Differential apomucin expression in normal and neoplastic human gastrointestinal tissues

Background/Aims: The cloning of genes encoding human mucins is the basis for the study of their normal tissue distribution and the alterations associated with cancer. The aim of this study was to determine the normal and tumor tissue expression of MUC1, MUC2, MUC5B, and MUC5C. Methods: The reactivity of apomucin-specific antibodies with fresh normal and tumor tissues was analyzed using immunohistochemical techniques. Results: Anti-MUC1 antibodies reacted with most glandular epithelia. Anti-MUC2 antibody was mainly reactive with intestinal goblet cells and cervical mucous cells. Anti-MUC5B was reactive with a wide range of epithelial tissues whereas anti-MUC5C was reactive with stomach, trachea, and endocervix. Double-labeling experiments showed coexpression of MUC1/MUC2 and MUC2/MUC5C in colonic tissue. Multiple apomucins were detected in colon cancers, but no relationship to histochemical mucus stains was observed. Conclusions: It is concluded that (1) each apomucin shows a distinct tissue expression pattern; (2) multiple apomucins are present in a single tissue and at the single cell level; and (3) altered apomucin expression takes place in pathological colonic tissue.