73 Scopus citations

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 γ-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 ≥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.

Original languageEnglish (US)
Pages (from-to)4689-4698
Number of pages10
JournalOncogene
Volume26
Issue number32
DOIs
StatePublished - Jul 12 2007

Keywords

  • ATM/ATR
  • Cdc2
  • Cdc25A/C
  • Chk1
  • ERK1/2
  • Irradiation and wee1

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cancer Research

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