title: Irradiation-induced G2/M checkpoint response requires ERK1/2 activation.
abstract: Following DNA damage, cells undergo G2/M cell cycle arrest, allowing time for DNA repair. G2/M checkpoint activation involves activation of Wee1 and Chk1 kinases and inhibition of Cdc25A and Cdc25C phosphatases, which results in inhibition of Cdc2 kinase. Results presented in this report indicate that gamma-irradiation (IR) exposure of MCF-7 cells resulted in extracellular signal regulated protein kinase 1 and 2 (ERK1/2) activation and induction of G2/M arrest. Furthermore, inhibition of ERK1/2 signaling resulted in >or=85% attenuation in IR-induced G2/M arrest and concomitant diminution of IR-induced activation of ataxia telangiectasia mutated- and rad3-related (ATR), Chk1 and Wee1 kinases as well as phosphorylation of Cdc25A-Thr506, Cdc25C-Ser216 and Cdc2-Tyr15. Moreover, incubation of cells with caffeine, which inhibits ataxia telangiectasia mutated (ATM)/ATR, or transfection of cells with short interfering RNA targeting ATR abrogated IR-induced Chk1 phosphorylation and G2/M arrest but had no effect on IR-induced ERK1/2 activation. In contrast, inhibition of ERK1/2 signaling resulted in marked attenuation in IR-induced ATR activity with little, if any, effect on IR-induced ATM activation. These results implicate IR-induced ERK1/2 activation as an important regulator of G2/M checkpoint response to IR in MCF-7 cells.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Yan
authors.forename: C P
authors.initials: CP
authors.lastname: Black
authors.forename: K H
authors.initials: KH
authors.lastname: Cowan
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D016203:CDC2 Protein Kinase / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D002455:Cell Division / Q000528:radiation effects*; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D016195:G2 Phase / Q000528:radiation effects*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D020687:cdc25 Phosphatases / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; C499349:WEE1 protein, human; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C517004:CDC25A protein, human; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases