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Toprani SM, Scheibler C, Mordukhovich I, McNeely E, Nagel ZD. Cosmic Ionizing Radiation: A DNA Damaging Agent That May Underly Excess Cancer in Flight Crews. Int J Mol Sci 2024; 25:7670. [PMID: 39062911 DOI: 10.3390/ijms25147670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 06/20/2024] [Accepted: 06/30/2024] [Indexed: 07/28/2024] Open
Abstract
In the United States, the Federal Aviation Administration has officially classified flight crews (FC) consisting of commercial pilots, cabin crew, or flight attendants as "radiation workers" since 1994 due to the potential for cosmic ionizing radiation (CIR) exposure at cruising altitudes originating from solar activity and galactic sources. Several epidemiological studies have documented elevated incidence and mortality for several cancers in FC, but it has not yet been possible to establish whether this is attributable to CIR. CIR and its constituents are known to cause a myriad of DNA lesions, which can lead to carcinogenesis unless DNA repair mechanisms remove them. But critical knowledge gaps exist with regard to the dosimetry of CIR, the role of other genotoxic exposures among FC, and whether possible biological mechanisms underlying higher cancer rates observed in FC exist. This review summarizes our understanding of the role of DNA damage and repair responses relevant to exposure to CIR in FC. We aimed to stimulate new research directions and provide information that will be useful for guiding regulatory, public health, and medical decision-making to protect and mitigate the risks for those who travel by air.
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Affiliation(s)
- Sneh M Toprani
- John B. Little Center for Radiation Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Christopher Scheibler
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Irina Mordukhovich
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Sustainability and Health Initiative (SHINE), Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA
| | - Eileen McNeely
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Sustainability and Health Initiative (SHINE), Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA
| | - Zachary D Nagel
- John B. Little Center for Radiation Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
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Rødland GE, Temelie M, Eek Mariampillai A, Hauge S, Gilbert A, Chevalier F, Savu DI, Syljuåsen RG. Potential Benefits of Combining Proton or Carbon Ion Therapy with DNA Damage Repair Inhibitors. Cells 2024; 13:1058. [PMID: 38920686 PMCID: PMC11201490 DOI: 10.3390/cells13121058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 06/27/2024] Open
Abstract
The use of charged particle radiotherapy is currently increasing, but combination therapy with DNA repair inhibitors remains to be exploited in the clinic. The high-linear energy transfer (LET) radiation delivered by charged particles causes clustered DNA damage, which is particularly effective in destroying cancer cells. Whether the DNA damage response to this type of damage is different from that elicited in response to low-LET radiation, and if and how it can be targeted to increase treatment efficacy, is not fully understood. Although several preclinical studies have reported radiosensitizing effects when proton or carbon ion irradiation is combined with inhibitors of, e.g., PARP, ATR, ATM, or DNA-PKcs, further exploration is required to determine the most effective treatments. Here, we examine what is known about repair pathway choice in response to high- versus low-LET irradiation, and we discuss the effects of inhibitors of these pathways when combined with protons and carbon ions. Additionally, we explore the potential effects of DNA repair inhibitors on antitumor immune signaling upon proton and carbon ion irradiation. Due to the reduced effect on healthy tissue and better immune preservation, particle therapy may be particularly well suited for combination with DNA repair inhibitors.
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Affiliation(s)
- Gro Elise Rødland
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Mihaela Temelie
- Department of Life and Environmental Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering, 077125 Magurele, Romania
| | - Adrian Eek Mariampillai
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Sissel Hauge
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Antoine Gilbert
- UMR6252 CIMAP, Team Applications in Radiobiology with Accelerated Ions, CEA-CNRS-ENSICAEN-Université de Caen Normandie, 14000 Caen, France (F.C.)
| | - François Chevalier
- UMR6252 CIMAP, Team Applications in Radiobiology with Accelerated Ions, CEA-CNRS-ENSICAEN-Université de Caen Normandie, 14000 Caen, France (F.C.)
| | - Diana I. Savu
- Department of Life and Environmental Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering, 077125 Magurele, Romania
| | - Randi G. Syljuåsen
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
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Li Z, Wang Y. Short Double-Stranded DNA (≤40-bp) Affects Repair Pathway Choice. Int J Mol Sci 2023; 24:11836. [PMID: 37511594 PMCID: PMC10380458 DOI: 10.3390/ijms241411836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
To repair ionizing radiation (IR)-induced double strand breaks (DSBs), mammalian cells primarily use canonical non-homologous end-joining (cNHEJ), the homologous recombination (HR) pathway, and the alternative non-homologous end-joining (aEJ) as a backup. These pathways function either compensatively or competitively. High linear energy transfer (LET) compared to low-LET IR kills more cells at the same doses by inhibiting only cNHEJ, but not HR or aEJ. The mechanism remains unclear. The activation of each repair pathway requires the binding of different proteins to DNA fragments of varying lengths. We previously observed an increased generation of small DNA fragments (≤40 bp) in cells following high-LET IR compared to low-LET IR, suggesting that short DNA fragments were one of the major factors interfering with cNHEJ. To provide direct evidence, here we compare the efficiencies of cNHEJ, HR, or aEJ in repairing DSBs containing 30- or 60-bp fragments in vitro and in cells. We show that only cNHEJ but not HR or a-EJ was inefficient for repairing DSBs with 30-bp fragments compared to 60-bp ones, which strongly supports our hypothesis. These results not only enhance our understanding of the DSB repair pathway choice but also hold potential benefits for protection against high-LET IR-induced damage or improving high-LET radiotherapy.
