Intestinal phenotypes of stomach cancers arising after Helicobacter pylori eradication in carcinogen-treated Mongolian gerbils. 
We have previously demonstrated the importance of gastric and intestinal phenotypic expression for the histogenesis of stomach cancer.  However, the phenotypes of stomach cancers arising after Helicobacter pylori (Hp) eradication have hitherto remained unclear.  We therefore examined a series of lesions occurring after Hp eradication in the Mongolian gerbil (MG) model.  Totals of 6 and 20 advanced glandular stomach cancers were evaluated in Hp-eradicated and Hp-infected MGs treated with N-methyl-N-nitrosourea (MNU-MGs), using several gastrointestinal epithelial phenotypic markers.  The lesions were divided phenotypically into gastric (G type), gastric-and-intestinal mixed (GI type), intestinal (I type), and null (N type) phenotypes.  All 4 differentiated type lesions in Hp-eradicated MNU-MGs were classified as G type, while both of the undifferentiated lesions exhibit the GI type.  In Hp-infected MNU-MGs, the lesions were classified as 10 G, 8 GI, and 2 I types, with undifferentiated type lesions having more intestinal phenotypic expression than their differentiated counterparts (P< 0.01).  Our data suggest that the differentiated stomach cancers exhibit the G type in Hp-eradicated MNU-MGs, suggesting that a kind of non-neoplastic G type gland may be precancerous.  Intestinalization may still occur, especially in undifferentiated stomach cancers, even if Hp eradication is successful.