Benzyl-N-acetyl-alpha-D-galactosaminide inhibits the sialylation and the secretion of mucins by a mucin secreting HT-29 cell subpopulation.
We have analysed the mucins synthesized by the HT-29 MTX cell subpopulation, derived from the HT-29 human colon carcinoma cells through a selective pressure with methotrexate (Lesuffleur et al., 1990, Cancer Res 50: 6334-43), in the presence of benzyl-N-acetyl-alpha-galactosaminide (GalNAc alpha-O-benzyl), which is a potential competitive inhibitor of the beta 1,3-galactosyltransferase that synthesizes the T-antigen. The main observation was a 13-fold decrease in the sialic acid content of mucins after 24 h of exposure to 5 mM GalNAc alpha-O-benzyl. This effect was accompanied by an increased reactivity of these mucins to peanut lectin, testifying to the higher amount of T-antigen. The second observation was a decrease in the secretion of the mucins by GalNAc alpha-O-benzyl treated cells. The decrease in mucin sialylation was achieved through the in situ beta-galactosylation of GalNAc alpha-O-benzyl into Gal beta 1-3GalNAc alpha-O-benzyl, which acts as a competitive substrate of Gal beta 1-3GalNAc alpha 2,3-sialyltransferase, as shown by the intracellular accumulation of NeuAc alpha 2-3Gal beta 1-3GalNAc alpha-O-benzyl in treated cells.
Laboratoire de Chimie Biologique, Unité Mixte de Recherche du CNRS no 111, Université des Sciences et Technologies de Lille, France.
P
P
Delannoy
I
I
Kim
N
N
Emery
C
C
De Bolos
A
A
Verbert
P
P
Degand
G
G
Huet
D000116:Acetylgalactosamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000957:Antigens, Viral, Tumor / Q000378:metabolism; D001593:Benzyl Compounds / Q000494:pharmacology*; D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D003110:Colonic Neoplasms / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005690:Galactose / Q000378:metabolism; D005700:Galactosyltransferases / Q000037:antagonists & inhibitors; D006031:Glycosylation / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D008727:Methotrexate / Q000494:pharmacology; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000032:analysis; D009077:Mucins / Q000378:metabolism*; D009439:Neuraminidase / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism*; D012799:Sialyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism
D000957:Antigens, Viral, Tumor; D001593:Benzyl Compounds; D004791:Enzyme Inhibitors; D009005:Monosaccharides; D009077:Mucins; D012794:Sialic Acids; C080739:benzyl-alpha-N-acetylgalactosamine; D005700:Galactosyltransferases; D012799:Sialyltransferases; D009439:Neuraminidase; D000116:Acetylgalactosamine; D005690:Galactose; D008727:Methotrexate