Adenomatous polyposis coli protein (APC)-independent regulation of β-catenin/Tcf-4 mediated transcription in intestinal cells

Abstract

Alterations in the transcriptional activity of the β-catenin-Tcf complex have been associated with the earlier stages of colonic transformation. We show here that the activation of protein kinase C by the phorbol ester PMA in several intestinal cell lines increases the levels of β-catenin detected in the nucleus and augments the transcriptional activity mediated by β-catenin. The response to PMA was not related to modifications in the cytosolic levels of β-catenin and was observed not only in cells with wild-type adenomatous polyposis coli protein (APC) but also in APC-deficient cells. Binding assays in vitro revealed that PMA facilitates the interaction of the β-catenin with the nuclear structure. Our results therefore show that β-catenin-mediated transcription can be regulated independently of the presence of APC.