| At present, gastric cancer represents the second. cause of mortality due to cancer,after the bronchopulmonary cancer in men and the fourth cause of mortality in women.Almost two-thirds of the cases occur in developing countries and 42% in China. The tumorigenesis of gastric cancer is a process of multiple stages, caused by many factors,such as the activation of oncogenes, disabling of tumor suppressor genes, immune changes, epigenetic changes and so on. Even after curative radical resection and adjuvant systemic chemotherapy, disease progression frequently occur in advanced gastric cancer patients, resulting in treatment failure and a high mortality rate. Hence there is an urge for the discovery of biomarkers for non-invasive early detection in gastric cancer patients. MicroRNAs (miRNA) are a class of -22 nucleotide non-coding RNAs that are participating in post-transcriptional regulation and controlling various important pathophysiological processes. MiRNA can play an important role in the regulation of various biological processes, including cell proliferation, apoptosis, migration and differentiation. The aberrant expression of miRNAs has been associated with a number of human pathologies, including cancer.Previous studies have shown that miRNAs play roles as tumor suppressors or oncogenes in gastric cancer. Up to the present, there are many reports about microRNA-217 involvement in various tumor formation and evolution. But researches related to microRNA-217 are unseen in gastric cancer.ObjectivesThis research is designed to investigate the expression of microRNA-217 in gastric cancer and its impact on formation and evolution of gastric cancer.Methods(1) The expression level of microRNA-217 was examined by using quantitative real-time PCR in 50 pairs of human gastric cancer tissues and pair-matched adjacent noncancerous gastric tissues. Furthermore, the expression level of microRNA-217 was evaluated with regards to the clinicopathological characteristics of the patients.(2) Northern Blot analysis was performed to analyze the expression of microRNA-217 in human gastric cancer epithelial cell lines(SGC-7901?HGC-27?MGC-803?MKN-45) and human immortalized gastric mucosa normal cell line(GES-1).(3) Quantitative real-time PCR analysis detected the expression of microRNA-217 in human gastric cancer epithelial cell lines(SGC-7901?HGC-27?MGC-803?MKN-45) and human immortalized gastric mucosa normal cell line(GES-1).(4) The synthesized microRNA-217 mimic or microRNA-217 inhibitor was transfected into cultured gastric cancer epithelial cell line HGC-27. Then the expression of transfection efficiency was measured by real-time PCR. After the accomplishment of ectopic expression was confirmed, CCK-8 was used to detect the cell proliferation of HGC-27 cell line.(5) Cell migration assay and cell invasion assay were used to evaluate the abilities of cell metastasis and invasion.Results(1) The expression of microRNA-217 is significantly down-regulated in gastric cancer tissues. Moreover,lower-level of microRNA-217 is associated with a more aggressive gastric cancer phenotype.(2) Northern blot analysis showed that the expression level of microRNA-217 is significantly lower in human gastric cancer epithelial cell lines compared with human immortalized gastric mucosa normal cell line.(3) Real-time PCR result showed that the expression level of microRNA-217 is significantly lower in human gastric cancer epithelial cell lines compared with human immortalized gastric mucosa normal cell line.(4) The CCK-8 assay demonstrated that cell proliferation rate is decreased after HGC-27 cell transfected with microRNA-217 mimic. And the cell proliferation rate is increased after HGC-27 cell transfected with microRNA-217 inhibitor.(5) The abilities of cell invasion and migration are decreased after HGC-27 cell transfected with microRNA-217 mimic. And the abilities of cell invasion and migration are increased after HGC-27 cell transfected with microRNA-217 inhibitor.Conclusions(1) Compared with noncancerous gastric tissues and cell line, the expression level of microRNA-217 are significantly lower in gastric cancer tissues and cell lines.(2) The expression level of microRNA-217 is negatively correlated with TNM stage.(3) Overexpressed microRNA-217 .can inhibit the abilities of cell proliferation,invasion and migration. |
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