Expression of prothymosin alpha is correlated with development and progression in human prostate cancers

BACKGROUND. Our previous study clearly demonstrated that decreased expression of prothymosin alpha (PTMA) was associated with inhibition of rat prostate carcinogenesis by isoflavones. The purpose of the present investigation was to provide a better understanding of the role of PTMA in human prostate cancers. METHODS AND RESULTS. PTMA expression in 68 prostate cancer cases and in prostate cancer cell lines was examined by immunohistochemistry and immunoblotting, and its levels were increased with progression from normal epithelium, through prostatic intraepithelial neoplasia (PIN) to carcinomas, correlating with the Gleason's pattern. All cell lines studied (LNCaP, 22Rv1, DU145, and PC3) showed high PTMA expression compared with prostate epithelial cells (PrEC). Knockdown of PTMA expression in PC3 cells by RNAi resulted in the inhibition of both cell growth and invasion in vitro. CONCLUSIONS. The present study clearly demonstrated that PTMA expression is intimately involved in the differentiation and progression of human prostate cancers, and could be a target for therapy and diagnostic purposes. Prostate 66: 463-469, 2006. (c) 2005 Wiley-Liss, Inc.