Emodin induced necroptosis in prostate cancer cells via the mitochondrial fission HSP90/MLKL/PGAM pathway

Background: Currently, prostate cancer is one of the major malignant tumors for males. Natural products from TCM are acknowledged as excellent anticancer agents to fight sensitive and resistant prostate cancer. We aimed to explore the potential mechanism and molecular targets of emodin (EG) against human prostate cancer cells based on RNA-sequencing measures and molecular biology techniques. Methods Seven robustaflavones and EG isolated from Selaginella trichoclada were identified by UV, HRESIMS, and 1D/2D NMR spectral techniques. Human prostate cancer PC3 and DU145 cells were evaluated to explore the potential mechanism and molecular targets of emodin by RNA-sequencing measure and KEGG functional enrichment analysis. We further verified the accuracy of the prediction results by colony formation assay, Hoechst 33258 stainings, TEM cell morphology analysis, qPCR, and western blot. Results RNA-sequencing measure and KEGG functional enrichment analysis revealed that the necroptosis-related pathway was activated upon EG treatment in PC3 cells. Furthermore, EG significantly decreased the cell viability of PC3 and DU145 cells and strikingly induced non-apoptotic cell death via necroptosis that was visualized through colony formation assay, Hoechst 33258 staining, and TEM analysis. mRNA and protein expression of necroptosis markers were analyzed by qPCR and immunoblotting, which implied that EG induced cell necroptosis via enhancing the expression of MLKL and HSP90AA1 activating PGAM pathway which is considered as a key mediator of mitochondrial fission and leading to ROS generation in PC3 and DU145 cells. Conclusions Our findings suggested that EG is a new small molecule agonist that induced necroptosis in prostate cancer cells via the mitochondrial fission HSP90/MLKL/PGAM pathway.