomics, which employs -omics tools to explore the interactions between metal or metalloid elements and RCD, can elucidate metalloptosis processes and discover novel pathways. This methodology integrates metallomics and multiomics approaches. Subsequently, techniques such as mass spectrometry, flow cytometry, and immunofluorescence, among other experimental methods, have been utilized to identify new metalloptosis pathways. Center: Formulating effective strategies for the advancement of metalloptosis therapies involves identifying natural medicines and small molecular compounds, alongside the application of molecular engineering and nanobiotechnology, to develop precision metalloptosis therapies. Right: The development and evaluation of metalloptosis-inducing pharmaceuticals hold the potential to enhance treatment options for various cancer types Future Directions for Metalloptosis Nanotherapeutics. Left: Metallomics, which employs -omics tools to explore the interactions between metal or metalloid elements and RCD, can elucidate metalloptosis processes and discover novel pathways. This methodology integrates metallomics and multiomics approaches. Subsequently, techniques such as mass spectrometry, flow cytometry, and immunofluorescence, among other experimental methods, have been utilized to identify new metalloptosis pathways. Center: Formulating effective strategies for the advancement of metalloptosis therapies involves identifying natural medicines and small molecular compounds, alongside the application of molecular engineering and nanobiotechnology, to develop precision metalloptosis therapies. Right: The development and evaluation of metalloptosis-inducing pharmaceuticals hold the potential to enhance treatment options for various cancer types Notably, advances in nanotechnology have expanded the utility of metalloptosis in anticancer therapy [ 28 ]. MNPs can directly deliver metalloptosis-inducing agents to tumors, improving drug efficacy while minimizing the systemic toxicity associated with conventional chemotherapy. Although MNPs show therapeutic potential, their clinical application faces several challenges. First, biocompatibility and off-target toxicity remain significant concerns, as MNPs may inadvertently damage healthy tissues and malignant cells [ 502 ]. Second, prolonged systemic exposure can lead to the accumulation of MNPs, particularly in the liver and spleen, increasing the potential risk of long-term adverse effects. Further barriers to clinical translation include inefficient drug loading and suboptimal cellular uptake, which are exacerbated by discrepancies between in vitro efficacy and in vivo performance. Additionally, the protracted and complex development process of MNP-based therapeutics hinders their rapid translation into clinical applications [ 601 ]. Fully exploit the potential of MNPs in cancer theranostics, several critical research directions must be explored. First, systematic optimization of the physicochemical properties of MNPs, including their size, shape, and surface chemistry, is essential, as these parameters significantly influence tumor targeting, cellular uptake, and therapeutic efficacy across various cancer subtypes. Elucidating the precise mechanisms governing MNPs and cancer cell interactions will facilitate the rational design of nanoparticles and the identification of synergistic targets for combination therapies. While preclinical studies have shown promise, rigorous evaluation of long-term safety and therapeutic efficacy through controlled clinical trials remains crucial for successful translation. A major translational challenge is overcoming the biological barriers to targeted delivery, including immune clearance and tumor-specific accumulation of the drug. Innovative delivery strategies, such as stimuli-responsive carriers, could enhance the precision of MNPs in the treatment of malignancies. Finally, integrating MNPs with existing modalities (e.g., chemotherapy and radiotherapy) may yield dual benefits by amplifying antitumor effects and mitigating off-target toxicity. Such combinatorial approaches could redefine cancer treatment paradigms, provided that their mechanistic synergy and safety are thoroughly validated. To advance metalloptosis-based cancer therapies, future research should prioritize enhancing the specificity and biocompatibility of metalloptosis inducers. The emergence of multi-omics approaches, including proteomics, spatial transcriptomics, single-cell sequencing, and advanced mass spectrometry, coupled with artificial intelligence and pharmacological innovations, has created unprecedented opportunities to decipher the molecular mechanism of metalloptosis. These technological advances underscore the need for comprehensive investigations into the precise regulatory mechanisms underlying metalloptosis. By fostering interdisciplinary collaboration and leveraging these cutting-edge tools, we can potentially overcome therapeutic resistance and fully elucidate the anticancer pathways associated with metalloptosis, paving the way for novel treatment strategies (Fig.  10 ).

Copper, an essential transition metal that cycles between oxidized and reduced states, plays an essential role in diverse biological processes, including redox signaling, electron transfer reactions, and iron metabolism [ 160 ]. However, dysregulated copper accumulation disrupts cellular homeostasis and triggers RCD [ 161 ]. Cellular copper uptake in tumor cells is mediated by the copper transporter CTR1 (SLC31A1), which directly regulates intracellular copper concentration [ 162 ]. CTR1 specifically transports Cu(I) ions, requiring the reduction of circulating Cu(II) to Cu(I), a process catalyzed by STEAP family reductases [ 163 ] (Fig.  4 ). The reduced copper ions are then stabilized by two conserved His-Met-Asp clusters at CTR1's N-terminus, facilitating their subsequent transport into the cell [ 164 ]. ATP-dependent copper transporters, ATP7A/B, are well-characterized mediators of copper efflux that utilize ATP hydrolysis to export copper ions from metal-binding sites [ 57 ]. ATP7A/B orchestrates copper ion homeostasis by facilitating transmembrane transport and regulating intracellular copper distribution. Fig. 4 Copper-based RCD pathways. The figure shows five pathways of copper-based RCD, including copper-based cuproptosis, apoptosis, ferroptosis, autophagy, and necroptosis. Cuproptosis can be induced through four distinct mechanisms that increase intracellular free copper concentrations: (1) copper is directly transported into the intracellular by copper ionophores, such as ES and DSF; (2) Overexpression of SLC31A1; (3) BSO inhibits GSH synthesis and decreases the release of free copper ions; and (4) decreased copper output by knocking down ATP7B. In copper-based cuproptosis , elesclomol induces cuproptosis by mediating excessive Cu 2 ⁺ influx into the mitochondria, where mitochondrial ferredoxin 1 (FDX1) reduces the elesclomol-Cu 2 ⁺ complex to release cytotoxic Cu⁺ ions. The FDX1/LIAS complex serves as a master regulator of protein lipoylation, and its dysfunction impairs both lipoylation and iron-sulfur (Fe-S) cluster biosynthesis. Cu + triggers the aggregation of lipoylated TCA cycle enzymes (e.g., DLAT) in the mitochondria, inducing proteotoxic stress and subsequent cell death. Copper activates NPL4 to suppress ATP synthase ubiquitination and disrupts proteasomal function. FDX2 is an essential component of the Fe-S cluster biosynthesis machinery and functions as the sole electron donor for mitochondrial Fe-S cluster assembly by providing the required electrons. The Fenton-like reaction is the principal pathway for copper-dependent ROS production, wherein Cu 2+ is reduced to Cu⁺ by cellular reductants. The six-transmembrane epithelial antigen of the prostate (STEAP) catalyzes the reduction of Cu 2 ⁺ to Cu + and regulates cellular copper homeostasis. This redox cycling enables catalytic decomposition of H 2 O 2 , generating hydroxyl radicals (·OH) through continuous Cu + /Cu 2 ⁺ interconversion CTR1 (SLC31A1) functions as the primary high-affinity copper transporter mediating cellular copper uptake across the plasma membrane. The pathways related to copper-based ferroptosis include GPX4-Cu 2 ⁺, MAP1LC3, TAX1BP1, and NRF2/MAPK. The DSF/copper/NRF2/MAPK axis also regulates copper-based ferroptosis. DSF/Cu 2+ can promote ROS production, activate the JNK/P38 pathway, and induce copper-based apoptosis. Additionally, copper overload triggers apoptosis through mitochondrial pathway activation, and the key pathways related to copper-based apoptosis include the Cytoc/bax/AIF/cleaved-caspase9/3/cleaved-PARP axis. In the copper-based necroptosis pathway, CuS-MnS₂ nanoflowers generate reactive oxygen species (ROS) to induce necroptosis. Homocysteine (Hcy) and Cu 2+ cooperatively stimulate reactive nitrogen species (RNS) generation, triggering copper-based necroptosis. The key pathways in copper-based autophagy include TFEB, ATG5, Beclin-1, p-AMPKα, and P-ULK1. IL-1b/NLRP3/Caspase1/NLRP3. Inflammasome also regulates copper-based pyroptosis Copper-based RCD pathways. The figure shows five pathways of copper-based RCD, including copper-based cuproptosis, apoptosis, ferroptosis, autophagy, and necroptosis. Cuproptosis can be induced through four distinct mechanisms that increase intracellular free copper concentrations: (1) copper is directly transported into the intracellular by copper ionophores, such as ES and DSF; (2) Overexpression of SLC31A1; (3) BSO inhibits GSH synthesis and decreases the release of free copper ions; and (4) decreased copper output by knocking down ATP7B. In copper-based cuproptosis , elesclomol induces cuproptosis by mediating excessive Cu 2 ⁺ influx into the mitochondria, where mitochondrial ferredoxin 1 (FDX1) reduces the elesclomol-Cu 2 ⁺ complex to release cytotoxic Cu⁺ ions. The FDX1/LIAS complex serves as a master regulator of protein lipoylation, and its dysfunction impairs both lipoylation and iron-sulfur (Fe-S) cluster biosynthesis. Cu + triggers the aggregation of lipoylated TCA cycle enzymes (e.g., DLAT) in the mitochondria, inducing proteotoxic stress and subsequent cell death. Copper activates NPL4 to suppress ATP synthase ubiquitination and disrupts proteasomal function. FDX2 is an essential component of the Fe-S cluster biosynthesis machinery and functions as the sole electron donor for mitochondrial Fe-S cluster assembly by providing the required electrons. The Fenton-like reaction is the principal pathway for copper-dependent ROS production, wherein Cu 2+ is reduced to Cu⁺ by cellular reductants. The six-transmembrane epithelial antigen of the prostate (STEAP) catalyzes the reduction of Cu 2 ⁺ to Cu + and regulates cellular copper homeostasis. This redox cycling enables catalytic decomposition of H 2 O 2 , generating hydroxyl radicals (·OH) through continuous Cu + /Cu 2 ⁺ interconversion CTR1 (SLC31A1) functions as the primary high-affinity copper transporter mediating cellular copper uptake across the plasma membrane. The pathways related to copper-based ferroptosis include GPX4-Cu 2 ⁺, MAP1LC3, TAX1BP1, and NRF2/MAPK. The DSF/copper/NRF2/MAPK axis also regulates copper-based ferroptosis. DSF/Cu 2+ can promote ROS production, activate the JNK/P38 pathway, and induce copper-based apoptosis. Additionally, copper overload triggers apoptosis through mitochondrial pathway activation, and the key pathways related to copper-based apoptosis include the Cytoc/bax/AIF/cleaved-caspase9/3/cleaved-PARP axis. In the copper-based necroptosis pathway, CuS-MnS₂ nanoflowers generate reactive oxygen species (ROS) to induce necroptosis. Homocysteine (Hcy) and Cu 2+ cooperatively stimulate reactive nitrogen species (RNS) generation, triggering copper-based necroptosis. The key pathways in copper-based autophagy include TFEB, ATG5, Beclin-1, p-AMPKα, and P-ULK1. IL-1b/NLRP3/Caspase1/NLRP3. Inflammasome also