Relationships between mucinous gastric carcinoma, MUC2 expression and survival.

To investigate the expression of the four secreted gel-forming mucins (MUC2, MUC5AC, MUC5B and MUC6) in a series of gastric carcinomas, classified according Lauren's, Mulligan's, WHO and Goseki's classifications, with special attention to all the different components (major and minor) present in tumors and to follow up clinical data. Expression of MUC2, MUC5AC, MUC5B and MUC6 was investigated using immunohistochemistry and in situ hybridization. Expression of secreted gel-forming mucins in gastric carcinoma was particularly complex, each mucin being not restricted to any histopathological type even considering all components (major and minor) present in a given tumor. There was a worst survival in patients with a higher content of mucus (Goseki II or IV) and high positive MUC2 expression. Complexity of mucin gene expression patterns in gastric cancer may reflect a precise state of differentiation at the cell level not recognized in used morphologic classification systems. High expression of MUC2 was nevertheless associated with mucinous subtype of the WHO classification and with group II of Goseki's classification identified by the major component of a particular tumor. The quantity and quality of mucus were related to survival.