Inhibition of the RORC/GPX4 mediated ferroptosis regulatory axis suppresses tumor growth and alleviates enzalutamide resistance in prostate cancer.

BACKGROUND

Patients with castration-resistant prostate cancer (CRPC) often develop resistance following long-term enzalutamide treatment. Building upon previous research, we aims to further explore the effect of ilicicolin A (ili-A) on enzalutamide resistance and to elucidate the underlying resistance mechanisms.

METHODS

Proliferation, migration, and invasion of prostate cancer (PCa) cells were evaluated by 5-ethynyl-2'-deoxyuridine (EdU) assays, colony formation, scratch, and Transwell. Cell Counting Kit 8 (CCK-8) was used to assess the efficacy of drug inhibition in CRPC cells. The expression of tumor cell apoptotic proteins and ferroptosis was assessed using western blot (WB) analysis. Coimmunoprecipitation (Co-IP) and proximity ligation assay (PLA) were used to identify the mechanism of interaction between ilicicolin A and ferroptosis. Tumor transplantation experiments with mice were conducted to confirm findings.

RESULTS

Ili-A showed dose-dependent inhibition of PCa cells including C4-2B and 22Rv1 cell lines. The overexpression of the RORC gene activated the expression of ferroptosis-related proteins, such as FTH1, GPX4 and SLC7A11, and enhanced proliferation of PCa cells. WB experiments indicated that RORC upregulated AR and AR-V7. An enzalutamide-resistant C4-2B cell line revealed that RORC serves as a gene target for enzalutamide resistance. Finally, it was observed that ili-A could suppress CRPC cells proliferation by downregulating RORC expression, thereby promoting ferroptosis and enhancing the sensitivity to enzalutamide.

CONCLUSIONS

Ili-A inhibited RORC expression, increased malondialdehyde (MDA) content, suppressed glutathione (GSH) production, released free Fe2+, increased reactive oxygen species (ROS), activated the ferroptosis pathway, enhanced enzalutamide sensitivity, and inhibited CRPC cell proliferation. Furthermore, ili-A enhances the interaction between ROR-γ and GPX4.