Modulation of fibronectin, laminin, and cellular adhesion in the transformation and differentiation of murine AKR fibroblasts.

The functional relationship between membrane/cell surface expression of fibronectin and laminin and transformation/differentiation was examined in an AKR mouse fibroblastic cell model. This model consisted of the untransformed AKR-2B cells, their chemically transformed counterpart (AKR-MCA cells) and the chemically differentiated form of the AKR-MCA cells. The transformed AKR-MCA cells were found to express more surface laminin and less fibronectin than the untransformed AKR-2B cells. The transformed AKR-MCA cells were slower to attach and spread on both plastic and type IV collagen-coated dishes in comparison to the AKR-2B cells. However, a higher percentage of the AKR-MCA cells ultimately attached and spread on the type IV collagen-coated dishes. The induction of differentiation in the AKR-MCA cells by N,N-dimethylformamide (DMF) restored fibronectin to the surface of the AKR-MCA cells but reduced laminin expression only slightly. The DMF-treated AKR-MCA cells resembled the AKR-2B cells in that they rapidly attached and spread on plastic dishes and dishes coated with type IV collagen. They also resembled the AKR-MCA cells in that a high proportion ultimately attached and spread on the collagen-coated dishes.