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Relationship: 1904


A descriptive phrase which clearly defines the two KEs being considered and the sequential relationship between them (i.e., which is upstream, and which is downstream). More help

Increase in RONS leads to Increase, DNA Damage

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help

Key Event Relationship Overview

The utility of AOPs for regulatory application is defined, to a large extent, by the confidence and precision with which they facilitate extrapolation of data measured at low levels of biological organisation to predicted outcomes at higher levels of organisation and the extent to which they can link biological effect measurements to their specific causes.Within the AOP framework, the predictive relationships that facilitate extrapolation are represented by the KERs. Consequently, the overall WoE for an AOP is a reflection in part, of the level of confidence in the underlying series of KERs it encompasses. Therefore, describing the KERs in an AOP involves assembling and organising the types of information and evidence that defines the scientific basis for inferring the probable change in, or state of, a downstream KE from the known or measured state of an upstream KE. More help

AOPs Referencing Relationship

AOP Name Adjacency Weight of Evidence Quantitative Understanding Point of Contact Author Status OECD Status
Increased DNA damage leading to increased risk of breast cancer adjacent High Not Specified Allie Always (send email) Under development: Not open for comment. Do not cite Under Development
Increased reactive oxygen and nitrogen species (RONS) leading to increased risk of breast cancer adjacent High Not Specified Evgeniia Kazymova (send email) Under development: Not open for comment. Do not cite Under Development
Ionizing radiation leads to reduced reproduction in Eisenia fetida via reduced spermatogenesis and cocoon hatchability adjacent Moderate Moderate Allie Always (send email) Under development: Not open for comment. Do not cite

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KER.In general, this will be dictated by the more restrictive of the two KEs being linked together by the KER.  More help

Sex Applicability

An indication of the the relevant sex for this KER. More help

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help

Key Event Relationship Description

Provides a concise overview of the information given below as well as addressing details that aren’t inherent in the description of the KEs themselves. More help

Increased RONS leads to an increase in DNA damage.

Evidence Collection Strategy

Include a description of the approach for identification and assembly of the evidence base for the KER. For evidence identification, include, for example, a description of the sources and dates of information consulted including expert knowledge, databases searched and associated search terms/strings.  Include also a description of study screening criteria and methodology, study quality assessment considerations, the data extraction strategy and links to any repositories/databases of relevant references.Tabular summaries and links to relevant supporting documentation are encouraged, wherever possible. More help

Evidence Supporting this KER

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help

Biological plausibiltiy is High. Reactive oxygen and nitrogen species from oxygen and respiratory activity are generally acknowledged to damage DNA under a range of cellular conditions.

Empirical support is High. Multiple studies show an increase in DNA damage with RONS treatment as well as dependent changes in both RONS and DNA damage in response to stressors. DNA damage increases with RONS dose, and temporal concordance between RONS and DNA damage events following ionizing radiation is consistent with a causative relationship, although few studies examine multiple doses and time points. A small number of studies do not find double strand breaks at physiological doses, or report an increase in one key event but not the other.

Biological Plausibility
Addresses the biological rationale for a connection between KEupstream and KEdownstream.  This field can also incorporate additional mechanistic details that help inform the relationship between KEs, this is useful when it is not practical/pragmatic to represent these details as separate KEs due to the difficulty or relative infrequency with which it is likely to be measured.   More help

High. Reactive oxygen and nitrogen species from oxygen and respiratory activity are generally acknowledged to damage DNA under typical cellular conditions (Dickinson and Chang 2011; Aziz, Nowsheen et al. 2012; Tubbs and Nussenzweig 2017). Damage commonly occurs via oxidation of a nucleotide by the hydroxyl radical (or by radicals created by nitric oxide), or can occur indirectly in nearby nucleotides following the secondary reaction of a radical created in nucleotides (Cadet, Davies et al. 2017). Oxidative damage predominantly consists of DNA lesions (structural modifications to nucleotides) including single strand breaks, although double strand breaks can occur when transcription or translation machinery encounters damaged strands (Tubbs and Nussenzweig 2017).

