Carbohydrate chains of
cancer glycoprotein antigens contain major outer changes dictated by tissue-specific regulation of
glycosyltransferase genes, the availability of
sugar nucleotides, and competition between
enzymes for acceptor intermediates during
glycan elongation. However, it is evident from recent studies with recombinant
mucin probes that the final glycosylation profiles of
mucin glycoproteins are mainly determined by the cellular repertoire of
glycosyltransferases. Hence, we examined various
cancer cell lines for the levels of fucosyl-, beta-galactosyl, beta-N-acetylgalactosaminyl-, sialyl-, and
sulfotransferase activities that generate the outer ends of the
oligosaccharide chains. We have identified
glycosyltransferases activities at the levels that would give rise to O-
glycan chains as reported by others in
breast cancer cell lines, T47D, ZR75-1, MCF-7, and MDA-MB-231. Most
breast cancer cells express Gal-3-O-sulfotransferase specific for T-
hapten Gal beta1-->3GalNAc alpha-, whereas the
enzyme from
colon cancer cells exhibits a vast preference for the Gal beta1,4GlcNAc terminal unit in O-
glycans. We also studied
ovarian cancer cells SW626 and PA-1 and
hepatic cancer cells HepG2. Our studies show that alpha1,2-L-fucosyl-T, alpha(2,3) sialyl-T, and 3-O-Sulfo-T capable of acting on the
mucin core 2 tetrasaccharide, Gal beta1,4GlcNAc beta1,6(Gal beta1,3)GalNAc alpha-, can also act on the
Globo H antigen backbone, Gal beta1,3GalNAc beta1,3Gal alpha-, suggesting the existence of unique
carbohydrate moieties in certain
cancer-associated
glycolipids. Briefly, our study indicates the following: (i) 3'-Sulfo-T-hapten has an apparent relationship to the tumorigenic potential of
breast cancer cells; (ii) the 3'-sulfo Lewis(x), the 3-O-sulfo-Globo unit, and the 3-fucosylchitobiose core could be uniquely associated with
colon cancer cells; (iii) synthesis of a
polylactosamine chain and T-
hapten are favorable in
ovarian cancer cells due to negligible
sialyltransferase activities; and (iv) a 6'-sialyl LacNAc unit and 3'-sialyl T-
hapten appear to be prevalent structures in
hepatic cancer cell
glycans. Thus, it is apparent that different
cancer cells are expressing unique
glycan epitopes, which could be novel targets for
cancer diagnosis and treatment.