title: Cytotoxicity of diacetoxyscirpenol is associated with apoptosis by activation of caspase-8 and interruption of cell cycle progression by down-regulation of cdk4 and cyclin B1 in human Jurkat T cells.
abstract: To understand the mechanism underlying T-cell toxicity of diacetoxyscirpenol (DAS) from Fusarium sambucinum, its apoptogenic as well as growth retardation activity was investigated in human Jurkat T cells. Exposure to DAS (0.01-0.15 microM) caused apoptotic DNA fragmentation along with caspase-8 activation, Bid cleavage, mitochondrial cytochrome c release, activation of caspase-9 and caspase-3, and PARP degradation, without any alteration in the levels of Fas or FasL. Under these conditions, necrosis was not accompanied. The cytotoxicity of DAS was not blocked by the anti-Fas neutralizing antibody ZB-4. Although the DAS-induced apoptotic events were completely prevented by overexpression of Bcl-xL, the cells overexpressing Bcl-xL were unable to divide in the presence of DAS, resulting from the failure of cell cycle progression possibly due to down-regulation in the protein levels of cdk4 and cyclin B1. The DAS-mediated apoptosis and activation of caspase-8, -9, and -3 were abrogated by either pan-caspase inhibitor (z-VAD-fmk) or caspase-8 inhibitor (z-IETD-fmk). While the DAS-mediated apoptosis and activation of caspase-9 and caspase-3 were slightly suppressed by the mitochondrial permeability transition pore inhibitor (CsA), both caspase-8 activation and Bid cleavage were not affected by CsA. The activated normal peripheral T cells possessed a similar susceptibility to the cytotoxicity of DAS. These results demonstrate that the T-cell toxicity of DAS is attributable to not only apoptosis initiated by caspase-8 activation and subsequent mitochondrion-dependent or -independent activation of caspase cascades, which can be regulated by Bcl-xL, but also interruption of cell cycle progression caused by down-regulation of cdk4 and cyclin B1 proteins.
authors.affiliation: Laboratory of Immunobiology, School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea.
authors.forename: Do Youn
authors.initials: DY
authors.lastname: Jun
authors.forename: Jun Seok
authors.initials: JS
authors.lastname: Kim
authors.forename: Hae Sun
authors.initials: HS
authors.lastname: Park
authors.forename: Woo Sun
authors.initials: WS
authors.lastname: Song
authors.forename: Young Seuk
authors.initials: YS
authors.lastname: Bae
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053181:Caspase 8 / Q000378:metabolism*; D061945:Caspase Inhibitors; D002453:Cell Cycle / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D019926:Cyclin B / Q000378:metabolism*; D056744:Cyclin B1; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism*; D016572:Cyclosporine / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D045304:Cytochromes c / Q000187:drug effects / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D019169:Jurkat Cells; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D009842:Oligopeptides / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014255:Trichothecenes / Q000494:pharmacology*; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000970:Antineoplastic Agents; C534699:CCNB1 protein, human; D061945:Caspase Inhibitors; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D015853:Cysteine Proteinase Inhibitors; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D009842:Oligopeptides; D010835:Phytohemagglutinins; D014255:Trichothecenes; D051020:bcl-X Protein; C403753:benzyloxycarbonyl-isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D016572:Cyclosporine; D045304:Cytochromes c; D051358:Cyclin-Dependent Kinase 4; D053181:Caspase 8; C001809:diacetoxyscirpenol