Identification of the roles of epigenetic alterations in
cancers has suggested that different molecules involved in this process are potentially therapeutic targets. Given the role of
histone deacetylases (HDACs)
enzymes in leukemogenesis, we designed a study to investigate the anti-leukemic property of
panobinostat, a
HDAC inhibitor, in
acute lymphoblastic leukemia (ALL) cells. Our results showed that
panobinostat decreased cell viability of
pre-B ALL-derived cells. The favorable anti-leukemic effects of the inhibitor was further confirmed by cell cycle analysis, where we found that
panobinostat prolonged the transition of the cells from G1 phase probably through c-Myc-mediated up-regulation of
cyclin-dependent kinase inhibitors. Unlike the apoptotic effect of
panobinostat on Nalm-6 cells, the expression of anti-apoptotic
nuclear factor-kappa B (NF-κB) target genes remained unchanged. Accordingly, we found that the inhibition of NF-κB pathway using
bortezomib boosted the effect of
panobinostat, indicating that
panobinostat-induced apoptosis could be attenuated through the activation of the NF-κB pathway. The results of the present study reflected another aspect of autophagy in leukemic cells, as we showed that although Nalm-6 cells could exploit autophagy to override the anti-survival effect of HDAC inhibition, the presence of an autophagy inhibitor could alter the compensatory circumstance to induce cell death. Beyond
panobinostat cytotoxicity as a single agent, synergistic experiments outlined that
pharmaceutical targeting of HDACs could amplify the cytotoxicity of
vincristine in ALL cells, delineating that
panobinostat, either as a single agent or in a combined modality, possesses novel promising potentials for the treatment of ALL.