Targeting Ferroptosis to Overcome Drug Resistance in Cancer: Molecular Mechanisms and Therapeutic Prospects.

Cancer remains a major global health burden and causes a substantial number of deaths worldwide ( Siegel et al ., 2024 ). Despite the advent of targeted therapies, therapeutic resistance frequently occurs, posing a significant challenge to effective cancer treatment ( Lei et al ., 2023 ). Ferroptosis is an iron-dependent form of regulated cell death characterized by lipid peroxidation and oxidative stress ( Fig. 1 ) ( Dixon et al ., 2012 ). Although ferroptosis may not completely account for chemotherapeutic agents-induced cell death, targeting this pathway could provide an alternative therapeutic strategy to overcome drug resistance in cancer. Drug-resistant cancer cells often exhibit elevated levels of reactive oxygen species (ROS) ( Shah and Rogoff, 2021 ; Viswanathan et al ., 2017 ), rendering them particularly vulnerable to ferroptosis. In this review, we discuss the molecular mechanisms underlying ferroptosis, the interplay between ROS and ferroptosis resistance, and emerging therapeutic approaches to sensitize drug-resistant cancer cells through ferroptosis activation.

The cytotoxic potential of ROS is highly dependent on their intracellular concentration, duration, and subcellular localization. Under physiological conditions, basal intracellular H₂O₂ levels remain within the low-nanomolar range (1-50 nM), functioning as signaling molecules that modulate kinases and transcription factors ( Lyublinskaya and Antunes, 2019 ). Minute increases of 3-10 nM are sufficient to alter phosphatase activity and trigger adaptive transcriptional responses. However, the same molecules become cytotoxic when the steady-state H₂O₂ level exceeds the buffering capacity of antioxidant systems. Experimental measurements using controlled steady-state delivery systems reveal that apoptosis can be initiated at extracellular H₂O₂ concentrations around 7 µM, corresponding to submicromolar intracellular levels ( Antunes and Cadenas, 2001 ). For example, Jurkat T cells, grown in suspension undergo apoptosis when maintained in a steady-state oxidative environment. In contrast, most adherent cancer cells, such as A549 lung carcinoma, require higher doses—approximately 100 µM H₂O₂ exposure for 6-24 h—to reach a similar threshold for cell death ( Vilema-Enriquez et al ., 2016 ). These discrepancies reflect the antioxidant capacities and metabolic adaptations of different cancer cell types. Cells with elevated GSH or Trx activity can transiently withstand oxidative insults, shifting the lethal threshold upward. Although H₂O₂ and superoxide (O₂•⁻) underlie classical oxidative cytotoxicity, lipid peroxidation–derived ROS represent another decisive trigger for regulated cell death, particularly ferroptosis. In this context, the quantitative determinant of death is not the total ROS concentration but the accumulation rate of lipid-ROS that exceeds the detoxifying ability of GPX4. Pharmacological inhibition of GPX4 by RSL3 has provided functional measures of this threshold. RSL3 induces irreversible cell death at submicromolar concentrations (<1 µM) in highly ferroptosis-sensitive cell lines such as MDA-MB-231 and HCC1954, whereas relatively resistant lines, such as MCF-7, SK-BR-3, and T47D, require 5-11 µM RSL3 to reach equivalent lipid-ROS levels ( Park et al ., 2019 ). Fluorescent reporters, such as BODIPY-C11, visualize this process, where a sharp increase in the oxidized/reduced ratio marks the lipid-ROS death threshold ( Co et al ., 2024 ). Altogether, these data indicate that the boundary between adaptive and lethal ROS is narrow and context-dependent. In most mammalian cells, intracellular H₂O₂ concentrations above several hundred nanomolar or sustained extracellular levels exceeding 5-10 µM begin to trigger apoptosis. In contrast, lipid-ROS–driven ferroptosis operates through membrane-localized oxidative chain reactions, often at total ROS levels lower than those required for necrosis or apoptosis but concentrated within phospholipid domains. These quantitative distinctions emphasize that the biological outcome of ROS is not absolute but relative, determined by the