Background Prostate Cancer (PCa) is the leading cause of cancer cases in U.S. men and the second leading cause of male cancer death. If detected in its initial stages, PCa is curable with surgery or radiation, or may even be amenable to periodic surveillance. However, an advanced form the disease, termed castration-resistant PCa (CRPC), is not curable, and accounts for most PCa mortality. CRPC is defined as a form of PCa that continues progressing despite using androgen deprivation therapy (ADT), the standard of care for advanced PCa. A western diet – rich in lipids- has been shown to increase the incidence of PCa, as well as the risk of advanced PCa. However, the exact mechanism of these outcomes remains to be elucidated. We hypothesize that dietary lipids impact the susceptibility of CRPC to ferroptosis, a lipid peroxidation-dependent form of cell death. Lipid peroxidation is dependent on the PUFA content in the cell membrane.

Methods To study this hypothesis, we have used western blotting, reverse transcription quantitative polymerase chain reaction (RT-qPCR), mass spectrometry, crystal violet assays, flow cytometry approaches, and RNA sequencing.

Results We have determined that the PUFA content is elevated in CRPC models relative to a model of castration-sensitive PCa (CSPC). The CRPC models with elevated PUFA content also exhibit increased sensitivity to ferroptosis inducing agents. To explore the link between diet and ferroptosis in PCa, we cultured these models in lipid depleted (LD) medium and identified a non-apoptotic increase in dead cells. This same treatment led to an increased level of lipid peroxides. Upon culture in LD medium, the hallmark cholesterol homeostasis gene set, including genes involved in cholesterol synthesis, was the top enriched gene set across all models. Mass spectrometry-based metabolomics also showed a significant decrease in cholesteryl ester levels across all models cultured in LD medium. Interestingly, we observed that CRPC models, but not the CSPC model, showed dependence on extracellular cholesterol for their growth.

Conclusion These results reveal an increased susceptibility of CRPC models to ferroptosis and a role for dietary lipids, specifically cholesterol, in the modulation of this mechanism of cell death. This finding can be used to design trials focused on further understanding the combination of ferroptosis inducing agents with dietary modifications for the treatment of CRPC.