regulates copper-based pyroptosis Cuproptosis, identified in 2022, primarily occurs in mitochondria. It is initiated by an increase in intramitochondrial Cu + concentration, leading to DLAT oligomerization [ 42 ]. Cuproptosis is mechanistically associated with oxidative stress. Copper drives its own intracellular accumulation by upregulating the copper transporters CTR1 and ATP7A, thereby potentiating cuproptosis through the FDX1-mediated activation of TCA cycle components under copper overload conditions [ 165 ]. Cuproptosis can be induced through four distinct mechanisms that increase intracellular free copper concentrations [ 44 ]: (1) copper is directly transported into the intracellular by copper ionophores, such as elesclomol (ES) and disulfiram (DSF); (2) Overexpression of SLC31A1; (3) BSO inhibits the GSH synthesis and decreases the release of free copper ions; (4) decreased copper output by knocking down ATP7B (Fig.  4 ). These processes contribute to the excessive accumulation of Cu + in the mitochondria. Mitochondrial copper transport across the inner membrane into the matrix is mediated by solute carrier family 25 member 3 (SLC25A3), a nuclear-encoded transmembrane transporter [ 161 ] (Fig.  4 ). The excess Cu + binds to the lipoyled DLAT, further resulting in DLAT oligomerization. ES binds ferredoxin 1 (FDX1), disrupting iron-sulfur (Fe–S) cluster biosynthesis [ 166 ]. Moreover, ES directly targets mitochondrial membranes, triggering membrane potential depolarization and subsequent ROS-dependent cell death. These findings align with the known interplay between copper-dependent RCD and mitochondrial metabolism. ES-Cu can induce a reduction in Fe-S stability, and the inactivation of Npl 4-p97 together contribute to copper-induced cell death [ 167 ]. Ferredoxin 1 (FDX1), as an upstream lipoylation key factor, plays a central role in the protein lipoacylation process which is involved in steroidogenesis, inhibiting the iron-sulfur cluster (Fe-S cluster) formation function, etc., can catalyze Cu 2+ to Cu + , and shows strong cytotoxicity. The most important characteristic of copper-based cuproptosis is that it can be rescued by copper chelators, whereas other inhibitors of regulatory cell death, such as ferroptosis, necroptosis, pyroptosis, and apoptosis, have no similar effect [ 42 ]. This evidence highlights the complex mechanism by which increased Cu + triggers cuproptosis. Copper ionophores, lipid-soluble molecules capable of reversible copper binding, have been instrumental in the discovery of copper-based cuproptosis and show promise as potential antitumor agents [ 168 ]. These compounds facilitate copper transport across cellular and mitochondrial membranes. Notably, DSF, an anti-alcoholism drug, exhibits copper ionophore activity that induces cell death by increasing the cellular levels of ROS [ 169 ]. In addition to ROS, the DSF-Cu complex promotes copper-dependent cell death by interacting with Npl4, a key component of the p97/VCP segregase complex. Copper impairs p97-mediated degradation of ubiquitinated proteins by binding to Npl4, potentially inducing protein aggregation [ 170 , 171 ]. Similarly, elesclomol (ES), another clinically investigated copper ionophore, has demonstrated potent cytotoxic effects [ 167 ]. In addition to copper-based cuproptosis, copper overload triggers other RCD pathways, including copper-based ferroptosis, apoptosis, necroptosis, and autophagy-dependent cell death (Table  2 , Fig.  4 ) [ 100 ]. Cuproptosis exhibits intricate crosstalk with other forms of RCD, and these interactions have substantial implications for cancer therapy. Emerging evidence demonstrates a robust mechanistic interplay between cuproptosis and ferroptosis mediated by shared regulatory factors. For example, Liu et al. demonstrated that exogenous copper directly binds to the cysteine residues C107 and C148 of GPX4, promoting its ubiquitination and aggregation. Their study further revealed that TAX1BP1 functions as a selective autophagy receptor that targets GPX4 for degradation, thereby driving copper-induced ferroptosis [ 153 ] (Fig.  4 ). Du et al. revealed that DSF/Cu enhances the anticancer effects of sorafenib and inhibits tumor progression in vitro and in vivo by concurrently blocking NRF2/MAPK signaling and triggering ferroptosis [ 172 ]. Copper ionophores induce cuproptosis in HCC cells and may activate ferroptosis [ 173 ]. Furthermore, in colorectal cancer cells, copper ionophores promote copper-dependent ferroptosis by degrading ATP7A [ 165 ]. Copper catalyzes the decomposition of hydrogen peroxide via Fenton-like and Haber–Weiss reactions, generating hydroxyl radicals and amplifying reactive oxygen species (ROS) production. Copper-driven oxidative stress may functionally intersect with multiple cell death pathways, including apoptosis [ 165 , 174 ]. For example, Patrick J. Farmer et al. demonstrated that DSF exhibits selective cytotoxicity against cultured melanoma cells, primarily inducing apoptosis while enhancing intracellular copper accumulation, with minimal effects on other tested cell lines [ 65 ]. Wang et al. found that the disulfiram/copper complex triggers ROS production and induces apoptosis in breast cancer cells through activation of JNK and p38 MAPK signaling pathways [ 175 ] (Fig.  4 ). Copper overload triggers hepatic apoptosis through mitochondrial pathway activation, as evidenced by mitochondrial membrane potential (MMP) depolarization and the dysregulation of apoptotic mediators. Key markers include the upregulation of cytosolic cytochrome c (Cyto c), apoptosis-inducing factor (AIF), endonuclease G (Endo G), Apaf-1, cleaved caspase-9/3, PARP cleavage, and pro-apoptotic Bcl-2 family members (Bak, Bax, and Bim), and the downregulation of anti-apoptotic proteins (Bcl-2 and Bcl-xL). Mechanistically, copper overload induces ROS-mediated oxidative stress and DNA fragmentation, and impairs antioxidant defenses, thereby amplifying mitochondrial apoptosis (Fig.  4 ) [ 176 ]. Cu exposure activates the NLRP3 inflammasome, triggering pyroptosis [ 165 ]. In vivo studies have further demonstrated that intracellular copper levels regulate NLRP3 inflammasome activation, as copper depletion markedly suppresses classical NLRP3-dependent pyroptosis in SOD1-deficient mice [ 177 ]. Copper overload triggers copper-based necroptosis via various molecular regulators. Zhang et al. discovered that homocysteine (Hcy) and Cu 2 ⁺ cooperatively stimulate ROS generation via NADPH oxidase (NOX) and nitric oxide (NO) through endothelial nitric oxide synthase (eNOS) (Fig.  4 ). The resultant overproduction of peroxynitrite (ONOO⁻) drives cardiac microvascular endothelial cell (CMEC) necroptosis [ 178 ]. Yuan et al. developed CuS–MnS₂ nanoflowers that potently generated ROS to induce necroptosis in ovarian cancer cells [ 179 ]. Together, these findings suggest that cuproptosis may interact with other types of RCD through multiple mechanisms that play a role in cancer therapy. Further investigations will help reveal the complex relationships between cuproptosis and diverse other RCD types and provide potential targets for the development of novel therapeutic strategies.

Different forms of cell death have specific biochemical and morphological characteristics, core target genes, and regulatory pathways [ 1 ]. Classical studies have long classified cell death into regulated cell death (RCD) and accidental cell death (ACD) [ 2 , 3 ]. RCD represents a form of cell death that can be regulated (induced, accelerated, inhibited, or blocked) [ 4 ]. In contrast, ACD refers to an unregulated form triggered by unexpected damaging stimuli that exceed the regulatory capacity of the cell, leading to cell death [ 3 ]. Apoptosis, the first identified RCD modality in 1972 [ 5 ], is regulated by anti-apoptotic proteins (Bcl-2/Bcl-w) and pro-apoptotic proteins (Bax/Bak) [ 6 , 7 ]. The hallmark characteristics of apoptosis include a decrease in mitochondrial membrane potential [ 8 ], the release of Cytochrome C into the cytosol, and the cleavage of caspase-3/8/9 and PARP proteins [ 9 ], which can be detected using the fluorescence probe Annexin V/PI and terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) kit [ 10 , 11 ]. Non-apoptotic RCD mainly includes autophagy-dependent cell death, lysosome-dependent cell death, necroptosis, pyroptosis, mitochondrial permeability transition (MPT)-driven necrosis, ferroptosis, cuproptosis, oxeiptosis, PANoptosis, entotic cell death, netotic cell death, alkaliptosis, parthanatos, and disulfidptosis [ 3 , 12 , 13 ] (Fig.  1 ). Targeting non-apoptotic RCD pathways is a promising strategy for overcoming tumor resistance [ 14 , 15 ]. Chemoresistance typically arises through several mechanisms, including drug inactivation or reduced activity, altered drug transport(increased efflux or decreased uptake), and evasion of apoptosis or ferroptosis [ 16 , 17 ]. Emerging evidence demonstrates that pharmacological induction of non-apoptotic RCD, either via chemotherapy agents alone or in combination with small molecules or nanomedicines, can effectively overcome these resistance pathways [ 12 , 18 – 20 ]. This approach opens new therapeutic opportunities when integrated with complementary modalities such as radiotherapy, ultrasound, hyperthermia, and immuno-oncology strategies [ 18 , 21 , 22 ]. Fig. 1 Timeline on the discovery of multiple forms of RCD, including metalloptosis. Apoptosis, the first characterized RCD subroutine, was identified in 1972, followed by the successive discoveries of non-apoptotic RCD subroutines. Manganism emerged as a pivotal metalloptosis subtype in 1837, followed by the discovery of calcicoptosis in 2003, lysozincrosis in 2021, ferroptosis in 2012, cuproptosis in 2022, and necrosis by sodium overload (NECSO) in 2025 Timeline on the discovery of multiple forms of RCD, including metalloptosis. Apoptosis, the first characterized RCD subroutine, was identified in 1972, followed by the successive discoveries of non-apoptotic RCD subroutines. Manganism emerged as a pivotal metalloptosis subtype in 1837, followed by the discovery of calcicoptosis in 2003, lysozincrosis in 2021, ferroptosis in 2012, cuproptosis in 2022, and necrosis by sodium overload (NECSO) in 2025 Metal ion-dependent RCD refers to RCD mediated by metal ions, including ferroptosis, cuproptosis, lysozincosis, manganism, calcicoptosis, and necrosis by sodium overload (NECSO) [ 23 – 27 ]. Wang et al. termed this metal ion-induced cell death as"metalloptosis" [ 28 ]. These RCD forms are modulated by diverse intracellular metal ions and exhibit distinct morphological characteristics (Table  1 ). Essential metal elements, including sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), and trace elements such as iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), and molybdenum (Mo), play vital roles in numerous biological processes [ 29 ]. These metals function as enzymatic cofactors that stabilize protein structures and enhance catalytic activity [ 30 ], and are also involved in various cell signaling pathways. Notably, Zn and Ca are indispensable for some cell differentiation and gene expression signaling pathways [ 31 ], Zn and Mg promote DNA replication and repair processes [ 32 ], and Fe and Cu particularly contribute to redox homeostasis maintenance by improving the efficiency of electron transfer between molecules [ 33 ]. Crucially, the disruption of metal homeostasis can trigger pathological consequences, including diverse forms of cell death that drive disease progression. Table 1 Morphological features of various regulated cell death induced by intracellular metal ions Types Morphological feature Key pathway regulators Cancer type Metal ion Ref Apoptosis Nuclear membrane rupture, apoptosome formation PARP, Caspase family(caspase3/6/7), BAX, BCL-2, p53 Multiple cancers Ca 2+ , Fe 2+ , Cu 2+ , Zn 2+ , Co 2+ , Mg 2+ [ 58 – 65 ] Autophagy-dependent