[Apoptosis-Inducing Effect of Ginsenoside Rh2 on Human Acute T Lymphoblastic Leukemia Jurkat Cells and Its Mechanism]

To investigate the apoptosis-inducing effect of Ginsenoside (Rh2) on human acute T lymphoblastic leukemia Jurkat cells and it mechamism.

The effects of different concentration of Rh2 (0, 10 , 20, 40 and 80 µg/ml) on the proliferation activity of Jurkat cells were detected by methyl thiazolyl tetrazolium (MTT) method, and the semi-inhibitory concentration (IC₅₀) of Rh2 on Jurkat cells at 48 h was calculated. Microscopy and Hoechst 33258 fluorescence staining were used to observe the apoptosis of Jurkat cells treated with IC₅₀ Rh2 for 48 h. And then, the cell experiment was divided into 4 groups: control, Rh2 (IC₅₀), PI3K inhibitor LY294002 (50 µmol/l) and Rh2 (IC₅₀) + LY294002 (50 µmol/l). After synchronous culture for 48 h, the apoptosis and cycle changes of Jurkat cells were detected by using PI single staining and Annexin V-FITC/PI double staining, respectively. Western blot was used to detect the expression level of apoptosis-related protein BAX, BCL-2, Cleaved-Caspasase 3, cell cycle-related protein Cyclin D1 and PI3K/AKT signaling pathway-related protein AKT and p-AKT.

Rh2 (10-80 µg/ml) inhibited the Jurkat cell proliferation in a dose-time dependent manner (r_48h = 0.999, P＜0.01; r_{80 µg/ml} = 0.991; P＞0.05), accompanied by obvious morphological changes of apoptosis cells. Flow cytometry showed that compared with the control group, the cell apoptosis rate in Rh2 or LY294002 group significantly increased, and the cell cycle was mostly blocked in G0/G1 phase. However, the cell apoptosis and cell cycle block in Rh2+LY294002 group were more significant than that in Rh2 and LY294002 group. Western blot showed that compared with the control group, Rh2 significantly promoted the expression of BAX and Cleaved-Caspasase 3, inhibited the expression of BCL-2, Cyclin D1 and p-AKT, furthermore LY294002 significantly promoted this effect.

Rh2 can induce the apoptosis of Jurkat cells in time-dose dependent manner, moreover, Rh2 also can result in an obvious block of Jurkat cells at G0/G1, that may be closely related to a series of apoptotic signaling cascades mediated by Rh2 inhibiting PI3K/AKT pathway.