Gastric adenomas and superficial adenocarcinomas display distinct patterns of mucin carbohydrate and core protein expression.

Abstract

To investigate the histogenetic relationship between gastric epithelial neoplasms we studied differences in expression of mucin carbohydrate antigens and mucin core protein, in normal and metaplastic gastric mucosa, and in gastric adenomas and superficial adenocarcinomas. We generated four monoclonal antibodies, including HGM72/75 against human gastric mucin and HCM14/21 against human colonic mucin, and investigated immunoreactivities of these antibodies and MUC2 protein expression in normal and metaplastic gastric mucosa, adenomas (15 samples) and superficial adenocarcinomas (intestinal-type, 77; diffuse-type, 59 samples). HGM72 reacted with mucous neck cells of the fundic glands and with pyloric glandular cells whereas HGM75 stained foveolar cells and metaplastic goblet cells. Weak binding of HCM14/21 and strong staining with MUC2 were found in metaplastic goblet cells. Binding of HGM75, HCM14, MUC2, but not HGM72 was high in adenomas. An equivalent staining with HGM72 and HGM75 with low expression of MUC2 and HCM14 was shown in intestinal-type carcinomas while the diffuse-type demonstrated more strong reactivity with HGM75 than with HGM72, MUC2 and HCM14. Little binding of HCM21 was observed in any specimens. This study demonstrates that adenomas predominantly have a intestinal phenotype, but both types of adenocarcinomas retain some cells with a gastric phenotype during the early steps of neoplastic development.