cell death Autophagosomes, mitophagy, lysosomes fusion P53, SQSTM1, LC3, HPCAL1, Beclin1, ERK, AMPK/mTOR Breast cancer Cu + , Zn 2+ , Ca 2+ [ 66 – 70 ] Lysosome-dependent cell death Lysosome membranerupture, release of lysosomal cathepsin TRPML1, LAMP3, GLP-1R, p53, Cathepsins Melanoma, lung cancer Zn 2+ , Ca 2+ [ 45 , 71 ] Pyroptosis Formation of inflammasomes Caspase-1, Caspase-3, Caspase-4, Caspase-5, Caspase-11, GSDMD, GPX4, eEF-2 K Multiple cancers Mn 2+ , Zn 2+ [ 72 – 76 ] MPT-driven necrosis Mitochondria permeability transition pore (MPTP) opening, and mitochondrial membrane depolarization, plasma membrane rupture Cyclophilin D Breast cancer, lung cancer Ca 2+ [ 77 , 78 ] NETotic cell death Formation of neutrophil extracellular traps Integrin-αvβ1, MMP9 Lung cancer Ca 2+ [ 79 – 81 ] Necroptosis Cell swelling, formation of necrosome TNFR1, RIPK1, RIPK3, MLKL Basophilic leukemia Pb 2+ , Cr +6 [ 82 , 83 ] Immunogenic cell death release of Damage Associated Molecular Patterns (DAMPs) Calreticulin (CRT), ATP, and HMGB1 Breast cancer Fe 2+ , Mn 2+ [ 84 , 85 ] Entotic cell death Cells"cannibalism" Orai1, Stim2, MLC, SEPT2 Breast cancer Ca 2+ [ 86 ] Calcicoptosis Increased cytoplasmic Ca 2+ concentration, mitochondrial dysfunction SOD, POD, CAT, GR Glioblastoma Ca 2+ [ 48 , 87 ] Parthanatos Membrane rupture, massive DNA strand breaks PARP-1, AIF, MIF Multiple cancers [ 88 , 89 ] Ferroptosis Mitochondrial shrinking, mitochondrial membrane rupture and lipid peroxidation SLC7A11, GPX4, LOX, NCOA4, NRF2, ZIP7 Multiple cancers Fe 2+ , Zn 2+ [ 90 – 92 ] Alkaliptosis Cell swelling, membrane rupture, leakage of cellular contents NF-kB, STAT3, IKBKG Multiple cancers [ 15 , 93 ] Oxeiptosis Cell nuclear condensation, DNA damage, membrane rupture KEAP1, PGAM5, AIFM1 Multiple cancers Ca 2+ [ 94 , 95 ] Cuproptosis Mitochondrial condensation, mitochondrial membrane rupture Fe-S cluster biosynthesis ruduce, FDX1, P53, DLAT, LIAS, HSP70 Glioblastoma, lung cancer Cu 2+ [ 96 , 97 ] Disulfidptosis Disruption of disulfide homeostasis during biological processes, excess disulfides GYS1 Breast cancer  / [ 98 ] NECSO Cell swelling, cell membrane rupture, leakage of cellular contents TRPM4 Breast cancer Na + [ 50 ] Morphological features of various regulated cell death induced by intracellular metal ions Cell swelling, cell membrane rupture, leakage of cellular contents Recent advances have significantly expanded our understanding of the mechanisms underlying metalloptosis, revealing multiple targetable pathways for therapeutic intervention. Notably, intracellular metal ion dysregulation, whether due to deficiency or excess, is a critical modulator of metalloptosis that disrupts key signaling cascades. Ferroptosis, an Fe 2 ⁺-dependent RCD first reported in 2012, is characterized by distinctive morphological and mechanistic features compared to other forms of RCD [ 3 , 34 ]. This process is initiated by the Fe 2 ⁺- catalyzed Fenton reaction, leading to membrane polyunsaturated fatty acids lipid peroxidation [ 35 , 36 ]. The accumulation of lipid peroxides in the cell membrane ultimately disrupts membrane integrity, leading to cell death [ 37 , 38 ]. Ferroptosis is governed by distinct metabolic pathways [ 39 , 40 ], and is protected by multiple defense systems [ 19 , 41 ]. Cuproptosis was identified by Tsvetkov et al. in 2022 as a novel form of RCD primarily induced by excess mitochondrial Cu [ 42 ]. Its hallmark is copper overload-induced abnormal oligomerization of lipoylated proteins in the tricarboxylic acid (TCA) cycle and depletion of Fe-S cluster proteins [ 43 , 44 ]. Lysozincrosis is lysosomal Zn-dependent cell death, recently identified in 2021 [ 45 ]. This process is mediated by mucolipin TRP channel 1 (TRPML1), a lysosomal Ca 2 ⁺/Zn 2 ⁺ release channel that is frequently upregulated in cancer cells. Synthetic TRPML1 agonists trigger lysozincrosis through mitochondrial swelling and dysfunction, demonstrating significant antitumor efficacy in metastatic melanoma models [ 45 ]. Importantly, the restricted expression of TRPML1 in malignant cells creates a therapeutic window, as normal cells remain resistant to agonist-induced lysozincrosis. Manganism, a neurological disorder resulting from chronic manganese exposure, was first clinically characterized by Couper et al. in 1837 [ 46 ]. It manifests as a triad of motor impairments (tremors, rigidity, and bradykinesia), speech dysfunction, and neuropsychiatric symptoms, including depression and cognitive deficits. Chronic Mn accumulation induces irreversible neurotoxicity through selective neuronal damage, particularly in basal ganglia circuits [ 47 ]. Calcicoptosis is a form of programmed cell death initiated by Ca 2+ overload [ 48 ].Calcium-triggered RCD usually involves the disorder of intracellular and extracellular calcium ions leading to cell death, which is a comprehensive manifestation of multiple cell death processes [ 49 ]. NECSO, identified by Fu et al. in 2025, is a programmed necrosis pathway induced by necrocide 1 (NC1) through TRPM4-dependent sodium influx [ 50 ]. NC1 selectively activates human TRPM4, a nonselective monovalent cation channel, promoting Na + accumulation and necrotic cell death. Genetic ablation of TRPM4 confers complete resistance to NC1-induced NECSO. In addition to these established forms of metalloptosis, the dysregulation of intracellular metal ions contributes to various other RCD processes, including apoptosis, autophagy, and necroptosis, wherein the molecular crosstalk between metalloptosis and other RCD modalities remains poorly understood. Elucidating the molecular mechanisms of metalloptosis and its interplay with other metal ion-dependent RCD pathways is a critical research priority that will advance novel therapeutic strategies against cancer. However, the clinical translation of metalloptosis-based cancer therapy faces significant challenges, particularly in achieving tumor-specific metal ion delivery and precise control of the concentration. Emerging nanomedicine and nanotechnology innovations offer substantial potential. Accumulating evidence highlights the promise of metal ion-driven nanotherapeutics for cancer treatment [ 51 , 52 ]. Nanotechnology tools have been widely employed to develop next-generation drug delivery systems, uniquely positioned to overcome drug resistance and enhance therapeutic efficacy [ 53 , 54 ], with the advantages of improved bioavailability, reduced adverse effects, and enhanced patient compliance [ 55 , 56 ]. Notably, studies have demonstrated the significant potential of ferroptosis-or cuproptosis-driven nanotherapeutics to reverse drug resistance in anticancer treatment and the synergistic effect of metal nanoparticles combined with other therapeutic modalities [ 17 , 20 , 57 ]. This review summarizes the key pathways of metalloptosis (primarily ferroptosis, cuproptosis, lysozincrosis, manganism, calcicoptosis, and NECSO) and the current advances in nanotherapeutics for metalloptosis in cancer. We discuss the regulatory mechanisms, recent advances, and effects of metalloptosis on malignant progression. In addition, the role of intracellular metal ion-triggered RCD in cancer is briefly outlined. We summarize the roles of metal ions and metalloptosis in tumor progression and immunomodulation in the TME based on recent evidence. Furthermore, we examined the impact of modulating metalloptosis for cancer therapy and its potential in reversing drug resistance, as well as the advantages of metal-nanoparticle-based cancer treatment. Finally, we discuss the prospects, opportunities, and challenges of targeting metal-ion- based RCD in cancer therapy.

Metastasis is the principal cause of cancer mortality and the most clinically challenging aspect of malignant progression worldwide. This multifaceted process is orchestrated by diverse signaling networks that regulate the proliferative, invasive, motile, and adhesive behaviors of cells [ 284 , 285 ]. Notably, metal ions, particularly iron and copper, are critical cofactors for many metastasis-associated proteins and enzymes. Their dysregulated accumulation is frequently correlated with advanced cancer [ 286 ]. Previous studies have identified metal homeostasis as an attractive therapeutic target for novel antimetastatic strategies [ 287 ]. Beyond their physiological roles, the unique redox-active properties and biological mimicry of metal ions offer additional opportunities for the selective targeting of aggressive malignancies. This section examines the essential roles of metals (focusing on iron and copper) in metastatic progression and highlights emerging therapeutic approaches that exploit metal biology to inhibit cancer dissemination. Iron is an indispensable transition metal that participates in fundamental biological processes, such as oxygen transport, mitochondrial respiration, ATP generation, and DNA synthesis [ 288 ]. In biological systems, iron primarily exists in two redox states, ferrous (Fe 2 ⁺) and ferric (Fe 3 ⁺), with its reactivity governed by electron transfer capacity [ 289 ]. Cellular iron homeostasis is precisely regulated by coordinated mechanisms that control iron uptake, utilization, storage, and export [ 290 ]. Notably, iron dysregulation has been implicated in tumor initiation and progression across multiple cancer types [ 291 ], positioning iron metabolism as a promising therapeutic target for anticancer strategies. Ferroptosis exhibits a double-edged sword effect in tumorigenesis, promoting or inhibiting cancer progression depending on the cellular milieu. Ferroptosis can be induced by p53 via SLC7A11 repression, whereas tumor-associated SLC7A11 overexpression confers ferroptosis resistance and bypasses p53(3KR)-mediated tumor growth suppression [ 110 , 292 ]. Ferroptosis is a vital regulator of the proliferation and malignant progression of several types of tumor cells, such as RCC, diffuse large B-cell lymphoma, and ovarian and melanoma cancer cells [ 293 , 294 ]. Costanzo et al. demonstrated that ECM-detached PEO1 ovarian cancer cells upregulated iron acquisition and storage pathways to confer resistance to ferroptosis [ 295 ]. These findings suggest that targeting ferroptosis in 3D tumor spheroids is a promising therapeutic strategy for blocking metastatic progression in ovarian cancer. Although cancer cell proliferation inherently elevates ROS levels, malignant cells defend themselves against oxidative stress through enhanced antioxidant mechanisms. This adaptive redox balance permits ROS-mediated proliferative signaling while maintaining oxidative stress below the ferroptosis threshold [ 296 , 297 ]. Artemisinin derivatives suppress the proliferation of ovarian tumor cells by upregulating ROS generation and triggering ferroptosis [ 298 ]. Dong et al. demonstrated that CircTMEM87A enhances gastric cancer cell proliferation and migration, while suppressing both apoptosis and ferroptosis through miR-1276-mediated upregulation of SLC7A11 [ 299 ]. Ferroptosis critically regulates metastatic dissemination, with melanoma cells exhibiting preferential lymphatic spread owing to the distinct biochemical composition of the lymph. Compared with blood plasma, lymph contains elevated GSH and oleic acid levels and reduced free iron concentrations, collectively creating an oxidative stress-protected niche that suppresses ferroptosis and facilitates metastatic progression [ 300 ]. The long non-coding RNA BDNF-AS exerts oncogenic functions in gastric cancer (GC) and peritoneal metastasis (PM) by conferring resistance to ferroptosis. Mechanistically, BDNF-AS recruits WDR5 to epigenetically regulate FBXW7 transcription, resulting in FBXW7-mediated ubiquitination and subsequent degradation of VDAC3 [ 301 ]. Metastatic cancer cells are characterized by persistent GPX4 expression. GPX4 silencing induces ferroptosis and potently suppresses tumorigenic and metastatic potential [ 302 ]. Guan et al. established