The Protective Effects of EMF-LTE against DNA Double-Strand Break Damage In Vitro and In Vivo

With the rapid growth of the wireless communication industry, humans are extensively exposed to electromagnetic fields (EMF) comprised of radiofrequency (RF). The skin is considered the primary target of EMFs given its outermost location. Recent evidence suggests that extremely low frequency (ELF)-EMF can improve the efficacy of DNA repair in human cell-lines. However, the effects of EMF-RF on DNA damage remain unknown. Here, we investigated the impact of EMF-long term evolution (LTE, 1.762 GHz, 8 W/kg) irradiation on DNA double-strand break (DSB) using the murine melanoma cell line B16 and the human keratinocyte cell line HaCaT. EMF-LTE exposure alone did not affect cell viability or induce apoptosis or necrosis. In addition, DNA DSB damage, as determined by the neutral comet assay, was not induced by EMF-LTE irradiation. Of note, EMF-LTE exposure can attenuate the DNA DSB damage induced by physical and chemical DNA damaging agents (such as ionizing radiation (IR, 10 Gy) in HaCaT and B16 cells and bleomycin (BLM, 3 μM) in HaCaT cells and a human melanoma cell line MNT-1), suggesting that EMF-LTE promotes the repair of DNA DSB damage. The protective effect of EMF-LTE against DNA damage was further confirmed by attenuation of the DNA damage marker γ-H2AX after exposure to EMF-LTE in HaCaT and B16 cells. Most importantly, irradiation of EMF-LTE (1.76 GHz, 6 W/kg, 8 h/day) on mice in vivo for 4 weeks reduced the γ-H2AX level in the skin tissue, further supporting the protective effects of EMF-LTE against DNA DSB damage. Furthermore, p53, the master tumor-suppressor gene, was commonly upregulated by EMF-LTE irradiation in B16 and HaCaT cells. This finding suggests that p53 plays a role in the protective effect of EMF-LTE against DNA DSBs. Collectively, these results demonstrated that EMF-LTE might have a protective effect against DNA DSB damage in the skin, although further studies are necessary to understand its impact on human health.

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The PARP inhibitor olaparib induces significant killing of ATM-deficient lymphoid tumor cells in vitro and in vivo

Blood ◽

10.1182/blood-2010-01-265769 ◽

2010 ◽

Vol 116 (22) ◽

pp. 4578-4587 ◽

Cited By ~ 189

Author(s):

Victoria J. Weston ◽

Ceri E. Oldreive ◽

Anna Skowronska ◽

David G. Oscier ◽

Guy Pratt ◽

...

Keyword(s):

Cell Line ◽

Tumor Cells ◽

Strand Break ◽

Double Strand Break ◽

Double Strand Break Repair ◽

Prolymphocytic Leukemia ◽

Dna Double Strand Break ◽

Break Repair

Abstract The Ataxia Telangiectasia Mutated (ATM) gene is frequently inactivated in lymphoid malignancies such as chronic lymphocytic leukemia (CLL), T-prolymphocytic leukemia (T-PLL), and mantle cell lymphoma (MCL) and is associated with defective apoptosis in response to alkylating agents and purine analogues. ATM mutant cells exhibit impaired DNA double strand break repair. Poly (ADP-ribose) polymerase (PARP) inhibition that imposes the requirement for DNA double strand break repair should selectively sensitize ATM-deficient tumor cells to killing. We investigated in vitro sensitivity to the poly (ADP-ribose) polymerase inhibitor olaparib (AZD2281) of 5 ATM mutant lymphoblastoid cell lines (LCL), an ATM mutant MCL cell line, an ATM knockdown PGA CLL cell line, and 9 ATM-deficient primary CLLs induced to cycle and observed differential killing compared with ATM wildtype counterparts. Pharmacologic inhibition of ATM and ATM knockdown confirmed the effect was ATM-dependent and mediated through mitotic catastrophe independently of apoptosis. A nonobese diabetic/severe combined immunodeficient (NOD/SCID) murine xenograft model of an ATM mutant MCL cell line demonstrated significantly reduced tumor load and an increased survival of animals after olaparib treatment in vivo. Addition of olaparib sensitized ATM null tumor cells to DNA-damaging agents. We suggest that olaparib would be an appropriate agent for treating refractory ATM mutant lymphoid tumors.

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DNA double-strand break repair: a theoretical framework and its application

Journal of The Royal Society Interface ◽

10.1098/rsif.2015.0679 ◽

2016 ◽

Vol 13 (114) ◽

pp. 20150679 ◽

Cited By ~ 9

Author(s):

Philip J. Murray ◽

Bart Cornelissen ◽

Katherine A. Vallis ◽

S. Jon Chapman

Keyword(s):

Dna Damage ◽

Auger Electron ◽

Strand Break ◽

Dna Double Strand Breaks ◽

Dsb Repair ◽

Histone H2ax ◽

Dna Double Strand Break ◽

A Cell

DNA double-strand breaks (DSBs) are formed as a result of genotoxic insults, such as exogenous ionizing radiation, and are among the most serious types of DNA damage. One of the earliest molecular responses following DSB formation is the phosphorylation of the histone H2AX, giving rise to γ H2AX. Many copies of γ H2AX are generated at DSBs and can be detected in vitro as foci using well-established immuno-histochemical methods. It has previously been shown that anti- γ H2AX antibodies, modified by the addition of the cell-penetrating peptide TAT and a fluorescent or radionuclide label, can be used to visualize and quantify DSBs in vivo . Moreover, when labelled with a high amount of the short-range, Auger electron-emitting radioisotope, 111 In, the amount of DNA damage within a cell can be increased, leading to cell death. In this report, we develop a mathematical model that describes how molecular processes at individual sites of DNA damage give rise to quantifiable foci. Equations that describe stochastic mean behaviours at individual DSB sites are derived and parametrized using population-scale, time-series measurements from two different cancer cell lines. The model is used to examine two case studies in which the introduction of an antibody (anti- γ H2AX-TAT) that targets a key component in the DSB repair pathway influences system behaviour. We investigate: (i) how the interaction between anti- γ H2AX-TAT and γ H2AX effects the kinetics of H2AX phosphorylation and DSB repair and (ii) model behaviour when the anti- γ H2AX antibody is labelled with Auger electron-emitting 111 In and can thus instigate additional DNA damage. This work supports the conclusion that DSB kinetics are largely unaffected by the introduction of the anti- γ H2AX antibody, a result that has been validated experimentally, and hence the hypothesis that the use of anti- γ H2AX antibody to quantify DSBs does not violate the image tracer principle. Moreover, it provides a novel model of DNA damage accumulation in the presence of Auger electron-emitting 111 In that is supported qualitatively by the available experimental data.

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