MZ3 induces apoptosis in human leukemia cells

Purpose 4-(4-Bromophenyl)-2,3-dihydro-N,3-bis(3,4,5-trimethoxyphenyl)-2-oxoidmi-dazole-1-carboxamide (MZ3) is one of the synthesized combretastatin-A-4 analogues and has been reported that it displayed a promising specific activity against leukemia cell lines. Our purpose was to investigate the mechanism of MZ3’s cytotoxicity. Methods Cytotoxicity was measured by MTT method, apoptosis was measured by flow cytometry. DNA fragmentation was tested by agarose gel electrophoresis. Mitochondrial membrane potential (ΔΨm) was detected by JC1 staining and flow cytometry, while intracellular reactive oxygen species (ROS) was detected by 5-(and-6)-carboxy-2′-7′-dichlorofluorescin diacetate staining and flow cytometry. Protein expression was analyzed by western blotting. In vivo activity of MZ3 was assayed through severe combined immunodeficiency (SCID) mice model of human leukemia engrafts. Results MZ3 exhibited high anti-cancer activity in six leukemia cell lines, including two drug-resistant cell lines. MZ3 induced DNA fragmentation, and caused an elevation of ROS and a loss of ΔΨm in HL60 cells. MZ3 also induced the activation of caspase-3, influenced the expression of Bcl-2 family members, MAPKs and other proteins relative to mitochondria-induced apoptosis. In addition, N-acetylcysteine cannot inhibit HL60 cell apoptosis caused by MZ3. Furthermore, a prolonged survival time was observed after treatment with MZ3 in SCID mice model of human leukemia engrafts. Conclusions MZ3 is a potent compound against leukemia cell lines both in vitro and in vivo, and the mitochondrial pathway mediated by Bcl-2 protein family and MAPKs might be involved in signaling MZ3-induced apoptosis.