title: Combination of panobinostat with ponatinib synergistically overcomes imatinib-resistant CML cells.
abstract: The major mechanism of imatinib (IM) resistance of CML is the reactivation of ABL kinase either through BCR-ABL gene amplification or mutation. We investigated the cytotoxicity of a pan-ABL tyrosine kinase inhibitor, ponatinib, and a pan-histone deacetylase inhibitor, panobinostat, against IM-resistant CML cells in vitro. Two different IM-resistant cell lines, K562/IM-R1 and Ba/F3/T315I were evaluated in comparison with their respective, parental cell lines, K562 and Ba/F3. K562/IM-R1 overexpressed BCR-ABL due to gene amplification. Ba/F3/T315I was transfected with a BCR-ABL gene encoding T315I-mutated BCR-ABL. Ponatinib inhibited the growth of both K562/IM-R1 and Ba/F3/T315I as potently as it inhibited their parental cells with an IC50 of 2-30 nM. Panobinostat also similarly inhibited the growth of all of the cell lines with an IC50 of 40-51 nM. This was accompanied by reduced histone deacetylase activity, induced histone H3 acetylation, and an increased protein level of heat shock protein 70, which suggested disruption of heat shock protein 90 chaperone function for BCR-ABL and its degradation. Importantly, the combination of ponatinib with panobinostat showed synergistic growth inhibition and induced a higher level of apoptosis than the sum of the apoptosis induced by each agent alone in all of the cell lines. Ponatinib inhibited phosphorylation not only of BCR-ABL but also of downstream signal transducer and activator of transcription 5, protein kinase B, and ERK1/2 in both K562/IM-R1 and Ba/F3/T315I, and the addition of panobinostat to ponatinib further inhibited these phosphorylations. In conclusion, panobinostat enhanced the cytotoxicity of ponatinib towards IM-resistant CML cells including those with T315I-mutated BCR-ABL.
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Matsuda
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamauchi
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Hosono
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Kanako
authors.initials: K
authors.lastname: Uzui
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Eiju
authors.initials: E
authors.lastname: Negoro
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Morinaga
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Nishi
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yoshida
authors.affiliation: Division of Hematology, Respiratory Medicine and Oncology, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kimura
authors.affiliation: Department of Transfusion Medicine and Cell Therapy, Kyoto University Hospital, Kyoto, Japan.
authors.forename: Taira
authors.initials: T
authors.lastname: Maekawa
authors.affiliation: Department of Hematology and Oncology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Ueda
mesh_terms: D000107:Acetylation / Q000187:drug effects; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004357:Drug Synergism; D016044:Fusion Proteins, bcr-abl / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D000068877:Imatinib Mesylate / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology*; D000077767:Panobinostat; D010766:Phosphorylation / Q000187:drug effects; D011724:Pyridazines / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D018840:HSP70 Heat-Shock Proteins; D006657:Histones; D006877:Hydroxamic Acids; D007093:Imidazoles; D007211:Indoles; D011724:Pyridazines; C545373:ponatinib; D000068877:Imatinib Mesylate; D000077767:Panobinostat; D016044:Fusion Proteins, bcr-abl; D006655:Histone Deacetylases
keywords: Chronic myelogenous leukemia; combination therapy; imatinib-resistant; panobinostat; ponatinib