M-FISH analysis shows that complex chromosome aberrations induced by α-particle tracks are cumulative products of localized rearrangements

Anderson, Rhona M.; Stevens, David L.; Goodhead, Dudley T.

doi:10.1073/pnas.182426799

Cited by 142 publications

(81 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, at higher doses or along high-LET tracks, DSBs clustering could increase risk of translocations and cell death, as recently reviewed [14]. For example, DSB clustering in human white blood cells has been proposed as a mechanism for chromosomal rearrangements observed after exposure to densely ionizing radiation [32]. We test here two potential mechanisms for DSB clustering.…”

Section: Discussionmentioning

confidence: 84%

Combinatorial DNA Damage Pairing Model Based on X-Ray-Induced Foci Predicts the Dose and LET Dependence of Cell Death in Human Breast Cells

et al. 2014

View full text Add to dashboard Cite

In contrast to the classic view of static DNA double strand breaks (DSBs) being repaired at the site of damage, we hypothesize that DSBs move and merge with each other over large distances (µm). As X-ray dose increases, the probability of having DSB clusters increases and so does the probability of misrepair and cell death. Experimental work characterizing the dose dependence of radiation-induced foci (RIF) from X-ray in nonmalignant human mammary epithelial cells (MCF10A) is used here to validate a DSB clustering model. We then use the principles of the local effect model (LEM) to predict the yield of DSB at the sub-micron level. Two mechanisms for DSB clustering are first compared: random coalescence of DSBs versus active movement of DSBs into repair domains. Simulations that best predict both RIF dose dependence and cell survival following X-ray favor the repair domain hypothesis, suggesting the nucleus is divided into an array of regularly spaced repair domains of ~1.55 µm sides. Applying the same approach to high-LET ion tracks, we can predict experimental RIF/µm along tracks with an overall relative error of 12%, for LET ranging between 30 and 350 keV/µm and for three different ions. Finally, cell death is predicted by assuming an exponential dependence on the total number of DSBs and of all possible combinations of paired DSBs within each simulated RIF. RBE predictions for cell survival of MCF10A exposed to high-LET show an LET dependence that matches previous experimental results for similar cell types. Overall, this work suggests that microdosimetric properties of ion tracks at the sub-micron level are sufficient to explain both RIF data and survival curves for any LET, similarly to the LEM assumption. On the other hand, high-LET death mechanism does not have to infer linear-quadratic dose formalism as done in the LEM. In addition, the size of repair domains derived in our model are based on experimental RIF and are three times larger than the hypothetical LEM voxel used to fit survival curves. Our model is therefore an alternative to previous approaches by providing a testable biological mechanism (i.e. RIF). More generally, DSB pairing will help develop more accurate alternatives to the simplistic linear cancer risk model (LNT) currently used for regulating exposure to very low levels of ionizing radiation.Vadhavkar et al.

show abstract

Section: Discussionmentioning

confidence: 84%

Combinatorial DNA Damage Pairing Model Based on X-Ray-Induced Foci Predicts the Dose and LET Dependence of Cell Death in Human Breast Cells

et al. 2014

View full text Add to dashboard Cite

show abstract

“…However, there are some data suggesting their existence in human cells. For example, there were indications in human blood cells that chromosomal rearrangements observed after exposure to high LETcould be explained by localized movement of chromatin containing damaged DNA into local repair centers (24). Following up on this work, it was more recently shown that increasing LET of an α particle did not increase the total number of aberrations per track traversal, and instead increased the ratio of complex to total aberrations (25).…”

Section: Where βðDþmentioning

confidence: 81%

Evidence for formation of DNA repair centers and dose-response nonlinearity in human cells

