title: Induction of redox imbalance and apoptosis in multiple myeloma cells by the novel triterpenoid 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid.
abstract: The synthetic oleanane triterpenoid 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and its chemical derivatives induce differentiation and apoptosis of human leukemia cells. The precise mechanisms responsible for the effects of CDDO, however, remain unclear. In the present study, we examined the effects of CDDO and its C-28 imidazolide ester (CDDO-Im) on apoptosis of multiple myeloma (MM) cells. The results show that both CDDO and CDDO-Im are potent inducers of MM cell apoptosis and that CDDO-Im is more active than CDDO. CDDO-Im treatment was associated with (a) depletion of glutathione, (b) increases in reactive oxygen species, (c) a reduction of the Fas-associated death domain (FADD)-like interleukin-1-converting enzyme (FLICE) inhibitory protein, (d) activation of caspase-8, and (e) a decrease of the mitochondrial transmembrane potential. The reducing agents, N-acetyl-L-cysteine, DTT, and catalase inhibited each of these CDDO-Im-induced proapoptotic signals. Inhibition of caspase-8 with z-IETD-fmk also abrogated CDDO-Im-induced decreases of the mitochondrial transmembrane potential and inhibited apoptosis. These results demonstrate that CDDO-Im disrupts intracellular redox balance and thereby activates the extrinsic caspase-8-dependent apoptotic pathway. We further show that CDDO-Im induces apoptosis of primary MM cells at submicromolar concentrations and that MM cells are more sensitive to this agent than normal bone marrow mononuclear cells. These results suggest that CDDO compounds have potential as new agents for the treatment of MM.
authors.affiliation: Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ikeda
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Nakata
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Kimura
authors.forename: Ken
authors.initials: K
authors.lastname: Sato
authors.forename: Kenneth
authors.initials: K
authors.lastname: Anderson
authors.forename: Kazuo
authors.initials: K
authors.lastname: Motoyoshi
authors.forename: Michael
authors.initials: M
authors.lastname: Sporn
authors.forename: Donald
authors.initials: D
authors.lastname: Kufe
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000502:physiology; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: C472829:1-(2-cyano-3,12-dioxooleana-1,9-dien-28-oyl) imidazole; C116817:2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid; D000975:Antioxidants; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D017382:Reactive Oxygen Species; D009828:Oleanolic Acid; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases; D005978:Glutathione