In 1000 primary gastric carcinomas, 70 (7.0%) contained Epstein-Barr virus (EBV) genomic sequences detected by PCR and Southern blots. The positive tumors comprised 8 of 9 (89%) undifferentiated lymphoepithelioma-like carcinomas, 27 of 476 (5.7%) poorly differentiated adenocarcinomas, and 35 of 515 (6.8%) moderately to well-differentiated adenocarcinomas. In situ EBV-encoded small RNA 1 hybridization and hematoxylin/eosin staining in adjacent sections showed that the EBV was present in every carcinoma cell but was not significantly present in lymphoid stroma and in normal mucosa. Two-color immunofuorescence and hematoxylin/eosin staining in parallel sections revealed that every keratin-positive epithelial maiant cell expressed EBV-determined nuclear antigen 1 (EBNA1) but did not significantly express CD45+ infiltrating leukocytes. A single fused terminal fragment was detected in each of the EBNA1-expressing tumors, thereby suggesting that the EBV-carrying gastric carcinomas represent clonal proliferation of cells infected with EBV. The carcinoma cells had exclusively EBNA1 but not EBNA2, -3A, -3B, and -3C; leader protein; and latent membrane protein 1 because of methylation. The patients with EBV-carrying gastric carcinoma had elevated serum EBVspecific antibodies. The EBV-specific cellular immunity was not signficantly reduced; however, the cytotoxic T-cell target antigens were not expressed. These findings strongly suggest a causal relation between a significant proportion of gastric carcinoma and EBV, and the virus-carrying carcinoma cells may evade immune surveillance.

Our previous immunohistochemical study on intrahepatic bile duct tumors showed that invasive cholangiocarcinoma (ICC) with a poor outcome expressed MUC1 mucin but was negative for MUC2 mucin, whereas bile duct cystadenocarcinoma (BDCC) with a favorable outcome was MUC1 negative and MUC2 positive. In the present study, ICC was further subdivided into 2 subtypes: intraductal growth type and/or periductal infiltrating type (ICC-IP) and mass forming type (ICC-M). The survival of patients with BDCC or ICC-IP is significantly better than that of patients with ICC-M. We examined these subtypes (ICC-IP Mucins are high molecular weight glycoproteins having oligosaccharides attached to serine or threonine residues of the apomucin protein backbone by O-glycosidic linkages. [1][2][3][4] During the past several years, a number of human mucins (MUC1-MUC9) have been identified. 5-13 MUC1 is a membrane-associated glycoprotein with an extracellular domain consisting of a variable number of highly conserved tandem repeats of 20 amino acids, a transmembrane domain, and a cytoplasmic tail of 69 amino acids. 14,15 MUC2-MUC7 are expressed by secretory cell types. 2,3 MUC8 and MUC9 are expressed in reproductive tract tissue. 12,13 There is a strong correlation between expression of mucin antigens and patient survival. A difference in the expression of MUC1 and MUC2 mucins is one useful indicator of malignancy potential of the neoplasms in several organs. Our previous immunohistochemical studies on the expression of MUC1 and MUC2 in pancreatic and intrahepatic bile duct tumors indicated that patients with invasive carcinoma and a poor outcome have tumor tissues that were MUC1 positive and MUC2 negative. In contrast, many of the patients with noninvasive tumors and a favorable outcome have tissues that were MUC1 negative and MUC2 positive. [16][17][18] Sasaki et al. 19 also reported frequent and extensive expression of MUC1, and low and focal expression of MUC2 in cholangiocarcinoma. In our study of patients with carcinomas of the ampulla of Vater 20 or gastric carcinomas, 21 patients that were positive for MUC1 in their tumors had significantly worse survival than those negative for MUC1. Moreover, the patients positive for MUC2 showed significantly better survival than those negative for MUC2.MUC1 mucins isolated from tumor and normal cell types differ in their degree of glycosylation. The carbohydrate side chains of MUC1 from breast adenocarcinomas are shorter, less densely distributed, than those produced by normal breast cells. [22][23][24][25][26] On the other hand, colorectal carcinomas had a high level of fully glycosylated MUC1 mucin in the advanced stages or in metastatic lesions. 27 In our previous study on intrahepatic bile duct tumors, we noted that there were discrepancies in the reactivities of various MUC1 antibodies. 17 This difference may be because of the differences in carbohydrate requirements of these antibodies. In the present study we examined the glycosylation status of Abbreviations: mAb, monoclonal antibody; ...