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Affiliation(s)
- Zhentian Li
- Department of Radiation Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ya Wang
- Department of Radiation Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
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Wilkinson B, Hill MA, Parsons JL. The Cellular Response to Complex DNA Damage Induced by Ionising Radiation. Int J Mol Sci 2023; 24:4920. [PMID: 36902352 PMCID: PMC10003081 DOI: 10.3390/ijms24054920] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/24/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023] Open
Abstract
Radiotherapy (ionising radiation; IR) is utilised in the treatment of ~50% of all human cancers, and where the therapeutic effect is largely achieved through DNA damage induction. In particular, complex DNA damage (CDD) containing two or more lesions within one to two helical turns of the DNA is a signature of IR and contributes significantly to the cell killing effects due to the difficult nature of its repair by the cellular DNA repair machinery. The levels and complexity of CDD increase with increasing ionisation density (linear energy transfer, LET) of the IR, such that photon (X-ray) radiotherapy is deemed low-LET whereas some particle ions (such as carbon ions) are high-LET radiotherapy. Despite this knowledge, there are challenges in the detection and quantitative measurement of IR-induced CDD in cells and tissues. Furthermore, there are biological uncertainties with the specific DNA repair proteins and pathways, including components of DNA single and double strand break mechanisms, that are engaged in CDD repair, which very much depends on the radiation type and associated LET. However, there are promising signs that advancements are being made in these areas and which will enhance our understanding of the cellular response to CDD induced by IR. There is also evidence that targeting CDD repair, particularly through inhibitors against selected DNA repair enzymes, can exacerbate the impact of higher LET, which could be explored further in a translational context.
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Affiliation(s)
- Beth Wilkinson
- Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6 West Derby Street, Liverpool L7 8TX, UK
| | - Mark A. Hill
- MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Jason L. Parsons
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Huang CY, Lai ZY, Hsu TJ, Chou FI, Liu HM, Chuang YJ. Boron Neutron Capture Therapy Eliminates Radioresistant Liver Cancer Cells by Targeting DNA Damage and Repair Responses. J Hepatocell Carcinoma 2022; 9:1385-1401. [PMID: 36600987 PMCID: PMC9807134 DOI: 10.2147/jhc.s383959] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 12/04/2022] [Indexed: 12/29/2022] Open
Abstract
Introduction For advanced hepatocellular carcinoma (HCC), resistance to conservative treatments remains a challenge. In previous studies, the therapeutic effectiveness and DNA damage responses of boric acid-mediated boron neutron capture therapy (BA-BNCT) in HCC have been demonstrated in animal models and HCC cell line. On the other hand, numerous studies have shown that high linear energy transfer (LET) radiation can overcome tumor resistance. Since BNCT yields a mixture of high and low LET radiation, we aimed to explore whether and how BA-BNCT could eliminate radioresistant HCC cells. Methods Radioresistant human HCC (HepG2-R) cells were established from HepG2 cells via intermittent irradiation. HepG2 and HepG2-R cells were then irradiated with either γ-ray or neutron radiation of BA-BNCT. Colony formation assays were used to assess cell survival and the relative biological effectiveness (RBE). The expression of phosphorylated H2AX (γH2AX) was also examined by immunocytochemistry and Western blot assays to evaluate the extent of DNA double-strand breaks (DSBs). Finally, the expression levels of DNA damage response-associated proteins were determined, followed by cell cycle analysis and caspase-3 activity analysis. Results Our data demonstrated that under the same dose by γ-ray, BNCT effectively eliminated radioresistant HCC by increasing the number of DNA DSBs (p < 0.05) and impeding their repair (p < 0.05), which verified the high RBE of BNCT. We also found that BNCT resulted in delayed homologous recombination (HR) and inhibited the nonhomologous end-joining (NHEJ) pathway during DNA repair. Markedly, BNCT increased cell arrest (p < 0.05) in the G2/M phase by altering G2 checkpoint signaling and increased PUMA-mediated apoptosis (p < 0.05). Conclusion Our data suggest that DNA damage and repair responses could affect the anticancer efficiency of BNCT in radioresistant HepG2-R cells, which highlights the potential of BNCT as a viable treatment option for recurrent HCC.