balance between generation and scavenging, the spatial distribution of oxidative events, and the intrinsic redox tolerance of the cell. Therapeutically, these insights imply that manipulating ROS levels toward either side of the survival threshold can determine the fate of cancer. Sublethal ROS promote oncogenic signaling and resistance, whereas exceeding the oxidative limit, through mitochondrial overload, GPX4 inhibition, or radiotherapy, irreversibly commits cells to death. Thus, although ROS may serve as a “friend” to cancer during its growth, carefully controlled perturbation of its redox homeostasis transforms it into a potent “foe.” Sublethal levels of ROS may promote oncogenic signaling and resistance to anticancer therapy. The balance of ROS levels transforms ROS into a potent foe. Below are certain targets that regulate ROS levels and induce ferroptosis. Transcription factors and related targets: Multiple transcription factors regulate ROS; among them, NRF2 (Rojo de la Vega et al ., 2018; Sun et al ., 2016 ) plays a prominent role in ferroptosis, particularly in drug-resistant cancer cells. Activation of MAPK signaling may potentiate NRF2 nuclear translocation and transcriptional activity, allowing antioxidant defense mechanisms to inhibit ferroptosis. In contrast, NRF2 downregulation results in the depletion of antioxidants, such as GSH, as well as an increase in lipid peroxidation to promote ferroptosis. Not surprisingly, one of the key molecular targets involved in the induction of ferroptosis, system Xc - , is transcriptionally regulated by NRF2. Moreover, NRF2 regulates several key genes involved in GSH synthesis (SLC7A11, GCLC, GCLM, and GSR) and iron metabolism (FTH1) ( Tang and Kang, 2024 ). Therefore, NRF2 is a critical therapeutic target for overcoming resistance to ferroptosis. Enhanced chemosensitivity has been reported in ovarian cancer cells treated with tripterygium glycosides, which downregulate of NRF2 ( Ma et al ., 2023 ). Carnosic acid inactivates NRF2 and sensitizes oral squamous cell carcinoma cells to cisplatin ( Han et al ., 2022 ). In addition, the suppression of NRF2 signaling by triptolide induces ferroptosis in doxorubicin-resistant leukemia cells ( Wu et al ., 2023 ), and the inhibition of NRF2 by trigonelline sensitizes head and neck cancer cells to cisplatin ( Roh et al ., 2017 ). In contrast, curcumol sensitizes cisplatin-resistant gastric cancer cells by regulating the p62/KEAP1/NRF2 pathway ( Feng et al ., 2024 ). The activation of the NRF2 pathway confers drug resistance, whereas its inhibition leads to ferroptosis ( Roh et al ., 2017 ). In addition to NRF2, other transcription factors could be utilized in inducing ferroptosis. RE1-silencing transcription factor (REST) is an inhibitory transcription factor ( Plaisance et al ., 2005 ). Erianin, a natural product, targets REST leading to the upregulation of LRSAM1 expression that ubiquitinates and degrades ferroportin, resulting in ferroptosis in TMZ-resistant glioma cells ( Mansuer et al ., 2024 ). Although not a transcription factor, LINC00152 is involved in the transcriptional regulation of ferroptosis signaling. LINC00152 is an oncogenic long noncoding RNA that enhances the stability of PDE4D mRNA, which encodes a phosphodiesterase ( Li et al ., 2022 ). Inhibition of LINC00152 reduces PDE4D expression, thereby potentiating cAMP signaling through PKA and CREB, ultimately leading to increased ROS generation and lipid peroxidation ( Saatci et al ., 2024 ). The downregulation of a single enzyme can trigger the induction of multiple gene products and ferroptosis, possibly overcoming tamoxifen resistance. Antioxidant systems: Drug-resistant cancer cells exhibit elevated ROS levels and sustain their viability by upregulating antioxidant systems. However, once these antioxidant systems are compromised, cancer cells can no longer protect themselves from high ROS levels, and this vulnerability can be leveraged to overcome resistance. GPX4 is one of the most commonly used targets for the induction of ferroptosis. Fin56 is a well-known inducer of ferroptosis that targets GPX4 ( Sun et al ., 2021 ), and siRNA treatment targeting GPX4 can induce ferroptosis in oxaliplatin-resistant