The expression rate of MUC1/CORE and MUC1/HMFG-1, which is related to poor prognosis in the gastric and colorectal cancers, is low in mucinous carcinomas. The high expression rate of gel-forming secretory mucins (MUC2 and MUC6) in mucinous carcinoma suggests that high production of these types of mucins may act as a barrier to cancerous extension resulting in their less aggressive biological behaviour.

The expression of mucin carbohydrates [Tn, sialosyl-Tn(STn), and T antigens] and core proteins [MUCI-apomucin-related antigen (ARA) and MUC2-ARA] was examined immunohistochemically in tissues from 40 patients with hepatolithiasis and 26 patients with intrahepatic bile-duct carcinoma. Tn and STn antigens were expressed in most of the carcinomas, and were also often expressed in the atypical bile-duct epithelium of the patients with hepatolithiasis or carcinoma, whereas they were rarely or never expressed in the normal bile duct, suggesting that they are effective tumor markers. T antigen was less useful as a marker for intrahepatic bile-duct carcinoma or the atypical epithelium, because it was expressed in normal bile-duct of some cases. Regarding the expression of ARAs in the carcinomas, non-invasive bile-duct cyst adenocarcinomas with favorable prognosis either expressed no MUCI-ARA with [DF3(-), MUSEII(-) and 139H2(-)] staining pattern or expressed MUCI-ARA with [DF3(-), MUSEII(+) and 139H2(+)] staining pattern. However these tumors often expressed MUC2-ARA with [anti-MRP(+) and CCP58(+)] staining pattern. In contrast, most invasive non-papillary cholangiocarcinomas with poor prognosis expressed MUCI-ARA with [DF3(+), MUSEII(+) and 139H2(+)] staining pattern, but expressed no MUC2-ARA with [anti-MRP(-) and CCP58(-)] staining pattern. These results suggests that different apomucins are produced by bile-duct cystadenocarcinomas and cholangiocarcinomas with differing prognosis. Furthermore, expression of Tn and STn antigens is a useful indicator of malignancy in the intrahepatic duct.

Previously it has been found that the MUC2 gene for intestinal type secretory mucin is highly expressed in intraductal papillary mucinous tumors (IPMT), which are characterized by non-invasive growth and a favorable outcome. In contrast, MUC2 mRNA is rarely expressed in invasive ductal carcinomas (IDC), which have poor outcomes. The gastric type secretory mucin, MUC5AC, is strongly expressed in the surface mucous cells of gastric mucosa. As both MUC2 and MUC5AC mucins share the characteristics of forming highly viscous gels, it is expected that not only MUC2 mucin expression but also MUC5AC mucin expression may be associated with a favorable prognosis in patients with pancreatic tumors. MUC5AC mucin gene expression was examined in 24 cases of IPMT and 38 cases of IDC by in situ hybridization using a digoxigenin-labeled oligonucleotide. The results were compared with MUC2 mucin gene expression. Neither MUC5AC mRNA nor MUC2 mRNA was detected in normal pancreatic tissues. MUC5AC mRNA was expressed in 20 of 24 cases of IPMT (83%) and in five of 38 cases of IDC (13%). In contrast, MUC2 mRNA was expressed in 14 of 24 cases of IPMT (58%) and in none of the 38 cases of IDC (0%). The expression rates of MUC5AC mRNA and MUC2 mRNA in IPMT were significantly higher than those in IDC (P< 0.001, respectively). Intraductal papillary mucinous tumors are characterized by three histological types: (i) villous dark cell type; (ii) papillary clear cell type; and (iii) compact cell type. The villous dark cell type generally expressed both MUC5AC+ and MUC2+ genes. Alternatively, the papillary clear cell type and the compact cell type usually showed MUC5AC+ and MUC2- expression. Patients with MUC5AC mRNA expression had a significantly better survival prognosis than those with no MUC5AC mRNA expression (P< 0.005). In conclusion, MUC5AC gene expression occurs in a majority of IPMT cases, even in those with no MUC2 production. MUC5AC expression can be