Wnt/β-Catenin activation promotes prostate tumor progression in a mouse model

Our previous studies have found that activation of Wnt/beta-catenin signaling resulted in mouse prostatic intraepithelial neoplasia (mPIN). In the large probasin promoter directed SV40-large T-antigen ( LPB- Tag) expressing mouse prostate, mPIN forms with rare areas of adenocarcinoma. Combining expression of both Wnt-signaling and Tag expression in the mouse prostate, we have studied the role of Wnt/beta-catenin signaling in the progression from mPIN to adenocarcinoma. Our results show that the prostates of mice expressing Tag alone or nuclear beta-catenin alone developed mPIN, whereas the activation of both Tag and the Wnt/beta-catenin pathway resulted in invasive prostate adenocarcinoma. Furthermore, Foxa2, a forkhead transcription factor, was induced by active Wnt/beta-catenin signaling, and the expression of Foxa2 was associated with the invasive phenotype in the primary prostate cancer. In the LPB-Tag/dominant active (DA) b-catenin prostates, MMP7, a Wnt/beta-catenin target gene, was upregulated. Furthermore, we also assessed AR and AR signaling pathway in these LPB-Tag/DA beta-catenin mice. Although beta-catenin is a well-known AR co-activator in vitro, our study provides strong in vivo evidences indicating that both AR protein and the AR pathway were downregulated in the prostate of LPB-Tag/DA beta-catenin mice. Histological analysis shows that prostate sections derived from the LPB-Tag/DA beta-catenin mice display neuroendocrine differentiation (NED), but NE cancer does not develop. Together, our findings indicate that Wnt/beta-catenin signaling has an important role in the progression of mPIN to prostate adenocarcinoma. Oncogene (2011) 30, 1868-1879; doi: 10.1038/onc.2010.560; published online 13 December 2010