Neumaier

Swenson

Pham

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

247

195

View full text Add to dashboard Cite

The concept of DNA "repair centers" and the meaning of radiationinduced foci (RIF) in human cells have remained controversial. RIFs are characterized by the local recruitment of DNA damage sensing proteins such as p53 binding protein (53BP1). Here, we provide strong evidence for the existence of repair centers. We used live imaging and mathematical fitting of RIF kinetics to show that RIF induction rate increases with increasing radiation dose, whereas the rate at which RIFs disappear decreases. We show that multiple DNA double-strand breaks (DSBs) 1 to 2 μm apart can rapidly cluster into repair centers. Correcting mathematically for the dose dependence of induction/resolution rates, we observe an absolute RIF yield that is surprisingly much smaller at higher doses: 15 RIF∕Gy after 2 Gy exposure compared to approximately 64 RIF∕Gy after 0.1 Gy. Cumulative RIF counts from time lapse of 53BP1-GFP in human breast cells confirmed these results. The standard model currently in use applies a linear scale, extrapolating cancer risk from high doses to low doses of ionizing radiation. However, our discovery of DSB clustering over such large distances casts considerable doubts on the general assumption that risk to ionizing radiation is proportional to dose, and instead provides a mechanism that could more accurately address risk dose dependency of ionizing radiation. DNA damage-sensing proteins localize at sites of DNA double-strand breaks (DSBs) within seconds to minutes following ionizing radiation (IR) exposure, resulting in the formation of immunofluorescently stainable nuclear domains referred to as radiation-induced foci (RIF) (1-3). RIF numbers are routinely used to assess the amount of DNA damage and repair kinetics after different treatments (4). However, there is a controversy surrounding the question of whether there is a 1∶1 correspondence between RIF and DSBs. For example, pulse field gel electrophoresis (PFGE) analysis suggests that DSBs decay exponentially with time immediately after exposure (5). In contrast, DNA damage-sensing proteins do not instantaneously detect DSBs, leading to delayed kinetics for both detection and resolution. More specifically, the maximum number of 53BP1 or γH2AX RIF is not reached until 15 to 30 min after exposure, and the yield of DSBs predicted by RIF is typically lower than the expected 25-40 DSB∕Gy measured by PFGE (4).Dose response provides another assay for assessing the relationship between DSBs and RIF. Based on theoretical Monte Carlo simulations and PFGE measurements (6, 7), the frequency of DSBs should be highly correlated with radiation dose. Confirming this prediction, two research groups reported that RIF number is proportional to radiation dosage from 1 mGy to 2 Gy (8, 9). In both studies, methods were applied to identify "real" RIF at low doses, where frequencies may be close to background levels before IR (e.g., 10 mGy would lead to about 0.3 DSB∕cell). They either used cells with very low γH2AX background foci (i.e., 0.05 background foci∕cell in primary human l...

show abstract

“…This included 71 damaged cells from previously published data (Anderson et al 2002) and 96 damaged cells from new unpublished data of a-particle-induced damage in human peripheral blood lymphocytes (PBL). In total, data from four different female donors was pooled for analysis.…”

Section: Experimental Methodsmentioning

confidence: 99%

Chromosome breakpoint distribution of damage induced in peripheral blood lymphocytes by densely ionizing radiation

Anderson

Sumption

Papworth

et al. 2006

International Journal of Radiation Biology

View full text Add to dashboard Cite

M-FISH analysis shows that complex chromosome aberrations induced by α-particle tracks are cumulative products of localized rearrangements

Cited by 142 publications

References 37 publications

Combinatorial DNA Damage Pairing Model Based on X-Ray-Induced Foci Predicts the Dose and LET Dependence of Cell Death in Human Breast Cells

Combinatorial DNA Damage Pairing Model Based on X-Ray-Induced Foci Predicts the Dose and LET Dependence of Cell Death in Human Breast Cells

Evidence for formation of DNA repair centers and dose-response nonlinearity in human cells

Chromosome breakpoint distribution of damage induced in peripheral blood lymphocytes by densely ionizing radiation

Contact Info

Product

Resources

About