Glycosyltransferase and glycosidase activities in cultured human fetal and colonic adenocarcinoma cell lines.

Abstract

Abstract Three galactosyltransferases, an N-acetylgalactosaminyltransferase, two sialyltransferases, and glycosidase activities were examined in cultured human colonic fetal and tumor cells and in colonic tumors and adjacent normal mucosa. Although tumor tissues generally had the lowest specific activities of these enzymes, of the four sources examined cultured cancer cells had the highest levels of two galactosyltransferases. A substantial amount of glycosyltransferase activity in cell cultures was secreted into the culture fluid. Differential appearance of glycosyltransferases in the culture media suggests that the media activities are a result not of cell death but of cellular secretion. Thin-layer isoelectric focusing of cell extracts and examination of galactosyltransferase activity revealed differences in isoenzyme profiles among cultured tumor lines. Although most tumor lines had a component with an isoelectric point of pH 4.8, each cell line had a unique complement of galactosyltransferase isoenzymes. The findings that cells secrete large amounts of glycosyltransferases and that tumor cells differ in their galactosyltransferase isoenzyme profiles suggest that the development and chemotherapeutic response of human colonic adenocarcinoma might be followed in an animal model by examination of these enzymes in the sera of nude mouse recipients of these tumor cells or by similar analysis in cancer patients.