Aberrant signalling activities of β-catenin, originally identified as a component of cell-adhesion complexes, are now considered to be an important factor in colorectal carcinogenesis. However, recently it was shown that also γ- as well as p120 catenins have a dual role either in cell adhesion or in affecting some gene activation. Therefore, the levels and interactions of these three catenins in human colorectal carcinoma cell lines were analysed. A great heterogeneity in the expression of all catenins tested was found in colorectal carcinoma cell lines HT29 and LS174T. Detailed analysis of β-catenin interactions was done. GST-APC fragment-fused proteins were used to absorb β-catenin and its complexes from cell lysates. Similarly, the E-cadherin binding capacity of the residual pool of β-catenin was analysed using the GST-ECT construct. It was found that the level of β-catenin does not necessarily depend either on the APC or β-catenin gene mutations and that co-precipitation of β-, γ-, and p120 catenins is not limited to cells that express E-cadherin.

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