OVEREXPRESSION OF EMS1 CORTACTIN IN NIH3T3 FIBROBLASTS CAUSES INCREASED CELL MOTILITY AND INVASION IN-VITRO/

Cortactin, a p80/85 protein first identified as a src kinase substrate , is thought to be involved in the signaling pathway of mitogenic rece ptors and adhesion molecules mediating cytoskeletal reorganization. Th e cortactin gene, EMS1, maps to chromosome 11q13, a region amplified i n head and neck squamous cell carcinomas (HNSCC) and breast cancer, wh ich display lymph node metastasis and an unfavorable clinical outcome. To further address the role of cortactin in the malignant phenotype o f cells, we stably overexpressed cortactin in NIH3T3 fibroblasts and e valuated the effects of elevated cortactin on cellular proliferation, motility and invasiveness. Cortactin overexpressing cells did not disp lay any striking morphological changes, nor any significant difference s in cell proliferation or saturation density as compared to control N IH3T3 cells. Furthermore, the cortactin overexpressing cells were anch orage dependent for growth. Interestingly, cortactin overexpressing ce lls were more motile and invasive in modified Boyden chamber assays. T hese results suggest that overexpression of cortactin may play a role in tumor progression by influencing tumor cell migration and invasion.