Developmental mucin gene expression in the gastroduodenal tract and accessory digestive glands. I. Stomach: A relationship to gastric carcinoma

Studies were undertaken to provide information regarding cell-specific expr ession of mucin genes in stomach and their relation to developmental and ne oplastic patterns of epithelia[ cytodifferentiation. In situ hybridization was used to study mRNA expression of eight mucin genes (MUC1-4, MUC5AC, MUC 5B, MUC6, MUC7) in stomach of 13 human embryos and fetuses (8-27 weeks' ges tation), comparing these with normal, metaplastic, and neoplastic adult tis sues. These investigations have demonstrated that MUC1, MUC4, MUC5AC, MUC5B , and MUC6 are already expressed in the embryonic stomach at 8 weeks of ges tation. MUC3 mRNA expression can be observed from 10.5 weeks of gestation. MUC2 is expressed at later stages, concomitant with mucous gland cytodiffer entiation. Normal adult stomach is characterized by strong expression of MU C1, MUC5AC, and MUC6, less prominent MUC2, and sporadic MUC3 and MUC4, with out MUC5B and MUC7. Intestinal metaplasia is characterized by an intestinal -type pattern with MUC2 and MUC3 mRNA expression. Gastric carcinomas exhibi t altered mucin gene expression patterns with disappearance of MUC5AC and M UC6 mRNAs in some tumor glands, abnormal expression of MUC2, and reappearan ce of MUC5B mRNAs. In conclusion, we have observed that patterns of mucin g ene expression in embryonic and fetal stomach could show similarities with some gastric carcinomas in adults. Differences in mucin gene expression in developmental, metaplastic, and neoplastic stomach compared to normal adult stomach suggest a possible regulatory role for their products in gastric e pithelial cell proliferation and differentiation.