Mucins MUC1, MUC2, MUC5AC and MUC6 expression in the evaluation of differentiation and clinico-biological behaviour of gastric carcinoma.

Normal gastric mucosa expresses MUC1 and MUC5AC in foveolar epithelium and MUC6 in mucous neck cells of the body and deep glands of the antrum. Several studies have reported aberrant expression of an under-glycosylated form of MUC1, decreased expression of "gastric" mucins and aberrant expression of "non-gastric" mucins in gastric carcinoma. In this study, we analysed the expression profile of mucins MUC1, MUC2, MUC5AC and MUC6 in 94 gastric carcinomas using immunohistochemistry. Our results showed that: (1) mucin expression is associated with tumour type (MUC5AC with diffuse and infiltrative carcinomas and MUC2 with mucinous carcinomas) but not with the clinico-biological behaviour of the tumours; and (2) mucin expression is associated with tumour location (MUC5AC with antrum carcinomas and MUC2 with cardia carcinomas), indirectly reflecting differences in tumour differentiation according to tumour location.