Relationship of intracellular Ca2 + and apoptosis in liver cancer cell line HepG2 treated with triptolide

Abstract

Objective To observe the inhibitory effects of different concentrations of triptolide on in vitro growth,proliferation,apoptosis and intracellular Ca2+ of human liver cancer cell line HepG2.Methods In vitro,HepG2 cells were treated with triptolide in various concentrations respectively (12.5,25.0,50.0 and 100.0 μg/L),and examined at 24,48 and 72 h.The inhibitory effect on cell growth was assayed by using MTT method.Cell apoptosis rate was detected by using flow cytometry (FCM) with annexin V/propidium iodide (Annexin V/PI) double stainings.The intracellular Ca2+ was determined by using a laser scanning confocal microscope.Results (1) After treatment with triptolide (12.5,25.0,50.0,and 100.0 μg/L),the cell proliferation was inhibited in time-and dose-dependent manners.The apoptosis morphologic changes of HepG2 cells treated with triptolide (12.5,25.0,50.0,and 100.0 μg/L)were observed through AnnexinV-Pl staining.AnnexinV-PI staining showed that triptolide could induce HepG2 cell apoptosis and the apoptosis ratio was time-and dose-dependent (P ＜ 0.05 or P ＜ 0.01).The concentration of intracellular Ca2+ in HepG2 cells treated withtriptolide (12.5,25.0,50.0 and 100.0 μg/L) at 24 and 48 h was statistically different from that in the control group cells (P ＜0.01),but at 72 h,the concentration of intracellular Ca2 + was gradually reduced and even showed no stastically different from that in control group cells (P ＞ 0.05).Conclusion Triptolide could inhibit the growth of human liver cancer cell line HepG2 in a dose-and time-dependent manner.The molecular mechanism of triptolie inducing apoptosis of HepG2 cells may be related to the increased concentration of intracellular Ca2+ in HepG2 cells. Key words: Triptolide; Carcinoma, hepatocellular; Calcium; Apoptosis