Differentiation-related alterations in the plasma membranes of chemically transformed murine fibroblasts

One of the pathways of action of the differentiation-inducing agent DMF, in chemically transformed AKR-MCA fibroblastic cells, is through the concurrent restoration of the synthesis of the cell-surface adhesion molecule fibronectin and receptors for fibronectin. In order to identify plasma membrane components that are intimately associated with the induction of differentiation by DMF in the AKR-MCA cells, we have purified, characterized and compared the plasma membranes prepared from DMF treated and untreated AKR-MCA cells and from DMF treated and untreated AKR-2B cells (untransformed control cells). While DMF was found to have a non-discernible effect on the plasma membranes of the untransformed AKR-2B control cells, it restored the expression of several major AKR-2B associated plasma membrane proteins to the transformed AKR-MCA cells. These included major plasma membrane proteins of molecular weight 46 and 38 kilodaltons which were identified by one-dimensional SDS-PAGE, and two other major silver staining proteins identified by two-dimensional gel electrophoresis. Plasma membrane carbohydrate moieties were also analyzed by 125I-lectin probes following SDS-PAGE fractionation and electrophoretic transfer of plasma membranes to nitrocellulose. Differences in the radiolabeled Con A and RCA 1 binding profiles were observed between the untransformed and transformed cells. DMF induced an overall restoration of the untransformed AKR-2B associated lectin binding profiles to the differentiated AKR-MCA cells. This study identified several plasma membrane proteins and lectin binding carbohydrate moieties, the qualitative or quantitative alterations of which were intimately associated with chemical transformation and differentiation induction of the transformed cells.