title: Cell surface glycopeptides from human intestinal epithelial cell lines derived from normal colon and colon adenocarcinomas.
abstract: The cell surface glycopeptides from an epithelial cell line (CCL 239) derived from normal human colon were compared with those from three cell lines (HCT-8R, HCT-15, and CaCo-2) derived independently from human colonic adenocarcinomas. Cells were incubated with D-[2-3H]mannose or L-[5,6-3H]fucose for 24 h and treated with trypsin to release cell surface components which were then digested exhaustively with Pronase and fractionated on Bio-Gel P-6 before and after treatment with endo-beta-N-acetylglucosaminidase H. The most noticeable difference between the labeled glycopeptides from the tumor and CCL 239 cells was the presence in the former of an endo-beta-N-acetylglucosaminidase H-resistant high molecular weight glycopeptide fraction which was eluted in the void volume of Bio-Gel P-6. This fraction was obtained with both labeled mannose and fucose as precursors. However, acid hydrolysis of this fraction obtained after incubation with [2-3H]mannose revealed that as much as 60-90% of the radioactivity was recovered as fucose. Analysis of the total glycopeptides (cell surface and cell pellet) obtained after incubation with [2-3H]mannose showed that from 40-45% of the radioactivity in the tumor cells and less than 10% of the radioactivity in the CCL 239 cells was recovered as fucose. After incubation of the HCT-8R cells with D-[1,6-3H]glucosamine and L-[1-14C]fucose, strong acid hydrolysis of the labeled glycopeptide fraction excluded from Bio-Gel P-6 produced 3H-labeled N-acetylglucosamine and N-acetylgalactosamine. This high molecular weight glycopeptide fraction was susceptible to mild alkaline borohydride reduction, yielding a mixture of labeled oligosaccharides which contained N-acetylgalactosaminitol. Thus, the HCT-8R cells are expressing fucosylated mucin-type glycoproteins on their surface.
mesh_terms: D000230:Adenocarcinoma / Q000032:analysis*; D002460:Cell Line; D003106:Colon / Q000032:analysis*; D003110:Colonic Neoplasms / Q000032:analysis*; D005643:Fucose / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D006020:Glycopeptides / Q000032:analysis*; D006801:Humans; D006868:Hydrolysis; D008358:Mannose / Q000378:metabolism; D014316:Tritium
chemical_list: D006020:Glycopeptides; D014316:Tritium; D005643:Fucose; D008358:Mannose; D005690:Galactose