Ferroptosis vulnerability of enzalutamide resistant prostate cancer conferred by ACSL4 overexpression and GPX4 antagonism.

Enzalutamide, as a second-generation anti-androgen agent, has been used to treat castration-resistant prostate cancer (CRPC) or metastatic castration-sensitive prostate cancer (mCSPC). However, enzalutamide resistance inevitably developed for most treated CRPC/mCSPC, and limited effective therapies are currently available for these enzalutamide-resistant prostate cancers. In this study, we utilize our established enzalutamide-resistant prostate cancer cell lines to reveal a vulnerability of these cancer cells to GPX4-targeted ferroptosis. Interestingly, the established enzalutamide-resistant prostate cancer cells are mixed populations that predominantly exhibit stem cell-like (SCL) and neuroendocrine-like (NEL) phenotypes and may reflect cellular heterogeneity during the development of enzalutamide resistance in prostate cancer. We further demonstrated that ACSL4, a long-chain fatty acid-CoA ligase, was upregulated by the JAK/STAT pathway in enzalutamide-resistant SCL/NEL cells, thereby facilitating tumor proliferation and metastasis while increasing sensitivity to ferroptosis. To antagonize the ACSL4-conferred ferroptosis risk, SCL/NEL cells upregulated GPX4 through AP-1 transcription complex to suppress ferroptosis and thus promoted the malignant progression of SCL/NEL cells. Notably, we characterized Auranofin, an anti-rheumatoid arthritis drug, as a ferroptosis inducer for these SCL/NEL cells in vitro and in vivo by targeting AP-1 and decreasing GPX4 expression, suggesting a new application for Auranofin in treating enzalutamide-resistant stem cell-like AP-1High CRPC.