Uncertainties and Inconsistencies
Addresses inconsistencies or uncertainties in the relationship including the identification of experimental details that may explain apparent deviations from the expected patterns of concordance. More help

While the bulk of the evidence support a mechanism where RONS increases DNA damage, including double strand DNA breaks, not all studies report these effects. Some studies report the induction of single strand breaks by H2O2, but only show double strand breaks with H2O2 doses at or above 1 mM H2O2 (Dahm-Daphi, Sass et al. 2000; Lorat, Brunner et al. 2015) or do not find an effect of H2O2 on double strand breaks at any concentration (Gradzka and Iwanenko 2005; Ismail, Nystrom et al. 2005). These conflicting results may be partially explained by experimental variations including temperature (two of the studies showing reduced or no effect were exposed to H2O2 at 4C or colder) or other factors including catalysts required to transform H2O2 into DNA damaging OH radicals (Nakamura, Purvis et al. 2003). The reduction of IR-induced DNA damage (including double strand breaks) by antioxidants is strong evidence for an essential role of RONS in DNA damage, but antioxidants don’t reduce all DNA damage from IR and anti-oxidants that reduce double strand breaks and chromosomal aberrations after IR don’t necessarily reduce baseline DNA damage (Fetisova, Antoschina et al. 2015). This incomplete effect suggests either that antioxidants are unable to fully reduce endogenous RONS, or that additional sources of DNA damage are also at work. Furthermore, RONS can be observed following IR in the absence of DNA nucleotide damage (Yoshida, Goto et al. 2012) and counter to expectations lower (10 uM) doses of H2O2 applied six days after IR were associated with a decrease in detectable micronuclei (Werner, Wang et al. 2014), suggesting that additional factors (such as repair and apoptosis or changes in endogenous antioxidants) may influence the effect of RONS on IR-induced DNA damage. Finally, double strand breaks and chromosomal damage can be observed following IR in the absence of measured RONS (Suzuki, Kashino et al. 2009), although since antioxidants are still capable of reducing DNA damage in the absence of measurable RONS, such a discrepancy might be attributable to a lack of sensitivity in RONS detection methods (Yang, Asaad et al. 2005).

Known modulating factors

This table captures specific information on the MF, its properties, how it affects the KER and respective references.1.) What is the modulating factor? Name the factor for which solid evidence exists that it influences this KER. Examples: age, sex, genotype, diet 2.) Details of this modulating factor. Specify which features of this MF are relevant for this KER. Examples: a specific age range or a specific biological age (defined by...); a specific gene mutation or variant, a specific nutrient (deficit or surplus); a sex-specific homone; a certain threshold value (e.g. serum levels of a chemical above...) 3.) Description of how this modulating factor affects this KER. Describe the provable modification of the KER (also quantitatively, if known). Examples: increase or decrease of the magnitude of effect (by a factor of...); change of the time-course of the effect (onset delay by...); alteration of the probability of the effect; increase or decrease of the sensitivity of the downstream effect (by a factor of...) 4.) Provision of supporting scientific evidence for an effect of this MF on this KER. Give a list of references.  More help
Response-response Relationship
Provides sources of data that define the response-response relationships between the KEs.  More help
Information regarding the approximate time-scale of the changes in KEdownstream relative to changes in KEupstream (i.e., do effects on KEdownstream lag those on KEupstream by seconds, minutes, hours, or days?). More help
Known Feedforward/Feedback loops influencing this KER
Define whether there are known positive or negative feedback mechanisms involved and what is understood about their time-course and homeostatic limits. More help

RONS activates or is essential to many inflammatory pathways including TGF-β  (Barcellos-Hoff and Dix 1996; Jobling, Mott et al. 2006), TNF (Blaser, Dostert et al. 2016), Toll-like receptor (TLR) (Park, Jung et al. 2004; Nakahira, Kim et al. 2006; Powers, Szaszi et al. 2006; Miller, Goodson et al. 2017; Cavaillon 2018), and NF-kB signaling (Gloire, Legrand-Poels et al. 2006; Morgan and Liu 2011). These interactions principally involve ROS, but RNS can indirectly activate TLRs and possibly NF-kB. Since inflammatory signaling and activated immune cells can also increase the production of RONS, positive feedback and feedforward loops can occur (Zhao and Robbins 2009; Ratikan, Micewicz et al. 2015; Blaser, Dostert et al. 2016).

Damage inflicted by RONS on cells activate TLRs and other receptors to promote release of cytokines (Ratikan, Micewicz et al. 2015). For example, oxidized lipids or oxidative stress-induced heat shock proteins can activate TLR4 (Miller, Goodson et al. 2017; Cavaillon 2018).

