Comparative Study of the N‐Linked Oligosaccharides Released from Normal Human Esophageal Epithelium and Esophageal Squamous Carcinoma

摘要

N‐Linked sugar chains of normal human esophageal epithelium and esophageal squamous carcinoma were quantitatively released as oligosaccharides from their membrane preparations by hydrazinolysis. After being fractionated by serial lectin column chromatography using concanavalin A‐Sepharose and Datura stramonium agglutinin‐Sepharose, their structures were elucidated by exoglycosidase digestion in combination with methylation analysis. Both normal epithelium and esophageal carcinoma contained bi‐, tri‐ and tetraantennary oligosaccharides as well as high mannose‐type oligosaccharides. Interestingly, carcinoma had about 1.6 times larger amounts of tri‐ and tetraantennary oligosaccharides with the GlcNAcβ1→4Manα1→ and/or the GlcNAcβ1→6Manα1→ linkages than normal epithelium. Tri‐ and tetraantennary oligosaccharides with N‐acetyllactosamine repeating units (the Galβ1→4GlcNAcβ1→3Galβ1→4GlcNAc group) were also increased in carcinoma. These data indicated that the altered glycosylation of proteins previously found in transformed rodent cells also occurs widely in human esophageal carcinoma.