RUNX3 expression correlates with chief cell differentiation in human gastric cancers.

RUNX3 is a novel tumor suppressor in gastric carcinogenesis and an important factor for differentiation of chief cells in the normal gastric fundic mucosa. In this study, we confirmed RUNX3 immunolocalization in the fundic gland (bottom part) but minimum in surface mucous cell epithelium (top part) in the isolated gland from fundic mucosa. We also analyzed RUNX3 expression by immunohistochemistry in 102 gastric cancers and made a histological assessment of the expression of differentiation markers to evaluate interrelations. Among them, 45 and 57 cases were judged to be RUNX3 positive and negative, respectively, and 33 and 69 cases were pepsinogen I positive and negative, with no link to histological types. RUNX3 expression was significantly associated with that of pepsinogen I (P<0.001), but not mucins, including MUC5AC and MUC6, or the parietal or intestinal phenotypes. In conclusion, the present study showed, for the first time to our knowledge, a relation between RUNX3 and pepsinogen I expression in human gastric cancers. RUNX3 is strongly associated with chief cell phenotypic expression in human gastric cancers, as well as in normal gastric mucosa, and could be considered to play an important role in maintaining the chief cell phenotype.

Loss of MUC2 expression correlates with progression along the adenoma-carcinoma sequence pathway as well as de novo carcinogenesis in the colon.

AIMS: We have previously demonstrated links between clinicopathological findings and phenotypes using several gastric and intestinal phenotypic markers in stomach and pancreatic cancers. However, the clinicopathological significance of the phenotype and Cdx2 expression has hitherto remained unclear in colorectal carcinogenesis. METHODS AND RESULTS: We examined the correlation between gastric and intestinal phenotypic expression in 91 primary early carcinomas of the colon. MUC2 expression demonstrated a significant decrease from tubular/tubulovillous adenomas with moderate atypia, through intramucosal carcinomas, to cancers with submucosal invasion (P<0.0001). Intramucosal de novo carcinomas (flat type carcinomas without adenomatous components) exhibited a greater decrease of MUC2 than intramucosal lesions with adenomatous components. Expression of MUC5AC also decreased significantly with progression according to the tubular/tubulovillous adenoma-carcinoma sequence, carcinomas with villous adenomatous components having a higher level compared with their tubular adenomatous counterparts, suggesting differences in the pathway of malignant transformation. Cdx2 nuclear expression was maintained in all of the adenomas and early carcinomas examined. CONCLUSIONS: Our data suggest that the reduction of MUC2 expression may be associated with the occurrence and progression of colorectal carcinomas in both adenoma-carcinoma sequence pathway and de novo carcinogenesis. Tumor-suppressive effects of Cdx2 may be preserved during early stages of colorectal carcinogenesis.

Sequential histopathological changes in vivo after suicide gene therapy of gastric cancer induced by N-methyl-N'-nitro-N-nitrosoguanidine in rats.

Gastrointestinal cancer is the most important clinical target of gene therapy. Suicide gene therapy, such as with the herpes simplex virus type 1 thymidine kinase (HSV-TK) gene, has been shown to exert antitumor efficacy in various cancer models in vitro. We previously reported in situ gene transfer and gene therapy for gastric cancer induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) in dogs. Here, we describe the sequential histopathological changes after suicide gene therapy of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric cancer in rats. Gastric tumors were induced by MNNG in 38 / 73 (52%) of Wistar strain rats. The suicide gene therapy group (14 rats) was subjected to in situ gene transfer with a recombinant adenovirus vector carrying the HSV-TK gene driven by CAG promoter (Ad.CAGHSV-TK) in gastric tumor, followed by the antiviral drug ganciclovir (GCV). To observe the histopathological changes at various times after HSV-TK / GCV gene therapy, groups of animals were sacrificed at 3, 8, and 30 days after gene transfer. Apoptosis in the gastric tumors was detected by the TUNEL method to assess the efficacy of HSV-TK / GCV gene therapy, and it was marked in the 8- and 30-day treatment groups compared to the sham operation controls (P < 0.001). Various histopathological changes, degeneration of cancer tissue and fibrosis after necrosis and apoptosis were significantly greater in the 30-day treatment group. The HSV-TK gene was detectable in peripheral blood by PCR until 30 days after gene transfer. These results may be useful in devising a method of suicide gene therapy for humans.

New animal model of glandular stomach carcinogenesis in Mongolian gerbils infected with Helicobacter pylori and treated with a chemical carcinogen.

In 1994 WHO/IARC concluded that "Helicobacter pylori is a definite carcinogen" based on epidemiological studies, but there have been few reports demonstrating a relation between H. pylori and stomach cancer in animal models. We have succeeded in producing adenocarcinomas in the glandular stomachs of Mongolian gerbils with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or N-methyl-N-nitrosourea as carcinogens and hope to establish an experimental stomach carcinogenesis model using H. pylori. Male Mongolian gerbils, 7 weeks old, were infected with H. pylori followed by MNNG administration at a concentration of 100ppm administration or treated with MNNG at a concentration of 300ppm in their drinking water followed by inoculation with H. pylori. They were then killed sequentially, and their excised stomachs underwent microbiological and histopathological examinations. H. pylori were detected in all infected gerbils. Hyperplastic change of pyloric mucosa was observed with high 5-bromo-2'-deoxyuridine incorporation in affected animals. H. pylori infection persists on administration of MMNG and enhances glandular stomach proliferation in Mongolian gerbils. Whether long-term colonization promotes carcinogenesis in the glandular stomach of Mongolian gerbils is a matter of great interest.