Isolation and characterization of Chinese hamster ovary cell variants defective in adhesion to fibronectin-coated collagen

Variant clones of Chinese hamster ovary (CHO) cells were selected for reduced adhesion to serum-coated tissue culture plates. These clones also displayed reduced adhesion to substrata composed of collagen layers coated with bovine serum or with fibronectin (cold-insoluble globulin). Wild-type (WT) and adhesion variant (ADv) cells grew at comparable rates in suspension culture, but the adhesion variants could not be grown in monolayer culture because of their inability to attach to the substratum. The adhesion deficit in these cells was not corrected by raising the concentration of divalent cations or of serum to levels 10-fold greater than those normally utilized in cell culture. However, both WT and ADv clones could adhere, spread, and attain a normal CHO morphology on substrata coated with concanavalin A or poly-L- lysine. In addition, the adhesion variants could attach to substrata coated with "footpad" material (substratum-attached material) derived from monolayers of human diploid fibroblasts or WT CHO cells. These observations suggest that the variant clones may have a cell surface defect that prevents them from utilizing exogeneous fibronectin as an adhesion-promoting ligand; however the variants seem to have normal cytoskeletal and metabolic capacities that allow them to attach and spread on substrata coated with alternative ligands. These variants should be extremely useful in studying the molecular basis of cell adhesion.