Abstract:

Abstract:Objective  To study the  apoptosis of K562 cells induced by a new immunosuppressive agent FTY720 and its mechanism,and to provide experimental basis for the treatment of leukemia in clinic.Methods The K562 cells were cultured in vitro　and  divided into blank control  group and FTY720 treatment  group.The K562 cells in FTY720 treatment  group were treated with 6 μmol?L-1 FTY720  for 3,6,and 12 h,or treated with different concentrations of FTY720 (2，4，6,8 μmol•L^-1 ) for 24 h.The apoptosis,level  of reactive oxygen species(ROS), mitochondrial membrane potential(MMP) and cell cycle were measured by flow cytometry.The  inhibitory rate of proliferation of  K562 cells after treated with FTY720 was detected by WST-1 reducting assay.Results The results of  flow cytometry showed that the percentages of apoptotic  cells were increased  after treated with 6 μmol•L^-1    FTY720 for 3,6, and 12 h with the prolongation of time compared with blank control group（P<0.01）.The percentages of apoptotic cells were also increased  after treated with different concentrations of FTY720 for 24 h compared with blank control group（P<0.01）. Compared with blank control group,the ROS levels were  increased with the increasing of  FTY720 concentration,while the MMP was decreased（P<0.01）.Compared with blank control group,the percentage of cells at G0／G1 phase was increased,while those at S and G2/M phases were decreased with the increasing of  FTY720 concentration (P<0.05).The WST-1 reduction assay results indicated that the  inhibitory rates of proliferation of K562 cells after treated with 2,4,6, and 8 μmol•L^-1  FTY720 for 72 h were (24.0±4.1)%，(46.4±3.9)%，(67.0±4.8)%, and (88.2±5.6)%, respectively,compared with blank control group.The concentration of FTY720 to result the   inhibitory rate of 50% (IC50) on K562 cells was 5.5 μmol•L^-1 .Conclusion FTY720 could inhibit the proliferation of K562 cells   by blocking  cell cycle and  inducing  apoptosis through provoking ROS.

Key words: FTY720, apoptosis, reactive oxygen species, cell cycle