Relationship of Proteasome Inhibitor PS-341 Induced Apoptosis with Cytoplasmic [Ca~(2+)] Changes in U266 Cells

Objective To investigate the influence of proteasome inhibitor PS-341(Bortezomib)on apoptosis-induced cell line U266 cytoplasmic [Ca~(2+)]([Ca~(2+)]i).Methods U266 cells were exposed to different concentrations of PS-341 for 4 hours,then cells apoptosis were analyzed by fluorescence microscope and flow cytometry(FCM)with Annexin V-FITC/PI double staining,and cytoplasmic free calcium were detected on FCM throught Fluo-3/AM loading.Results(1)Apoptotic cells were gradually increased with PS-341 concentrantions increased under fluorescence microscope;(2)The appearance rates of apoptotic cells were 0.56%、7.71%、19.84%、31.10%、40.72% respectively on FCM and apoptotic cells rates were in dose-dependent;(3)The mean of [Ca~(2+)]i were 403.65 nmol/L、418.20 nmol/L、378.65 nmol/L、356.36 nmol/L、349.21 nmol/L,respectively,treated with PS-341.(4)PS-341 induced U266 cells apoptosis following [Ca~(2+)]i change,and was related to the down regulation of [Ca~(2+)]i when the dose exceeded 50nmol/L.Conclusion PS-341 induced U266 cells apoptosis in dose-dependent fashion;when concentration excessed 50 nmol/L PS-341 down regulated [Ca~(2+)]i,and to exert its induce apoptosis activity by these pathways.