title: Epidermal growth factor receptor exposed to cigarette smoke is aberrantly activated and undergoes perinuclear trafficking.
abstract: Exposure to hydrogen peroxide (H2O2), one of the reactive oxidants in the gas phase of cigarette smoke (CS), induces aberrant phosphorylation of the epidermal growth factor receptor (EGFR), resulting in the lack of ubiquitination by c-Cbl, and impaired degradation. EGFR activation without the feedback regulation of normal degradation leads to uncontrolled cell growth and tumor promotion. Using immunoprecipitation, immunoblotting, and confocal microscopy, we now demonstrate that the pattern of EGFR activation by CS is similar to H2O2. We found that exposure of human airway epithelial cells to CS, as with exposure to H2O2, not only results in an increase in EGFR activation over time, but the EGFR activated by H2O2 or CS is neither ubiquitinated nor subsequently degraded due to its inability to bind the E3 ubiquitin ligase, c-Cbl, either directly or indirectly via the Grb2 adapter protein. Moreover, the stabilized H2O2- and CS-activated EGFR remains plasma membrane-bound, while a population of the receptor is trafficked to a perinuclear region. Concomitantly, CS exposure results in the activation of downstream Akt and ERK1/2 survival and proliferation pathways. Therefore, exposure to CS, like exposure to H2O2, results in prolonged signaling by the EGFR and may contribute to uncontrolled lung cell growth.
authors.affiliation: Signal Transduction Laboratory, Department of Internal Medicine, University of California, School of Medicine, Davis, California, 95616, USA.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Khan
authors.forename: Roni
authors.initials: R
authors.lastname: Lanir
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Danielson
authors.forename: Tzipora
authors.initials: T
authors.lastname: Goldkorn
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000009:adverse effects / Q000494:pharmacology*; D008168:Lung / Q000166:cytology; D010766:Phosphorylation / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D050721:Proto-Oncogene Proteins c-cbl / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012906:Smoke; D013997:Time Factors; D014026:Nicotiana
chemical_list: D012906:Smoke; D006861:Hydrogen Peroxide; D050721:Proto-Oncogene Proteins c-cbl; D066246:ErbB Receptors; C067419:CBL protein, human