Effects of silencing of COX-2 gene expression by siRNA on cell proliferation,cell cycles,apoptosis and tumorigenicity of human pancreatic cancer Capan-2 cells

AIM: To investigate the effects of silencing of cyclooxygenase-2(COX-2) gene expression by siRNA on the proliferation,apoptosis,cell cycle and tumorigenicity of human pancreatic cancer Capan-2 cells.METHODS: The gene transfection was performed using Lipofectamine 2000(Lipo).The proliferation,apoptosis and cell cycle of Capan-2 cells were tested by the methods of cell counting,microscopy and FCM.The mRNA expression of COX-2 was determined by RT-PCR and real-time PCR.The protein level of COX-2 was detected by Western blotting.The tumorigenicity of Capan-2 cells transfected with siRNA-COX-2 was determined using the model of nude mice.RESULTS: Transfection efficiency of 96.47% was obtained under the conditions that the transfection volume was 2 mL,concentration of Lipo was 5 μL and that of siRNA-COX-2 was 50 nmol/L.The best sequence of siRNA-COX-2 for silencing of COX-2 gene expression was siRNA006 with the silencing rate of up to 73% 24 h after tansfection.siRNA-COX-2 slowed down the growth of Capan-2 cells 48 h after transfection(P0.05).At time points of 48 h and 72 h after transfection,the protein expression of COX-2 was down-regulated to 67% and 61% of the normal level,the proliferation inhibition rate was 35.48% and 56.32%,and the apoptotic rate was 2.03% and 3.27%,respectively.At time points of 24 h,48 h and 72 h after transfection,the proportion of the cells in G0/G1 phrase was 58.03%,63.31% and 65.66%,and that of the cells in S phase was 30.27%,24.87% and 22.2%,respectively.The mean volume and weight of tumor tissues were remarkably decreased due to the transplantation of Capan-2 cells transfected with siRNA-COX-2.CONCLUSION: siRNA-COX-2 effectively silences the expression of COX-2 gene,inhibits the growth and decreases the tumorigenicity of Capan-2 cells.