title: Apicidin potentiates the imatinib-induced apoptosis of Bcr-Abl-positive human leukaemia cells by enhancing the activation of mitochondria-dependent caspase cascades.
abstract: Apicidin, a histone deacetylase inhibitor, is a novel cyclic tetrapeptide with potent antiproliferative activity against various cancer cells. We examined whether apicidin potentiates the imatinib-induced apoptosis of Bcr-Abl-positive human leukaemia cells. In K562 cells, the co-administration of minimally toxic concentrations of imatinib and apicidin (imatinib/apicidin) for 48 h produced a marked increase in mitochondrial damage, processing of caspase cascades and apoptosis. Similar results were observed in leukaemic blasts obtained from patients with chronic myeloid leukaemia in blast crisis. Imatinib/apicidin co-treatment for 48 h resulted in a near complete loss of the full-length XIAP (X-linked inhibitor of apoptosis) protein, with a corresponding increase in the 29-kDa XIAP cleavage product. Both the degradation of XIAP and increased release of second mitochondria-derived activator of caspase/direct IAP-binding protein with low pI (Smac/DIABLO) into the cytosol were abrogated by pretreatment with the caspase-3 inhibitor DEVD-CHO. Imatinib/apicidin co-treatment for 48 h produced a prominent decrease in Bcr-Abl protein levels in a caspase-dependent manner. In summary, these data indicate that apicidin potentiates the imatinib-induced apoptosis of Bcr-Abl-positive leukaemia cells through the enhanced activation of the mitochondria-dependent caspase cascades, accompanied by caspase-dependent downregulation of Bcr-Abl and XIAP. These findings generate a rationale for further investigation of apicidin and imatinib as a potential therapeutic strategy in Bcr-Abl-positive leukaemias.
authors.affiliation: Department of Internal Medicine, National Health Insurance Corporation, Ilsan Hospital, Kyunggi-do, Korea.
authors.forename: Jin Seok
authors.initials: JS
authors.lastname: Kim
authors.forename: Hoi Kyung
authors.initials: HK
authors.lastname: Jeung
authors.forename: June-Won
authors.initials: JW
authors.lastname: Cheong
authors.forename: Hoyoung
authors.initials: H
authors.lastname: Maeng
authors.forename: Seung Tae
authors.initials: ST
authors.lastname: Lee
authors.forename: Jee Sook
authors.initials: JS
authors.lastname: Hahn
authors.forename: Yun Woong
authors.initials: YW
authors.lastname: Ko
authors.forename: Yoo Hong
authors.initials: YH
authors.lastname: Min
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D016313:Genes, abl; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D008928:Mitochondria / Q000201:enzymology; D010456:Peptides, Cyclic / Q000008:administration & dosage*; D010879:Piperazines / Q000008:administration & dosage*; D011743:Pyrimidines / Q000008:administration & dosage*
chemical_list: D001549:Benzamides; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D010456:Peptides, Cyclic; D010879:Piperazines; D011743:Pyrimidines; C102351:apicidin; D000068877:Imatinib Mesylate; D020169:Caspases