Evaluation of the Comet Assay for Assessing the Dose-Response Relationship of DNA Damage Induced by Ionizing Radiation

Wang, Yan; Xu, Chang; Du, Li; Cao, Jia; Liu, Jian‐Xiang; Su, Xu; Zhao, Hui; Fan, Feiyue; Wang, Bing; Katsube, Takanori; Fan, Sai Jun; Liu, Qiang

doi:10.3390/ijms141122449

Cited by 55 publications

(28 citation statements)

References 28 publications

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“…The dose-dependent increases in DNA damage, expressed as OTM values, are shown immediately after irradiation of up to 8 Gy at the LDR (3.6 Gy/min) and HDR (36 Gy/min). The range of OTM values at 0 h corresponded with the data reported in the literature for the similar doses of irradiation [ 16 ]. After 24 h of LDR irradiation, the levels of DNA breaks in K562 cells were significantly lower than immediately after exposure and did not differ from the corresponding control.…”

Section: Resultssupporting

confidence: 84%

Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro

Babayan

Hovhannisyan

Grigoryan

et al. 2017

Journal of Radiation Research

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Laser-generated electron beams are distinguished from conventional accelerated particles by ultrashort beam pulses in the femtoseconds to picoseconds duration range, and their application may elucidate primary radiobiological effects. The aim of the present study was to determine the dose-rate effect of laser-generated ultrashort pulses of 4 MeV electron beam radiation on DNA damage and repair in human cells. The dose rate was increased via changing the pulse repetition frequency, without increasing the electron energy. The human chronic myeloid leukemia K-562 cell line was used to estimate the DNA damage and repair after irradiation, via the comet assay. A distribution analysis of the DNA damage was performed. The same mean level of initial DNA damages was observed at low (3.6 Gy/min) and high (36 Gy/min) dose-rate irradiation. In the case of low-dose-rate irradiation, the detected DNA damages were completely repairable, whereas the high-dose-rate irradiation demonstrated a lower level of reparability. The distribution analysis of initial DNA damages after high-dose-rate irradiation revealed a shift towards higher amounts of damage and a broadening in distribution. Thus, increasing the dose rate via changing the pulse frequency of ultrafast electrons leads to an increase in the complexity of DNA damages, with a consequent decrease in their reparability. Since the application of an ultrashort pulsed electron beam permits us to describe the primary radiobiological effects, it can be assumed that the observed dose-rate effect on DNA damage/repair is mainly caused by primary lesions appearing at the moment of irradiation.

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Section: Resultssupporting

confidence: 84%

Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro

Babayan

Hovhannisyan

Grigoryan

et al. 2017

Journal of Radiation Research

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“…Related to this, it is still unknown how quickly a Cas9-induced break is repaired. DSBs have been measured by comet assays ( Wang et al., 2013 ) or pulsed-field gel electrophoresis, typically ( DiBiase et al., 2000 ) after exposure to high doses of ionizing radiation that cause hundreds of DSBs per cell. Time courses of such bulk measurements in mammalian cells have consistently shown that DSBs are generally repaired with a half-life of 10–60 min ( DiBiase et al., 2000 , Metzger and Iliakis, 1991 , Núñez et al., 1995 , Schwartz et al., 1988 , Stenerlöw et al., 2003 , Wang et al., 2006 ).…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Fidelity of the Repair of Cas9-Induced Double-Strand DNA Breaks

et al. 2018

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SummaryThe RNA-guided DNA endonuclease Cas9 is a powerful tool for genome editing. Little is known about the kinetics and fidelity of the double-strand break (DSB) repair process that follows a Cas9 cutting event in living cells. Here, we developed a strategy to measure the kinetics of DSB repair for single loci in human cells. Quantitative modeling of repaired DNA in time series after Cas9 activation reveals variable and often slow repair rates, with half-life times up to ∼10 hr. Furthermore, repair of the DSBs tends to be error prone. Both classical and microhomology-mediated end joining pathways contribute to the erroneous repair. Estimation of their individual rate constants indicates that the balance between these two pathways changes over time and can be altered by additional ionizing radiation. Our approach provides quantitative insights into DSB repair kinetics and fidelity in single loci and indicates that Cas9-induced DSBs are repaired in an unusual manner.

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“…The comet assay is a single‐cell gel electrophoresis assay that assesses the extent of DNA damage in nucleated white blood cells by applying a computerized scoring algorithm. The extent of DNA damage is estimated from approximately 100 comets per sample analyzed by CASP software (CaspLab, Wroclaw, Poland) and values are expressed as a mean score from 0 to 4 (maximum damage/large tail) …”

Section: Methodsmentioning

confidence: 99%

“…The extent of DNA damage is estimated from approximately 100 comets per Cancer January 15, 2019 sample analyzed by CASP software (CaspLab, Wroclaw, Poland) 52 and values are expressed as a mean score from 0 to 4 (maximum damage/large tail). 53…”

Section: Dna Damagementioning

confidence: 99%

Cognitive performance in survivors of breast cancer and markers of biological aging

Carroll

Dyk

Bower

et al. 2018

Cancer

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Background Biological aging pathways accelerated by cancer treatments may be a mechanism for cognitive impairment in cancer survivors. The goal of the current study was to examine whether indicators of biological aging, namely elevated levels of DNA damage, reduced telomerase enzymatic activity, and shorter peripheral blood mononuclear cell (PBMC) telomere length (TL) would be related to cognitive function in a cohort of survivors of breast cancer. Methods The authors evaluated a cross‐sectional sample of 94 women aged 36 to 69 years who were treated for early‐stage breast cancer 3 to 6 years previously. Leukocyte DNA damage, PBMC telomerase enzymatic activity, PBMC TL, and the inflammatory marker soluble tumor necrosis factor receptor II (sTNF‐RII) were determined from blood samples. Cognitive function was assessed using a neuropsychological test battery and self‐report. Linear regression models examined the relationship between biological aging predictors and cognitive outcomes. Results Both higher DNA damage and lower telomerase were found to be statistically significantly related to lower executive function scores adjusting for age, body mass index, race, years from treatment, and intelligence score (standardized coefficients [B], ‐0.23 and 0.30; all P values <.05). In addition, lower telomerase activity was associated with worse attention and motor speed scores (B values, 0.30 and 0.24; P <.05). sTNF‐RII and TL were found to be unrelated to any of the neurocognitive domains. Conclusions The results of the current study suggest a significant association between measures of biological aging and objective measures of cognitive performance in survivors of breast cancer. Future prospective studies are needed to confirm a causal role of biological aging as a driver of declines in cognitive function after cancer treatment.

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Evaluation of the Comet Assay for Assessing the Dose-Response Relationship of DNA Damage Induced by Ionizing Radiation

Cited by 55 publications

References 28 publications

Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro

Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro

Kinetics and Fidelity of the Repair of Cas9-Induced Double-Strand DNA Breaks

Cognitive performance in survivors of breast cancer and markers of biological aging

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