Abstract 3421: Twist1 and clusterin regulate epithelial-mesenchymal transition

Abstract

Abstract INTRODUCTION AND OBJECTIVE: Clusterin (CLU) is a stress-activated, cytoprotective molecular chaperone, and is highly expressed in cells surviving apoptotic stimuli and in advanced and treatment-resistant cancers. In addition, CLU has recently been reported to be implicated in epithelial-mesenchymal transition (EMT). Similarly, oncogenic transcription factor Twist1 which binds to E-box (core sequence, 5’-CANNTG-3’) is known to be a master regulator of EMT. Although CLU is known to be transcriptionally activated by heat-shock factor 1, the mechanism CLU expression in EMT is not fully elucidated. This study begins to define mechanism of CLU expression and relevance in EMT of prostate cancer. METHODS: Human prostate cancer PC-3 and LNCaP cells were used to examine whether the manipulation of Twist1 expression affected CLU expression using quantitative real-time PCR, Western blotting and luciferase reporter assay using CLU promoter region. Chromatin-immunoprecipitation (ChIP) assays were used to determine whether Twist1 binds to CLU promoter region. We also examined markers of EMT after treatment with TGF-β1 and manipulation of Twist1/CLU expression. RESULTS: Twist1 overexpression was shown to upregulate CLU expression whereas Twist1 knockdown reduced CLU expression. ChIP assay and luciferase reporter assay revealed that Twist1 was bound to CLU promoter region and regulated CLU transcription. Treatment with TGF-β1, which is known to be an EMT-inducing cytokine, upregulated Twist1 expression followed by CLU expression. Furthermore, CLU knockdown ameliorated EMT induced by TGF-β1 and Twist1. CONCLUSIONS: This study indicates that CLU regulates EMT induced by TGF-β1 and Twist1 in prostate cancer cells. Modulation of CLU expression may be a useful strategy for developing novel therapeutics regulating EMT. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3421. doi:10.1158/1538-7445.AM2011-3421