Expression change of apoptosis protein (Bcl-2 and Caspase 3) in HepG2 cell line induced by COX-2 inhibitor NS-398

Objective To investigate the possible role of selective cyclooxygenase 2 on the inhibition of induced apoptosis by liver tumor HepG2 cell line.Methods HepG2 cell was treated by selective COX-2 inhibitor NS-398.Cell apoptosis was determined by flowcytometry analysis using PI staining.The expression of Bcl-2 and caspase3 protein was detected by Western blotting.Caspase3 activity was evaluated by active Caspase3 apoptosis kit with flow cytometry.Results Selective COX-2 inhibitor NS-398 stimulated apoptosis in liver tumor HepG2 cell line significantly.Flowcytometry revealed the apoptotic rate with different concentrations of NS-398(0,100,200,300,400μmol/L),the result was(10.51±1.04)%,(27.79±2.40)%,(45.72±3.32)%,(60.22±2.03)% respectively.The apoptotic peak did not appear in the control group,which showed a dose-dependent manner(P 0.01).The expression of caspase3 protein was up-regulated while Bcl-2 protein was down-regulated,and the percentage of the cells with active Caspase3 was(2.67±0.22)%、(9.53±0.15)%,(21.28±0.43)%,(39.63±0.8)%,(63.40±0.69)%,showing a dose-dependent manner(P0.01).Conclusion Selective COX-2 inhibitor NS-398 may activate Caspase3 by down-regulating the expression of Bcl-2 protein,which causes apoptosis of HepG2 cells.Selective COX-2 inhibition may be a novel therapeutics of liver cancer.