Abstract: Objective To explore the production of calreticulin (CRT) and apoptosis of acute myeloid leukemia cells induced by bortezimib combinated with idarubicin, so as to improve the strategy of leukemia treatments.Methods Peripheral mononucleated cells were isolated by lymphocyte separation and density gradient centrifugation in 20 patients with newly diagnosed AML. The CD34⁺CD38⁺ cells and CD34⁺CD38^- cells were detected by flow cytometry. Under optimal time and concentration, the leukemia cells were treated with bortezimib or idarubicin alone or in combination of the both, and the apoptosis and CRT expression on CD34⁺CD38⁺ and CD34⁺CD38^- cells were analyzed.Results No significant difference of the apoptotic rate of the cells and expression level of CRT was observed between the bortezimib and idarubicin treatments but combination of the both agents significantly ameliorated the cell injuries. Additionally, the apoptosis were more deteriorated in CD34⁺CD38⁺ cells compared with CD34⁺CD38^- cells in idarubicin (P=0.007),bortezimib (P=0.01) and idarubicin+Bortezimib treatments (P=0.009）. Similar results were seen in CRT expression (P=0.000, P=0.01, and P=0.006).ConclusionIdarubicin and proteasome inhibitors may induce apoptosis and increase the expression of calreticulin on leukemic cells, particularly of CD34⁺CD38⁺ cells, and combination therapy is synergistically effective.

Key words: Acute myeloid leukemia, Idarubicin, Bortezomib, Apoptosis