title: Obatoclax interacts synergistically with the irreversible proteasome inhibitor carfilzomib in GC- and ABC-DLBCL cells in vitro and in vivo.
abstract: Interactions between the irreversible proteasome inhibitor carfilzomib and the pan-BH3 mimetic obatoclax were examined in germinal center (GC)- and activated B-cell-diffuse large B-cell lymphoma (ABC-DLBCL) cells. Cotreatment with minimally toxic concentrations of carfilzomib (i.e., 2-6 nmol/L) and subtoxic concentrations of obatoclax (0.05-2.0 μmol/L) synergistically increased apoptosis in multiple DLBCL cell lines and increased lethality toward primary human DLBCL but not normal CD34(+) cells. Synergistic interactions were associated with sharp increases in caspase-3 activation, PARP cleavage, p-JNK induction, upregulation of Noxa, and AKT dephosphorylation. Combined treatment also diminished carfilzomib-mediated Mcl-1 upregulation whereas immunoprecipitation analysis revealed reduced associations between Bak and Mcl-1/Bcl-xL and Bim and Mcl-1. The carfilzomib/obatoclax regimen triggered translocation, conformational change, and dimerization of Bax and activation of Bak. Genetic interruption of c-jun-NH(2)-kinase (JNK) and Noxa by short hairpin RNA knockdown, ectopic Mcl-1 expression, or enforced activation of AKT significantly attenuated carfilzomib/obatoclax-mediated apoptosis. Notably, coadministration of carfilzomib/obatoclax sharply increased apoptosis in multiple bortezomib-resistant DLBCL models. Finally, in vivo administration of carfilzomib and obatoclax to mice inoculated with SUDHL4 cells substantially suppressed tumor growth, activated JNK, inactivated AKT, and increased survival compared with the effects of single-agent treatment. Together, these findings argue that a strategy combining carfilzomib and obatoclax warrants attention in DLBCL.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA.
authors.forename: Girija
authors.initials: G
authors.lastname: Dasmahapatra
authors.forename: Dmitry
authors.initials: D
authors.lastname: Lembersky
authors.forename: Minkyeong P
authors.initials: MP
authors.lastname: Son
authors.forename: Hiral
authors.initials: H
authors.lastname: Patel
authors.forename: Derick
authors.initials: D
authors.lastname: Peterson
authors.forename: Elisa
authors.initials: E
authors.lastname: Attkisson
authors.forename: Richard I
authors.initials: RI
authors.lastname: Fisher
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Friedberg
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D045744:Cell Line, Tumor; D004357:Drug Synergism; D018858:Germinal Center / Q000187:drug effects / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D007211:Indoles; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011758:Pyrroles / Q000008:administration & dosage / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; C468783:H2AX protein, human; D006657:Histones; D007211:Indoles; C579094:Mcl1 protein, mouse; D008565:Membrane Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009842:Oligopeptides; C498702:PMAIP1 protein, human; D061988:Proteasome Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011758:Pyrroles; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; C524865:carfilzomib; D051057:Proto-Oncogene Proteins c-akt; D048670:MAP Kinase Kinase 4; D046988:Proteasome Endopeptidase Complex; C520962:obatoclax