Researches On The Effect Of SiRNA Inhibiting The Expression Of Cyclooxygenase-2 On Gastric Adenocarcinoma Cell

Background: Gastric cancer is the most frequent malignancies and the leading cause of cancer mortality in China. Gastric cancer is not sensitive to traditional therapy such as chemotherapy and radiotherapy, and low 5-year-survival is still the problem. The enzyme cyclooxygenase-2 (COX-2) is highly expressed in gastric adenocarcinoma cell and play a key role in gastric carcinogenesis. Epidemiological studies indicate that gastric cancer incidence can be reduced by long term taking nonsteroidal anti-inflammatory drugs (NSAIDs). RNA interference (RNAi) has been used as a revolutionized research tool to control the expression of specific genes in numerous experiments in vitro. Inhibiting COX-2 expression with small interfering RNA (siRNA) has potential as a therapeutic strategy of gastric adenocarcinoma.Objective: To observe the COX-2 expression and cell proliferation and apoptosis of gastric adenocarcinoma cell after transiently transfecting gastric cancer cell using siRNA, and discuss the role of COX-2 in gastric tumorigenesis and the effect of RNAi as anti-cancer gene therapy.Methods: Three groups are divided, RNAi group, non-sense group and control group. Gastric adenocarcinoma cell SGC7901 is cultured at 37°C in atmosphere containing 5% CO₂. For 72 hours after transfecting SGC7901 cells with specific anti-COX-2 siRNA or N.C.FAM siRNA, RT-PCR is taken to detect COX-2 mRNA, immunohistochemistry is taken to detect the expression of COX-2 protein, flow cytometry is taken to detect the cell cycle and apoptosis. MTT method was used to detect the proliferation of the cells every day in one week after transfection.Results: The expression of COX-2 mRNA and protein of RNAi group is obviously suppressed compared with non-sense group and control group, no changes have been found between non-sense group and control group. The reduced expression of COX-2 can inhibit SGC7901 cells proliferation and induce cell apoptosis, but have no effect on cancer cell cycle.Conclusions: The experimental results suggest RNAi as a gene therapeutic method can effectively inhibit the expression of COX-2 and the proliferation of gastric cancer cell, promote the cancer cell apoptosis process.