title: Cytotoxicity induced by inhibition of thioredoxin reductases via multiple signaling pathways: role of cytosolic phospholipase A(2)alpha-dependent and -independent release of arachidonic acid.
abstract: The thioredoxin (Trx) system, comprising Trx, the selenoprotein thioredoxin reductase (TrxR), and NADPH, functions as an antioxidant system. Trx has various biological activities including growth control and anti-apoptotic properties, and the Trx system offers a target for the development of drugs to treat and/or prevent cancer. We evaluated the role of TrxR inhibition in the release of arachidonic acid (AA), cell toxicity, and intracellular signaling pathways in L929 mouse fibrosarcoma cells. Treatment with 1-chloro-2,4-dinitrobenzene (DNCB, an inhibitor of TrxR) under conditions involving limited inhibition of TrxR activity in cells, released AA before causing cytotoxicity. Treatment with an inhibitor of p38 kinase, a downstream enzyme of the apoptosis signal-regulating kinase 1 pathway, and pyrrophenone (an inhibitor of alpha-type cytosolic phospholipase A(2), cPLA(2)alpha) partially but significantly decreased the DNCB-induced release of AA and cell death. The responses were much weaker in cPLA(2)alpha knockdown L929 cells. Exogenously added AA showed cytotoxicity. DNCB increased intracellular reactive oxygen species (ROS) levels, and butylated hydroxyanisole (an antioxidant) reduced DNCB-induced ROS formation and cell toxicity but not the phosphorylation of p38 kinase and release of AA. Auranofin, another inhibitor of TrxR having a different formula, released AA resulting in toxicity in L929 cells. DNCB caused the release of AA and cytotoxicity in A549 human lung carcinoma cells, and caused p38 kinase-dependent toxicity in PC12 rat pheochromocytoma cells. Our data suggest that a dysfunctional Trx system triggers multiple signaling pathways, and that the AA released by cPLA(2)alpha-dependent and -independent pathways is important to cytotoxicity. J. Cell. Physiol. 219: 606-616, 2009. (c) 2009 Wiley-Liss, Inc.
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kurosawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakamura
authors.forename: Erika
authors.initials: E
authors.lastname: Yamaura
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Fujino
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Matsuzawa
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kawashima
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Murayama
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D003600:Cytosol / Q000378:metabolism; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D054513:Group IV Phospholipases A2 / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D016716:PC12 Cells; D011725:Pyridines / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013880:Thioredoxin-Disulfide Reductase / Q000037:antagonists & inhibitors*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D004137:Dinitrochlorobenzene; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D011759:Pyrrolidines; D017382:Reactive Oxygen Species; C455981:pyrrophenone; D016718:Arachidonic Acid; D013880:Thioredoxin-Disulfide Reductase; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D054513:Group IV Phospholipases A2; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole