Expression of mucin carbohydrate antigens (T, Tn and sialyl Tn) and MUC-1 gene product in intraductal papillary-mucinous neoplasm of the pancreas.

Aberrant or incomplete glycosylation of mucins results in expression of T, Tn, and sialyl-Tn (STn) antigens in various malignant neoplasms. MUC-1 gene product (a mucin core protein of mammary type) is known to alter or overexpress in several malignant tumors. However, expression of these mucin-related antigens has rarely been examined in intraductal papillary-mucinous neoplasm (IPN) of the pancreas. The authors examined immunohistochemically the expression of these antigens and MUC-1 gene product in nine IPN. In normal pancreas (n = 5), pancreatic ducts did not express T, Tn, or STn antigens, but expressed MUC-1 gene product. Among the nine IPNs, two (22%) expressed T antigen, nine (100%) expressed Tn antigen, and seven (78%) expressed STn antigen. MUC-1 gene product was expressed in nine (100%) IPNs. In invasive ductal adenocarcinoma of the pancreas (n = 6), all cases showed strong expression of Tn and STn antigens and the MUC-1 gene product, but expressed no T antigen. The expression of these antigens and MUC-1 gene product was focal in IPN, whereas it was diffuse in invasive ductal adenocarcinoma of the pancreas. These data suggest that aberrant or incomplete glycosylation occurs in epithelial mucins of IPN, that IPN is a borderline or low grade malignant neoplasm in terms of mucin-related antigen expression, and that mucin core protein (MUC-1 gene product) does not alter during pancreatic ductal carcinogenesis.