Isoleucine and valine promote prostate cancer progression via propionyl-CoA-mediated cholesterol metabolism.

Enhanced cholesterol synthesis and lipid droplet accumulation are hallmarks of aggressive prostate cancer, yet how tumour cells sense metabolic inputs to dynamically regulate cholesterol homeostasis remains poorly defined. Here we uncover a metabolic signalling mechanism in which prostate cancer cells remodel propionyl-CoA metabolism to support stress adaptation during disease progression. We show that the catabolism of branched-chain amino acid, specifically isoleucine and valine, is the primary source of intracellular propionyl-CoA in prostate cancer cells. Beyond its metabolic role, propionyl-CoA functions as a signalling molecule that stabilizes nuclear sterol regulatory element-binding protein 2 (SREBP2) through site-specific lysine propionylation, thereby enhancing its transcriptional activity. This activation promotes cholesterol biosynthesis, fuels de novo androgen production, and sustains androgen receptor signalling under metabolic and therapeutic stress, including androgen deprivation. Together, our findings establish propionyl-CoA as a key metabolic signal linking amino acid catabolism to cholesterol-driven oncogenic programmes and highlight targeting isoleucine and valine metabolism as a potential strategy to disrupt lipid reprogramming in prostate cancer.