Enhanced effect of epidermal growth factor on pulmonary metastasis and in vitro invasion of rat mammary carcinoma cells

We examined the effects of epidermal growth actor (EGF) on metastatic and in vitro invasive capacity of weakly malignant ER-1 cells derived from a rat mammary carcinoma cell line, c-SST-2. EGF enhanced the metastatic capacity and in vitro invasiveness to reconstituted basement membrane, Matrigel, of ER-1 cells in a dose-dependent fashion. EGF-stimulated invasiveness was inhibited by anti-EGF antibody, which is able to neutralize the binding of EGF to EGF receptor, in the invasion assay system. EGF stimulated chemotactic migration toward fibronectin, laminin or newborn rat fibroblast-conditioned medium which was used as a chemoattractant in the in vitro invasion assay, but showed neither adhesion to Matrigel nor production of gelatinase and plasminogen activators. These results suggested that the increased metastatic and invasive capacity of ER-1 cells by EGF might be due to the increase in cell motility.