Gastric and intestinal phenotypes of gastric carcinoma with reference to expression of brain (fetal)-type glycogen phosphorylase

Purpose. Although reports have suggested that differentiated gastric carcin omas have different phenotypes, i.e., gastric and intestinal type, this cla ssification is complicated and can be confusing. Our previous studies have demonstrated a close relationship between carcinogenesis in differentiated- type gastric cancer and the expression of brain (fetal)-type glycogen phosp horylase (BGP). The purpose of this study was to investigate the relationsh ip between the mucin phenotype of gastric carcinoma and BGP expression. Met hods. Ninety-six specimens of gastric carcinoma were studied using specific anti-BGP antibody. Correlation of BGP expression with intestinal and gastr ic phenotypes was determined with the anti-mucin antibodies, HGM, CD10, and MUC2. Results. BGP was expressed in 82.6% (38/46) of differentiated type a nd in 24.0% (12/50) of undifferentiated type carcinomas. The incidence of B GP positivity was significantly greater in the differentiated-type carcinom a than in the undifferentiated type (P < 0.001). The proportions of gastric , mixed and intestinal types in differentiated and undifferentiated gastric carcinomas were 13.0%, 47.8%, and 39.2%, and 56.0%, 32.0%, and 12.0%, resp ectively. In both differentiated and undifferentiated types, the phenotype of gastric and intestinal mucin expression corresponded very well with BGP expression, that is, more than 90% of carcinomas with gastric type did not express BGP, whereas approximately 90% of carcinomas with intestinal type d id express BGP. Conclusions. The classification of gastric and intestinal p henotypes of gastric carcinoma in terms of BGP expression was simpler and c learer than such classification in terms of mucin immunohistochemistry. It is suggested that BGP is a useful biomarker for the classification of intes tinal and gastric type carcinoma of the human stomach, including classifica tion from the carcinogenetic point of view.