The use of 125I-lectin probes in defining plasma membrane carbohydrate moieties in 3 subpopulations of human colonic carcinoma cells.

The molecular mechanism(s) responsible for the generation of phenotypic diversity within tumors is not understood. Since the cell surface/plasma membrane components are involved in a variety of important biological function such as growth and differentiation regulation which may be mediated through intercellular and/or extracellular matrix interaction, the plasma membranes from 3 human colonic carcinoma cell lines (originally isolated from a single primary tumor) were purified and characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Membrane carbohydrate moieties were also characterized by a panel of 5 125I-labeled lectin probes following their electrophoretic fractionation and transfer onto nitrocellulose. Though these cell lines possessed diverse biological properties, their Coomassie blue stained electrophoretic protein profiles were found to be very conserved. The altered quantitative expression of only 1 membrane protein (Mr = 46 KD) was found to be associated with the more neoplastic HCT 116a cells which distinguished this cell line from the less neoplastic HCT 116b and HCT 116 cells. All 5 lectin binding profiles, on the other hand, clearly and easily distinguished the HCT 116a cells from the HCT 116b and HCT 116 cells. Thus, heterogeneity in terms of differences in membrane carbohydrate moieties was more obvious.