Regulation of the oncodevelopmental expression of type 1 chain ABH and Lewis(b) blood group antigens in human colon by alpha-2-L-fucosylation

Inappropriate expression of blood group antigens on biliary and colonic epithelia in primary sclerosing cholangitis

The distribution of carbohydrate antigens of the ABO, Lewis, and Kell systems was examined in biliary and colonic epithelial of 11 patients with primary sclerosing cholangitis (PSC) using a panel of 11 monoclonal antibodies. Controls consisted of 27 liver biopsy specimens (11 normal, six alcoholic liver disease, five extrahepatic obstruction, and five primary biliary cirrhosis) and 24 colonic biopsy specimens (six normal, four Crohn's disease, and 14 ulcerative colitis). There was inappropriate staining with anti-A (four of six, 66%) and anti-B (nine of 11, 81%) in biliary epithelium of PSC patients compared with normal and disease controls. Expression of Lewis antigens was increased in patients with cholestatic liver disease. Ninety one per cent of PSC patients showed a similar pattern of inappropriate staining by anti-A and anti-B antibodies in colonic epithelium compared with 33% of normal and 42% of inflammatory bowel disease controls. There is inappropriate expression of A and B carbohydrate antigens in biliary and colonic epithelium in PSC. Whether these oncofetal antigens are implicated in the pathogenesis of this condition is discussed.

Development and characterization of a novel anti-fucosylated antigen monoclonal antibody YB-2 and its usefulness in the immunohistochemical diagnosis of colorectal cancer

A novel monoclonal antibody, YB-2 was obtained after immunization of mice with fucosylated antigens isolated from human saliva. The antibody was demonstrated to react with Y (Fuc alpha 1-->2Gal-beta 1-->4[Fuc alpha 1-->3]GlcNAc beta),Leb (Fuc alpha 1-->2Gal beta 1-->3[Fuc alpha 1-->4]GlcNAc beta) and H type 2 (Fuc alpha 1-->2Gal-beta 1-->4GlcNAc beta) antigens, but not with H type 1 (Fuc alpha 1-->2Gal beta 1-->3GlcNAc beta), Lea (Gal beta 1-->3[Fuc alpha 1-->4]GlcNAc beta), X (Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc beta) or with non-fucosylated antigens. Inhibition assays of YB-2 antibody with such reactive antigens showed that YB-2 antibody preferentially reacted with Y antigen. Formalin-fixed and paraffin-embedded sections prepared from normal and malignant colorectal tissues were examined immunohistochemically with YB-2. The positive rates of staining with YB-2 antibody were 88.6% in malignant and 12.0% in normal tissues. The expression of fucosylated antigens detected by YB-2 antibody seemed to be correlated with survival among patients with primary colorectal cancer. Therefore, YB-2 antibody could be useful as an immunochemical tool for diagnosis and evaluation of the prognosis of colorectal cancer.

Clinical aspects of glycoprotein biosynthesis

Glycoproteins are widely distributed among species in soluble and membrane-bound forms, associated with many different functions. The heterogenous sugar moieties of glycoproteins are assembled in the endoplasmic reticulum and in the Golgi and are implicated in many roles that require further elucidation. Glycoprotein-bound oligosaccharides show significant changes in their structures and relative occurrences during growth, development, and differentiation. Diverse alterations of these carbohydrate chains occur in diseases such as cancer, metastasis, leukemia, inflammatory, and other diseases. Structural alterations may correlate with activities of glycosyltransferases that assemble glycans, but often the biochemical origin of these changes remains unclear. This suggests a multitude of biosynthetic control mechanisms that are functional in vivo but have not yet been unraveled by in vitro studies. The multitude of carbohydrate alterations observed in disease states may not be the primary cause but may reflect the growth and biochemical activity of the affected cell. However, knowledge of the control mechanisms in the biosynthesis of glycoprotein glycans may be helpful in understanding, diagnosing, and treating disease.

Expression of histo-blood-group-A/B-gene-defined glycosyltransferases in normal and malignant epithelia: correlation with A/B-carbohydrate expression

Malignant transformation of oral and bladder epithelia is often associated with loss of histo-blood-group-A- and -B-carbohydrate antigens, whereas these antigens, which are absent in normal adult distal colon (but present in fetal colon) reappear in malignant distal colon. In order to gain insight into the genetic basis of the biosynthetic regulation for these changes, we have correlated the expression of the A- and B-carbohydrate antigens with that of the A/B-gene-defined glycosyltransferases in colon, bladder and oral carcinomas by immunohistology. A newly developed anti-A/B-transferase monoclonal antibody (MAb) was used to demonstrate the in situ localization of transferase expression at the individual cell level with correlation to carbohydrate antigen expression, and gave the essential information that the transferase is derived from the ABO gene complex. The reappearance of A- and B-carbohydrate antigens in carcinomas of the distal colon was found to be unrelated to the expression of the A/B-transferase proteins, which were expressed throughout normal adult colon in accordance with previous enzymatic studies. In contrast, the loss of A- and B-carbohydrate antigens in malignant bladder and oral epithelia was accompanied by concordant loss of enzymes.