The Effect Of Silencing COX-2Gene On Iological Behavior Of Gastric Cancer Cell

Objective:To investigate the effectiveness of silencing COX-2gene on biological behavior of gastric cancer cell line BGC823and its mechanism.Method:Use of RNAi silencing to influence the COX-2gene in high expressing cell lines of BGC823.Using SqRT-PCR to detect the expression and silencing efficiency of COX-2mRNA. Changes in cell proliferation was measured by cell counting method. MTT assay was used to detect sensitivity changes of docetaxel,oxaliplatin,5-fluorouracil before and after transfection. The cell migration and proliferation was evaluated using Transwell.Cell apoptosis was detected by flow cytometry before and after transfection.The transcription of COX-2and β-catenin was detected by semi-quantitative reverse transcription-polymerase chain reaction,and the protein expression level of COX-2,p-catenin,MMP9,Bcl-2was detected by Western blotting.Result:COX-2and β-catenin were high expression in gastric cancer cell line BGC823detected by SqRT-PCR. SiRNA can effectively reduce the COX-2mRNA expression after transfection. β-catenin mRNA also was high expression after COX-2gene silencing. The cells numbers of siRNA-COX-2pass through the Transwell chambers microporous membrane was significantly decreased. The IC50of gastric cancer cells to docetaxel,oxaliplatin and5-fluorouracil are1.90±0.11mg/L vs2.74±0.17mg/L,0.98±0.37mg/L vs1.66±0.11mg/L,0.54±0.32mg/L vs0.99±0.09mg/L (P<0.05) at24h,19.46±0.50mg/L vs26.55±0.82mg/L,6.89±0.32mg/L vs10.45±0.40mg/L,2.57±0.18mg/L vs4.87±0.32mg/L at48h,20.38±0.89vs39.58±1.94mg/L,6.69±0.60mg/L vs14.42±1.19mg/L,3.16±0.19mg/L vs7.94±0.43mg/L (P<0.05) at72h. The drug sensitivity increased significantly after transfection. Compared with the previous transfection, cells with migratation (97.7±6.1vs48.3±3.1P<0.05) and invasion(84.9±6.5vs37.6±5.2P<0.05)were significantly lower after transfection,but the apoptosis rate of gastric cancer cells were markedly increased after transfection(16.14%±1.89%vs3.08%±0.27%,(P<0.05).The expression of COX-2mRNA,β-catenin mRNA,MMP-9mRNA and Bcl-2mRNA were significantly lower, the comparison values are113.24%±5.46%vs16.432%±1.47%,95.26%±4.27%vs34.44%±5.63%,103.42%±3.88%vs43.25%±5.26%,91.00%±6.74%vs 34.22%±3.63%(P<0.05), respectively. The protein expression of COX-2,P-catenin,MMP-9and Bcl-2were also significantly lower, the comparison values are133.95%±7.66%vs34.10%±3.33%,122.35%±5.13%vs37.70%±3.32%,111.65%±2.73%vs55.25%±4.64%,117.65%±6.52%vs60.46%±2.38%(P<0.05), respectively. The difference is statistically significant.Conclusion:Downregulation the expression of COX-2gene can effectively inhibit the activation of WNT signaling pathway, and also can reduce the expression of MMP-9and Bcl-2gene. Inhibition of COX-2gene expression in gastric cancer cell line BGC823can effectively reduce cell proliferation, migration and invasion.It also can improve the drug sensitivity of docetaxel, oxaliplatin,5-fluorouracil, promote the cell apoptosis.