Study of mechanism of mucin antigen expression which is related with prognosis of patients carrying cancer

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1.Tumors of pancreas and intrahepatic bile duct : (1) We have previously reported that MUC2 mucin (secretory mucin) was dominantly expressed in non-invasive tumors (NITs) with a favorable outcome, whereas it was rarely expressed in the invasive tumors (ITs) with a poor prognosis, in the pancreas and intrahepatic bile duct (Cancer 71 : 2191-2199,1993 ; Int.J.Cancer 55 : 82-91,1993) .In situ hybridization (ISH) study in the present project disclosed that MUC2 mRNA was expressed in most of NITs but was not expressed in ITs. The localization of MUC2 mRNA and that of MUC2 apomucin was usually coincided. These results indicates that the difference in MUC2 apomucin expression between NITs and ITs is due to the difference in the MUC2 message but not due to masking of the MUC2 apomucin epitope by carbohydrate chains. Since MUC2 glycoprotein is a secretory mucin, the production of abundant extracellular mucin is responsible for the histological pattern of the NITs which may be associated with le … More ss aggressive biological property. (2) In the study of MUC1 mucin (membrane bound mucin) , expression of sialylated MUC1 mucin was positive in ITs but was negative in NITs. On the other hand, expression of MUC1 core protein showed no relation with invasive character of the tumors. Sialic acid of the carcbohydrate side chain of MUC1 mucin seems to play an important role in the carcinoma invasion.2.Breast cancer : MUC2 apomucin was expressed in mucinous carcinomas (MCs) which show less frequent lymph node metastasis and more favorable outcome compared with invasive ductal carcinomas which do not express MUC2 apomucin. ISH study showed positive MUC2 mRNA expression in MCs. Namely, MUC2 gene expression is strongly related with the formation for the special histologic configuration in MCs through the production of abundant extracellular mucin which is thought to be a barrier to cancerous extension in MCs.3.Carcinoma of ampulla of Vater : The cases with MUC1(+) expression showed poorer outcome than those with MUC1 (-) expression, whereas the cases with MUC2 (+) expression showed more favorable outcome than those with MUC1 (-) expression.4.Conclusion : The results of the present project suggest that MUC2 mucin expression is related with non-invasive character of tumors, whereas MUC1 mucin expression, particularly sialylated MUC1 mucin, is related with invasive character of tumors. Less