beta-Catenin signaling in biological control and cancer.

A coordinated integration of cell-cell adhesion and the control of gene expression is essential for the development of multicellular, differentiated organisms. beta-Catenin fulfils important regulatory functions in both cell-cell adhesion by linking cadherin adhesion receptors to the cytoskeleton, and also as a key element in the Wnt signaling pathway where it acts as cotranscriptional activator of target genes in the cell nucleus. Wnt signaling is involved in numerous aspects of embryonic development and in the control of tissue self-renewal in a variety of adult tissues. Hyperactivation of Wnt signaling, mostly by affecting beta-catenin functions, is a hallmark of colon cancer and of many other human cancers. In this prospect, we discuss studies pointing to the molecular mechanisms that govern the integration between cell-cell adhesion and gene expression, as reflected in the switches between these two functions of beta-catenin in colon cancer cells. (c) 2007 Wiley-Liss, Inc.