Beta-1,3-galactosyltransferase and alpha-1,2-fucosyltransferase involved in the biosynthesis of type-1-chain carbohydrate antigens in human colon adenocarcinoma cell lines.
We studied the beta-1,3-galactosyltransferase (GalT) and alpha-1,2-fucosyltansferase (FT) involved in the biosynthesis of type-1-chain carbohydrate antigens in human colon adenocarcinoma cell lines. We detected a GalT activity able to use GlcNAc as acceptor and found that lacto-N-biose I (Galbeta1-3GlcNAc) is the only reaction product. Such beta1,3GalT is kinetically similar to a pig trachea enzyme involved in mucin synthesis. The specific activity is high in cells that react strongly with anti-Lewis a and anti-Lewis b antibodies, and undetectable in a cell line that lacks antibody reaction. Reverse-transcriptase-mediated PCR analysis followed by DNA sequencing indicated that secretor-type alpha1,2FT is expressed in the cells, while the H type alpha1,2FT is not. The apparent Km values for donor and acceptor substrates determined for alpha1,2FT are similar to those of secretor-type alpha1,2FT and the specific activity measured correlates with Lewis b antigen expression on the cell surface. Moreover, some of the cell lines express Lewis y and H type 2 antigens, indicating that secretor type alpha1,2FT is responsible for their synthesis. Results suggest that biosynthesis of type-1-chain tumor-associated antigens in human colon carcinoma cells is operated by secretor-type alpha1,2FT, as reported in normal mucosa, and that beta1,3GalT activity may play a relevant role in its control.
Department of Biochemistry, University of Pavia, Italy.
M
M
Valli
A
A
Gallanti
S
S
Bozzaro
M
M
Trinchera
D000117:Acetylglucosamine / Q000031:analogs & derivatives / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology; D002241:Carbohydrates / Q000096:biosynthesis / Q000276:immunology*; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000276:immunology; D005434:Flow Cytometry; D005647:Fucosyltransferases / Q000378:metabolism*; D005700:Galactosyltransferases / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006056:Golgi Apparatus / Q000201:enzymology; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA; D014407:Tumor Cells, Cultured; D005644:alpha-L-Fucosidase / Q000378:metabolism
D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D002241:Carbohydrates; D012333:RNA, Messenger; C033398:galactosyl-1,3-N-acetylglucosamine; D005647:Fucosyltransferases; D005700:Galactosyltransferases; D005644:alpha-L-Fucosidase; D000117:Acetylglucosamine