Mucin associated Tn and sialosyl-Tn antigen expression in colorectal polyps.
Sialosyl-Tn antigen and its immediate precursor, Tn antigen, are carbohydrate structures associated with the earliest steps of mucin O-linked glycosylation. Both antigens have been shown previously to be highly sensitive and specific markers of colorectal cancer. One hundred and three colorectal polyps (79 adenomatous; 24 hyperplastic) were examined for expression of Tn antigen using vicia villosa isolectin B4, and for sialosyl-Tn antigen by monoclonal antibody TKH2. Tn antigen was expressed by all of the polyps studied. Sialosyl-Tn, on the other hand was expressed weakly by a few cells in 7 of 24 (29%) hyperplastic polyps. Among the adenomatous polyps, 56% expressed sialosyl-Tn and expression correlated with larger adenoma size, greater villous component, and more severe grades of dysplasia. In individuals with two or more synchronous adenomas, the level of sialosyl-Tn expression within an adenoma was associated with the severity of cytological atypia. All the adenomas that contained a focus of invasive carcinoma expressed sialosyl-Tn. These results indicate that colorectal polyps manifest incomplete glycosylation, exposing antigens in the innermost region of mucin oligosaccharides. In addition, the correlation of sialosyl-Tn antigen expression with the adenoma-carcinoma sequence may make this a useful marker for studying malignant progression in the colon.
Itzkowitz
S H
SH
Department of Medicine, Mount Sinai School of Medicine, New York.
Bloom
E J
EJ
Lau
T S
TS
Kim
Y S
YS
D000951:Antigens, Neoplasm / Q000032:analysis*; D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor / Q000032:analysis*; D003110:Colonic Neoplasms / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007417:Intestinal Polyps / Q000276:immunology*; D009077:Mucins / Q000276:immunology; D012004:Rectal Neoplasms / Q000276:immunology*
D000951:Antigens, Neoplasm; D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; D009077:Mucins; C040286:Tn antigen; C055491:sialosyl-Tn antigen