that ferroptosis activation through both ferritinophagy and KEAP1/NRF2/HO-1 signaling converges to inhibit EMT progression in GC [ 303 ]. Therapeutic induction of ferroptosis through GPX4 inhibition, GSH depletion, and iron accumulation is a promising strategy for targeting metastatic cancers. Copper (Cu) is an essential enzymatic cofactor in fundamental metabolic processes that simultaneously regulates neoplastic proliferation and metastasis. Strikingly, tumor cells maintain elevated Cu levels compared to normal tissues, creating a pro-tumorigenic environment that drives malignant growth and tumor dissemination. Both copper deficiency and excess disrupt systemic homeostasis, indicating that precise regulation of copper homeostasis is required for physiological function [ 163 ]. Cancer cells display markedly increased Cu requirements compared to normal cells, reflecting their heightened metabolic activity [ 304 ]. Clinically, it is evidenced by consistently elevated serum copper levels in multiple cancer types [ 305 – 307 ]. Accumulation of intracellular Cu in malignancies orchestrates key oncogenic processes by modulating critical signaling pathways involved in proliferation, angiogenesis, and metastasis, thereby driving tumor progression. Paradoxically, elevated intracellular Cu concentrations can exert tumor-suppressive effects, as evidenced by multiple studies demonstrating the anticancer activity of Cu in malignant cells [ 308 ]. Copper chelation disrupts mitochondrial oxidative phosphorylation, thereby suppressing metastatic progression in triple-negative breast cancer (TNBC). Within primary tumors, highly metastatic SOX2/OCT4 + TNBC cells display elevated intracellular copper levels and are highly vulnerable to tetrathiomolybdate [ 309 ]. Serum copper levels progressively increase during cancer progression, indicating a strong correlation with both tumor incidence and burden. Furthermore, Cu ions directly activate key pro-angiogenic factors, including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), tumor necrosis factor-α (TNF-α), and interleukin (IL) signaling pathways [ 310 ]. Copper (Cu) modulates HIF-1α expression to promote tumor angiogenesis through vascular endothelial growth factor (VEGF) production [ 311 , 312 ]. Notably, recent studies have identified FDX1 as a key mediator of cuproptosis in endometriosis through the regulation of the G6PD pathway, effectively suppressing endometrial cancer cell proliferation and metastasis [ 313 ]. Copper (Cu) activates AKT, promoting substrate phosphorylation and subsequent tumorigenesis [ 314 ]. Moreover, Cu directly potentiates MEK1 kinase activity, enhancing ERK1/2 phosphorylation and MAPK pathway activation to drive tumor cell proliferation [ 315 ]. Clinical studies have revealed significant dysregulation of copper (Cu) homeostasis across multiple malignancies, with elevated Cu levels observed in both tumor tissues and serum of patients with lung cancer [ 316 ], breast cancer [ 317 ], leukemia [ 318 ], and prostate cancer [ 319 ]. This consistent Cu imbalance may drive tumor progression, enhance invasiveness, and contribute to therapeutic resistance [ 320 ]. Copper (Cu) is essential for autophagic kinase activity, as it directly binds to ULK1/2. Genetic ablation of the Cu transporter Ctr1 or ULK1 mutations that impair Cu binding attenuates ULK1/2-dependent signaling and autophagosome formation. Notably, intracellular Cu accumulation promotes starvation-induced autophagy by enhancing ULK1 kinase activity and the subsequent autophagic flux [ 321 ]. Pro-inflammatory signaling drives colorectal carcinogenesis via an IL-17/NF-κB-dependent mechanism that transcriptionally activates copper uptake pathways, establishing a critical link between inflammation and copper dysregulation during cancer progression [ 322 ]. Mounting evidence indicates that tumor metastasis involves the suppression of multiple RCD pathways, whereas therapy-induced RCD can effectively block metastatic progression [ 302 , 323 ]. These findings highlight the critical need to develop novel RCD-targeting strategies to constrain tumor proliferation and dissemination. Cuproptosis, a copper-dependent cell death intrinsically linked to mitochondrial metabolism, is a critical regulator of tumor proliferation and metastatic progression [ 174 , 324 , 325 ]. Cuproptosis may exert dual antitumor effects by simultaneously suppressing malignant cell proliferation and blocking metastasis. Intriguingly, cancer cells have evolved adaptive mechanisms to evade cuproptosis and ensure survival. Zhang et al. revealed marked downregulation of FDX1, the central regulator of cuproptosis, in HCC patients, conferring tumor cell resistance to the cuproptosis pathway [ 326 ]. Additionally, arecoline-mediated cuproptosis inhibition markedly enhanced cancer-associated fibroblast (CAF) viability in oral squamous cell carcinoma (OSCC) patients with betel nut consumption [ 327 ]. This finding holds clinical significance because CAFs actively drive tumor progression by facilitating epithelial-mesenchymal transition (EMT), promoting metastasis, and conferring chemotherapy resistance [ 328 , 329 ]. MEMO1, a Cu(I)-binding oncoprotein, drives the metastasis of breast cancer. Contrary to the initial models suggesting Cu(II)-mediated ROS production, Zhang et al. showed that it protects against copper redox activity [ 330 , 331 ]. Cu ions drive tumor cell invasion and metastasis by biochemically activating critical enzymes involved in cellular metabolism and proliferation [ 332 , 333 ]. For instance, the copper-binding protein MEMO1 orchestrates metastatic progression in breast cancer through the coordinated regulation of cell migration, invasion, and distant lung colonization [ 330 ]. Therefore, targeting the Cu(I)-binding site in MEMO1 represents a promising therapeutic strategy for disrupting copper homeostasis and inhibiting tumor cell metastasis. Cu serves as an essential cofactor for mitochondrial oxidative phosphorylation (OXPHOS), fueling the heightened energy demands of rapidly proliferating malignant cells [ 174 ]. Beyond its classical role as a metalloenzyme cofactor, Cu has emerged as a master regulator of oncogenic signaling and gene expression networks. This essential metal orchestrates multiple facets of cancer biology by simultaneously modulating mitochondrial function, glycolytic flux, lipid metabolism, and tumor microenvironment (TME) remodeling, collectively driving tumor proliferation, angiogenesis, metastasis, and therapeutic resistance [ 334 ]. Although these findings establish important foundations, the prevalence and functional significance of cuproptosis in diverse cancer types remain poorly characterized. Systematic investigations using complementary in vitro and in vivo models are essential to define the precise role of cuproptosis in regulating tumor proliferation and metastatic dissemination.

The tumor microenvironment (TME) critically regulates tumor development, progression, and therapeutic responses through complex signaling networks that influence chemosensitivity, angiogenesis modulation, and malignant cell survival [ 335 – 337 ]. Metal ions serve as key regulators of immune cell crosstalk, modulating intercellular signaling pathways and cell interactions [ 338 ]. The TME comprises diverse non-malignant components that functionally interact with tumor cells, including immune cells, cancer-associated fibroblasts (CAFs), endothelial cells, mesenchymal stem/stromal cells (MSCs), and non-cellular elements [ 337 , 339 ]. Metal ions serve as fundamental regulators of immune homeostasis through three key mechanisms: controlling immune cell proliferation and effector functions, modulating intercellular communication networks, and influencing cellular differentiation and secretory programs [ 247 ]. These coordinated actions enable metal ions to systemically regulate innate and adaptive immunity. Iron metabolism actively shapes the immune microenvironment in both inflammatory and infectious disease states and in cancer-associated inflammation [ 340 ]. Iron metabolism critically regulates multiple facets of tumor biology and therapy resistance by modulating cancer stemness properties [ 341 ], regulating cellular senescence programs, controlling iron metabolism-related protein expression, orchestrating antitumor immune responses [ 342 ], and remodeling the tumor immune microenvironment [ 343 , 344 ]. Elevated intracellular iron levels in cancer stem cells (CSCs) drive the hyperactivation of the IL-6/STAT3 pathway, thereby enhancing CSC invasiveness and metastatic potential [ 345 ]. Raggi et al. demonstrated that iron supplementation promotes oncogenic reprogramming by upregulating stemness markers and inducing an increase in EMT transcription factors, whereas iron chelation effectively reverses the protumorigenic effects [ 346 ]. Cancer-associated fibroblasts (CAFs) drive tumor progression via iron dysregulation pathways in the tumor microenvironment. Emerging research has revealed that CAF-derived IL-6 upregulates hepcidin expression in breast cancer cells [ 347 ]. This iron regulatory axis can be disrupted by IL-6 blockade. These findings establish that iron metabolism is a critical regulator of EMT, cancer stemness, and the TME, revealing a mechanistic link between iron homeostasis and malignant progression. IFN-γ plays an essential role in regulating the TME during ferroptosis. For example, elevated APOL3 expression correlates with enhanced ferroptosis sensitivity and improved antitumor capacity in CD8 + T cells. Mechanistically, the APOL3-LDHA axis promotes tumor ferroptosis while boosting CD8 + T cell cytotoxicity by modulating IFN-γ production and reducing lactate accumulation in the tumor microenvironment [ 348 ]. Moreover, Zou et al. revealed that CD8 + T cell-derived IFN-γ synergizes with arachidonic acid (AA) to drive immunogenic tumor ferroptosis through ACSL4 upregulation, altered lipid metabolism favoring AA incorporation into C16/C18 phospholipids, and enhanced sensitivity to palmitoleic/oleic acid-induced ferroptosis [ 349 ]. IFN-γ signaling synergizes with specific fatty acids to drive tumor ferroptosis, revealing a key effector mechanism of cytotoxic T lymphocyte (CTL) antitumor activity. Additionally, the cholesterol-rich TME upregulates CD36 expression in tumor-infiltrating CD8 + T cells, promoting tumor progression by attenuating IFN-γ production and enhancing lipid peroxidation and ferroptosis susceptibility. Notably, CD36 ablation in effector CD8 + T cells restored antitumor function by increasing IFN-γ secretion and potentiating tumor cell eradication [ 350 ]. TAMs exhibit heterogeneous ferroptosis susceptibility, which correlates with their immunosuppressive capacity. Specifically, M2-polarized TAMs show heightened ferroptosis vulnerability owing to reduced inducible nitric oxide synthase (iNOS) expression. The consequent decrease in nitric oxide (NO•) availability limits radical-mediated termination of lipid peroxidation cascades, thereby promoting ferroptotic cell death in this subset [ 351 ]. Recent studies have shown that neutrophil ferroptosis plays a crucial role in regulating the TME. For example, Zeng et al. revealed that neutrophils in chemoresistant breast cancer exhibit increased susceptibility to ferroptosis. These ferroptotic neutrophils secrete immunosuppressive mediators, including PGE2, IDO, and oxidized lipids, which impair CD8 + T cell proliferation and cytotoxic function. Intriguingly, neutrophil ferroptosis was linked to a unique IL1 β  + CXCL3 + CD4 + T cell subset (Fer-CD4), which was markedly enriched in chemoresistant tumors [ 352 ]. Fer-CD4 T cells perpetuated neutrophil recruitment via CXCL3, IL8, and S100A9 secretion, establishing a feedforward loop wherein ferroptotic neutrophils further promoted Fer-CD4 T cell differentiation. In spontaneous tumor models, disrupting this crosstalk, either by