title: Oxidative stress induces arachidonate release from human lung cells through the epithelial growth factor receptor pathway.
abstract: Oxidative stress is thought to be a factor influencing many inflammatory responses, including arachidonic acid (AA) release. We have studied the effect of hydrogen peroxide on AA and prostaglandin E(2) release, cytosolic phospholipase (cPLA(2)) steady-state mRNA, cPLA(2) protein levels, cPLA(2) enzyme activity, and cPLA(2) phosphorylation in a human lung epithelial cell line: A549 cells. Hydrogen peroxide caused a dose-dependent increase of A23187-stimulated AA and prostaglandin E(2) release, with a maximum effect at 1 h. This effect is associated with a maximum specific cPLA(2) activity at 1 h, and with a significant increase in cPLA(2) Serine 505 phosphorylation. All these effects were abolished, in a dose-related manner, by the epithelial growth factor receptor kinase inhibitor, AG 1478. To further investigate the pathway leading to the increase cPLA(2) phosphorylation, we used cells transfected with a Ras dominant negative vector and mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) and p38 kinase inhibitors. Cells transfected with the Ras dominant negative vector exhibited diminished hydrogen peroxide-induced AA release and cPLA(2) phosphorylation as compared with cells transfected with the Ras expression vector. Both MEK and p38 kinase inhibitors inhibited the hydrogen peroxide effect on AA release and specific cPLA(2) activity. Finally, cells stably transfected with an antisense cPLA(2) vector exhibited diminished A23187-stimulated AA release in response to hydrogen peroxide as compared with cells stably transfected with empty expression vector. Collectively, these data show that hydrogen peroxide increases cPLA(2) activity through its phosphorylation utilizing an epithelial growth factor/Ras/extracellular signal-regulated kinase and p38 pathway.
authors.affiliation: Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Rafal
authors.initials: R
authors.lastname: Pawliczak
authors.forename: Xiu-Li
authors.initials: XL
authors.lastname: Huang
authors.forename: Uday B
authors.initials: UB
authors.lastname: Nanavaty
authors.forename: Marion
authors.initials: M
authors.lastname: Lawrence
authors.forename: Patricia
authors.initials: P
authors.lastname: Madara
authors.forename: James H
authors.initials: JH
authors.lastname: Shelhamer
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D016718:Arachidonic Acid / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D048728:MAP Kinase Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010972:Platelet Activating Factor / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D011799:Quinazolines; D012333:RNA, Messenger / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D007476:Ionophores; D016877:Oxidants; D010972:Platelet Activating Factor; D011725:Pyridines; D011799:Quinazolines; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D020032:Tyrphostins; C101044:RTKI cpd; D016718:Arachidonic Acid; D014443:Tyrosine; D006861:Hydrogen Peroxide; D066246:ErbB Receptors; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D010741:Phospholipases A; D018631:ras Proteins; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium