Journal Article

β-catenin/TCF4 complex induces the epithelial-to-mesenchymal transition (EMT)-activator ZEB1 to regulate tumor invasiveness

Sánchez-Tilló, Ester, de Barrios, Oriol, Castells, Antoni, Postigo, Antonio, Siles, Laura, Cuatrecasas, Miriam

2011

Overview

In most carcinomas, invasion of malignant cells into surrounding tissues involves their molecular reprogramming as part of an epithelial-to-mesenchymal transition (EMT). Mutation of the APC gene in most colorectal carcinomas (CRCs) contributes to the nuclear translocation of the oncoprotein β-catenin that upon binding to T-cell and lymphoid enhancer (TCF-LEF) factors triggers an EMT and a proinvasive gene expression profile. A key inducer of EMT is the ZEB1 transcription factor whose expression promotes tumorigenesis and metastasis in carcinomas. As inhibitor of the epithelial phenotype, ZEB1 is never present in the epithelium of normal colon or the tumor center of CRCs where β-catenin remains membranous. We show here that ZEB1 is expressed by epithelial cells in intestinal tumors from human patients (familial adenomatous polyposis) and mouse models (APCMin/+) with germline mutations of APC that result in nuclear accumulation of β-catenin. However, ZEB1 is not expressed in the epithelium of hereditary forms of CRCs that carry wild-type APC and where β-catenin is excluded from the nucleus (Lynch syndrome). We found that β-catenin/TCF4 binds directly to the ZEB1 promoter and activates its transcription. Knockdown of β-catenin and TCF4 in APC-mutated CRC cells inhibited endogenous ZEB1, whereas forced translocation of β-catenin to the nucleus in APC-wild-type CRC cells induced de novo expression of ZEB1. Upregulation of MT1-MMP and LAMC2 by β-catenin/TCF4 has been linked to invasiveness in CRCs, and we show here that both proteins are activated by ZEB1 coexpressing with it in primary colorectal tumors with mutated APC. These results set ZEB1 as an effector of β-catenin/TCF4 signaling in EMT and tumor progression.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Adenoma / Animals / Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - genetics / Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - metabolism / beta Catenin - genetics / beta Catenin - metabolism / Biological Sciences / Blotting, Western / carcinogenesis / Cell Line / Cell lines / Cell nucleus / Chromatin Immunoprecipitation / colon / Colorectal cancer / Colorectal neoplasms / DNA Primers - genetics / Epithelial cells / Epithelial-Mesenchymal Transition - physiology / epithelium / Fluorescent Antibody Technique / gene expression / gene expression regulation / Gene Expression Regulation, Neoplastic - physiology / Gene Knockdown Techniques / genes / HCT116 cells / Homeodomain Proteins - genetics / Homeodomain Proteins - metabolism / Humans / Immunohistochemistry / Lynch syndrome II / metastasis / Mice / Multiprotein Complexes - metabolism / Mutagenesis, Site-Directed / mutation / Neoplasm Invasiveness - physiopathology / patients / phenotype / promoter regions / Promoter Regions, Genetic - genetics / protein transport / Real-Time Polymerase Chain Reaction / RNA, Small Interfering - genetics / Signal Transduction - physiology / Stromal cells / transcription (genetics) / Transcription Factor 4 / transcription factors / Transcription Factors - genetics / Transcription Factors - metabolism / Tumors / Zinc Finger E-box-Binding Homeobox 1