Caveolin-1 regulates hormone resistance through lipid synthesis, creating novel therapeutic opportunities for castration-resistant prostate cancer

Abstract

Caveolin-1 (Cav-1) is overexpressed in aggressive and metastatic prostate cancer (PCa) and induces PCa cell proliferation. Androgens mediate lipid synthesis through acetyl-CoA carboxylase-1 (ACC1) and fatty acid synthase (FASN). We investigated the Cav-1-mediated lipid synthesis in the development of castration resistance, and identified novel therapeutic opportunities. Using the PBCre⁺;Pten^loxp/loxp;PBCav-1⁺ mouse model we found that Cav-1 induction increased cancer incidence and growth, and ACC1-FASN expression in intact and castrated mice. We demonstrated that Cav-1 regulated ACC1 and FASN expression in an AR-independent way and increased palmitate synthesis using western blot analysis, qRT-PCR and mass spectrometry in vitro. By using FASN siRNA and C-75, we found that FASN inhibition was more effective in Cav-1-overexpressing cells. This inhibition was abrogated by ACC1si RNA, revealing the role of malonyl-CoA, an ACC1 product, as a mediator of cytotoxicity. Cav-1 was associated with ACC1 in human tumors and ACC1, FASN, and Cav-1 expression were increased in metastatic PCa compared to primary tumors and normal prostate epithelium. Palmitoleate and oleate levels were higher in BMA from patients with metastatic PCa who responded poorly to abiraterone acetate. Our findings suggest that Cav-1 promotes hormone resistance through the upregulation of ACC1-FASN and lipid synthesis under androgen deprivation, suggesting that FASN inhibition could be used to treat PCa that demonstrates Cav-1 overexpression.