Glycoprotein alterations in human colonic adenocarcinoma.

A marked diminution in membrane glycoproteins containing blood group A activity was observed in colonic cancer tissues. This change was associated with a reduction of the enzyme responsible for its biosynthesis and a decreased concentration of N-acetylgalactosamine in the cancer tissues. Glycosidase activities were unchanged. In addition to the changes associated with blood group A, we also found a decrease in sugar content, alterations in other antigens, and changes in the levels of several glycosyltransferases in cancerous tissues.