Stable expression of a cDNA encoding a human beta 1 --> 3galactosyltransferase responsible for lacto-series type 1 core chain synthesis in non-expressing cells: variation in the nature of cell surface antigens expressed.

Abstract

Transient expression of a human colonic adenocarcinoma Colo 205 cell derived cDNA in cell lines which ordinarily express only neolacto-series glycolipids has resulted in the expression of a beta 1 --> 3galactosyltransferase gene responsible for synthesis of glycolipids based upon the lacto-series type 1 core chain. Calcium phosphate transfected cells were panned on anti-IgM coated plates after initial treatment with a combination of monoclonal antibodies specific for type 1 chain terminal structures (TE-3) and a very broadly specific antibody reactive with multiple type 1 chain derivatives (TE-2). Adherent cells after panning were capable of efficiently transferring Gal in beta 1 --> 3-linkage to the acceptor glycolipid Lc3. Using these reagents, clones of stably transfected human colonic adenocarcinoma HCT-15 cells were produced and isolated. Parental HCT-15 cells do not express type 1 chain based antigens. The nature of the type 1 chain based antigens produced in each of these clones was analyzed by solid phase antibody binding assays. Three types of behavior were observed. Formation of type 1 terminal structures that were either exclusively sialylated or fucosylated, or a mixture of sialylated and fucosylated determinants occurred. In contrast, no difference in type 2 antigen expression between any clone and the parental cells was observed. These data suggest that coordination of subsequent reactions capable of modifying type 1 chain structures is not the same in all clones. The relationship of these results to aspects of cellular regulation of carbohydrate biosynthesis is discussed.