tailieunhanh - Báo cáo khóa học: Suppression of b1,3galactosyltransferase b3Gal-T5 in cancer cells reduces sialyl-Lewis a and enhances poly N-acetyllactosamines and sialyl-Lewis x on O-glycans Lydia Mare and Marco Trinchera

We investigated the role ofb3Gal-T5, a member of the b1,3galactosyltransferase (b1,3Gal-T) family, in cancer-associated glycosylation, focusing on the expression of sialyl-Lewis a (sLe a , the epitope of antigen), poly N-acetyllactosamines, and sialyl-Lewis x (sLe x ) clone permanently expressing an antisense fragment of b3Gal-T5 was obtained from the human pancreas adeno-carcinoma cell line BxPC3 and characterized. Bothb1,3Gal-T activity and sLe a expression are dramatically impaired in the clone. . | Eur. J. Biochem. 271 186-194 2004 FEBS 2003 doi Suppression of b1 3galactosyltransferase p3Gal-T5 in cancer cells reduces sialyl-Lewis a and enhances poly N-acetyllactosamines and sialyl-Lewis x on O-glycans Lydia Mare and Marco Trinchera Department of Biomedical Sciences Experimental and Clinical DSBSC University of Insubria Varese Italy We investigated the role of b3Gal-T5 a member of the p1 3galactosyltransferase b1 3Gal-T family in cancer-associated glycosylation focusing on the expression of sialyl-Lewis a sLea the epitope of antigen poly N-acetyllactosamines and sialyl-Lewis x sLex antigen. A clone permanently expressing an antisense fragment of b3Gal-T5 was obtained from the human pancreas adenocarcinoma cell line BxPC3 and characterized. Both b1 3Gal-T activity and sLea expression are dramatically impaired in the clone. Analysis of the oligosaccharides synthesized in cells metabolically labelled with tritiated galactose shows that a relevant amount of radioactivity is associated to large O-glycans. Endo-b-galactosidase mostly releases Neu-Aca2-3Galp1-3 Fuca1-4 GlcNAcp1-3Gal and NeuAca2-3 cilp1-3 ile Aep1-3 lil from such O-glycans of BxPC3 membranes but GlcNAcb1-3Gal and type 2 chain oligosaccharides including NeuAca2-3Galb1-4 Fuca1-3 Glc-NAcb1-3Gal from those of the antisense clone. Furthermore BxPC3 cells secrete sLea in the culture media but not sLex while antisense clone secretes mostly sLex and accumulation of both antigens is prevented by benzyl-a-GalNAc. These data indicate that b3Gal-T5 suppression turns synthesis of type 1 chain O-glycans to poly N-ace-tyllactosamine elongation and termination by sLex. In other cell lines and clones b3Gal-T5 transcript b1 3Gal-T activity and sLea antigen are also correlated but quantitatively the relative expression ratios are very different from cell type to cell type. We suggest that b3Gal-T5 plays a relevant role in gastrointestinal and pancreatic tissues counteracting the

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