E- and N-cadherin differ with respect to their associated p120ctn isoforms and their ability to suppress invasive growth in pancreatic cancer cells
E-cadherin functions as suppressor of invasion in epithelial cells and its loss is described in many invasive carcinomas. In some tumours, the disappearance of E-cadherin has been correlated with upregulation of other classical cadherins, such as N- or P-cadherin. To analyse the different cellular functions of cadherin molecules, we stably expressed E-cadherin or N-cadherin in the E- and N-cadherin-deficient pancreatic tumour cell line MIA PaCa-2. Only E-cadherin was able to induce a mesenchymal-epithelial transition and suppressed invasion of MIA PaCa-2 cells. Furthermore, only re-expression of E-cadherin resulted in an upregulation of alpha- and beta-catenin mRNAs and protein concentrations. Ectopically expressed N-cadherin failed to assemble cadherin/catenin adhesion complexes and failed to inhibit invasion. Analysis of p120ctn, which was associated with both cadherins, demonstrated that E-cadherin was linked to a shorter isoform of p120ctn. In contrast, N-cadherin was associated with the long, 120 kDa p120ctn isoforms. In addition, p120ctn connected with N-cadherin was phosphorylated at tyrosine residues, whereas the isoform linked to E-cadherin was not phosphorylated. Thus, the differences between E- and N-cadherin in recruiting different phosphorylated isoforms of p120ctn to the membrane might be responsible for the inability of N-cadherin to replace E-cadherin as suppressor of invasion in pancreatic carcinoma cells.