title: Arachidonate lipoxygenases as essential regulators of cell survival and apoptosis.
abstract: Arachidonic acid (AA) metabolites derived from both cyclooxygenase (COX) and lipoxygenase (LOX) pathways transduce a variety of signals related to cell growth. Here, we report that the AA LOX pathway also functions as a critical regulator of cell survival and apoptosis. Rat Walker 256 (W256) carcinosarcoma cells express 12-LOX and synthesize 12(S)- and 15(S)-hydroxyeicosatetraenoic acids as their major LOX metabolites. W256 cells transfected with 12-LOX-specific antisense oligonucleotide or antisense oligonucleotides directed to conserved regions of LOXs underwent time- and dose-dependent apoptosis. Likewise, treatment of W256 cells with various LOX but not COX inhibitors induced apoptotic cell death, which could be partially inhibited by exogenous 12(S)- or 15(S)-hydroxyeicosatetraenoic acids. The W256 cell apoptosis induced by antisense oligos and LOX inhibitors was followed by a rapid downregulation of bcl-2 protein, a dramatic decrease in the bcl-2/bax ratio, and could be suppressed by bcl-2 overexpression. In contrast, p53, which is wild type in W256 cells, did not undergo alterations during apoptosis induction. The results suggest that the LOX pathway plays an important physiological role in regulating apoptosis.
authors.affiliation: Department of Radiation Oncology, Wayne State University, Detroit, MI 48202, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Tang
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Chen
authors.forename: K V
authors.initials: KV
authors.lastname: Honn
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001092:Arachidonate 12-Lipoxygenase / Q000096:biosynthesis / Q000378:metabolism*; D001483:Base Sequence; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006706:Homeostasis; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D007975:Leukotriene B4 / Q000494:pharmacology; D017997:Leukotriene C4 / Q000494:pharmacology; D015289:Leukotrienes / Q000494:pharmacology; D008054:Lipid Peroxides / Q000494:pharmacology; D044045:Lipoxins; D009637:Masoprocol / Q000494:pharmacology; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D010957:Plasmids; D051381:Rats; D014162:Transfection
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D015289:Leukotrienes; D008054:Lipid Peroxides; D044045:Lipoxins; D016376:Oligonucleotides, Antisense; C040527:lipoxin A4; D007975:Leukotriene B4; D017997:Leukotriene C4; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C021201:12-HPETE; C025086:15-hydroperoxy-5,8,11,13-eicosatetraenoic acid; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D009637:Masoprocol; C042651:lipoxin B4; D001092:Arachidonate 12-Lipoxygenase