ROS is essential to TLR4 activation of downstream signals including NF-kB. Activation of TLR4 promotes the surface expression and movement of TLR4 into signal-promoting lipid rafts (Nakahira, Kim et al. 2006; Powers, Szaszi et al. 2006). This signal promotion requires NADPH-oxidase and ROS (Park, Jung et al. 2004; Nakahira, Kim et al. 2006; Powers, Szaszi et al. 2006). ROS is also required for the TLR4/TRAF6/ASK-1/p38 dependent activation of inflammatory cytokines (Matsuzawa, Saegusa et al. 2005). ROS therefore amplifies the inflammatory process.

RONS can also fail to activate or actively inhibit inflammatory pathways, and the circumstances determining response to RONS are not well known (Gloire, Legrand-Poels et al. 2006).

Barcellos-Hoff, M. H. and T. A. Dix (1996). "Redox-mediated activation of latent transforming growth factor-beta 1." Mol Endocrinol 10(9): 1077-1083.

Blaser, H., C. Dostert, et al. (2016). "TNF and ROS Crosstalk in Inflammation." Trends in cell biology 26(4): 249-261.

Cavaillon, J.-M. (2018). Damage-associated Molecular Patterns. Inflammation: From Molecular and Cellular Mechanisms to the Clinic. J.-M. Cavaillon and M. Singer, Wiley-VCHVerlagGmbH&Co.KGaA.: 57-80.

Gloire, G., S. Legrand-Poels, et al. (2006). "NF-kappaB activation by reactive oxygen species: fifteen years later." Biochem Pharmacol 72(11): 1493-1505.

Jobling, M. F., J. D. Mott, et al. (2006). "Isoform-specific activation of latent transforming growth factor beta (LTGF-beta) by reactive oxygen species." Radiation research 166(6): 839-848.

Matsuzawa, A., K. Saegusa, et al. (2005). "ROS-dependent activation of the TRAF6-ASK1-p38 pathway is selectively required for TLR4-mediated innate immunity." Nat Immunol 6(6): 587-592.

Miller, M. F., W. H. Goodson, et al. (2017). "Low-Dose Mixture Hypothesis of Carcinogenesis Workshop: Scientific Underpinnings and Research Recommendations." Environmental health perspectives 125(2): 163-169.

Morgan, M. J. and Z. G. Liu (2011). "Crosstalk of reactive oxygen species and NF-kappaB signaling." Cell Res 21(1): 103-115.

Nakahira, K., H. P. Kim, et al. (2006). "Carbon monoxide differentially inhibits TLR signaling pathways by regulating ROS-induced trafficking of TLRs to lipid rafts." J Exp Med 203(10): 2377-2389.

Park, H. S., H. Y. Jung, et al. (2004). "Cutting edge: direct interaction of TLR4 with NAD(P)H oxidase 4 isozyme is essential for lipopolysaccharide-induced production of reactive oxygen species and activation of NF-kappa B." J Immunol 173(6): 3589-3593.

Powers, K. A., K. Szaszi, et al. (2006). "Oxidative stress generated by hemorrhagic shock recruits Toll-like receptor 4 to the plasma membrane in macrophages." J Exp Med 203(8): 1951-1961.

Ratikan, J. A., E. D. Micewicz, et al. (2015). "Radiation takes its Toll." Cancer Lett 368(2): 238-245.

Zhao, W. and M. E. Robbins (2009). "Inflammation and chronic oxidative stress in radiation-induced late normal tissue injury: therapeutic implications." Curr Med Chem 16(2): 130-143.

Domain of Applicability

A free-text section of the KER description that the developers can use to explain their rationale for the taxonomic, life stage, or sex applicability structured terms. More help


List of the literature that was cited for this KER description. More help

Ameziane-El-Hassani, R., M. Boufraqech, et al. (2010). "Role of H2O2 in RET/PTC1 chromosomal rearrangement produced by ionizing radiation in human thyroid cells." Cancer Res 70(10): 4123-4132.

Ameziane-El-Hassani, R., M. Talbot, et al. (2015). "NADPH oxidase DUOX1 promotes long-term persistence of oxidative stress after an exposure to irradiation." Proceedings of the National Academy of Sciences of the United States of America 112(16): 5051-5056.

Aziz, K., S. Nowsheen, et al. (2012). "Targeting DNA damage and repair: embracing the pharmacological era for successful cancer therapy." Pharmacology & therapeutics 133(3): 334-350.

Azzam, E. I., S. M. De Toledo, et al. (2002). "Oxidative metabolism modulates signal transduction and micronucleus formation in bystander cells from alpha-particle-irradiated normal human fibroblast cultures." Cancer research 62(19): 5436-5442.

