Axin, an inhibitor of the Wnt signalling pathway, interacts with β-catenin, GSK-3β and APC and reduces the β-catenin level

Background: The Wnt/Wingless signalling pathway plays an important role in both embryonic development and tumorigenesis. beta-Catenin and Axin are positive and negative effectors of the Wnt signalling pathway, respectively. Results: We found that Axin interacts with beta-catenin and glycogen synthase kinase-3 beta (GSK-3 beta). Furthermore, the regulation of the G-protein signalling (RGS) domain of Axin is associated with the colorectal tumour suppressor adenomatous polyposis coli (APC). Overexpression of Axin in the human colorectal cancer cell line SW480 induced a drastic reduction in the level of beta-catenin. Interaction with beta-catenin and GSK-3 beta was required for the Axin-mediated beta-catenin reduction. Conclusion: Axin interacts with beta-catenin, GSK-3 beta and APC, and negatively regulates the Wnt signalling pathway, presumably by regulating the level of beta-catenin.