Correlation Of The Expression Of Gastrin, Gastrin Receptor And Reg Gene In Gastric Cancer

Gastric cancer occurs with a high incidence in the world. As a peptide hormone, gastrin is secreted by gastrin-containing cell (G cell) in the gastrointestinal tract. Gastrin is now firmly established as the physiological regulator of gastric acid secretion and an important regulator of gastrointestinal mucosal cell proliferation. Gastrin is a gastrointestinal (GI) peptide that possesses potent trophic effects on most of the normal and neoplastic mucosa of the GI tract, and plays an important role in the malignant process of gastric mucosa. Gastrin promotes cell dividing and DNA synthesis mediated by its receptor, stimulates the growth of gastric cancer, colorectal cancer and etc. However, the mechanisms governing gastrin-induced proliferation of gastric cancer cells are still largely unknown.Reg I alpha protein was over expressed in gastric cancer, and its positive ratio up to 37.7%. REG Ialpha protein might function as a trophic and/or anti-apoptotic factor in the development of gastric cancer. REG Ialpha-positive early gastric cancers showed a significantly higher PCNA labeling index. REG Ialpha protein promoted cell growth and cell resistance to H₂O₂-induced apoptosis in AGS cells. REG expression was correlated with tumor differentiation status and patient survival. Overall and disease-free survival was found to be poor for patients with REG-positive tumors. REG expression in infiltrating tumors was found to be significantly higher compared with localized tumors.Reg protein stimulated the proliferation of several gastric cancer cell types. In patients with chronic hypergastrinemia, Reg production was stimulated, with the increased proliferation of gastric mucosal cells. Reg protein showed a dose-dependent and time-dependent stimulation of cultured gastric mucosal cell proliferation. Gastrin had no direct growth-stimulating effect on cultured gastric mucosal cells, whereas it might stimulated the proliferation of gastric mucosal cell s indirectly via the stimulation of Reg production. In gastric tissues, Reg I was found to be expressed mainly in gastric fundic enterochromaffin-lik (ECL) cells. Reg I production in ECL cells is stimulated by gastrin. Less papers related to the coexpression of gsatrin, gastrin receptor and Reg gene in gastric cancers, and its relationship to clinicopathological factors have been found. Up to date, few studies on Reg gene have been found in China, and mainly on colorectal cancer, no one on gastric cancer.In this study, immunohistochemistry technique was used to observe the expression of gsatrin and gastrin receptor in gastric cancer tissues, adjacent cancer tissues and normal gastric mucosal tissues. RT-PCR technique was used to detect the expression of Reg I gene in above mentioned tissues. The coexpression of gsatrin, gastrin receptor and Reg gene and its relationship to clinicopathological factors was assessed. For further identification of the relationship of Reg expression to gastrin, the alteration of Reg expression in gastrin knock-down gastic cancer cell line BGC-823 was detected by using RT-PCR. The results might provide new experimental data for elucidating the mechanism governing gastrin-induced development of gastric cancer.Materials and methods1. Materials 36 cases of gastric cancer tissues, 15 cases of adjacent cancer tissuesand 11 cases of normal gastric mucosal tissues were removes from First AffiliatedHospital of Zhengzhou University.Gastrin knock-down gastric cancer cell line BGC-823. (Xia Bin paper)2. Immunohistochemistry Immunohistochemistry technique was used to observethe expression of gsatrin and gastrin receptor in gastric cancer tissues, adjacent cancer tissues and normal gastric mucosal tissues. The coexpression of gsatrin and gastrin receptor and its relationship to clinicopathological factors was assessed. 3. RT-PCR RT-PCR technique was used to detect the expression of Reg I gene inabove mentioned tissues. The coexpression of gsatrin, gastrin receptor and Reg gene and its relationship to clinicopathological factors was assessed. The alteration of Reg expression in gastrin knock-down gastic cancer cell line BGC-823 was detected by using RT-PCR.4. Statistical analysis SPSS10.0 statistical software was used to analyze experimental data. a= 0.05 was selected as test level.Results1. Immunohistochemistry The positive incidence of gastrin expression in gastriccancer tissues, adjacent cancer tissues and normal gastric mucosal tissues was 72.22% (26/36), 46.67% (7/15) and 9.09% (1/11) respectively; and that of gastrin receptor was 61.11% (22/36), 53.33 % (8/15) and 0 %(0/11) respectively. In gastric cancer specimens, the number of cases with both gastrin and gastrin receptor positive was 22, negative 10. A positive correlation occurred between them (P<0.05). Coexpression of gastrin and gastrin receptor was related to differentiation status, infiltration, lymph node metastasis and TNM stage of gastric cancers.2. RT-PCR The positive incidence of Reg I gene in gastric cancer tissues, adjacentcancer tissues and normal gastric mucosal tissue was 69.44% (25/36) , 40.00% (6/15) and 18.18 (2/11) %. In gastric cancer tissues, 23 cases showed both gsatrin and Reg I positive, 8 cases double negative; 20 cases showed both gsatrin receptor and Reg I positive, 9 cases double negative. There was an obvious positive correlation between gsatrin, gsatrin receptor and Reg I expression in gastric cancer tissues (P<0. 05) . Coexpression of gastrin, gastrin receptor and Reg I was related to differentiation status, infiltration, lymph node metastasis and TNM stage of gastric cancers.The length of amplified products of Reg I and 8-actin was 557bp and 385bp respectively. The ratio of Reg I /β-actin was 0.54±0.29 in experimental group, and 1.04±0.22 in control group. A significant difference occures between them (p < 0.01) .Conclusion1. Both gsatrin and gastrin receptor are over expressed in gastric cancer tissues . Apositive correlation appeared between them. Coexpression of gastrin and gastrin receptor is related to differentiation status, infiltration, lymph node metastasis and TNM stage of gastric cancers.2. In gastric cancer tissue, there was an obvious positive correlation between gsatrin, gsatrin receptor and Reg I expression. Coexpression of gastrin, gastrin receptor and Reg I was related to differentiation status, infiltration, lymph node metastasis and TNM stage of gastric cancers.3. After suppression of gsatrin expression, Reg I expressed is significantly inhibitedin gsatric cancer cell line BGC-823. Reg I gene may be a key down stream gene in the process of gsatrin promoting gastric cancer development.