Abstract 1303: The Wilms’ tumor gene, WT1, regulates E-cadherin expression and migration of prostate cancer cells.

Abstract

Abstract Carcinoma of the prostate is one of the most common malignancies and second leading cause of death among American men. Even though patients with localized disease have high survival rates, patients with detectable metastasis have a median survival of only 12-15 months. One key step in the metastatic process is the loss of E-cadherin expression associated with tumor invasion. However the regulation of E-cadherin gene expression in prostate cancer (PrCa) cells is not well understood. Recently, the zinc finger transcription factor, WT1 was shown to regulate E-cadherin in NIH 3T3 cells and epicardial cells. We have previously reported the presence of WT1 protein in high grade prostate tumor sections, with little or no WT1 staining in non-neoplastic or benign prostatic hyperplasia (BPH) tissues. However, the significance of WT1 expression in prostate cancer has not been established. The objective of this study was to determine whether WT1 might contribute to increase migration of PrCa cells by repressing E-cadherin expression. Using quantitative real-time PCR (QRTPCR), WT1 and E-cadherin mRNA levels were measured and found to be inversely related in PrCa cells. Similarly, QRTPCR results showed a decrease in E-cadherin mRNA in GFP/WT1 transfected PrCa cells, while E-cadherin levels were increased in PrCa cells with suppressed WT1 expression. Titration of WT1 levels also affected the migration of PrCa cells in wound healing and transwell migration assays. Silencing of WT1 by siWT1 RNA decreased the migratory potential of PC3 cells and the overexpression of GFP/WT1 increased the migration of LNCaP cells. A bioinformatics approach was used to identify potential WT1 binding sites in E-cadherin promoter, then direct in vivo binding of WT1 to the E-cadherin promoter in the chromatin of PrCa cells was confirmed by Chromatin Immunoprecipitation. Transcriptional control was quantified by co-transfection of a GFP/WT1 expression construct with E-cadherin promoter constructs. Results showed that WT1 decreased the activity of the proximal E-cadherin promoter in PC3 cells and DU145 cells. Using site directed mutagenesis, a newly identified WT1 binding site located 146 bp from the transcription start site was shown to be required for the repression of the E-cadherin proximal promoter by WT1. Overall these results demonstrate that WT1 transcriptionally down-regulates E-cadherin expression and thereby increases migration of PrCa cells. This finding suggests that the biological significance of WT1 expression in high grade prostate cancer lies in its contribution to cell migration and potentially to the promotion of metastasis. Supported by NIHR15CA11360 and the Ohio Board of Regents. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1303. doi:1538-7445.AM2012-1303