title: Inhibition of ERK oscillations by ionizing radiation and reactive oxygen species.
abstract: The shuttling of activated protein kinases between the cytoplasm and nucleus is an essential feature of normal growth factor signaling cascades. Here we demonstrate that transforming growth factor alpha (TGFα) induces oscillations in extracellular signal regulated kinase (ERK) cytoplasmic-nuclear translocations in human keratinocytes. TGFα-dependent ERK oscillations mediated through the epidermal growth factor receptor (EGFR) are inhibited by low dose X-irradiation (10 cGy) and low concentrations of hydrogen peroxide (0.32-3.26 µM H(2)O(2)) used as a model reactive oxygen species (ROS). A fluorescent indicator dye (H2-DCFDA) was used to measure cellular ROS levels following X-irradiation, 12-O-tetradecanoyl phorbol-13-acetate (TPA) and H(2)O(2). X-irradiation did not generate significant ROS production while 0.32 µM H(2)O(2) and TPA induced significant increases in ROS levels with H(2)O(2)  > TPA. TPA alone induced transactivation of the EGFR but did not induce ERK oscillations. TPA as a cotreatment did not inhibit TGFα-stimulated ERK oscillations but qualitatively altered TGFα-dependent ERK oscillation characteristics (amplitude, time-period). Collectively, these observations demonstrate that TGFα-induced ERK oscillations are inhibited by ionizing radiation/ROS and perturbed by epigenetic carcinogen in human keratinocytes.
authors.affiliation: Computational Biology and Bioinformatics, Pacific Northwest National Laboratory, Richland, Washington 99354, USA.
authors.forename: Harish
authors.initials: H
authors.lastname: Shankaran
authors.forename: William B
authors.initials: WB
authors.lastname: Chrisler
authors.forename: Ryan L
authors.initials: RL
authors.lastname: Sontag
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Weber
mesh_terms: D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D016877:Oxidants / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D016211:Transforming Growth Factor alpha / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects / Q000528:radiation effects
chemical_list: D016877:Oxidants; D017382:Reactive Oxygen Species; D016211:Transforming Growth Factor alpha; D006861:Hydrogen Peroxide; D048049:Extracellular Signal-Regulated MAP Kinases