Objective      To investigate the effect of Thldiantha nudiflora Hemsl extract on the apoptosis in human cervix cancer HeLa cells.       Methods      HeLa cells were treated with Thldiantha nudiflora Hemsl extract at different concentrations of 0.10

0.25

0.50

1.00

and 2.00 mg/ml for different times (24

48

and 72 h). Cell viability was determined by MTT assay. After HeLa cells were treated with Thldiantha nudiflora Hemsl extract (0.5 and 1.0 mg/ml)

cell morphology was examined by hoechst33258 through fluorescence microscopy. Annexin V/PI double-staining was performed to detect apoptosis of HeLa cells by flow cytometry. The mitochondrial membrane potential of HeLa cells was measured by JC-1 staining. The activities of Caspase-9 and Caspase-3 were measured by Caspase assay kit. The expression of Bcl-2 and Bax at mRNA level was detected by real-time PCR

and Bcl-2/Bax ratio was analyzed.       Results      The inhibitory effect of Thldiantha nudiflora Hemsl extract on HeLa cells showed a significant time-dose response. Thldiantha nudiflora Hemsl extract (0.50 and 1.00 mg/ml) significantly decreased the mitochondrial membrane potential of HeLa cells

promoteed apoptosis（P0.05

P0.01

respectively)

up-regulated the mRNA expression of Bax

down-regulated the expression of Bcl-2 and Bcl-2/Bax ratio

and increased the activities of Caspase-9 and Caspase-3

when compared with the negative control group（P0.05

P0.01).       Conclusion      Thldiantha nudiflora Hemsl extract effectively induces the apoptosis in HeLa cells. The mechanism may be related to decreasing the mitochondrial membrane potential of HeLa cells

and regulating the expression of apoptosis-related genes Bcl-2

Bax

Caspase-9

and Caspase-3.