Oncodevelopmental expression of--GlcNAc beta 1-6Man alpha 1-6Man beta 1--branched asparagine-linked oligosaccharides in murine tissues and human breast carcinomas.
Increased--GlcNAc beta 1-6Man alpha 1-6Man beta--branching in asparagine-linked oligosaccharides has been observed in murine and human tumor cells and has recently been linked to enhanced metastatic potential in experimental tumor models. Leukoagglutinin (L-PHA) requires the beta 1-6-linked lactosamine antenna (beta 1-6 branch) for high affinity binding and was used in this study to quantitate these structures on glycoproteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Normal rodent tissues and cell lines were used to standardize the experimental conditions required to quantitate beta 1-6-branched oligosaccharide structures and the glycosyltransferase activity which initiates the synthesis of the antenna, beta 1-6 N-acetylglucosamine (GlcNAc)-transferase V (EC 2.4.1.155). Secondly, the levels of L-PHA-reactive oligosaccharide were compared in a series of benign and malignant human breast biopsies. Normal human breast tissue and benign lesions showed low expression but 50% of the primary malignancies examined showed significantly elevated L-PHA reactivity. GlcNAc transferase V activities in the human breast carcinomas and in normal murine tissues correlated with the levels of L-PHA reactive oligosaccharide in the tissues. GlcNAc transferase V showed similar ranges of activities, differing by approximately 5-fold between high and low expressing mouse tissues; fibroblasts with and without an activated H-ras oncogene; and low and high expressing human breast carcinomas. The results show that beta 1-6 branching in asparagine-linked oligosaccharides is dependent on tissue-specific regulation of GlcNAc transferase V activity. Secondly, a subset of human breast malignancies showed elevated levels of beta 1-6-branched oligosaccharides compared to benign samples, suggesting that further studies are warranted to determine whether the presence of these oligosaccharides is associated with metastatic disease and reduced patient survival time.
Dennis
J W
JW
Division of Cancer and Cell Biology, Mount Sinai Hospital Research Institute, Toronto, Ontario, Canada.
Laferté
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D000818:Animals; D001216:Asparagine; D001940:Breast / Q000201:enzymology; D001943:Breast Neoplasms / Q000201:enzymology*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D005260:Female; D011905:Genes, ras; D005964:Glucosyltransferases / Q000378:metabolism; D006801:Humans; D051379:Mice; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases; D009362:Neoplasm Metastasis; D009844:Oligosaccharides / Q000096:biosynthesis*; D009928:Organ Specificity
D009844:Oligosaccharides; D001216:Asparagine; D005964:Glucosyltransferases; D017351:N-Acetylglucosaminyltransferases; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase