Perturbation of gastric mucosa in mice expressing the temperature-sensitive mutant of SV40 large T antigen. Potential for establishment of an immortalised parietal cell line

A human mode of intestinal type gastric carcinoma

Gastric cancer is a malignant tumor originating from the gastric mucosa epithelium. Intestinal type gastric cancer is frequently taken on elderly men, and there are many high incidence areas around the world. Intestinal type gastric cancer often is accompanied by gastric mucosal atrophy, intestinal metaplasia. The clinical manifestation involves hypergastrinemia, low stomach acid, PG I/II progressive decreasing, anemia, and protein energy malnutrition. The neck cells of gastric glands act as tissue stem cells to regenerate the gastric glands. In addition to secreting gastric acid and intrinsic factor, the parietal cells also have the function of inducing differentiation of themselves and gastric epithelial cells. When the function of parietal cells is normal, the neck cells differentiate into mature cells, and the glands regenerate intact. When the function of parietal cells is defective, the neck cells maybe differentiate into mature intestinal cells, and the gastric glands will regenerate in form of the intestinal metaplasia. When the function of parietal cells is lost, the neck cells can not differentiate into mature cells successfully, and the accumulation of immature cells in gastric mucosal tissue forms atypical hyperplasia of different degrees and cancers of various differentiation grades. Any factors that can reduce the function of parietal cell could result in intestinal type gastric carcinogenesis. Adrenal cortical hypofunction can make the parietal cell hypofunction, hypohematopoiesis, protein synthesis rates reducing and protein degradation rates increasing. The patients develop gastric cancer, and come with lack of gastric acid and intrinsic factor, anemia, protein energy malnutrition. Autoimmune gastritis can produce parietal cell antibodies to damage parietal cells. Patients with autoimmune gastritis gastric exhibit hypergastrinemia, lack of gastric acid and internal factor, higher incidence of gastric cancer. H. pylori can damage gastric parietal cells directly and indirectly. When declining in quantity of parietal cells, the patients exhibit hypergastrinemia, low gastric acid, mucosa atrophy, intestinal metaplasia and gastric cancer. Medicine that inhibits the function of parietal cells also could increase the risk of gastric cancer development. The distribution of mucosa atrophy, intestinal metaplasia and intestinal type gastric cancer is opposite with the distribution of parietal cells in stomach. With age the quantity of parietal cells decreases, the atrophy area of gastric mucosa extends upward from antrum to body and downward from cardia to body along lesser curvature, and the location of distal gastric cancer moves upward and the gastric cardiac cancer increase.

Transgenic and gene knockout mice in gastric cancer research

Mouse models are useful tool for carcinogenic study. They will greatly enrich the understanding of pathogenesis and molecular mechanisms for gastric cancer. However, only few of mice could develop gastric cancer spontaneously. With the development and improvement of gene transfer technology, investigators created a variety of transgenic and knockout/knockin mouse models of gastric cancer, such as INS-GAS mice and gastrin knockout mice. Combined with helicobacter infection and carcinogens treatment, these transgenic/knockout/knockin mice developed precancerous or cancerous lesions, which are proper for gene function study or experimental therapy. Here we review the progression of genetically engineered mouse models on gastric cancer research, and emphasize the effects of chemical carcinogens or infectious factors on carcinogenesis of genetically modified mouse. We also emphasize the histological examination on mouse stomach. We expect to provide researchers with some inspirations on this field.

Mouse models of gastric carcinogenesis

Gastric cancer is one of the most common cancers in the world. Animal models have been used to elucidate the details of the molecular mechanisms of various cancers. However, most inbred strains of mice have resistance to gastric carcinogenesis. Helicobacter infection and carcinogen treatment have been used to establish mouse models that exhibit phenotypes similar to those of human gastric cancer. A large number of transgenic and knockout mouse models of gastric cancer have been developed using genetic engineering. A combination of carcinogens and gene manipulation has been applied to facilitate development of advanced gastric cancer; however, it is rare for mouse models of gastric cancer to show aggressive, metastatic phenotypes required for preclinical studies. Here, we review current mouse models of gastric carcinogenesis and provide our perspectives on future developments in this field.

CD4+CD25+ Regulatory T Cells Inhibit the Antigen-Dependent Expansion of Self-Reactive T Cells In Vivo

A deficiency of CD4+CD25+ regulatory T cells (CD25+ Tregs) in lymphopenic mice can result in the onset of autoimmune gastritis. The gastric H/K ATPase alpha (H/Kalpha) and beta (H/Kbeta) subunits are the immunodominant autoantigens recognized by effector CD4+ T cells in autoimmune gastritis. The mechanism by which CD25+ Tregs suppress autoimmune gastritis in lymphopenic mice is poorly understood. To investigate the antigenic requirements for the genesis and survival of gastritis-protecting CD25+ Tregs, we analyzed mice deficient in H/Kbeta and H/Kalpha, as well as a transgenic mouse line (H/Kbeta-tsA58 Tg line 224) that lacks differentiated gastric epithelial cells. By adoptive transfer of purified T cell populations to athymic mice, we show that the CD25+ Treg population from mice deficient in either one or both of H/Kalpha and H/Kbeta, or from the H/Kbeta-tsA58 Tg line 224 mice, is equally effective in suppressing the ability of polyclonal populations of effector CD4+ T cells to induce autoimmune gastritis. Furthermore, CD25+ Tregs, from either wild-type or H/Kalpha-deficient mice, dramatically reduced the expansion of pathogenic H/Kalpha-specific TCR transgenic T cells and the induction of autoimmune gastritis in athymic recipient mice. Proliferation of H/Kalpha-specific T cells in lymphopenic hosts occurs predominantly in the paragastric lymph node and was dependent on the presence of the cognate H/Kalpha Ag. Collectively, these studies demonstrate that the gastritis-protecting CD25+ Tregs do not depend on the major gastric Ags for their thymic development or their survival in the periphery, and that CD25+ Tregs inhibit the Ag-specific expansion of pathogenic T cells in vivo.

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