Insulin-like growth factor-I receptor, E-cadherin and alpha v integrin form a dynamic complex under the control of alpha-catenin.

Dynamic crosstalk between cell adhesion molecules, extracellular matrix and soluble informative factors is essential for cancer cell migration and invasion. Here, we investigated the mechanisms by which the E-cadherin/catenin complex and alpha v integrin can modulate insulin-like growth factor-I (IGF-I)-induced cell migration. Human colon mucosa, human colon cancer cell lines, HT29-D4 and HCT-8 derivatives that differ in their expression of alpha-catenin, were used as models. Interactions between E-cadherin, alpha v integrin and IGF-I receptor (IGF-IR) were analyzed by coimmunoprecipitation and immunolocalization experiments. The impact of these interactions on cell mobility was determined by haptotaxis assays. We report that alpha v integrin, E-cadherin and IGF-IR form a ternary complex in both cultured cancer cells and human normal colonic mucosa. alpha-Catenin regulates the scaffolding of this complex. IGF-IR ligation by IGF-I induces the disruption of the complex and the relocalization of alpha v integrin from cell-cell contacts to focal contact sites. This perturbation is correlated with the observed increase in cell migration. These results suggest that regulation of the alpha v integrin/E-cadherin/IGF-IR scaffolding is essential for the modulation of cell mobility. Its alteration could be of major importance to sustain alterations in cell adhesion that occur during cancer cell invasion and metastasis.