The Effects And The Combined Mechanism Of SAHA And MG132on Chronic Myeloid Leukemia Cells

Aim:To study cytotoxic effects and apoptosis induced by SAHA on chronic myeloid leukemia cells lines. To investigate the mechanism of enhanced apoptosis induced by SAHA with proteasome inhibitor MG132on CML cells.Methods:The effect of SAHA was determined by the MTT assay. The combined effect of SAHA and MG132was also assessed by the MTT assay. Colony forming was used to observe cells cloning ability, The activation of Caspase pathway and the expression of acetylated-H3,and Bcr/Abl were examined by western blotting. Intracellular ROS generation was observed by Fluorescence microscope.Results:(1) SAHA inhibited the growth of K562and K562/G cells in a dose-dependent manner.(2) Apoptosis induced by SAHA in CML cells is associated with down-regulation of Bcr/Abl oncoprotein and increasing in the expression of acetylated histone H3protein.(3)MG132could enhance the SAHA s antileukemia effect.(4) Pan-caspase inhibitor z-VAD-fmk only partially reverses the suppressive effects of SAHA and MG132on CML cells.(5) SAHA combined with MG132could strongly cause an increased level of ROS. scavenger NAC almost completely reverses cell death and Bcr/Abl downregulation induced by this combination treatment.Conclusion:Apoptosis induced by SAHA in CML cells is associated with down-regulation of Bcr/Abl oncoprotein and increasing in the expression of acetylated histone H3protein. MG132could enhance the SAHA,s antileukemia effect. Increased intracellular ROS level play a critical role in the cell death and downregulation of Bcr/Abl by SAHA combined with MG132. Our results suggest that combined treatment of SAHA and MG132may serve as a promising therapy for CML.