ROR-? drives androgen-receptor expression and represents a therapeutic target in castration-resistant prostate cancer

The androgen receptor (AR) is overexpressed and hyperactivated in human castration-resistant prostate cancer (CRPC). However, the determinants of AR overexpression in CRPC are poorly defined. Here we show that retinoic acid receptor–related orphan receptor ? (ROR-?) is overexpressed and amplified in metastatic CRPC tumors, and that ROR-? drives AR expression in the tumors. ROR-? recruits nuclear receptor coactivator 1 and 3 (NCOA1 and NCOA3, also known as SRC-1 and SRC-3) to an AR–ROR response element (RORE) to stimulate AR gene transcription. ROR-? antagonists suppress the expression of both AR and its variant AR-V7 in prostate cancer (PCa) cell lines and tumors. ROR-? antagonists also markedly diminish genome-wide AR binding, H3K27ac abundance and expression of the AR target gene network. Finally, ROR-? antagonists suppressed tumor growth in multiple AR-expressing, but not AR-negative, xenograft PCa models, and they effectively sensitized CRPC tumors to enzalutamide, without overt toxicity in mice. Taken together, these results establish ROR-? as a key player in CRPC by acting upstream of AR and as a potential therapeutic target for advanced PCa. Overall design: A total of 6 samples were analyzed in this study. The study included one cell line C4-2B. C4-2B cells were cultured in medium containing vehicle control and/or SR2211 and/or XY011 and/or Enzalutamide (ENZ). The untreated C4-2B cells served as controls for the study.