title: Reactive oxygen species mediate Met receptor transactivation by G protein-coupled receptors and the epidermal growth factor receptor in human carcinoma cells.
abstract: Cross-communication between the Met receptor tyrosine kinase and the epidermal growth factor receptor (EGFR) has been proposed to involve direct association of both receptors and EGFR kinase-dependent phosphorylation. Here, we demonstrate that in human hepatocellular and pancreatic carcinoma cells the Met receptor becomes tyrosine phosphorylated not only upon EGF stimulation but also in response to G protein-coupled receptor (GPCR) agonists. Whereas specific inhibition of the EGFR kinase activity blocked EGF- but not GPCR agonist-induced Met receptor transactivation, it was abrogated in the presence of a reducing agent or treatment of cells with a NADPH oxidase inhibitor. Both GPCR ligands and EGF are further shown to increase the level of reactive oxygen species within the cell. Interestingly, stimulation of the Met receptor by either GPCR agonists, EGF or its cognate ligand HGF, resulted in release of Met-associated beta-catenin and in its Met-dependent translocation into the nucleus, as analyzed by small interfering RNA-mediated knockdown of the Met receptor. Our results provide a new molecular explanation for cell surface receptor cross-talk involving the Met receptor and thereby link the wide diversity of GPCRs and the EGFR to the oncogenic potential of Met signaling in human carcinoma cells.
authors.affiliation: Department of Molecular Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18A, D-82152 Martinsried, Germany.
authors.forename: Oliver M
authors.initials: OM
authors.lastname: Fischer
authors.forename: Silvia
authors.initials: S
authors.lastname: Giordano
authors.forename: Paolo M
authors.initials: PM
authors.lastname: Comoglio
authors.forename: Axel
authors.initials: A
authors.lastname: Ullrich
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000378:metabolism; D002458:Cell Fractionation; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000502:physiology; D019255:NADPH Oxidases / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D019859:Proto-Oncogene Proteins c-met; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D017978:Receptors, Growth Factor; D015534:Trans-Activators / Q000378:metabolism; D015533:Transcriptional Activation; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D008024:Ligands; D011506:Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D043562:Receptors, G-Protein-Coupled; D017978:Receptors, Growth Factor; D015534:Trans-Activators; D051176:beta Catenin; D004815:Epidermal Growth Factor; D019255:NADPH Oxidases; D066246:ErbB Receptors; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met; D020794:Receptor Protein-Tyrosine Kinases