title: Role of tyrosine kinase activity of epidermal growth factor receptor in the lysophosphatidic acid-stimulated mitogen-activated protein kinase pathway.
abstract: Recent evidence indicates that the epidermal growth factor (EGF) receptor mediates a branch of lysophosphatidic acid (LPA)-induced signal transduction pathways that activate mitogen-activated protein (MAP) kinase. However, it is unclear whether the intrinsic tyrosine kinase activity of EGF receptor is involved. We previously showed that reactive oxygen species (ROS) were involved in the LPA-stimulated MAP kinase pathway. Here, we identify tyrosine phosphorylation of EGF receptor as an LPA signaling step that requires ROS. To evaluate the role of the tyrosine kinase activity of EGF receptor in the LPA-stimulated MAP kinase pathway, we examined the effects of an EGF receptor-specific tyrosine kinase inhibitor, PD158780. PD158780 potently inhibited the LPA-stimulated MAP kinase kinase 1/2 (MKK1/2) activation and EGF receptor tyrosine phosphorylation in HeLa cells, while it had no detectable effect on c-Src kinase activity. PD158780 also inhibited LPA-induced MKK1/2 activation and DNA synthesis in NIH 3T3 cells. Furthermore, we compared LPA-stimulated MKK1/2 and MAP kinase activation, transcriptional activity of the c-fos promoter, and DNA synthesis in B82L cells, which lack endogenous EGF receptor, and B82L cells expressing kinase-defective or wild-type human EGF receptor. Results obtained from analysis of these cell lines suggest that the EGF receptor tyrosine kinase contributes to the LPA-stimulated MAP kinase activation, c-fos transcription, and mitogenesis.
authors.affiliation: Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida College of Medicine, Tampa, Florida 33612, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Cunnick
authors.forename: J F
authors.initials: JF
authors.lastname: Dorsey
authors.forename: T
authors.initials: T
authors.lastname: Standley
authors.forename: J
authors.initials: J
authors.lastname: Turkson
authors.forename: A J
authors.initials: AJ
authors.lastname: Kraker
authors.forename: D W
authors.initials: DW
authors.lastname: Fry
authors.forename: R
authors.initials: R
authors.lastname: Jove
authors.forename: J
authors.initials: J
authors.lastname: Wu
mesh_terms: D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000502:physiology*; D016762:Genes, fos / Q000235:genetics; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008246:Lysophospholipids / Q000494:pharmacology*; D048369:MAP Kinase Kinase 1; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000032:analysis; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics; D019061:src-Family Kinases
chemical_list: C107875:6-(methylamino)pyrido(3,4-d)pyrimidine; D004791:Enzyme Inhibitors; D008246:Lysophospholipids; D011743:Pyrimidines; D017382:Reactive Oxygen Species; D019000:Phosphotyrosine; D006861:Hydrogen Peroxide; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases