title: Protection of human endothelial cells from oxidative stress: role of Ras-ERK1/2 signaling.
abstract: BACKGROUND
  Reactive oxygen species play a critical role in inducing apoptosis. The small GTPase p21 Ras and the ERK1/2 MAPK have been proposed as key regulators of the signaling cascade triggered by oxidative stress (H2O2). Harvey-Ras (Ha-Ras) and Kirsten-Ras (Ki-Ras) isoforms are so far functionally indistinguishable, because they activate the same downstream effectors, including ERK1/2. Moreover, ERK1/2 signaling has been involved in both protection and induction of apoptosis.
  
  
  RESULTS
  Human umbilical vein endothelial cells (HUVECs) were subjected to H2O2, and apoptosis was detected by fluorescence-activated cell sorting analysis, fluorescence microscopy, and caspase-3 activation. Transfection of Ha-Ras and Ki-Ras genes in HUVECs was performed to evaluate the response to H2O2. We have found that, whereas Ha-Ras decreases tolerance to oxidative stress, Ki-Ras has a potent antiapoptotic activity. Both effects are mediated by ERK1/2. Tolerance to H2O2 is encoded by a unique stretch of lysines at the COOH terminus of the Ki-Ras, lacking in Ha-Ras, and it is relatively independent of the farnesylated anchor. Inhibition of p21 Ras signaling by farnesylation inhibitors increased the resistance to apoptosis in Ha-Ras-expressing cells.
  
  
  CONCLUSIONS
  These findings explain the opposite effects of ERK1/2 stimulation on apoptosis found in different cell types and suggest that local activation of ERK1/2 signaling may account for the opposing response to oxidative stress by Ha-Ras or Ki-Ras-expressing cells. Modulation of cell reactivity to oxidative stress by p21 Ras points to the specific and predictive effects of Ras inhibitors in vivo as potential therapeutic drugs in disorders produced by increase of reactive oxygen species inside the cells.
authors.affiliation: Dipartimento di Medicina Sperimentale e Clinica G. Salvatore, Università di Catanzaro Magna Graecia, Napoli, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cuda
authors.forename: Roberto
authors.initials: R
authors.lastname: Paternò
authors.forename: Roberto
authors.initials: R
authors.lastname: Ceravolo
authors.forename: Mafalda
authors.initials: M
authors.lastname: Candigliota
authors.forename: Nicola
authors.initials: N
authors.lastname: Perrotti
authors.forename: Francesco
authors.initials: F
authors.lastname: Perticone
authors.forename: Maria Concetta
authors.initials: MC
authors.lastname: Faniello
authors.forename: Filippo
authors.initials: F
authors.lastname: Schepis
authors.forename: Antonio
authors.initials: A
authors.lastname: Ruocco
authors.forename: Evelina
authors.initials: E
authors.lastname: Mele
authors.forename: S
authors.initials: S
authors.lastname: Cassano
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bifulco
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Santillo
authors.forename: Enrico V
authors.initials: EV
authors.lastname: Avvedimento
mesh_terms: D019943:Amino Acid Substitution; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D011905:Genes, ras; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008715:Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D017368:Protein Prenylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: D004791:Enzyme Inhibitors; C096856:FTI 277; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D008715:Methionine; D006861:Hydrogen Peroxide; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D015689:Oncogene Protein p21(ras)