Blood-group-related antigens in colonic carcinogenesis

Blood group antigen expression in medullary carcinoma of the thyroid. An immunohistochemical study on the occurrence of type 1 chain-derived antigens

Using monoclonal antibodies (MoABs) against blood group determinants and related carbohydrate sequences, it is now possible to clarify their carcinoma-associated modulation at a molecular level. In the present study a panel of MoABs against different type 1 chain derived blood group antigens, comprising A, B, H type 1, Le(a), sialyl-Le(a) (CA 19-9), sialyl type 1 structure (CA 50), and Le(b) was used to investigate their immunoreactivity in 38 medullary carcinomas of the thyroid (MTC) and in normal thyroid tissue. The antigens were not expressed in normal follicular or C-cells but were expressed to a various extent in MTC. The studies revealed some characteristic anomalies in the frequency and patterns of tumor-associated antigen expression. The MoAB C 50 stained 32 of the 38 tumors, H type 1 (Le(d)) was demonstrated in 21 and the Le(b) antigen in 27. The Le(a)- and the A antigen were detected in 10 and 12 tumors and the B antigen in one. From the results some rules about the pathways for tumor-associated re-expression of these antigens can be deduced. Le(a) antigen expression was significantly correlated with the CA 50 and Le(b) antigens. The significant relation observed between A-, H1-, and Le(b) antigen formation in MTC suggests the existence of a carcinoma-associated fucosyltransferase committing the type 1 precursor chain along the H1-antigen pathway, and by further glycosylation to an A-, B-, or a Le(b) antigen. Comparative studies of tumor-associated H type 1 and H type 2 antigen expression revealed that H type 2 antigen synthesis was significantly related to a blood type 0 in the host. On the other hand, H1 antigen reactivity was independent of the AB0 blood type of the hosts and was also detected in H type 2 antigen-negative tumors. These findings support the proposal that even in tumor tissue, H antigen expression is still determined by the interaction of at least two different genes. Despite the occurrence of the precursor substance (CA 50) and the formation of the Le(a)- and Le(b) antigens, indicating the presence of a alpha 1,4-fucosyl-transferase (Lewis-enzyme), only two tumors showed the formation of CA 19-9. In conclusion, the investigations demonstrated the dominant re-expression of three type 1 chain-derived structures in MTC, namely H type 1, Le(b), and CA 50. These findings support the general concept demonstrated in other carcinomas, that fucosyl- and sialyltransferases are preferentially activated in MTC.(ABSTRACT TRUNCATED AT 400 WORDS)

F11C antigen: a membrane marker able to distinguish two regressive and progressive variants from a rat colon adenocarcinoma

Cell variants that differ in their tumorigenicity and immunogenicity have been isolated from a BDIX rat colon adenocarcinoma cell line, DHD/K12. One variant, PRO, and the clones derived from it, are poorly immunogenic and induce progressive and metastatic tumors; the other one, REG, and its clones, are highly immunogenic and induce regressive tumors. When looking for a membrane marker distinguishing between PRO and REG lines, we obtained monoclonal hybridomas by immunizing BALB/c mice with PROb or REGb cell clones. Hybridoma F11C, producing an IgM monoclonal antibody (MAb) was able to distinguish between the cell variants on membrane immunofluorescence. All REGb cells strongly express F11C membrane antigen. On PROb cells, F11C antigen expression is weak, as demonstrated by cytofluorimetric analysis, and limited to a fraction of the cell population. The F11C membrane antigen is highly specific for the DHD/K12 cell line and the variants derived from it, but is not expressed on cells dissociated from the DHD transplanted tumor, from which DHD/K12 was established, suggesting that F11C antigen emerged during cell culture. Fluorescence absorption on synthetic oligosaccharides demonstrated that F11C antibody cross-reacts with A type 3, A type 4 and A type 5 chain blood group tetrasaccharides.

Cancer-associated carbohydrates identified by monoclonal antibodies

"New" carbohydrate structures on the surface of or secreted by cancer cells, identified as epitopes by monoclonal antibodies, are reviewed. These structures may represent the accumulation of precursor chains because of decreased activity of synthesizing enzymes, the production of new oligosaccharides due to increased or aberrant glycosylation of carbohydrate chains, a change in density of carbohydrates on the cell surface, or exposure of chains usually covered by other structures. Alterations in glycolipid synthesis include aberrant fucosylation and/or sialyation of the lacto series, sialylation or fucosylation of the globo series, and sialyation of the ganglio series. Many of these carbohydrate epitopes have become useful for the diagnosis, prognosis, and monitoring of patients with cancer. Some of the important markers include CA 15.3, CA 19.9, CA 50, CA 125, CA 242, MCA, SLEX, etc. Incomplete glycosylation of O-linked mucin oligosaccharide is recognized as the important "cancer antigen" B72.3, which is sialyated Tn. The oligosaccharide components of alpha-fetoprotein, carcinoembryonic antigen, and epidermal growth factor receptor are also reviewed. In many instances the glycosylation seen in cancer cells or their products reflects patterns seen during normal development. Thus, cancer-associated oligosaccharides are oncodevelopmental in nature. The biologic significance of carbohydrates on cell surfaces is not known, but several possibilities include a role in cell to cell recognition, intracellular processing of glycoproteins, cell activation, and ability of cancer cells to metastasize.