Purification and analysis of glycoproteins bearing blood group-a determinants from hamster pancreatic ductal adenocarcinomas

Although the hamster pancreas does not express A, B or H blood group antigens, all hamster pancreatic ductal adenocarcinomas induced by treatment with N-nitrosobis(2-oxopropyl)amine express blood group-A antigen. Thus, the acquisition of blood group-A antigen expression in this system is a cancer-associated alteration. We have purified three major blood group-A antigen bearing glycoproteins (gpl20, gpl35 and gpl50) from hamster pancreatic cancer cell membrane preparations using affinity chromatography on DBA (Dolichos biflorus) agglutinin-agarose. When assayed by immunoblotting, gpl20 and gpl35 showed strong blood group-A reactivity, which was removed by treating membrane samples with peptide-N-glycosidase F. Blood group-A reactivity was unchanged by treatment of the membrane fractions with endoglycosidases F and H. In addition, these two glycoproteins bearing blood group-A antigen also bound L-PHA (Phaseohis vulgaris leueoagglutinin). These results demonstrate that gpl20 and gpl35 express blood group-A antigen on Asn-linked multi-antennary complex type glycan structures. The gpl50 showed weak blood group-A expression. This is the first demonstration of the neoexpression of cancer-associated blood group-A determinants which reside on Asn-linked glycan structures.