Phosphorylation of Histone H2AX in Radiation-Induced Micronuclei

Medvedeva, Natalia G.; Panyutin, Irina V.; Panyutin, Igor G.; Neumann, Ronald D.

doi:10.1667/rr0788.1

Cited by 52 publications

(30 citation statements)

References 24 publications

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“…Moreover, this assay was found to be more sensitive than the comet assay when we compare our results regarding PAHs genotoxicity with published data on the same cell line (Plazar et al, 2007;Winter et al, 2008;Tarantini et al, 2009). Concerning the comparison of the γ-H2AX assay with the micronucleus test, it is now well established that the micronucleus formation correlates well with H2AX phosphorylation (Medvedeva et al, 2007;Terradas et al, 2009;Yoshikawa et al, 2009). …”

Section: Genotoxicity Of Pahs In Human Cell Linessupporting

confidence: 59%

Comparative potency approach based on H2AX assay for estimating the genotoxicity of polycyclic aromatic hydrocarbons

Audebert

Zeman

Beaudoin

et al. 2012

Toxicology and Applied Pharmacology

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a b s t r a c t a r t i c l e i n f oPolycyclic Aromatic Hydrocarbons (PAHs) constitute a family of over one hundred compounds and can generally be found in complex mixtures. PAHs metabolites cause DNA damage which can lead to the development of carcinogenesis. Toxicity assessment of PAH complex mixtures is currently expressed in terms of toxic equivalents, based on Toxicity Equivalent Factors (TEFs). However, the definition of new TEFs for a large number of PAH could overcome some limitations of the current method and improve cancer risk assessment. The current investigation aimed at deriving the relative potency factors of PAHs, based on their genotoxic effect measured in vitro and analyzed with mathematical models. For this purpose, we used a new genotoxic assay (γH2AX) with two human cell lines (HepG2 and LS-174T) to analyze the genotoxic properties of 13 selected PAHs at low doses after 24 h treatment. The dose-response for genotoxic effects was modeled with a Hill model; equivalency between PAHs at low dose was assessed by applying constraints to the model parameters. In the two cell lines tested, we observed a clear dose-response for genotoxic effects for 11 tested compounds. LS-174T was on average ten times more sensitive than HepG2 towards PAHs regarding genotoxicity. We developed new TEFs, which we named Genotoxic Equivalent Factor (GEF). Calculated GEF for the tested PAHs were generally higher than the TEF usually used. Our study proposed a new in vitro based method for the establishment of relevant TEFs for PAHs to improve cancer risk assessment.

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Section: Genotoxicity Of Pahs In Human Cell Linessupporting

confidence: 59%

Comparative potency approach based on H2AX assay for estimating the genotoxicity of polycyclic aromatic hydrocarbons

Audebert

Zeman

Beaudoin

et al. 2012

Toxicology and Applied Pharmacology

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“…Reduction in γH2AX over the weekend is substantial and would be explained by both cell loss and additional time for repair. Lethal damage that results in nuclei without foci includes damage that occurs during tumor disaggregation as well as elimination of γH2AX foci into micronuclei (24). The remaining nucleus could lack γH2AX foci and be scored as viable, but loss of critical DNA with the micronucleus would lead to cell death.…”

