title: Tn antigen and UDP-Gal:GalNAc alpha-R beta 1-3Galactosyltransferase expression in human breast carcinoma.
abstract: The serine/threonine O-linked carbohydrates GalNAc alpha and Gal beta 1-3GalNAc alpha, referred to as Tn and T antigens, respectively, appear to be more prevalent in some human carcinomas than in surrounding tissues. Tn/T antigens may represent incomplete synthesis of O-linked oligosaccharides, due to decreased activity of specific glycosyltransferases, or alternatively, increased glycosidases activity in tumors which may expose these internal O-linked oligosaccharide sequences. To explore these possibilities, we measured UDP-Gal:GalNAc alpha-R beta 1-3 galactosyltransferase (beta 3Gal-T) and Gal beta 1-3GalNAc alpha-R beta 1-3 galactosidase in a series of human breast tumors. In addition, glycoproteins extracted from the tumors were separated by SDS-PAGE and stained with the lectins HPA (GalNAc alpha-R reactive) and PNA (Gal beta-3GalNAc alpha-R reactive). The relative levels of HPA- to PNA-reactive glycoproteins in the carcinomas correlated inversely with beta 3Gal-T activities. The results suggest that Tn antigen expression in human breast carcinoma is due in part to low beta 3Gal-T activity, a situation similar to that observed previously in haematopoietic cells of individuals with a condition called Tn syndrome.
authors.affiliation: Samuel Lunenfeld Research Institute, Mt. Sinai Hospital, Toronto, Ontario.
authors.forename: D
authors.initials: D
authors.lastname: Zhuang
authors.forename: S
authors.initials: S
authors.lastname: Yousefi
authors.forename: J W
authors.initials: JW
authors.lastname: Dennis
mesh_terms: D015295:Antigens, Tumor-Associated, Carbohydrate / Q000378:metabolism*; D000957:Antigens, Viral, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000201:enzymology / Q000378:metabolism*; D002240:Carbohydrate Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D037102:Lectins; D008969:Molecular Sequence Data; D009237:N-Acetyllactosamine Synthase / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis / Q000302:isolation & purification; D014407:Tumor Cells, Cultured
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D000957:Antigens, Viral, Tumor; D006023:Glycoproteins; D037102:Lectins; D009844:Oligosaccharides; C040286:Tn antigen; D009237:N-Acetyllactosamine Synthase