Androgen-dependent repression of estrogen-related receptor γ expression mediates metabolic reprogramming in prostate cancer

Androgens are central to prostate cancer (PCa) development and targeting this pathway is currently the main therapeutic axis in the clinic, but the mechanism by which androgen signaling contributes to the oncometabolic state of PCa cells remains to be fully elucidated. The intersection of gene expression, binding-events and motif finding analyses following androgen exposure identified a metabolic gene signature associated with the action of estrogen-related receptors (ERRs). Unexpectedly, we show that ERRγ acts as a negative regulator of mitochondrial respiration in the context of PCa, and that AR-dependent direct repression of ERRγ promotes the reactivation of a functional TCA cycle. This metabolic state, which parallels the loss of ERRγ expression, was observed in both androgen-dependent and castration-resistant PCa and was associated with cell proliferation. Interrogation of several clinical studies revealed a strong inverse relationship between ERRγ expression and the severity of the disease. Our study uncovers a novel mechanism by which AR-dependent repression of ERRγ contributes to the reprogramming of PCa cell metabolism to favor mitochondrial activity and cell proliferation. We used microarrays to investigate the transcriptional regulation of metabolic genes by 72h treatment with R1881, a synthetic androgens, with or without repression of the estrogen-related receptor gamma, in LNCaP prostate cancer cells. Cells were seeded in media containing 2% serum deprived from steroids and transfected with siRNA controls or against estrogen-related receptor gamma. 48h later, cell were trypsinized and seeded in 6-well plates for treatment with 10nM R1881 or vehicle (EtOH) for 72h, with fresh medium and treatment added after 48h. Triplicate samples were sent for each conditions.