ELEVATED LEVELS OF THE ALPHA-5-BETA-1-FIBRONECTIN RECEPTOR SUPPRESS THE TRANSFORMED PHENOTYPE OF CHINESE HAMSTER OVARY CELLS

We report here on gene transfer studies designed to investigate the function of the α5β1 integrin and its role in transformation. Transfection of the human α5 and β1 cDNAs into transformed Chinese hamster ovary (CHO) cells followed by methotrexate-induced amplification yielded clonal cell lines overexpressing this fibronectin receptor. The overexpressors deposited more fibronectin in their extracellular matrix and migrated less than control cells. In addition, they showed reduced saturation density and reduced ability to grow in soft agar. The overexpressor cells, unlike the control CHO cells, were nontumorigenic when injected subcutaneously into nude mice. The results indicate that extracellular matrix recognition by the α5β1 integrin plays a role in the control of cell proliferation and suggest that a reduction of this fibronectin receptor may be responsible for the acquisition of anchorage independence by transformed cells. © 1990.