title: Ectopic overexpression of second mitochondria-derived activator of caspases (Smac/DIABLO) or cotreatment with N-terminus of Smac/DIABLO peptide potentiates epothilone B derivative-(BMS 247550) and Apo-2L/TRAIL-induced apoptosis.
abstract: Second mitochondria-derived activator of caspases (Smac)/DIABLO is a mitochondrial protein that is released into the cytosol along with cytochrome c (cyt c) during the execution of the intrinsic pathway of apoptosis. Smac/DIABLO promotes apoptosis by neutralizing the inhibitory effect of the inhibitor of apoptosis (IAP) family of proteins on the processing and activities of the effector caspases. Present studies demonstrate that, upon engagement of the mitochondrial pathway of apoptosis, epothilone (Epo) B derivative BMS 247550, a novel nontaxane antimicrotubule agent, as well as the death ligand Apo-2L/TRAIL (tumor necrosis factor-alpha-related apoptosis-inducing ligand) induce the mitochondrial release and cytosolic accumulation of Smac/DIABLO, along with cyt c, in human acute leukemia Jurkat T cells. While it had no activity alone, ectopic overexpression of Smac/DIABLO or treatment with the N-terminus heptapeptide (Smac-7) or tetrapeptide (Smac-4) of Smac/DIABLO significantly increased Epo B- or Apo-2L/TRAIL-induced processing and PARP cleavage activity of caspase-3. This produced a significant increase in apoptosis of Jurkat cells (P <.05). Increased apoptosis was also associated with the down-regulation of XIAP, cIAP1, and survivin. Along with the increased activity of caspase-3, ectopic overexpression of Smac/DIABLO or cotreatment with Smac-4 also increased Epo B- or Apo-2L/TRAIL-induced processing of caspase-8 and Bid, resulting in enhanced cytosolic accumulation of cyt c. This was not due to increased assembly and activity of Apo-2L/TRAIL-induced DISC (death-inducing signaling complex) but dependent on the feedback activity of caspase-3. These findings demonstrate that cotreatment with the N-terminus Smac/DIABLO peptide is an effective strategy to enhance apoptosis triggered by the death receptor or mitochondrial pathway and may improve the antitumor activity of Apo-2L/TRAIL and Epo B.
authors.affiliation: Interdisciplinary Oncology Program, Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, FL 33612, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Guo
authors.forename: Ramadevi
authors.initials: R
authors.lastname: Nimmanapalli
authors.forename: Shanthi
authors.initials: S
authors.lastname: Paranawithana
authors.forename: Sylvie
authors.initials: S
authors.lastname: Wittman
authors.forename: David
authors.initials: D
authors.lastname: Griffin
authors.forename: Purva
authors.initials: P
authors.lastname: Bali
authors.forename: Erica
authors.initials: E
authors.lastname: O'Bryan
authors.forename: Carlos
authors.initials: C
authors.lastname: Fumero
authors.forename: Hong Gang
authors.initials: HG
authors.lastname: Wang
authors.forename: Kapil
authors.initials: K
authors.lastname: Bhalla
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D004357:Drug Synergism; D034261:Epothilones; D004852:Epoxy Compounds / Q000494:pharmacology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D018942:Macrolides / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000494:pharmacology* / Q000502:physiology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand; D013844:Thiazoles / Q000494:pharmacology*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology* / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; C412403:DIABLO protein, human; D034261:Epothilones; D004852:Epoxy Compounds; D047908:Intracellular Signaling Peptides and Proteins; D018942:Macrolides; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D010446:Peptide Fragments; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D013844:Thiazoles; D014409:Tumor Necrosis Factor-alpha; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; C430592:ixabepilone; C093788:epothilone B