Apoptosis induced by oleanolic acid and its relation to intracellular calcium of human lung adenoma A549 cells

Objective To examine the effect of Oleanolic acid(OA) on inducing apoptosis in human lung adenoma cell line A549 and to explore the mechanism of induction.Methods Human lung adenoma A549 cells were incubated and the experiment was performed as following: the apoptosis status was detected by Annexin V-FITC/PI and flow cytometry(FCM) at concentrations of 0,10,20 and 40 μg/ml OA in 24 h;fluorescent intensity of A549 was assessed by FCM,and the level of intracellular calcium was calculated;the relation of apoptosis and calcium fluorescent intensity was illustrated by curve fitting.Results FCM showed 10,20 and 40 μg/ml of OA could induce apoptosis in A549 cells in a concentration-dependent manner.The intervention with 20 μg/ml and 40 μg/ml OA for 24 h showed increased A549 cell apoptosis,significantly different from that in 0 μg/ml group(P0.01).Both fluorescent intensity and intracellular calcium concentrations in 10,20 and 40 μg/ml OA groups were significantly higher than those of 0 μg/ml group after 24 h intervention.The fluorescent intensity showed an increasing trend as concentration of OA elevated,and there was a statistically significant difference(P0.01).Curve fitting showed the significant correlation of apoptosis and calcium concentration of A549(R=0.981,P0.01).Regression equation was Y=0.508x-1.627.Conclusion OA plays an important role in inducing the apoptosis of the human lung adenoma cells in a concentration-dependent manner and the apoptosis caused by OA is responsible for intracellular calcium overload of the tumor.