[Apoptosis of myeloid leukemia cell line HL60 induced by Bortezomib, a proteasome inhibitor].

OBJECTIVE: To explore the mechanism of apoptosis of myeloid leukemia cells induced by Bortezomib, a proteasome inhibitor. METHODS: Human acute myeloid leukemia cells of the line HL60 were cultured and treated with Bortezomib of the concentrations of 0, 10, 20, 30, and 40 micromol/L for 24 hours. MTT assay and flow cytometry were used to detect the proliferation inhibition and apoptosis. Hoechst 33342 staining was used to observe the morphology of the cells. Western blotting was used to detect the protein expression of Bcl-2, Caspase-9, Caspase-3, and poly ADP-ribose polymerase (PARP). RESULTS: Bortezomib could induce HL60 cell apoptosis dose- and time-dependently. After treated for 24 hours by 30 nmol/L Bortezomib the HL60 cells' proliferation was significantly inhibited, the inhibition rate was 76%, and the cell nuclei became progressively pyknotic and were extensively fragmented. FCM showed apoptosis peaks 24 hours after treatment of Bortezomib of the concentrations of were 10 and 20 nmol/L, the apoptosis rate was 62.6%. Bcl-2 protein expression was down-regulated and the protein expressions of Caspase-9, Caspase-3, and PARP were all up-regulated. CONCLUSION: The mechanism of Bortezomib to induce apoptosis of myeloid leukemia cells is associated with down-regulation of Bcl-2 protein expression and cleaved activation of Caspase-9, Caspase-3 and PARP proteins.