Objective To investigate Helicobacter pylori combined with N-methyl-N-nitrosourea (MNU) gavage for preparing balb/c mouse gastric cancer model.Methods Eighty balb/c mice were randomly divided into four groups after 1-week adaptive feed,normal group,model group Ⅰ,Ⅱ and Ⅲ,20 cases in each group.The model group Ⅰ,Ⅱ and Ⅲ were given Helicobacter pylori bacteria liquid (CFU=109/mL) gavage,once every other day for 5 times;then,the freshly configured MNU solution 0.15,0.3,0.6 mL gavages were in turn given,MNU and pure water allocation ratio was 5mg:3mL.Once gavage per week for continuous 10 weeks.Results The model group II had 66.67% adenocarcinoma,the model group I were gastritis with mild atypical hyperplasia,and all mice in the model group III died.Conclusion This method can prepare the gastric cancer model.

OBJECTIVE To study the mechanism of Qingre huashi decoction in the treatment of gastric cancer by intervening in miRNA-155 and inhibiting Wnt/β-catenin signaling pathway. METHODS Thirty nude mice were randomly divided into model group， control group （0.004 g/kg cisplatin+0.02 g/kg fluorouracil）， overexpression group， Qingre huashi prescription low-dose， medium-dose and high-dose groups （2.71， 5.43， 10.86 g/kg）， with 5 mice in each group. The overexpression group was inoculated with miRNA-155 AGS cell line， and the other groups were inoculated with AGS cells to induce tumor-bearing gastric cancer model. The control group was given relevant medicine intraperitoneally， and other groups were given relevant medicine or normal saline intragastrically， once a day， for 3 consecutive weeks. The weight of tumor tissue in nude mice was determined； the pathological morphology of tumor tissue was observed； the miRNA-155 expression， mRNA and protein expressions of Wnt7， β-catenin and T- cell factor-4（TCF-4） in tumor tissue were detected. RESULTS Compared with the model group， the tumor weights of nude mice in the control group， the overexpression group and Qingre huashi decoction high-dose group were significantly reduced （P＜0.05）； mRNA and protein expressions of Wnt7， β -catenin and TCF-4 were significantly decreased （P＜0.05）， while miRNA-155 expression was increased significantly （P＜0.05）. Tumor cells exhibited varying degrees of loose arrangement， shallow nuclear staining， and necrotic foci. CONCLUSIONS Qingre huashi decoction can inhibit the protein and mRNA expressions of Wnt7， β-catenin and TCF-4 in Wnt/β-catenin signaling pathway by up-regulating miRNA-155， thus inhibiting the tumor growth of tumor-bearing nude mice.