Abstract 1237: WT1, Wnt signaling and E-cadherin in prostate cancer

Abstract Prostate carcinoma is the most common malignancy and second leading cause of death among American men. The molecular mechanisms that control the progression of this type of cancer are still poorly understood. Among the genes proposed to play a role in prostate cancer is the zinc finger transcription factor, WT1. Previous studies in our lab have shown WT1 protein in a majority of high grade prostate tumor sections with little or no WT1 staining in non-neoplastic or benign prostatic hyperplasia (BPH) tissues. However, a mechanistic role for WT1 in prostate cancer has not been established. Recently, WT1 has been associated with the Wnt signaling pathway and Beta catenin, the central molecule in the pathway. The cytoplasmic levels of Beta catenin can be regulated through the canonical Wnt signaling or through the intracellular adhesion complex where it binds to E-cadherin. Importantly, E-cadherin has previously been identified as a WT1 target gene in NIH 3T3 cells. The objective of this study was to determine whether WT1 might regulate genes that, in turn, regulate the levels of Beta catenin in prostate cancer cells. First potential WT1 binding sites were identified in the promoters of two candidate genes, GSK3 Beta and E-cadherin, using a bioinformatics approach. Then the effect of transfection of LNCaP prostate cancer cells with GFP-tagged WT1 expression constructs was tested by quantitative real time PCR (QRT-PCR). In vivo evidence of direct binding of these gene promoters by WT1 protein was obtained by Chromatin immunoprecipitation (ChIP) of GFP/WT1 transfected LNCaP cells. Using evolutionary conservation analysis we identified two WT1 binding sites in the E-cadherin promoter conserved among primate species and one that was conserved among primates, rodents and dog. QRT- PCR results showed a decrease in E-cadherin transcripts in GFP/WT1 transfected LNCaP cells, compared with untransfected cells. ChIP was used to demonstrate that this effect on E-cadherin expression was direct and mediated by DNA binding to the E-cadherin promoter in vivo. Overall these results suggest that WT1 modulates E-cadherin and the Wnt signaling pathway in LNCaP cells. These findings suggest a novel mechanism for proliferation and migration of prostate cancer cells and ultimately may contribute towards an improved cancer therapy. This work was supported by NIHR15CA11360 (GF) and GSS KSU grant(AB) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1237.