CCDC62/ERAP75 functions as a coactivator to enhance estrogen receptor beta-mediated transactivation and target gene expression in prostate cancer cells

• Published in: Carcinogenesis (New York) 2009-05, Vol.30 (5), p.841-850
• Main Authors: Chen, Ming, Ni, Jing, Chang, Hong-Chiang, Lin, Chen-Yong, Muyan, Mesut, Yeh, Shuyuan
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Carcinogenesis, carcinogens and anticarcinogens; Cell Division; Cell Line, Tumor; Cloning, Molecular; Estrogen Receptor beta - physiology; Gene Expression Regulation, Neoplastic; Gynecology. Andrology. Obstetrics; Humans; Male; Male genital diseases; Medical sciences; Mice; Nephrology. Urinary tract diseases; Polymerase Chain Reaction; Prostatic Neoplasms - genetics; Prostatic Neoplasms - pathology; Receptors, Estrogen - physiology; RNA Interference; Signal Transduction; Testis - physiology; Transcription Factors - physiology; Transcriptional Activation; Tumors; Tumors of the urinary system; Urinary tract. Prostate gland
• ISSN: 0143-3334; 1460-2180
• DOI: 10.1093/carcin/bgn288

Human prostate cancer (PCa) and prostate epithelial cells predominantly express estrogen receptor (ER) β, but not ERα. ERβ might utilize various ER coregulators to mediate the E2-signaling pathway in PCa. Here, we identified coiled-coil domain containing 62 (CCDC62)/ERAP75 as a novel ER coactivator. CCDC62/ERAP75 is widely expressed in PCa cell lines and has low expression in MCF7 cells. Both in vitro and in vivo interaction assays using mammalian two-hybrid, glutathione S-transferase pull-down and coimmunoprecipitation methods proved that ERβ can interact with the C-terminus of CCDC62/ERAP75 via the ligand-binding domain. The first LXXLL motif within CCDC62/ERAP75 is required for the interaction between ERβ and CCDC62/ERAP75. Electrophoretic mobility shift assay showed that CCDC62/ERAP75 can be recruited by the estrogen response element–ER complex in the presence of ligand. Furthermore, a chromatin immunoprecipitation assay demonstrated the hormone-dependent recruitment of CCDC62/ERAP75 within the promoter of the estrogen-responsive gene cyclin D1. In addition, using silencing RNA (siRNA) against endogeneous CCDC62/ERAP75, we demonstrated that inhibition of endogenous CCDC62/ERAP75 results in the suppression of ERβ-mediated transactivation as well as target gene expression in LNCaP cells. More importantly, using the tet-on overexpression system, we showed that induced expression of CCDC62/ERAP75 can enhance the E2-regulated cyclin D1 expression and cell growth in LNCaP cells. Together, our results revealed the role of CCDC62/ERAP75 as a novel coactivator in PCa cells that can modulate ERβ transactivation and receptor function.