Bortezomib Combined with Harringtonine or Arsenious Acid Induced Apoptosis in HL-60 Cells and Its Mechanism

Objective To explore the apoptosis effect induced by bortezomib combined with homoharringtonine or arsenious acid in HL-60 cell line and the mechanism.Methods Cell' s apoptosis was demonstrated by MTT assay and Hoechst33342 staining.Expression of bcl-2,Caspase-9,Caspase-3 and PARP protein was detected by Western blot.Results HL-60 cells' apoptosis could be induced by bortezomib,homoharringtonine and arsenious acid respectively.Proliferation inhibition of HL-60 cells could be enhanced significantly when treated by bortezomib combined with homoharringtonine or arsenious acid compared with treated by any of the three drugs alone (P ＜ 0.05).At the same time morphology shows the apoptosis induced by drugs combined is more obviously than by one drug.Western blot showed bcl-2 protein was down-regulated and Caspase-9,Caspase-3 and PARP proteins were all cleaved activation when cells were treated by 15 μmol/ L arsenious acid alone,but only cleaved activation of PARP and down-regulation of bcl-2 protein be detected when cells were treated with 30 nmol/L homoharringtonine alone,expression of Caspase-9 and Caspase-3 had no change compared with the control.The changes of associated proteins were paralleled with the cell' s apoptosis when treated with combined drugs.Conclusion HL-60 cells' apoptosis effect is inhanced significantly when bortezomib combined with homoharringtonine or arsenious acid.Arsenious acid and bortezomib can inhibit caspase signaling pathway and down-regulate the expression of bcl-2 protein together,but homoharringtonine and bortezomib can only down-regulate the expression of bcl-2 protein and induce cleaved activation of PARP together. Key words: Cells, HL-60; Bortezomib; Homoharringtonine; Arsenious acid; Apoptosis