AIM: To investigate the inhibitory effect of microRNA-9 (miR-9) on epithelial-mesenchymal transition (EMT) in the gastric cancer SGC-7901 cells and its mechanism.METHODS: The gastric cancer cell line SGC-7901 was transfected with miR-9 mimics or negative control mimic (NCM), as miR-9 or NCM group, respectively.The SGC-7901 cells without transfection were used as control group.The expression level of miR-9 in each group was detected by RT-qPCR.The migration and invasion abilities of the SGC-7901 cells in the 3 groups were detected by Transwell assay.The protein expression of N-cadherin, E-cadherin, α-catenin and neuropilin-1 (NRP1) was determined by Western blot.Antagonistic effect of NRP1 over-expression on miR-9 inhibition of EMT was detected by Western blot.The relationship between miR-9 and NRP1 was analyzed by dual luciferase assay.RESULTS: The expression level of miR-9 in miR-9 group was significantly up-regulated, which was 538 times higher than that in control group (P<0.05).The number of migratory cells in miR-9 group was significantly lower than that in control group (P<0.05).Compared with control group, the protein expression of N-cadherin and NRP1 in miR-9 group was significantly decreased, while the protein expression of E-cadherin and α-catenin protein was significantly increased.Over-expression of NRP1 resulted in the increase in the protein expression of N-cadherin in the gastric cancer cells of miR-9 group, and the decrease in the protein expression of E-cadherin and α-catenin significantly.The result of dual luciferase assay showed that NRP1 was a downstream target gene of miR-9 (P<0.05).CONCLUSION: miR-9 may inhibit the expression of EMT-related proteins through the downstream target gene NRP1, thus inhibiting the EMT of gastric cancer SGC-7901 cells.

Objective To investigate the clinical epidemiological characteristics of gastric carcinoma detected by endoscopy in Gansu province.Methods Data of patients with gastric carcinoma,which was detected by endoscopy and confirmed pathologically from January 1977 to December 2006 in 163 hospitals of Gansu province,were reviewed.The endoscopic findings,clinical manifestations and epidemiological features were retrospectively analyzed.Results A total of 34,116 patients were diagnosed as gastric carcinoma with the overall screening rate as 5.30%,which was decreasing in the recent years.The rate of cardiac and noncardiac cancer was 18.5%and 81.5%,respectively,and the rate of cardiac cancer raised from 16.1%to 20.0%in the last decade.The tumor was most likely detected in antrum(38.63%).The male/female ratio of gastric cancer is 3.56:1.The screening rate of gastric carcinoma was the highest in Wuwei district (8.19%).The poorly differentiated adenocarcinoma accounted for 49.64%in all patients.Conclusion Gastric carcinoma occurs most frequently in Wuwei district of Gansu province and was mostly detected in gastric antrum.The most common pathological type is poorly differentiated adenocarcinoma.In the past three decades,the detection rate of gastric cancer is decreasing,SO is that of cardiac cancer,and that of the early gastric cancer is relatively low.