title: Ras-mediated activation of ERK by cisplatin induces cell death independently of p53 in osteosarcoma and neuroblastoma cell lines.
abstract: Activation of the mitogen-activated protein kinases ERK1/2 by the chemotherapeutic agent cisplatin has been shown to result in either survival or cell death. The downstream mediators of these opposing effects are unknown, as are the upstream signaling molecules. Activation of ERK is required for accumulation and phosphorylation of p53 following cisplatin treatment. We studied the role of ERK activation after cisplatin treatment under p53-negative and p53-positive conditions using a tetracycline-dependent expression vector in Saos-2 osteosarcoma cells. Dose-dependent activation of ERK first occurred 3-6 h after a 2-h cisplatin incubation and declined after 12-24 h in several tumor cell lines. Incubation of cell lines with the MEK1 inhibitors PD98059 or UO126 after, but not during, cisplatin treatment completely inhibited cisplatin-induced activation of ERK. The activation of ERK by cisplatin was inhibited by transient transfection with dominant-negative Ras-N17 in Saos-2 cells. Treatment of cells with PD98059 or UO126 after cisplatin incubation or inhibition of signaling through ERK by tetracycline-regulated expression of dominant-inhibitory ERK enhanced resistance to cisplatin in p53-negative osteosarcoma cells and reduced cisplatin-induced apoptosis. P53 was stabilized and phosphorylated in a MEK1-dependent manner after cisplatin incubation in Kelly neuroblastoma cells. Inhibition of signaling through ERK increased cell survival after cisplatin treatment in these cells as well. Expression of functional p53 did not change the proapoptotic effects of ERK activation in response to cisplatin in Saos-2 cells. Our results suggest that cisplatin-induced activation of ERK is mediated by Ras. ERK activation increased cisplatin-induced cell death independently of p53 in osteosarcoma and neuroblastoma cell lines.
authors.affiliation: Department of Pediatric Hematology and Oncology, Justus-Liebig-University, 35385 Giessen, Germany. wilhelm.woessmann@paediat.med.uni-giessen.de
authors.forename: Willi
authors.initials: W
authors.lastname: Woessmann
authors.forename: Xinbin
authors.initials: X
authors.lastname: Chen
authors.forename: Arndt
authors.initials: A
authors.lastname: Borkhardt
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001859:Bone Neoplasms / Q000473:pathology*; D002070:Butadienes / Q000494:pharmacology; D002945:Cisplatin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D016158:Genes, p53; D011905:Genes, ras; D006801:Humans; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D009363:Neoplasm Proteins / Q000502:physiology*; D009447:Neuroblastoma / Q000473:pathology*; D009570:Nitriles / Q000494:pharmacology; D012516:Osteosarcoma / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000502:physiology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology
chemical_list: D000970:Antineoplastic Agents; D002070:Butadienes; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009363:Neoplasm Proteins; D009570:Nitriles; D011993:Recombinant Fusion Proteins; C113580:U 0126; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D002945:Cisplatin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one