Isoleucine and valine promote prostate cancer progression via propionyl-CoA-mediated cholesterol synthesis and storage

Cholesterol performs multiple essential roles in cells. Enhanced cholesterol synthesis and storage in lipid droplets have been linked to cancer aggressiveness, particularly in lipid-rich and hormone-sensitive cancers such as prostate cancer . Cholesterol anabolism and catabolism are finely regulated in tumor cells in response to various nutritional states. Mitochondria have increasingly been recognized as a signal transduction organelle, particularly concerning metabolites derived from mitochondrial activity. The link between mitochondrial regulation and cholesterol synthesis remains inadequately understood. Here, we show that propionyl-CoA promotes cholesterol synthesis, storage, and further progression in prostate cancer cells. We found that propionyl-CoA, mainly produced by isoleucine and valine metabolism in the mitochondria, can translocate through the mitochondrial membrane and serves as a substrate for modifying cleaved SREBP2, stabilizing it and thereby promoting cholesterol synthesis and storage in lipid droplets. This process facilitates cancer metastasis and castration resistant partially through enhancing androgen synthesis in prostate cancer cells. Our results demonstrate that branched-chain amino acid (BCAA) catabolism and propionate metabolism in mitochondria are involved in the regulation of cholesterol synthesis and utilization through metabolite-mediated protein modification. We anticipate that our findings provide a critical link between amino acid metabolism and cholesterol anabolism, highlighting a mechanism that plays a crucial role in the development of castration resistance in prostate cancer patients. This study offers a theoretical rationale for targeting the production of propionyl-CoA, particularly through the metabolism of isoleucine and valine, as an effective strategy to inhibit cholesterol synthesis and its related diseases.