targeting IL1 β  + CD4 + T cells or IL1R1 + neutrophils, reduced neutrophil ferroptosis, restored antitumor immunity, and sensitized tumors to chemotherapy. Together, these findings delineate the critical role of neutrophil ferroptosis in shaping the immunosuppressive TME and identify novel therapeutic targets to overcome chemoresistance in breast cancer. Moreover, Zhao et al. identified aconitate decarboxylase 1 (Acod1) as the most significantly upregulated metabolic enzyme in tumor-infiltrating neutrophils (TINs) in both mouse and human tumors [ 353 ]. Mechanistically, GM-CSF-JAK/STAT5-C/EBP β signaling activates Acod1 to generate itaconate, which confers ferroptosis resistance in TINs via NRF2-mediated antioxidant defense. Genetic ablation of Acod1 reduced TIN accumulation, suppressed metastatic progression, enhanced antitumor T cell responses, and synergized with immune checkpoint blockade. This study uncovers a critical immunometabolic axis whereby Acod1-driven itaconate production enables TIN survival in the tumor microenvironment and identifies Acod1 inhibition as a promising strategy to overcome immunosuppression and enhance immunotherapy efficacy against metastatic disease. Additionally, pathologically activated neutrophils (PMNs), referred to as myeloid-derived suppressor cells (PMN-MDSCs), undergo spontaneous ferroptosis in the tumor microenvironment. While this process reduces PMN-MDSC abundance, it also generates oxygenated lipids that impair T cell function in both human and mouse models. In immunocompetent models, genetic or pharmacological inhibition of ferroptosis disrupts PMN-MDSC-mediated immunosuppression, delays tumor progression, and synergizes with immune checkpoint blockade to enhance antitumor immunity. In contrast, ferroptosis induction accelerates tumor growth [ 354 ]. These findings establish ferroptosis as a key immunosuppressive mechanism of PMN-MDSCs and highlight their potential as a therapeutic target. . Strategically modulating this pathway may offer a novel approach to curbing tumor progression in the future. Notably, recent studies have revealed that tumor-infiltrating natural killer (NK) cells display hallmark features of ferroptosis, including elevated lipid peroxidation and oxidative damage. Human NK cell dysfunction results from lipid peroxidation-induced oxidative stress, which disrupts the glycolytic metabolism. Pharmacological activation of the NRF2 antioxidant pathway rescued both the metabolic activity and cytotoxic function of NK cells, significantly enhancing their antitumor efficacy in vivo [ 355 ]. Notably, early stage ferroptotic cancer cells drive dendritic cell (DC) maturation and induce a protective, vaccination-like T cell response, highlighting their immunomodulatory potential [ 356 ]. The transcription factor NRF2 is a key suppressor of ferroptosis. It is activated downstream of oncogenic signals, including c-MYC, KRAS, and BRAF. Paradoxically, while genetic or pharmacological inhibition of NRF2 enhances ferroptosis, emerging evidence suggests that this may accelerate malignant progression in certain contexts [ 357 , 358 ] . Tumor cells play a pivotal role in shaping the immunostimulatory TME, providing new opportunities for developing novel cancer immunotherapy strategies. Cu ions serve as essential cofactors for immune cell activation and orchestrate diverse functions across multiple cell types. As a critical trace element, Cu potentiates T cell responses by enhancing T cell receptor (TCR) signaling to amplify antigen sensitivity and activate proliferative pathways (MAPK/ERK and PI3K/AKT) to drive T cell proliferation and differentiation [ 44 , 160 ]. The MAPK/ERK signaling axis is indispensable for T cell activation and proliferation. Copper ions potentiate these processes by activating the ERK pathway and thereby enhancing antitumor immunity. Strikingly, copper bioavailability exhibits a biphasic effect on T cell function; while deficiency impairs immune responses, optimal levels augment antitumor activity, and excess induces either proliferative arrest or apoptosis [ 359 ]. Copper ions orchestrate innate and adaptive immune responses through multiple mechanisms, including enhancing macrophage antioxidant defense and phagocytic activity via copper-zinc superoxide dismutase activation [ 360 ]. Copper modulates the cytotoxicity of natural killer (NK) cells and their cytokine production. This modulation enhances NK cell-mediated elimination of infected and malignant cells, optimizes antigen presentation, and improves T cell priming capacity. Additionally, copper regulates NF-κB signaling, thereby balancing the secretion of inflammatory cytokines and the intensity of the inflammatory response [ 160 ]. Cu ions serve as critical metabolic regulators, sustaining the bioenergetics of immune cells to meet the heightened demands for activation and effector functions. Furthermore, they coordinate immune cell trafficking and spatial organization by modulating intercellular communication, thereby optimizing immune surveillance and response fidelity. Collectively, these pleiotropic functions establish Cu as a master regulator of immune homeostasis and host defense mechanisms. Cu 2 ⁺ remodels the TME by inducing M1 macrophage polarization [ 360 ] and modulating angiogenesis [ 42 ], thereby exerting a dual effect on tumor growth and dissemination. Cu ions serve as crucial mediators of redox homeostasis by enhancing antioxidant enzyme activity, thereby safeguarding immune cells from oxidative damage and preserving their effector functions [ 361 ]. Notably, oxidative stress exerts dual oncogenic effects by promoting tumor progression and impairing the activity of immune cells. Copper-mediated antioxidant activity sustains immune cell function while amplifying tumoricidal capacity. Cu serves as an essential cofactor for mitochondrial oxidative phosphorylation (OXPHOS), which fuels the increased energy demands of rapidly proliferating tumor cells [ 300 ]. In addition to disrupting mitochondrial homeostasis, elevated copper levels reprogram the TME to drive oncogenic processes including proliferation, metastatic dissemination, and therapy resistance [ 334 ]. Notably, copper-based cuproptosis may directly modulate antitumor immunity within the TME [ 362 , 363 ]. Transcriptomic analysis of triple-negative breast cancer (TNBC) has revealed two molecularly distinct cuproptosis-related gene (CRG) signatures with divergent immune infiltration profiles. These CRG clusters significantly associated with patient survival outcomes, TME characteristics, and clinicopathological parameters, positioning them as promising predictive biomarkers for TNBC progression and therapeutic response [ 364 ]. CRGs modulate immune cell infiltration patterns directly through TME remodeling and indirectly via the regulation of cuproptosis-related lncRNA networks. Clinically, patients with lung adenocarcinomawith high cuproptosis-related lncRNA-based risk scores exhibit increased immune evasion and reduced response to immunotherapy, highlighting the therapeutic relevance of copper-regulated immune modulation [ 365 ]. LIPT1, a key CRG, exhibits dual immunomodulatory effects, positive correlation with PD-L1 expression and negative association with regulatory T cell (Treg) infiltration [ 366 ]. These findings suggest that combining cuproptosis inducers with PD-L1-targeted immune checkpoint blockade may enhance therapeutic efficacy. In esophageal squamous cell carcinoma, aberrant overexpression of CRGs is anomalously associated with increased infiltration of bystander T-cells, suggesting a potential dysregulation of copper-mediated immune surveillance [ 367 ]. Copper dysregulation in tumor-associated immune cells modulates the TME through pleiotropic mechanisms. Notably, the upregulation of the copper-dependent enzyme lysyl oxidase (LOX) in M2-polarized macrophages (THP-1-derived MΦs) promotes metastatic progression in leukemia models, revealing a specific metal-enzyme axis in tumor dissemination [ 368 ]. Copper-associated synaptic modification signatures serve as predictive biomarkers for TME immune infiltration patterns and patient-specific responses to immune therapy [ 369 ]. Zinc ions orchestrate adaptive and innate immunity through multiple mechanisms, enhancing T cell proliferation and cytotoxicity via NF-κB and MAPK pathway activation [ 370 , 371 ], improving CAR-T cell therapeutic efficacy by promoting T cell activation [ 372 ], boosting NK cell antitumor activity through increased cytotoxic granule release, and enhancing IFN-γ production [ 371 ]. By modulating macrophage polarization, zinc ions induce M1 phenotype commitment, creating an antitumor microenvironment that constrains malignant growth [ 371 , 373 ]. Zinc ions are key regulators of immune function in the TME. Zinc overload induces tumor pyroptosis via caspase-1/GSDMD and caspase-3/GSDME pathway activation, eliciting DAMP-driven antitumor immunity that constrains tumor growth [ 373 ]. These findings highlight the intricate signaling networks orchestrated by zinc ions within the TME. This understanding provides a mechanistic foundation for the development of zinc-based antitumor therapeutics and advances metalloimmunotherapies. As a redox-active transition metal, Mn is an essential cofactor for numerous enzymes involved in core metabolic pathways. Manganese ions regulate immune function by activating immune cells, controlling T-cell responses, and maintaining immunological balance [ 25 ]. Mn 2⁺ ions drive three critical immunological processes: kinase/phosphatase activation, T-cell priming, and antigen response amplification through coordination with PKC and phosphatases in TCR signaling. Manganese ions play a critical role in regulating macrophage function through two primary mechanisms: enhancing superoxide dismutase (SOD) activity, which increases antioxidant capacity, and potentiating phagocytic efficiency [ 25 ]. Collectively, these manganese-mediated effects significantly bolster macrophage-dependent antimicrobial and antiviral immune responses. Manganese ions enhance the antitumor activity of NK cells by upregulating enzymes that generate reactive oxygen species (ROS) and promote increased cytokine production. This coordinated regulation significantly amplifies NK cell-mediated tumor cell killing [ 25 ]. Overall, Mn 2 ⁺ orchestrates immune function by regulating T cells, macrophages, and NK cell activity, maintaining homeostasis, and optimizing antimicrobial and antitumor responses. As a divalent cation (Mg 2 ⁺), magnesium participates in over 300 enzymatic reactions while structurally stabilizing bones and regulating neuronal membrane potentials. Clinical and epidemiological studies have linked both dietary magnesium deficiency and hypomagnesemia to increased disease susceptibility, particularly to cancer and infections [ 374 ]. Experimental evidence has demonstrated that Mg-depleted diets promote tumor dissemination and metastatic progression in murine models [ 375 ]. Emerging evidence has revealed that magnesium ions (Mg 2 ⁺) play a critical role in modulating adaptive immunity by regulating LFA-1-dependent CD8 + T cell activation pathways [ 376 ]. These findings suggest that Mg homeostasis is a strategic target for potentiating antitumor immunity, offering novel translational opportunities to enhance the efficacy of checkpoint immunotherapy in oncology. Recently, Sun et al. demonstrated that palmitic acid (PA), the predominant saturated free fatty acid in mouse plasma, promotes tumor progression by driving CD8 + T cell exhaustion and expanding Treg populations within the tumor microenvironment [ 377 ]. Mechanistically, PA-mediated immunosuppression requires CD36-dependent long-chain fatty acid uptake and subsequent suppression of calcium signaling through Akt/mTOR pathway inhibition, as evidenced by reduced Ca 2+ flux and decreased phosphorylation of Akt and mTOR after PA treatment.

