V-ATPase-dependent repression of androgen receptor in prostate cancer cells.

ABSTRACT: Prostate Cancer (PCa) is the most commonly diagnosed cancer and the third leading cause of death for men in the United States. Suppression of androgen receptor (AR) expression is a desirable mechanism to manage PCa. Our studies showed that AR expression was reduced in LAPC4 and LNCaP PCa cell lines treated with nanomolar concentrations of the V-ATPase inhibitor concanamycin A (CCA). This treatment decreased PSA mRNA levels, indicative of reduced AR activity. V-ATPase-dependent repression of AR expression was linked to defective endo-lysosomal pH regulation and reduced AR expression at the transcriptional level. CCA treatment increased the protein level and nuclear localization of the alpha subunit of the transcription factor HIF-1 (HIF-1?) in PCa cells via decreased hydroxylation and degradation of HIF-1?. The addition of iron (III) citrate restored HIF-1? hydroxylation and decreased total HIF-1? levels in PCa cells treated with CCA. Moreover, iron treatment partially rescued CCA-mediated AR repression. Dimethyloxalylglycine (DMOG), which prevents HIF-1? degradation independently of V-ATPase, also decreased AR levels, supporting our hypothesis that HIF-1? serves as a downstream mediator in the V-ATPase-AR axis. We propose a new V-ATPase-dependent mechanism to inhibit androgen receptor expression in prostate cancer cells involving defective endosomal trafficking of iron and the inhibition of HIF-1 ?-subunit turnover.

SUBMITTER: Licon-Munoz Y 

PROVIDER: S-EPMC6034745 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature