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 harringtonine or arsenious acid in HL60 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 blotting.

Results: HL60 cells’ apoptosis could be induced by bortezomib, harringtonine and arsenious acid respectively, and the apoptosis effect was inhanced significantly when bortezomib combined with harringtonine or arsenious acid. Western blotting showed Bcl-2 protein was down-regulated and Caspase-9, Caspase-3 and PARP proteins were all cleaved activation when cells were treated by 15uM arsenious acid alone, but only cleaved activation of PARP and down-regulation of Bcl-2 protein be detected when cells were treated with 30nM harringtonine alone, expression of Caspase-9 and Caspase-3 has no change compared with the control. The changes of associated proteins were paralleled with the cell’s apoptosis when treated with combined drugs.

Conclusion: HL60 cells’ apoptosis could be inhanced significantly when treated by bortezomib combined with harringtonine or arsenious acid compared with treated by bortezomib alone. Arsenious acid and bortezomib can inhibit caspase signaling pathway and down-regulate the expression of Bcl-2 protein together, but harringtonine and bortezomib can only down-regulate the expression of Bcl-2 protein and induce cleaved activation of PARP together.