Cuproptosis, a recently identified form of RCD, has emerged as an innovative and promising avenue for cancer therapy [ 42 ]. This unique type of cell death is driven by the disruption of copper ion homeostasis, a process that selectively targets cancer cells owing to their dysregulated copper metabolism [ 475 ]. Unlike traditional cell death pathways, such as apoptosis or ferroptosis, cuproptosis is induced by the accumulation of toxic copper levels within cells, leading to a cascade of molecular events, such as copper binding to mitochondrial lipoylated proteins and destabilization of Fe-S cluster proteins, leading to proteotoxic effects caused by protein aggregation and eventually resulting in cell death [ 476 ]. Inducing cuproptosis in cancer cells is a promising therapeutic strategy in oncology. For example, various small molecules have been identified as cuproptosis inducers through the direct modulation of copper metabolism. The 8-hydroxyquinoline derivative PBT2 and nitroxoline exploit cancer-specific vulnerabilities in copper metabolism and redox homeostasis to achieve selective cytotoxicity [ 477 , 478 ]. Their ability to preferentially target malignant cells while sparing normal tissues makes these compounds promising therapeutic candidates, either as monotherapies or in combination with conventional chemotherapeutic agents. Lei et al. recently established radiotherapy (RT) as a potent inducer of cuproptosis in cancer cells, distinct from apoptosis and ferroptosis pathways [ 479 ]. Their analysis of patient tumors revealed RT-mediated depletion of lipoylated and iron-sulfur cluster proteins, which are the molecular hallmarks of cuproptosis. Mechanistically, RT promotes cuproptosis through mitochondrial copper accumulation driven by the upregulation of copper transporter CTR1 and glutathione depletion. Integrated multi-omics analysis identified BACH1 downregulation as a key mediator of radioresistance in esophageal cancer, which alleviates copper sequestration by de-repressing metallothionein MT1E/X expression. Notably, copper ionophores restored RT sensitivity in resistant models by enhancing cuproptotic cell death, suggesting a promising combinatorial strategy for treating radioresistant cancers. Additionally, Liao et al. identified circFRMD4A as a key mediator of p53-dependent metabolic reprogramming and cuproptosis sensitivity [ 480 ]. This circular RNA, derived from p53-transactivated FRMD4A transcripts and processed by the RNA-binding protein EWSR1, functions as a tumor suppressor by enhancing cancer cell vulnerability to elesclomol-induced cuproptosis. Mechanistically, circFRMD4A inhibits pyruvate kinase PKM2, redirecting the glycolytic flux from lactate production to the TCA cycle. The study further demonstrated that combined p53 activation and elesclomol treatment synergistically inhibited tumor growth in vivo. These findings establish a novel p53-circFRMD4A-PKM2 axis that couples metabolic rewiring with cuproptosis induction, offering a promising therapeutic strategy for p53-wild-type cancers. However, advancing these agents to clinical translation will require optimization of their therapeutic windows, comprehensive elucidation of their molecular targets, and development of targeted delivery systems to maximize tumor selectivity and minimize off-target effects. Copper chelators are compounds designed to bind copper ions, thereby reducing their bioavailability and preventing toxic accumulation, which can lead to cuproptosis. Historically, the academic community has recognized the potential of copper chelators in cancer treatment because of their ability to modulate copper levels within cells. Copper is an essential trace element required for numerous physiological processes, including angiogenesis, enzyme activity, and cellular respiration [ 163 ]. However, cancer cells often exhibit a higher demand for copper to support their rapid proliferation and metastatic potential [ 184 ]. Chelators, such as tetrathiomolybdate and D-penicillamine, were initially investigated for their ability to control copper levels in conditions, such as Wilson's disease, where copper accumulation is harmful. Over time, researchers have noted that these agents can selectively target copper-overloaded tumors, opening a new avenue for cancer therapy. By binding to copper ions, these chelators can prevent the metal from participating in reactions that generate reactive oxygen species (ROS), which are particularly detrimental to cancer cells owing to their compromised antioxidant defenses [ 287 ]. The current research landscape on copper chelators in cancer therapy is vibrant and evolving. For instance, tetrathiomolybdate has been extensively studied for its potential to reduce angiogenesis, a critical process in tumor growth and metastasis. Studies have shown that it can effectively lower copper levels in the blood and tissues, thereby inhibiting tumor vascularization in preclinical models of various cancers, including non-small cell lung cancer [ 481 ], breast cancer, and liver cancer [ 482 – 484 ]. Similarly, D-penicillamine has been explored for its ability to induce cell death, although its underlying mechanisms require further investigation. Preclinical studies have demonstrated that D-penicillamine can cause significant oxidative stress and mitochondrial dysfunction in leukemia and breast cancer cells, leading to cell death [ 485 ]. Notably, Ji et al. reported a 50% reduction in tumor volume in mouse models treated with an iron-containing metal–organic framework with D-penicillamine, highlighting the therapeutic potential of copper chelation [ 486 ]. Moreover, the selectivity of copper chelators to target copper-overloaded tumors while sparing normal tissues has made them an attractive adjunct to conventional therapies. The specificity of copper chelators minimizes systemic toxicity, offering a safer alternative or complement to traditional chemotherapy [ 476 ]. Emerging therapeutic strategies focus on combining copper chelators with complementary agents to potentiate anticancer efficacy, overcome drug resistance, and enhance clinical outcomes in diverse malignancies. Copper ionophores are a class of small molecules that facilitate copper transport across cell membranes, thereby increasing intracellular copper concentrations [ 487 ]. Clinically available agents, such as DSF and elesclomol, exploit this mechanism to preferentially target cancer cells, where accumulated copper induces oxidative stress and triggers cuproptosis [ 488 ]. This selective toxicity capitalizes on the heightened copper dependency of malignant cells, which require elevated copper levels to sustain their proliferative metabolism. The resulting Cu overload disrupts cellular redox homeostasis and initiates a lethal cascade of oxidative damage [ 489 ]. Notably, DSF has emerged as a particularly promising therapeutic candidate, with the DSF/copper complex demonstrating potent antitumor activity across multiple cancer types. Preclinical studies have documented significant tumor growth suppression in prostate, breast, and lung cancer models following DSF-Cu combination therapy [ 490 , 491 ]. Copper ionophores also represent a promising therapeutic strategy for overcoming resistance to cancer treatment through targeted disruption of redox homeostasis [ 492 ]. Cancer drug-resistant cells frequently develop resistance by upregulating antioxidant defenses or repairing oxidative damage [ 393 ]. However, copper ionophores override these adaptations by inducing the accumulation of reactive oxygen species (ROS) associated with lipid peroxidation. This triggers non-apoptotic cell death pathways, particularly ferroptosis, which exploits the inherent redox vulnerabilities of resistant tumors [ 493 ]. By selectively targeting the altered redox balance of cancer cells, copper ionophores offer a mechanistically distinct approach for eradicating drug-resistant tumors and overcoming drug resistance. In addition, copper ionophores have the potential to reverse drug resistance in cancer by selectively targeting CSCs. CSCs are a subpopulation of tumor cells with stem cell-like properties that are responsible for tumor initiation, metastasis, and recurrence due to their inherent resistance to conventional therapies. Copper ionophores, including elesclomol and disulfiram (DSF), exhibit potent activity against therapy-resistant CSCs that evade conventional treatments, including platinum-based chemotherapeutics, proteasome inhibitors, and molecular -targeted agents [ 494 ]. Elesclomol treatment markedly impaired the cancer stem cells of ovarian cancer under conditions enriched for tumor-initiating cells, as demonstrated by a reduction in sphere formation capacity and the selective depletion of CD133 high/ALDH high populations. Notably, DSF, a clinically approved copper ionophore, exhibits similar effectiveness [ 495 ]. The ability of copper ionophores to selectively target CSCs provides a novel therapeutic strategy to overcome resistance and prevent tumor relapse, thereby enhancing the overall effectiveness of cancer treatment. The development of copper ionophores as anticancer agents continues to evolve, aiming to refine their selectivity and efficacy, thereby providing a new therapeutic paradigm that exploits the unique biochemical vulnerabilities of cancer cells. Copper complexes have emerged as dynamic therapeutic agents because of their ability to participate in redox cycling and generate ROS. These complexes interact with biomolecules in the tumor microenvironment, enhancing oxidative damage and inducing cell death via cuproptosis. By designing copper-based drugs that release copper ions in response to specific stimuli, researchers can achieve the targeted and controlled induction of cuproptosis. Olar et al. conducted an extensive investigation into the antiproliferative effects of copper(II) complexes with different ligands against melanoma cells [ 496 ]. Their research highlighted the selective toxicity of these complexes towards tumor cells at low micromolar concentrations, suggesting their efficacy in inducing cell cycle arrest and cuproptosis. Notably, these complexes also exhibited ROS-scavenging abilities, which may contribute to their anticancer mechanisms. Using bioinformatics tools, the authors evaluated the drug-likeness, pharmacokinetics, and pharmacodynamics of these compounds, providing a comprehensive view of their potential therapeutic applications. Graur et al. systematically evaluated a series of transition-metal complexes (Cu, Ni, Co, and Zn) for their anticancer properties. Their study revealed distinct cellular selectivity patterns: nickel complexes exhibited preferential cytotoxicity toward HL-60 leukemia cells, whereas zinc complexes exhibited specificity for rhabdomyosarcoma cells. Copper derivatives exhibit the most potent anticancer activity, albeit with reduced selectivity and increased toxicity compared to other metals [ 497 ]. Zhai et al. designed and synthesized copper(II) complexes leveraging adenine as a ligand, demonstrating superior cytotoxicity compared to cisplatin and highlighting their potential as novel anticancer agents through DNA targeting and apoptosis induction [ 498 ]. This study research provides crucial scientific support for the development of new anticancer drugs based on Cu(II) complexes, emphasizing the need for further optimization to enhance therapeutic effects while minimizing side effects. These studies collectively advocate continued research into metal-based compounds as a promising avenue for cancer treatment, with a focus on understanding their full spectrum of biological interactions and therapeutic potential.

