Activation of beta-Catenin in mouse prostate causes HGPIN and continuous prostate growth after castration

The role of Wnt/beta-Catenin signaling in embryogenesis and carcinogenesis has been extensively studied in organs such as colon, lung and pancreas, but little is known about Wnt/beta-Catenin signaling in the prostate. Although stabilizing mutations in APC and beta-Catenin are rare in primary prostate tumors, recent studies suggest that cytoplasmic/nuclear beta-Catenin is associated with advanced, metastatic, hormone-refractory prostate carcinoma.

To better understand the role of beta-Catenin in prostatic development and carcinogenesis, we studied Wnt expression during prostate development and activated Wnt/beta-Catenin signaling in the developing and adult prostate.

Our results demonstrated that during prostate development Wnt ligands display a dynamic expression pattern. Activation of beta-Catenin during prostate development caused epithelial hyperplasia followed by prostatic intraepithelial neoplasia (PIN) in prostate. In the adult prostate, activation of beta-Catenin resulted in high grade PIN (HGPIN) and continuous prostatic growth after castration. As a result of activation of beta-Catenin, AR was first up-regulated with the emergence of epithelial hyperplasia, but was later down-regulated when HGPIN developed. Furthermore, activation of beta-Catenin induced Foxa2 re-expression in adult prostate which normally is only expressed in the embryonic budding stage during prostate development.

The results from this study strongly suggest that Wnt/beta-Catenin signaling is involved in the regulation of prostate development and confirm that constitutive activation of this pathway enables the mouse prostate to grow after castration.