Objective:To study the effects of proliferation and apoptosis on K562 cells induced by 17-hydroxy-jolkinolide B（HJB）.Method:After the cells were treated with HJB at various concentrations（0

6.25

12.5

25

50

100

200

400 μmol · L-1）for 24 h

or at 200 μmol · L-1for various times（12

24

48 h）

cell viability was measured by 3-（4

5-dimethylthiazol-2-yl）-2

5-diphenyltetrazolium bromide（MTT）.Annexin V-FITC was used to test the apoptosis rate.Absorption spectrometry was adopt to measure the relative activity of Caspase-3 and Caspase-8.Result:The HJB evidently inhibited the growth of K562 cells in a time and dose-dependent manner（P<0.05）

with IC50value for 24 h being 158.7 μmol·L-1

and it could induce apoptosis of K562 cells.After HJB treatment at 50

100

200 μmol · L-1 for 24 h

the apoptosis rate of K562 cells was 12.14%

19.26% and 21.78%

respectively（P<0.05）

and the relative activity of Caspase-3 or Caspase-8 was advanced with dose-dependent manner.Conclusion: The HJB evidently inhibits the growth of K562 and induces the apoptosis of K562.The mechanism of apoptosis-induced of HJB may be mediated by death receptor pathways.