Bensimon, J., D. Biard, et al. (2016). "Forced extinction of CD24 stem-like breast cancer marker alone promotes radiation resistance through the control of oxidative stress." Mol Carcinog 55(3): 245-254.

Berdelle, N., T. Nikolova, et al. (2011). "Artesunate induces oxidative DNA damage, sustained DNA double-strand breaks, and the ATM/ATR damage response in cancer cells." Molecular cancer therapeutics 10(12): 2224-2233.

Buonanno, M., S. M. de Toledo, et al. (2011). "Long-term consequences of radiation-induced bystander effects depend on radiation quality and dose and correlate with oxidative stress." Radiation research 175(4): 405-415.

Cadet, J., K. J. A. Davies, et al. (2017). "Formation and repair of oxidatively generated damage in cellular DNA." Free radical biology & medicine 107: 13-34.

Choi, K. M., C. M. Kang, et al. (2007). "Ionizing radiation-induced micronucleus formation is mediated by reactive oxygen species that are produced in a manner dependent on mitochondria, Nox1, and JNK." Oncol Rep 17(5): 1183-1188.

Dahm-Daphi, J., C. Sass, et al. (2000). "Comparison of biological effects of DNA damage induced by ionizing radiation and hydrogen peroxide in CHO cells." International journal of radiation biology 76(1): 67-75.

Datta, K., S. Suman, et al. (2012). "Exposure to heavy ion radiation induces persistent oxidative stress in mouse intestine." PLoS One 7(8): e42224.

Dayal, D., S. M. Martin, et al. (2008). "Hydrogen peroxide mediates the radiation-induced mutator phenotype in mammalian cells." Biochem J 413(1): 185-191.

Dayal, D., S. M. Martin, et al. (2009). "Mitochondrial complex II dysfunction can contribute significantly to genomic instability after exposure to ionizing radiation." Radiation research 172(6): 737-745.

Denissova, N. G., C. M. Nasello, et al. (2012). "Resveratrol protects mouse embryonic stem cells from ionizing radiation by accelerating recovery from DNA strand breakage." Carcinogenesis 33(1): 149-155.

Dickinson, B. C. and C. J. Chang (2011). "Chemistry and biology of reactive oxygen species in signaling or stress responses." Nature chemical biology 7(8): 504-511.

Douki, T., J. L. Ravanat, et al. (2006). "Minor contribution of direct ionization to DNA base damage inducedby heavy ions." International journal of radiation biology 82(2): 119-127.

Driessens, N., S. Versteyhe, et al. (2009). "Hydrogen peroxide induces DNA single- and double-strand breaks in thyroid cells and is therefore a potential mutagen for this organ." Endocrine-related cancer 16(3): 845-856.

Du, C., Z. Gao, et al. (2009). "Mitochondrial ROS and radiation induced transformation in mouse embryonic fibroblasts." Cancer Biol Ther 8(20): 1962-1971.

Fetisova, E. K., M. M. Antoschina, et al. (2015). "Radioprotective effects of mitochondria-targeted antioxidant SkQR1." Radiation research 183(1): 64-71.

Gradzka, I. and T. Iwanenko (2005). "A non-radioactive, PFGE-based assay for low levels of DNA double-strand breaks in mammalian cells." DNA repair 4(10): 1129-1139.

Han, W., S. Chen, et al. (2010). "Nitric oxide mediated DNA double strand breaks induced in proliferating bystander cells after alpha-particle irradiation." Mutation research 684(1-2): 81-89.

Ismail, I. H., S. Nystrom, et al. (2005). "Activation of ataxia telangiectasia mutated by DNA strand break-inducing agents correlates closely with the number of DNA double strand breaks." J Biol Chem 280(6): 4649-4655.

Jones, J. A., P. K. Riggs, et al. (2007). "Ionizing radiation-induced bioeffects in space and strategies to reduce cellular injury and carcinogenesis." Aviat Space Environ Med 78(4 Suppl): A67-78.

Liu, X. and J. L. Zweier (2001). "A real-time electrochemical technique for measurement of cellular hydrogen peroxide generation and consumption: evaluation in human polymorphonuclear leukocytes." Free radical biology & medicine 31(7): 894-901.

Lorat, Y., C. U. Brunner, et al. (2015). "Nanoscale analysis of clustered DNA damage after high-LET irradiation by quantitative electron microscopy--the heavy burden to repair." DNA repair 28: 93-106.

