Disulfiram/copper markedly induced myeloma cell apoptosis through activation of JNK and intrinsic and extrinsic apoptosis pathways

Disulfiram (DSF) is an FDA approved anti-alcoholism drug in use for more than 60 years. Recently, antitumor activity of the DSF/copper (DSF/Cu) complex has been identified. Its anti-multiple myeloma activity, however, has barely been investigated. In the present study, our results demonstrated that the DSF/Cu complex induced apoptosis of MM cells and MM primary cells. The results indicated that DSF/Cu significantly induced cell cycle arrest at the G2/M phase in MM.1S and RPMI8226 cells. Moreover, JC-1 and Western blot results showed that DSF/Cu disrupted mitochondrial membrane integrity and cleaved caspase-8 in MM cells, respectively, suggesting that it induced activation of extrinsic and intrinsic apoptosis pathways. Interestingly, DSF/Cu induced caspase-3 activation was partly blocked by Z-VAD-FMK (zVAD), a pan-caspase inhibitor, indicating at caspase-dependent and -independent paths involved in DSF/Cu induced myeloma cell apoptosis machinery. Additionally, activation of the c-Jun N-terminal kinase (JNK) signaling pathway was observed in DSF/Cu treated MM cells. More importantly, our results demonstrated that DSF/Cu significantly reduced tumor volumes and prolonged overall survival of MM bearing mice when compared with the controls. Taken together, our novel findings showed that DSF/Cu has potent anti-myeloma activity in vitro and in vivo highlighting valuable clinical potential of DSF/Cu in MM treatment.