Ca 2+ signaling pathways are involved in regulating various intracellular physiological processes, including cell proliferation, signal transduction, muscle contraction, and cell death. As a vital Ca 2+ storage organelle, the endoplasmic reticulum (ER) plays a significant role in maintaining Ca 2+ homeostasis through complex interactions with other organelles and the plasma membrane. Imbalance in Ca 2+ homeostasis has been proposed as a driving force of tumorigenesis [ 180 ]. The difference in intracellular and extracellular Ca 2+ concentrations provides an excellent intervention strategy for calcium-mediated tumor precision targeting therapy for tumors [ 181 , 182 ]. Calcium overload is pathologically defined as a sustained elevation of cytosolic or mitochondrial Ca 2 ⁺ levels. Multiple compounds can trigger excessive Ca 2 ⁺ release from the endoplasmic reticulum (ER), the primary intracellular Ca 2 ⁺ reservoir, leading to cytosolic Ca 2 ⁺ accumulation and subsequent mitochondrial uptake [ 183 ]. As a key extracellular metal, exogenous Ca 2 ⁺ disrupts intracellular Ca 2 ⁺ homeostasis and induces overload-associated cell death. This distinct Ca 2 ⁺ overload cytotoxicity effect was recently termed'calcicoptosis' [ 184 ]. Ca 2+ -based RCD include calcium-based ferroptosis, apoptosis, pyroptosis, necroptosis, and autophagy-dependent cell death. Table  2 and Fig.  5  summarize recent research advancements elucidating the potential Ca 2+ -based RCD pathway. Fig. 5 Calcium-based RCD mechanisms. The figure shows five pathways of calcium-based RCD, including calcium-based apoptosis, ferroptosis, necroptosis, pyroptosis, and autophagy. In the calcium-based apoptosis pathway, upon apoptotic stimulation (e.g., compound treatment), IP3 binding induces conformational changes in IP₃ receptors (IP₃Rs), triggering channel opening and subsequent Ca 2+ release into the cytosol. This Ca 2+ is subsequently taken up by the mitochondria, amplifying apoptotic signaling. In extrinsic apoptosis, Fas receptor activation initiates sustained cytosolic Ca 2+ accumulation via the Fas/FasL/FADD/caspase-8/3 signaling axis. In intrinsic apoptosis, mitochondrial dysfunction occurs through the loss of membrane potential (ΔΨm), increased permeability, mitochondrial Ca 2+ overload, and Bax/Bak-mediated release of cytochrome c, AIF, and EndoG into the cytosol. Cytosolic cytochrome c (Cyto C) binds to Apaf-1 to form an apoptosome, which recruits and activates caspase-9, initiating a caspase cascade that executes intrinsic apoptosis through the Bax/AIF/Cyto C/caspase-9/3 axis. TRPC6 is a calcium channel involved in the influx of intracellular calcium. Intracellular Ca 2+ entry is mediated by store-operated calcium entry (SOCE). This process begins with surface receptor activation and subsequent inositol trisphosphate (IP3) production, leading to endoplasmic reticulum (ER) Ca 2+ depletion via IP3 receptor (IP3R) activation. The decreased ER Ca 2+ concentration is detected by the luminal N-terminal EF-hand motifs of the ER membrane protein stromal interaction molecule 1(STIM1), which then activates plasma membrane Orai1 channels to maintain cellular Ca 2+ homeostasis. Calcium-based ferroptosis is typically associated with the induction of reactive oxygen species (ROS) and lipid peroxidation in cells by calcium ion-related drugs. In calcium-based necroptosis, Ca 2+ overload triggers necroptosis through Ca 2+ /calmodulin-dependent kinase II (CaMKII) activation, which drives RIP1 phosphorylation and ROS production. In the calcium-based pyroptosis pathway, lidocaine induces pyroptosis via caspase-3/GSDME upregulation and CaMKII-TRPV1-Ca 2 ⁺ axis activation Calcium-based RCD mechanisms. The figure shows five pathways of calcium-based RCD, including calcium-based apoptosis, ferroptosis, necroptosis, pyroptosis, and autophagy. In the calcium-based apoptosis pathway, upon apoptotic stimulation (e.g., compound treatment), IP3 binding induces conformational changes in IP₃ receptors (IP₃Rs), triggering channel opening and subsequent Ca 2+ release into the cytosol. This Ca 2+ is subsequently taken up by the mitochondria, amplifying apoptotic signaling. In extrinsic apoptosis, Fas receptor activation initiates sustained cytosolic Ca 2+ accumulation via the Fas/FasL/FADD/caspase-8/3 signaling axis. In intrinsic apoptosis, mitochondrial dysfunction occurs through the loss of membrane potential (ΔΨm), increased permeability, mitochondrial Ca 2+ overload, and Bax/Bak-mediated release of cytochrome c, AIF, and EndoG into the cytosol. Cytosolic cytochrome c (Cyto C) binds to Apaf-1 to form an apoptosome, which recruits and activates caspase-9, initiating a caspase cascade that executes intrinsic apoptosis through the Bax/AIF/Cyto C/caspase-9/3 axis. TRPC6 is a calcium channel involved in the influx of intracellular calcium. Intracellular Ca 2+ entry is mediated by store-operated calcium entry (SOCE). This process begins with surface receptor activation and subsequent inositol trisphosphate (IP3) production, leading to endoplasmic reticulum (ER) Ca 2+ depletion via IP3 receptor (IP3R) activation. The decreased ER Ca 2+ concentration is detected by the luminal N-terminal EF-hand motifs of the ER membrane protein stromal interaction molecule 1(STIM1), which then activates plasma membrane Orai1 channels to maintain cellular Ca 2+ homeostasis. Calcium-based ferroptosis is typically associated with the induction of reactive oxygen species (ROS) and lipid peroxidation in cells by calcium ion-related drugs. In calcium-based necroptosis, Ca 2+ overload triggers necroptosis through Ca 2+ /calmodulin-dependent kinase II (CaMKII) activation, which drives RIP1 phosphorylation and ROS production. In the calcium-based pyroptosis pathway, lidocaine induces pyroptosis via caspase-3/GSDME upregulation and CaMKII-TRPV1-Ca 2 ⁺ axis activation Calcium ion overload is an emerging antitumor strategy to inhibit tumor growth by increasing intracellular calcium concentration, destroying intracellular calcium homeostasis, and inducing cancer cell damage and cell death [ 185 , 186 ]. Intracellular Ca 2 ⁺ entry is mediated by store-operated calcium entry (SOCE) (Fig.  5 ). This process begins with surface receptor activation and subsequent inositol trisphosphate (IP3) production, leading to endoplasmic reticulum (ER) Ca 2 ⁺ depletion through IP3 receptor (IP3R) activation [ 187 ]. Decreased ER Ca 2 ⁺ concentration is detected by the luminal N-terminal EF-hand motifs of the ER membrane protein stromal interaction molecule 1(STIM1), which activates plasma membrane Orai1 channels to maintain cellular Ca 2 ⁺ homeostasis [ 188 ]. Calcium overload is defined as a pathological elevation of cytosolic or mitochondrial Ca 2 ⁺ concentrations. This condition can arise through multiple mechanisms including sustained Ca 2 ⁺ release from the endoplasmic reticulum, which elevates cytosolic Ca 2 ⁺ and subsequently drives mitochondrial Ca 2 ⁺ accumulation, and disruption of Ca 2 ⁺ homeostasis by extracellular Ca 2 ⁺. Both pathways can culminate in mitochondrial Ca 2 ⁺ overload and trigger cell death under specific conditions. Calcium overload can trigger various forms of RCD, including calcium-based ferroptosis, apoptosis, pyroptosis, necroptosis, and autophagy-dependent cell death [ 189 , 190 ] (Table  2 , Fig.  5 ). Calcium-based ferroptosis is typically associated with the induction of ROS and lipid peroxidation in cells by calcium ion-related drugs (Fig.  5 ). For example, Ana J. García-Sáez et al. demonstrated that lipid peroxidation occurs along with sustained cytosolic Ca 2 ⁺ elevation, eventual nanopore formation, and plasma membrane rupture after both erastin and RSL3 treatments. Importantly, ferroptosis-associated Ca 2 ⁺ influx activates the ESCRT-III complex, which serves as a compensatory membrane repair pathway that temporally delays cell death [ 191 ]. Notably, mitochondrial Ca 2 ⁺ dysregulation actively modulates the susceptibility and execution of ferroptosis [ 183 ]. Sui et al. demonstrated that a bioactive compound erianin derived from Dendrobium chrysotoxum Lindl, triggers ferroptosis in lung cancer cells via activation of the Ca 2 ⁺/CaM/LVDCC signaling axis. This process is characterized by ROS generation, lipid peroxidation, GSH depletion, and elevated intracellular Ca 2 ⁺ levels. Moreover, Li et al. found that calcium oxalate (CaOx) has the potential to induce ferroptosis. This was achieved by modulating key ferroptosis-related components, including intracellular Fe 2+ accumulation and ROS generation, along with a decrease in SLC7A11 and GPX4 levels. Extrinsic apoptosis mediated by Fas cell surface death receptor (Fas) signaling is mechanistically linked to sustained cytosolic Ca 2 ⁺ accumulation [ 192 ]. In specific experimental systems, pharmacological inhibition of IP3 receptors (IP3Rs), which prevents ER Ca 2 ⁺ efflux, confers protection against diverse apoptotic stimuli [ 193 , 194 ]. The intrinsic apoptosis pathway is initiated in response to cellular stress (e.g., DNA damage) and culminates in mitochondrial outer membrane permeabilization (MOMP). This process involves mitochondrial depolarization and loss of membrane potential (ΔΨm), both of which are governed by the BCL-2 protein family [ 189 ]. MOMP is mediated by the BCL2 protein family, including BAX and BAK, the activation of which is coupled to ER Ca 2 ⁺ release through IP3Rs and subsequent mitochondrial Ca 2 ⁺ uptake, ultimately leading to cytochrome c release and caspase9/8/3 activation [ 190 ] (Fig.  5 ). Necroptosis is a caspase-independent RCD pathway characterized by RIPK3-dependent activation of the pore-forming effector MLKL [ 83 ]. Emerging evidence has implicated dysregulated Ca 2 ⁺ homeostasis as a key modulator of calcium-based necroptosis. For instance, Kaneda et al. demonstrated that elevated cytoplasmic Ca 2 ⁺ induce neuroblastoma cell necroptosis through Ca 2 ⁺/calmodulin-dependent kinase II (CaMKII) activation, which drives RIP1 phosphorylation(Fig.  5 ) [ 195 ]. Moreover, ER stress-induced cytosolic Ca 2 ⁺ accumulation promotes necroptosis in antimicrobial peptide-treated leukemia cells [ 196 ]. Similarly, sorafenib-treated cardiomyocytes display enhanced ER-mitochondria contact sites, leading to mitochondrial Ca 2 ⁺ overload and subsequent RIPK3/MLKL-dependent calcium-based necroptosis [ 197 ]. Furthermore, calcium overload has been demonstrated to triggers calcium-based pyroptosis. Lu et al. revealed that lidocaine induces pyroptosis in U87-MG glioblastoma cells via two synergistic pathways: CaMKII-mediated phosphorylation of TRPV1 channels, collectively driving lethal calcium overload, and caspase-3-dependent cleavage of GSDME initiated by CaMKII activation [ 198 ] (Fig.  5 ). Additionally, Jing et al. found that elevated intracellular Ca 2 ⁺ stimulates AMPK activation through CaMKK β -mediated phosphorylation, thereby suppressing mTOR signaling and promoting calcium-based autophagy(Fig.  5 ) [ 199 , 200 ]. Calcium homeostasis is central to vanadium-induced nephrotoxicity. In duck renal tubular epithelial cells, sodium metavanadate (NaVO₃) exposure elevates mitochondrial Ca 2 ⁺ levels, increases lactate dehydrogenase (LDH) release, and dysregulates apoptotic gene expression, ultimately inducing apoptosis, which is attenuated by the IP3R inhibitor 2-aminoethyl diphenylborate (2-APB) [ 201 ]. Additionally, NaVO₃ triggers intracellular Ca 2 ⁺ overload linked to endoplasmic reticulum (ER) stress, paradoxically promoting protective autophagy [ 202 ]. Although the ER-mitochondria axis appears to mediate vanadium-induced cell death, the precise molecular mechanisms remain unclear. Further research is necessary to elucidate the specific mechanistic role of cytosolic Ca 2+ overload–based RCD, as current explanations of Ca 2+ overload–based RCD mechanisms are mainly based on the known mechanisms of other forms of RCD. Zinc ions are essential for numerous biological functions, including neuronal function, cell communication, gastrointestinal function, meiosis, immune function, and other physiological processes [ 203 ]. The dysregulation of cellular zinc homeostasis is not only related to cancer progression but also results in various zinc overload -based RCD, including Zn 2 ⁺ -dependent lysosomal cell death, lysozincrosis, apoptosis, autophagy, and cytosolic calcium overload-based cell death [ 28 ]. In this review, we summarize Zn 2+ -triggered RCD, which primarily involves zinc-based apoptosis, zinc-based lysozincrosis, zinc-based ferroptosis, zinc-based autophagy, and zinc-based lysosome-dependent cell