title: Oxidative stress causes mucin synthesis via transactivation of epidermal growth factor receptor: role of neutrophils.
abstract: Oxidative stress has been implicated in the pathogenesis of inflammatory diseases of airways. Here we show that oxidative stress causes ligand-independent activation of epidermal growth factor receptors (EGFR) and subsequent activation of mitogen-activated protein kinase kinase (MEK)-p44/42 mitogen-activated protein kinase (p44/42mapk), resulting in mucin synthesis in NCI-H292 cells. Exogenous hydrogen peroxide and neutrophils activated by IL-8, FMLP, or TNF-alpha increased EGFR tyrosine phosphorylation and subsequent activation of p44/42mapk and up-regulated the expression of MUC5AC at both mRNA and protein levels in NCI-H292 cells. These effects were blocked by selective EGFR tyrosine kinase inhibitors (AG1478, BIBX1522) and by a selective MEK inhibitor (PD98059), whereas a selective platelet-derived growth factor receptor tyrosine kinase inhibitor (AG1295), a selective p38 MAPK inhibitor (SB203580), and a negative compound of tyrosine kinase inhibitors (A1) were without effect. Neutrophil supernatant-induced EGFR tyrosine phosphorylation, activation of p44/42mapk, and MUC5AC synthesis were inhibited by antioxidants (N-acetyl-cysteine, DMSO, dimethyl thiourea, or superoxide dismutase); neutralizing Abs to EGFR ligands (EGF and TGF-alpha) were without effect, and no TGF-alpha protein was found in the neutrophil supernatant. In contrast, the EGFR ligand, TGF-alpha, increased EGFR tyrosine phosphorylation, activation of p44/42mapk, and subsequent MUC5AC synthesis, but these effects were not inhibited by antioxidants. These results implicate oxidative stress in stimulating mucin synthesis in airways and provide new therapeutic approaches in airway hypersecretory diseases.
authors.affiliation: Cardiovascular Research Institute, Department of Medicine, University of California, San Francisco, CA 94143, USA.
authors.forename: K
authors.initials: K
authors.lastname: Takeyama
authors.forename: K
authors.initials: K
authors.lastname: Dabbagh
authors.forename: J
authors.initials: J
authors.lastname: Jeong Shim
authors.forename: T
authors.initials: T
authors.lastname: Dao-Pick
authors.forename: I F
authors.initials: IF
authors.lastname: Ueki
authors.forename: J A
authors.initials: JA
authors.lastname: Nadel
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D002474:Cell-Free System / Q000187:drug effects / Q000276:immunology; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006001:Glycoconjugates / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D017403:In Situ Hybridization; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000276:immunology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D055271:Mucin 5AC; D009077:Mucins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D018375:Neutrophil Activation / Q000187:drug effects / Q000276:immunology; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000276:immunology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D015533:Transcriptional Activation / Q000187:drug effects / Q000276:immunology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D006001:Glycoconjugates; D008024:Ligands; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D009077:Mucins; D012333:RNA, Messenger; D006861:Hydrogen Peroxide; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases