Regulation of androgen receptor transcriptional activity and specificity by RNF6

The androgen receptor (AR) plays a critical role in prostate cancer. We identified an ubiquitin E3 ligase RNF6 as one of AR-associated proteins in a proteomic screening. RNF6 induces AR ubiquitination and promotes AR transcriptional activity. Specific knockdown of the endogenous RNF6 alters expression of a subset of AR target genes and diminishes recruitment of AR and its coactivators to androgen responsive elements (AREs) present in the regulatory region of these genes. Furthermore, RNF6 is overexpressed in human hormone-refractory prostate cancer tissues and required for prostate cancer cell growth under androgen-depleted conditions. Our work has provided a novel mechanism by which AR transcriptional activity and specificity is regulated, and identified RNF6 as a potential new target for prostate cancer treatment. Total RNA was extracted from LNCaP cells treated with (1) No Treatment (NT-DHT) (2) shCon-DHT, (3) shRNF6-DHT, (4) NT+DHT, (5) shCon+DHT, (6) shRNF6+DHT, respectively. Total RNA from each of 5 treated LNCaP cells was labeled with Cy5 dye. RNA from LNCaP cells that received no DHT (NT-DHT) was also labeled with Cy3 dye and served as a common reference, with which each of the five labeled test samples were cohybridized in a classical two-color hybridization scheme.