death(Table  2 , Fig.  6 ). Fig. 6 Zinc-based RCD mechanisms. Schematic illustration of the zinc-based regulated cell death pathway. Under oxidative stress (e.g., H 2 O 2 or 4-hydroxynonenal exposure), Zn 2+ is released from the redox-sensitive zinc-binding protein MT3, which drives the pathological hyperactivation of autophagy, resulting in lysosomal Zn 2+ overload and membrane permeabilization. The consequent lysosomal content leakage synergizes with BID-mediated death signaling to execute Zn 2+ -dependent lysosomal cell death through catastrophic proteolytic degradation of cellular components and increased lysosomal membrane permeabilization. In the Zn 2+ -dependent necrotic cell death pathway, pharmacological activation of TRPML1 by ML-SAs induces lysosomal Zn 2+ efflux, which drives mitochondrial dysfunction, ATP exhaustion, and a distinct form of Zn 2+ -dependent lysozincrosis, characterized by lysosomal membrane permeabilization, mitochondrial swelling/damage, and necrotic cell death. Zn 2+ -based autophagy pathways include the NOD2/NF-κB/Caspase-1/IL-1/MTs/LC3-II axis. The zinc transporters Zip10 and ZnT2 regulated the Zn 2+ -based apoptosis pathways; The zinc importer Zrt- and Irt-like protein 7 (ZIP7) controls the transport of Zn 2+ from the ER to the cytosol and regulates the Zn 2+ -based ferroptosis pathway; ZnCl 2 can induce an increase in cytosolic Ca 2+ levels and a decrease in plasma membrane calcium ATPase (PMCA1//2), ultimately triggering Ca 2+ overload-based cell death Zinc-based RCD mechanisms. Schematic illustration of the zinc-based regulated cell death pathway. Under oxidative stress (e.g., H 2 O 2 or 4-hydroxynonenal exposure), Zn 2+ is released from the redox-sensitive zinc-binding protein MT3, which drives the pathological hyperactivation of autophagy, resulting in lysosomal Zn 2+ overload and membrane permeabilization. The consequent lysosomal content leakage synergizes with BID-mediated death signaling to execute Zn 2+ -dependent lysosomal cell death through catastrophic proteolytic degradation of cellular components and increased lysosomal membrane permeabilization. In the Zn 2+ -dependent necrotic cell death pathway, pharmacological activation of TRPML1 by ML-SAs induces lysosomal Zn 2+ efflux, which drives mitochondrial dysfunction, ATP exhaustion, and a distinct form of Zn 2+ -dependent lysozincrosis, characterized by lysosomal membrane permeabilization, mitochondrial swelling/damage, and necrotic cell death. Zn 2+ -based autophagy pathways include the NOD2/NF-κB/Caspase-1/IL-1/MTs/LC3-II axis. The zinc transporters Zip10 and ZnT2 regulated the Zn 2+ -based apoptosis pathways; The zinc importer Zrt- and Irt-like protein 7 (ZIP7) controls the transport of Zn 2+ from the ER to the cytosol and regulates the Zn 2+ -based ferroptosis pathway; ZnCl 2 can induce an increase in cytosolic Ca 2+ levels and a decrease in plasma membrane calcium ATPase (PMCA1//2), ultimately triggering Ca 2+ overload-based cell death Lysosomes serve as the principal degradative and signaling hubs in cellular biochemistry. MT3 dynamically regulates lysosomal zinc homeostasis, coordinating cellular processes through the dual modulation of lysosomal membrane integrity (via LAMP protein stabilization) and activation of key hydrolases (e.g., cathepsins) [ 204 ]. Under oxidative stress (e.g., H₂O₂ or 4-hydroxynonenal exposure), MT3, a redox-sensitive zinc chaperone, releases labile Zn 2 ⁺ from cultured neural cells. This mobilized Zn 2 ⁺ drives the pathological hyperactivation of autophagy, resulting in lysosomal Zn 2 ⁺ overload and membrane permeabilization. The consequent leakage of lysosomal contents synergizes with BID-mediated death signaling to execute Zn 2 ⁺-based lysosomal- dependent cell death through catastrophic proteolytic degradation of cellular components and an increase in lysosomal membrane permeabilization [ 205 ] (Fig.  6 ). Given the critical role of lysosomes as terminal degradative hubs in autophagy, the observed link between Zn dysregulation and lysosomal dysfunction motivated us to investigate the possible role of Zn 2 ⁺ overload in autophagy. In astrocytes, oxidative stress inducers (e.g., H₂O₂ and FeCl₂) trigger autophagy activation and intracellular Zn 2 ⁺ accumulation, as demonstrated by elevated LC3-II levels and enhanced autophagosome biogenesis [ 204 ]. Notably, Zn 2 ⁺ accumulated in both autophagosomes and lysosomes (Fig.  6 ). Abraham et al. demonstrated that chronic nucleotide-binding oligomerization domain-2 (NOD2) activation of the NF-κB/Caspase-1/IL-1/MTs/LC3-II axis and elevates intracellular Zn 2 ⁺ levels, which in turn enhances autophagy and promotes antibacterial defense [ 206 ] (Fig.  6 ). Additionally, Zn 2 ⁺ plays a dual regulatory role in apoptosis, where Zn 2 ⁺ can either suppress or promote apoptotic signaling in various cellular contexts. For example, Kelleher et al. found that ZnT2 overexpression in basal-like (MDA-MB-231) breast cancer cell lines drives profound cellular reprogramming, characterized by cell cycle arrest, enhanced apoptotic susceptibility, Zn 2 ⁺ vesicularization, and suppressed proliferative and invasive capacities [ 64 ]. In contrast, the zinc transporter ZIP10 orchestrates antiapoptotic signaling during early B-cell development by modulating Zn 2 ⁺-dependent suppression of caspase activity [ 207 ]. Zinc overload triggers necrotic cell death. For example, Du et al. found that ML-SAs, TRPML-specific synthetic agonists, can quickly trigger lysosomal Zn 2+ -dependent necrotic cell death in metastatic melanoma cells [ 45 ], and this form of death is called lysozincrosis [ 40 ]. The primary mechanism of lysozincrosis involves the activation of the TRPML1 channel by ML-SAs, which induces the release of Zn 2+ from lysosomes. The released zinc causes mitochondrial damage and rapid depletion of ATP through various mechanisms, resulting in cell death. Cells with elevated TRPML1 expression demonstrated increased susceptibility to lysosomal zinc-dependent cell death (Fig.  6 ). Notably, this form of cell death has shown antitumor effects in murine models of melanoma, suggesting potential novel therapeutic strategies for treating metastatic melanoma and other malignancies. Zn 2 ⁺ overload is also associated with ferroptosis. Overexpression of the endoplasmic reticulum (ER)-resident zinc importer Zrt-and Irt-like protein 7 (ZIP7) facilitates Zn 2 ⁺ efflux from the ER lumen into the cytosol, which serves as a critical driver of zinc-based ferroptosis by disrupting redox homeostasis and amplifying lipid peroxidation cascades [ 92 ] (Fig.  6 ). Furthermore, genetic or pharmacological suppression of ZIP7 induces ER stress and upregulates the ER stress-responsive factors HERPUD1 and ATF3. Additionally, ZnCl 2 treatment induced cytosolic Ca 2 ⁺ overload in 661 W cells, disrupting calcium homeostasis, inactivating Ca 2 ⁺-ATPase, and reducing plasma membrane calcium ATPase (PMCA1/2), which ultimately triggered Ca 2 ⁺ overload-based cell death (Fig.  6 ). However, the crosstalk between Zn 2 ⁺ and Ca 2 ⁺ homeostasis in regulating RCD pathways remains incompletely understood, presenting a critical gap in the understanding of metal ion-mediated cell death mechanisms. Na + plays a crucial role in determining the osmolarity of the tumor microenvironment, affecting cell volume, metabolism, and the immune system. In a normal intracellular environment, the extracellular concentration of sodium ions is usually higher than the intracellular concentration [ 208 ]. In contrast, the concentration of intracellular potassium (K + ) is maintained at a higher level. The asymmetrical Na + /K + concentration gradients are essential for transporting amino acids, maintaining pH balance, and regulating cell volume [ 209 , 210 ]. Disruption of sodium balance in cancer cells can cause substantial osmotic alterations, leading to cell death. Continuously increasing intracellular Na + concentration through different methods and strategies can induce Na + ion overload-based cell death. Recently, the Na + ion overload-based RCD form has been named necrosis by sodium overload (NECSO). Continuous ATP depletion under pathological conditions causes uncontrolled opening of TRPM4 channels, resulting in a large amount of sodium ion influx and membrane depolarization. Energy depletion (ATP depletion) can activate cardiomyocyte necrosis via sodium overload (NECSO), heart injury, and sudden cardiac death (SCD) (Fig.  7 A). Fu et al. recently identified a unique form of necrotic cell death triggered by the small molecule NC1, which they called NECSO [ 50 ]. NECSO is notably distinct from apoptosis, autophagy, and programmed cell death. It is characterized by the continuous activation of TRPM4, leading to abnormal opening of its channels, triggering massive sodium influx, membrane blebbing, cell Edema&Swelling, and cell membrane depolarization, which eventually leads to necrotic cell death(Fig.  7 B). Mechanistic studies revealed that NC1 directly binds and activates the ion channel activity of TRPM4; NC1 induced necrosis via TRPM4 is driven by sodium influx. NC1 induces NECSO by specifically targeting the transmembrane (TM) region of the human TRPM4 channel. TRPM4 transmembrane region determines NC1 sensitivity. In addition, drug library screening have studies identified two classes of small molecule inhibitors of NECSO: clotritriazole (CLT) and dihydropyridine calcium channel blockers (DHPs). CLT directly inhibit NECSO by competing with NC1 binding pockets on TRPM4. DHPs inhibits NECSO by targeting L-type calcium channels (LTCCs) to prevent TRPM4 activation [ 50 ]. Sodium-based nanomaterials play a crucial role in the induction of sodium -ion-based RCD. Smartly designed sodium-based nanoparticles can bypass cellular regulations on ion transport, enter the cell through entosis, and subsequently release Na + in the cytoplasm, increasing intracellular osmotic pressure and leading to Na + -based RCD [ 211 ]. Xie et al. synthesized phospholipid-coated NaCl nanoparticles (PSCNPs). PSCNPs enter cells through endocytosis and cause immunogenic cell death by increasing HMGB1 release, inducing Na + -based apoptosis by activating the caspase pathway, and pyroptosis by upregulating GSDMD-N and caspase 1(Fig.  7 C). Fig. 7 Sodium-Based RCD Mechanisms. Schematic illustration of the pathway of sodium-based regulation of cell death. A . Sustained ATP depletion in pathological contexts drives dysregulated TRPM4 channel activation, precipitating catastrophic Na + influx, and membrane depolarization. This bioenergetic crisis triggers cardiomyocyte necrosis due to sodium overload (NECSO), ultimately culminating in myocardial injury and sudden cardiac death (SCD). B . The small molecule, NC1 can continuous activation of TRPM4 leading to abnormal opening of its channels, triggering massive sodium influx, membrane blebbing, cell Edema&Swelling, and cell membrane depolarization, which eventually leads to NECSO. Two small molecule inhibitors of NECSO, clotritriazole (CLT) and dihydropyridine calcium channel blockers (DHPs), can directly inhibit NECSO by competing with NC1 binding pockets on TRPM4. C . Phospholipid-coated NaCl nanoparticles (PSCNPs). PSCNPs enter cells through endocytosis and can cause immunogenic cell death by increasing HMGB1 release and inducing Na + -based apoptosis by activating the caspase pathway, along with pyroptosis by upregulating GSDMD-N and caspase 1 Sodium-Based RCD Mechanisms. Schematic illustration of the pathway of sodium-based regulation of cell death. A . Sustained ATP depletion in pathological contexts drives dysregulated TRPM4 channel activation, precipitating catastrophic Na + influx, and membrane depolarization. This bioenergetic crisis triggers cardiomyocyte necrosis due to sodium overload (NECSO), ultimately culminating in myocardial injury and sudden cardiac death (SCD). B . The small molecule, NC1 can continuous activation of TRPM4 leading to abnormal opening of its channels, triggering massive sodium influx, membrane blebbing, cell Edema&Swelling, and cell membrane depolarization, which eventually leads to NECSO. Two small molecule inhibitors of NECSO, clotritriazole (CLT) and dihydropyridine calcium channel blockers (DHPs), can directly inhibit NECSO by competing with NC1 binding pockets on TRPM4. C . Phospholipid-coated NaCl nanoparticles (PSCNPs). PSCNPs enter cells through endocytosis and can cause immunogenic cell death by increasing HMGB1 release and inducing Na + -based apoptosis by activating the caspase pathway, along with pyroptosis by upregulating GSDMD-N and caspase 1