β-catenin interacts with and inhibits NF-κB in human colon and breast cancer

b-catenin plays an important role in development and homeostasis. Deregulated beta-catenin is involved in oncogenesis. In this study, we found that beta-catenin can physically complex with NF-kappaB, resulting in a reduction of NF-kappaB DNA binding, transactivation activity, and target gene expression. Repressed NF-kappaB activity is found in human colon cancer cells in which beta-catenin is activated. Importantly, activated beta-catenin was found to inhibit the expression of NF-kappaB target genes, including Fas and TRAF1. Furthermore, a strong inverse correlation was identified between the expression levels of beta-catenin and Fas in colon and breast tumor tissues, suggesting that beta-catenin regulates NF-kappaB and its targets in vivo. Thus, beta-catenin may play an important role in oncogenesis through the crossregulation of NF-kappaB.