CRC cells ( Golbashirzadeh et al ., 2023 ). Furthermore, the effect of GPX4 knockdown in lapatinib-resistant NSCLC cells indicates the central role of GPX4 in ferroptosis too ( Ni et al ., 2021 ). ALDH5A1, the succinic semialdehyde dehydrogenase (SSADH), is involved in ROS regulation ( Chambliss and Gibson, 1992 ). A xenograft mouse model demonstrated that ALDH5A1 expression is related to cisplatin-resistance and that ALDH5A1 silencing promotes ferroptosis signaling ( Song et al ., 2024 ). Antioxidant systems are inhibited by different mechanisms, including the regulation of ubiquitination. USP2 is a deubiquitinating enzyme (DUB) belonging to the ubiquitin-specific protease family ( Shin et al ., 2017 ). It is involved in the deubiquitination of p53 at the K305R stabilizing p53 and promoting its nuclear translocation, which enhances ferroptosis and reduces cisplatin-resistance in NSCLC cells ( Gong et al ., 2025 ). The role of USP2 is somewhat complicated as the upregulation of USP2 promotes migration and invasion in certain other cancer cells ( Qu et al ., 2015 ). USP14 is another DUB ( Wang et al ., 2021 ). Recently, the curcumin derivative mitocur-1 was demonstrated to inhibit USP14, leading to GSH depletion and SLC7A11 downregulation, which ultimately induces ferroptosis. These findings suggest that mitocur-1 can be used to treat vemurafenib-resistant melanoma cells ( Li et al ., 2024 ). Receptor tyrosine kinases (RTKs) and MAPK signaling: In Section II-2, we discuss the potential of modulating MAPK signaling and ROS generation to induce ferroptosis. As demonstrated in the case of the RON receptor tyrosine kinase, inhibition of RTK activity can downregulate MAPK signaling and induce of ferroptosis ( Jin et al ., 2024 ). Several growth factors, such as EGFR and MET, are RTKs, and their activation is closely related to carcinogenesis ( Du and Lovly, 2018 ). FMS-like tyrosine kinase 3 (FLT) is highly expressed in breast cancer cells, and it functions as a ferroptosis inhibitor ( Shen et al ., 2024 ). NRF2, a pivotal target for ferroptosis induction, is a downstream signaling pathway for RTKs ( Cirotti et al ., 2024 ). Overall, RTKs may be good targets for inducing ferroptosis, especially in cells resistant to anticancer drugs ( Viswanathan et al ., 2017 ). It also should be noted that the activation of RTKs, rather than their inhibition, can sometimes increase cellular susceptibility to ferroptosis. The upregulation of ACSL4, a kind of ferroptosis promoter, can be induced by RTK activation through the RAS/RAF/c-Myc axis, implicating the dual function of RTKs in regulating ferroptosis ( Fig. 3 ) ( Sun et al ., 2024 ).

We have provided a concise overview of ferroptosis, including the major regulators that drive the process, key signaling pathways such as the RTK, MAPK, and NRF2 pathways, and several molecular targets involved in ferroptosis induction. Molecules that selectively modulate key regulators of ferroptosis, such as GPX4, ferroportin, and other proteins involved in iron metabolism, need to be developed, in addition to the currently identified targets. These targets and modulators should exhibit tumor specificity, with a particular emphasis on drug-resistant cancer cells. We do not expect these approaches to replace current chemotherapies or targeted therapies. Combining ferroptosis inducers with conventional treatments may improve therapeutic outcomes and potentially overcome resistance mechanisms. To better utilize ferroptosis to overcome drug resistance in anticancer therapy, it is essential to understand the tumor microenvironment, particularly in relation to ferroptosis regulation involving immune cells and metabolic crosstalk. In the search for drug candidates that induce ferroptosis, drug repositioning, especially of inhibitors targeting the RTKs and MAPK signaling pathways, may provide valuable insights. Moreover, minimizing off-target effects and protecting normal tissues are critical for improving drug selectivity and facilitating clinical translation. In conclusion, inducing ferroptosis in drug-resistant cancer cells may provide a promising strategy for developing effective therapies against treatment-resistant malignancies.