Manna, K., U. Das, et al. (2015). "Naringin inhibits gamma radiation-induced oxidative DNA damage and inflammation, by modulating p53 and NF-kappaB signaling pathways in murine splenocytes." Free Radic Res 49(4): 422-439.

Martin, N. T., K. Nakamura, et al. (2014). "Homozygous mutation of MTPAP causes cellular radiosensitivity and persistent DNA double-strand breaks." Cell Death Dis 5: e1130.

Murnane, J. P. (2012). "Telomere dysfunction and chromosome instability." Mutation research 730(1-2): 28-36.

Nakamura, J., E. R. Purvis, et al. (2003). "Micromolar concentrations of hydrogen peroxide induce oxidative DNA lesions more efficiently than millimolar concentrations in mammalian cells." Nucleic acids research 31(6): 1790-1795.

Oya, Y., K. Yamamoto, et al. (1986). "The biological activity of hydrogen peroxide. I. Induction of chromosome-type aberrations susceptible to inhibition by scavengers of hydroxyl radicals in human embryonic fibroblasts." Mutation research 172(3): 245-253.

Ozyurt, H., O. Cevik, et al. (2014). "Quercetin protects radiation-induced DNA damage and apoptosis in kidney and bladder tissues of rats." Free Radic Res 48(10): 1247-1255.

Pazhanisamy, S. K., H. Li, et al. (2011). "NADPH oxidase inhibition attenuates total body irradiation-induced haematopoietic genomic instability." Mutagenesis 26(3): 431-435.

Saenko, Y., A. Cieslar-Pobuda, et al. (2013). "Changes of reactive oxygen and nitrogen species and mitochondrial functioning in human K562 and HL60 cells exposed to ionizing radiation." Radiation research 180(4): 360-366.

Sandhu, J. K. and H. C. Birnboim (1997). "Mutagenicity and cytotoxicity of reactive oxygen and nitrogen species in the MN-11 murine tumor cell line." Mutation research 379(2): 241-252.

Seager, A. L., U. K. Shah, et al. (2012). "Pro-oxidant induced DNA damage in human lymphoblastoid cells: homeostatic mechanisms of genotoxic tolerance." Toxicological sciences : an official journal of the Society of Toxicology 128(2): 387-397.

Sharma, V., L. B. Collins, et al. (2016). "Oxidative stress at low levels can induce clustered DNA lesions leading to NHEJ mediated mutations." Oncotarget 7(18): 25377-25390.

Stanicka, J., E. G. Russell, et al. (2015). "NADPH oxidase-generated hydrogen peroxide induces DNA damage in mutant FLT3-expressing leukemia cells." The Journal of biological chemistry 290(15): 9348-9361.

Suzuki, K., G. Kashino, et al. (2009). "Long-term persistence of X-ray-induced genomic instability in quiescent normal human diploid cells." Mutation research 671(1-2): 33-39.

Tubbs, A. and A. Nussenzweig (2017). "Endogenous DNA Damage as a Source of Genomic Instability in Cancer." Cell 168(4): 644-656.

Werner, E., H. Wang, et al. (2014). "Opposite roles for p38MAPK-driven responses and reactive oxygen species in the persistence and resolution of radiation-induced genomic instability." PLoS One 9(10): e108234.

Winyard, P. G., S. P. Faux, et al. (1992). "Bleomycin-induced unscheduled DNA synthesis in non-permeabilized human and rat hepatocytes is not paralleled by 8-oxo-7,8-dihydrodeoxyguanosine formation." Biochem Pharmacol 44(7): 1255-1260.

Yang, H., V. Anzenberg, et al. (2007). "The time dependence of bystander responses induced by iron-ion radiation in normal human skin fibroblasts." Radiation research 168(3): 292-298.

Yang, H., N. Asaad, et al. (2005). "Medium-mediated intercellular communication is involved in bystander responses of X-ray-irradiated normal human fibroblasts." Oncogene 24(12): 2096-2103.

Yang, Y., M. Durando, et al. (2013). "Cell cycle stage-specific roles of Rad18 in tolerance and repair of oxidative DNA damage." Nucleic acids research 41(4): 2296-2312.

Yoshida, T., S. Goto, et al. (2012). "Mitochondrial dysfunction, a probable cause of persistent oxidative stress after exposure to ionizing radiation." Free Radic Res 46(2): 147-153.

Zhou, H., V. N. Ivanov, et al. (2008). "Mitochondrial function and nuclear factor-kappaB-mediated signaling in radiation-induced bystander effects." Cancer Res 68(7): 2233-2240.