Section: Discussionmentioning

confidence: 99%

γH2AX Expression in Tumors Exposed to Cisplatin and Fractionated Irradiation

Bañuelos

Banáth

Kim

et al. 2009

Clinical Cancer Research

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Purpose: Is retention of γH2AX foci useful as a biomarker for predicting the response of xenograft tumors to cisplatin with X-ray? Is a similar approach feasible using biopsies from patients with cervical cancer? Experimental Design: Mice bearing SiHa, WiDr, or HCT116 xenograft tumors were exposed to cisplatin and/or three daily doses of 2 Gy. Tumors were excised 24 h after treatment and single cells were analyzed for clonogenic fraction and retention of γH2AX foci. Tumor biopsies were examined using 47 paraffin-embedded sections from untreated tumors and 24 sections from 8 patients undergoing radiochemotherapy for advanced cancer of the cervix. Results: Residual γH2AX measured 24 h after cisplatin injection accurately predicted surviving fraction in SiHa and WiDr xenografts. When a clinically equivalent protocol using cisplatin and fractionated irradiation was employed, the fraction of xenograft cells lacking γH2AX ranked survival accurately but underestimated tumor cell kill. Residual γH2AX foci were detected in clinical samples; on average, only 25% of tumor nuclei exhibited one or more γH2AX foci before treatment and 74% after the start of treatment. Conclusion: γH2AX can provide useful information on the response of human tumors to the combination of cisplatin and radiation, but prediction becomes less accurate as more time elapses between treatment and tumor biopsy. Use of residual γH2AX as a biomarker for response is feasible when cell survival exceeds ∼20%, but heterogeneity in endogenous and treatment-induced γH2AX must be considered.Prediction of tumor response to radiation remains an important goal in radiotherapy (1, 2). However, prediction is complicated by the use of combined modality therapy and the lack of a simple but effective predictor of response in situ. Ionizing radiation and many cancer therapeutics cause phosphorylation of histone H2AX at sites of individual DNA double-strand breaks, providing an exceptionally sensitive method for detection of this critical lesion (3, 4). Production of γH2AX foci can be detected microscopically or by using flow cytometry, and the extent of phosphorylation has been used as a biomarker of both exposure and DNA repair capacity (5-9). The fraction of cells that retain of γH2AX foci, measured 24 h after exposure to either radiation (6) or cisplatin (10), is correlated with the fraction of cells that lose clonogenicity in SiHa and WiDr tumor cells. These in vitro results and the availability of biopsies from patients treated with cisplatin and radiation provided the motivation to examine the response of xenograft tumors to the combination of cisplatin and radiation and then to measure γH2AX expression in clinical biopsies.The presence of residual γH2AX was examined using three human tumor xenograft models growing subcutaneously in immunodeficient mice given a single dose of cisplatin, 2 Gy × three daily fractions of X-ray, or the combination. To determine the importance of tumor cell location relative to functional blood vessels, tumor cells were sorte...

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“…The number of endogenous 53BP1 foci (< 3 foci/nucleus) appeared normal in mouse embryonic stem cells and is comparable with that found in other cell types (Banath et al 2009). In contrast to γ-H2AX foci, which may be produced by the DSB-relevant and DSB-unrelated mechanisms, 53BP1 is relocalized to DSBs, along with other DNA damage-response proteins, such as phosphorylated ATM (ataxia telangiectasia mutated), Rad50, and MRE11 (meiotic recombination 11), and there is no indication that DSB-unrelated events would result in the formation of the 53BP1 foci (Medvedeva et al 2007; Yoshikawa et al 2009). Therefore, in this study we analyzed only 53BP1 foci as a more relevant marker for DSBs.…”

mentioning

confidence: 99%

Microwaves from Mobile Phones Inhibit 53BP1 Focus Formation in Human Stem Cells More Strongly Than in Differentiated Cells: Possible Mechanistic Link to Cancer Risk

Markovà

Malmgren

Belyaev

2010

Environ Health Perspect

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BackgroundIt is widely accepted that DNA double-strand breaks (DSBs) and their misrepair in stem cells are critical events in the multistage origination of various leukemias and tumors, including gliomas.ObjectivesWe studied whether microwaves from mobile telephones of the Global System for Mobile Communication (GSM) and the Universal Global Telecommunications System (UMTS) induce DSBs or affect DSB repair in stem cells.MethodsWe analyzed tumor suppressor TP53 binding protein 1 (53BP1) foci that are typically formed at the sites of DSB location (referred to as DNA repair foci) by laser confocal microscopy.ResultsMicrowaves from mobile phones inhibited formation of 53BP1 foci in human primary fibroblasts and mesenchymal stem cells. These data parallel our previous findings for human lymphocytes. Importantly, the same GSM carrier frequency (915 MHz) and UMTS frequency band (1947.4 MHz) were effective for all cell types. Exposure at 905 MHz did not inhibit 53BP1 foci in differentiated cells, either fibroblasts or lymphocytes, whereas some effects were seen in stem cells at 905 MHz. Contrary to fibroblasts, stem cells did not adapt to chronic exposure during 2 weeks.ConclusionsThe strongest microwave effects were always observed in stem cells. This result may suggest both significant misbalance in DSB repair and severe stress response. Our findings that stem cells are most sensitive to microwave exposure and react to more frequencies than do differentiated cells may be important for cancer risk assessment and indicate that stem cells are the most relevant cellular model for validating safe mobile communication signals.

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Phosphorylation of Histone H2AX in Radiation-Induced Micronuclei

Cited by 52 publications

References 24 publications

Comparative potency approach based on H2AX assay for estimating the genotoxicity of polycyclic aromatic hydrocarbons

Comparative potency approach based on H2AX assay for estimating the genotoxicity of polycyclic aromatic hydrocarbons

γH2AX Expression in Tumors Exposed to Cisplatin and Fractionated Irradiation

Microwaves from Mobile Phones Inhibit 53BP1 Focus Formation in Human Stem Cells More Strongly Than in Differentiated Cells: Possible Mechanistic Link to Cancer Risk

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