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 c-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 X85% attenuation in IR-induced G2/M arrest and concomitant diminution of IR-induced activation of ataxia telangiectasia mutatedand 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.

Histone H2AX is a critical factor for cellular protection against DNA alkylating agents

“…Requirement for ERK1 and ERK2 activation has been demonstrated for DNA damage-induced G 2 /M arrest in mammalian cells (Chou et al, 2007;Yan et al, 2007). In this study, we demonstrated that the lack of activation and persistence of phosphorylated ERK1 and ERK2 proteins after alkylation damage correlate with lack of G 2 /M arrest in H2AX-deficient cells.…”

Cyclooxygenase-2 Up-Regulates Ataxia Telangiectasia and Rad3 Related through Extracellular Signal-Regulated Kinase Activation

“…decreasing Chk1 activation and repression of G 2 -M arrest (23). Taken together, these facts suggest that ERK activation may play a key role in the regulation of the ATR/Chk1-dependent G 2 -M checkpoint in cells with damaged DNA.…”

“…Celecoxib can also induce cell cycle arrest, apoptosis, or ERK activation through a COX-2-independent mode (21,22). These facts indicate that celecoxib acts through COX-2-dependent and COX-2-independent pathways (23)(24)(25)(26).…”

“…Several studies have suggested that DNAdamaging stimuli such as UV light, hydroxyurea, and IR induce ERK activation and result in G 2 -M arrest (23,27,28). In addition, when cells are exposed to DNA damage-inducing agents, ERK inhibition decreases ATR activity and results in B. HCT116-Mock and HCT116-COX-2 cells were stained with ATR and COX-2-specific antibodies, and the images were taken with confocal microscopy as described Materials and Methods.…”

Chromium induces chromosomal instability, which is partly due to deregulation of BubR1 and Emi1, two APC/C inhibitors

“…We next determined if co-treatment of HeLa cells with Cr(VI) and caffeine would have an effect on modulating cell cycle distributions, because caffeine is capable of weakening the DNA damage checkpoint by inhibiting activities of ATM/ATR. 15,16 Caffeine treatment alone did not have any noticeable effects on perturbing cell cycle distribution, whereas Cr(VI) greatly enriched S-phase cells (Figs. 3A and 4A).…”