EGF enhances attachment of metastatic rat mammary adenocarcinoma cell clone MTLn3 to fibronectin and collagen.

Attachment of highly metastatic rat mammary adenocarcinoma MTLn3 cells to matrix proteins and its modulation by EGF was examined. Plastic plates were coated with varying amounts of collagen or fibronectin. MTLn3 cells exhibited a dose-dependent adhesion to both matrix proteins, however, they attached more efficiently to collagen than to fibronectin. When EGF or TGF alpha were added at 0.3 to 10 ng/ml for 30 min, a dose-dependent increase in adhesion to both matrix proteins was observed. Maximal stimulation (2-fold) was seen with 10 ng/ml of either growth factor. However, EGF was more potent at lower concentrations (0.3-3 ng/ml) than TGF alpha. The ability of growth factors to stimulate adhesion was also dependent on the amount of matrix the cells were exposed to. While EGF increased rapid attachment of MTLn3 cells to both matrix proteins similarly, subsequent cell spreading and formation of lamellar extensions was faster in cells plated on collagen. These results are suggestive of a functional link between EGF receptor and specific integrin activities.