A novel enhancer RNA in castration-resistant prostate cancer

About This Grant

PROJECT SUMMARY/ABSTRACT Castration-resistant prostate cancer (CRPC) is the leading cause of death among prostate cancer (PCa) patients. CRPC is primarily driven by persistent activation of androgen receptor (AR) signaling, highlighting AR and its regulatory factors as promising therapeutic targets. Here, we identify a novel enhancer RNA (eRNA), CYP11A1-eRNA, that plays a critical role in regulating AR target gene transcription. CYP11A1-eRNA is transcribed from an active enhancer near the CYP11A1 locus. Knockdown of CYP11A1- eRNA does not affect CYP11A1 or AR expression, but significantly reduces the expression of AR target genes. CYP11A1-eRNA is upregulated in castration-resistant PCa cells and CRPC xenograft tissues compared to their castration-sensitive counterparts. Functionally, CYP11A1-eRNA knockdown inhibits PCa cell proliferation, particularly under androgen-deprived conditions, suggesting that elevated CYP11A1-eRNA expression contributes to CRPC progression. Preliminary data further indicate that CYP11A1-eRNA promotes RNA polymerase II (Pol II) pause release and transcription elongation of AR target genes, likely by facilitating P-TEFb recruitment. We therefore hypothesize that CYP11A1-eRNA enhances AR target gene expression and contributes to CRPC progression by promoting P-TEFb recruitment and Pol II pause release. Aim 1 will define the mechanisms by which CYP11A1-eRNA regulates AR target gene expression. Specifically, we will assess CYP11A1-eRNA expression in CRPC and determine its genome-wide impact on AR transcriptional program. We will investigate whether CYP11A1-eRNA facilitates P-TEFb recruitment and Pol II pause release at AR target gene promoters, and elucidate the molecular basis of CYP11A1-eRNA-mediated PTEFb recruitment. Aim 2 will evaluate whether CYP11A1-eRNA promotes androgen-independent PCa cell growth in vitro and in orthotopic or CRPC tumor models. The proposed animal studies have been limited to the minimum number of mice required to ensure statistically and biologically significant results. These experiments are essential for determining the functional role of CYP11A1-eRNA in castration resistance in vivo, as the complex interactions between tumor cells and the host microenvironment cannot be fully recapitulated in vitro. This study will uncover a previously unrecognized mechanism of AR target gene regulation mediated by CYP11A1-eRNA and establish CYP11A1-eRNA as a potential therapeutic target for CRPC.