APPLICATION OF IMMUNOHISTOCHEMISTRY FOR DIAGNOSIS OF NEOPLASMS - MUCIN ANTIGENS EXPRESSION AND BIOLOGICAL BEHAVIOR OF NEOPLASMS

Mucins are high molecular weight glycoproteins having oligosaccharides attached to serine or threonine residues of the core protein backbone. Synthesis and secretion of mucin are common features of glandular epithelial tissues. Alterations in the glycosylation of mucins have been described in cancer, however little is known about the expression of different types of mucin core protein. To evaluate whether mucin antigens expression is correlated with the biological behavior of neoplasms or not, we examined the expression of mucin carbohydrate antigens associated with the earliest steps in mucin glycosylation (Tn and sialosyl-Tn) and core protein antigens associated with MUC1 and MUC2 gene products (DF3 and MRP) in tumors of several organs using immunohistochemical methods. Simultaneous expression of Tn and sialosyl-Tn was observed in adenocarcinomas of the pancreas, intrahepatic bile-duct and ovary, in 100%, 92% and 100% of the cases respectively. It was not frequently observed in the breast cancers (10%), although a close association of Tn expression with lymph node metastasis was observed in the scirrhous type of breast cancer. In the pancreatic and intrahepatic bile-duct carcinomas, a pattern of DF3(+) and MRP(-) was found in 100% of the invasive carcinomas with a poor prognosis, whereas DF3(-) and MRP(+) pattern was seen in 79% of the non-invasive carcinomas with a favorable prognosis. In the breast cancers, DF3 was expressed in 95% but MRP was not expressed. In the ovary, MRP was expressed only in the mucinous tumors, but not in the serous tumors. Ovarian serous adenocarcinomas showed DF3(+) and MRP(-) pattern in 100%. On the other hand, ovarian mucinous adenocarcinomas showed DF3(+) and MRP(-) pattern in 45% of the cases, and DF3(+) and MRP(+) pattern in 55%, while benign mucinous adenomas did not show DP3(+) and MRP(+) pattern. These results suggest that the patterns of expression of several mucin antigens are associated with the biological properties of neoplasms, and are useful to predict prognosis of the patients.