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Affiliation(s)
- Chu-Yu Huang
- School of Medicine, National Tsing Hua University, Hsinchu, Taiwan,Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan,Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan
| | - Zih-Yin Lai
- School of Medicine, National Tsing Hua University, Hsinchu, Taiwan,Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan,Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan
| | - Tzu-Jung Hsu
- School of Medicine, National Tsing Hua University, Hsinchu, Taiwan,Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan,Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan
| | - Fong-In Chou
- Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan
| | - Hong-Ming Liu
- Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan
| | - Yung-Jen Chuang
- School of Medicine, National Tsing Hua University, Hsinchu, Taiwan,Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan,Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan,Correspondence: Yung-Jen Chuang, School of Medicine, National Tsing Hua University, Hsinchu, 300044, Taiwan, Tel +886-3-5742764, Fax +886-3-5715934, Email
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Mladenova V, Mladenov E, Chaudhary S, Stuschke M, Iliakis G. The high toxicity of DSB-clusters modelling high-LET-DNA damage derives from inhibition of c-NHEJ and promotion of alt-EJ and SSA despite increases in HR. Front Cell Dev Biol 2022; 10:1016951. [PMID: 36263011 PMCID: PMC9574094 DOI: 10.3389/fcell.2022.1016951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 09/14/2022] [Indexed: 11/13/2022] Open
Abstract
Heavy-ion radiotherapy utilizing high linear energy transfer (high-LET) ionizing radiation (IR) is a promising cancer treatment modality owing to advantageous physical properties of energy deposition and associated toxicity over X-rays. Therapies utilizing high-LET radiation will benefit from a better understanding of the molecular mechanisms underpinning their increased biological efficacy. Towards this goal, we investigate here the biological consequences of well-defined clusters of DNA double-strand breaks (DSBs), a form of DNA damage, which on theoretical counts, has often been considered central to the enhanced toxicity of high-LET IR. We test clonal cell lines harboring in their genomes constructs with appropriately engineered I-SceI recognition sites that convert upon I-SceI expression to individual DSBs, or DSB-clusters comprising known numbers of DSBs with defined DNA-ends. We find that, similarly to high-LET IR, DSB-clusters of increasing complexity, i.e. increasing numbers of DSBs, with compatible or incompatible ends, compromise classical non-homologous end-joining, favor DNA end-resection and promote resection-dependent DSB-processing. Analysis of RAD51 foci shows increased engagement of error-free homologous recombination on DSB-clusters. Multicolor fluorescence in situ hybridization analysis shows that complex DSB-clusters markedly increase the incidence of structural chromosomal abnormalities (SCAs). Since RAD51-knockdown further increases SCAs-incidence, we conclude that homologous recombination suppresses SCAs-formation. Strikingly, CtIP-depletion inhibits SCAs-formation, suggesting that it relies on alternative end-joining or single-strand annealing. Indeed, ablation of RAD52 causes a marked reduction in SCAs, as does also inhibition of PARP1. We conclude that increased DSB-cluster formation that accompanies LET-increases, enhances IR-effectiveness by promoting DNA end-resection, which suppresses c-NHEJ and enhances utilization of alt-EJ or SSA. Although increased resection also favors HR, on balance, error-prone processing dominates, causing the generally observed increased toxicity of high-LET radiation. These findings offer new mechanistic insights into high-LET IR-toxicity and have translational potential in the clinical setting that may be harnessed by combining high-LET IR with inhibitors of PARP1 or RAD52.
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Affiliation(s)
- Veronika Mladenova
- Department of Radiation Therapy, Division of Experimental Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Emil Mladenov
- Department of Radiation Therapy, Division of Experimental Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Shipra Chaudhary
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- Institute for Advanced Biosciences, Inserm U 1209 / CNRS UMR 5309 Joint Research Center, Grenoble Alpes University, Grenoble, France
| | - Martin Stuschke
- Department of Radiation Therapy, Division of Experimental Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - George Iliakis
- Department of Radiation Therapy, Division of Experimental Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- *Correspondence: George Iliakis,
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Frame CM, Chen Y, Gagnon J, Yuan Y, Ma T, Dritschilo A, Pang D. Proton induced DNA double strand breaks at the Bragg peak: Evidence of enhanced LET effect. Front Oncol 2022; 12:930393. [PMID: 35992825 PMCID: PMC9388940 DOI: 10.3389/fonc.2022.930393] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
PurposeTo investigate DNA double strand breaks (DSBs) induced by therapeutic proton beams in plateau and Bragg peak to demonstrate DSB induction due to the higher LET in the Bragg peak.Materials and MethodspUC19 plasmid DNA samples were irradiated to doses of 1000 and 3000 Gy on a Mevion S250i proton system with a monoenergetic, 110 MeV, proton beam at depths of 2 and 9.4 cm, corresponding to a position on the plateau and distal Bragg peak of the beam, respectively. The irradiated DNA samples were imaged by atomic force microscopy for visualization of individual DNA molecules, either broken or intact, and quantification of the DNA fragment length distributions for each of the irradiated samples. Percentage of the broken DNA and average number of DSBs per DNA molecule were obtained.ResultsCompared to irradiation effects in the plateau region, DNA irradiated at the Bragg peak sustained more breakage at the same dose, yielding more short DNA fragments and higher numbers of DSB per DNA molecule.ConclusionThe higher LET of proton beams at the Bragg peak results in more densely distributed DNA DSBs, which supports an underlying mechanism for the increased cell killing by protons at the Bragg peak.
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Danforth JM, Provencher L, Goodarzi AA. Chromatin and the Cellular Response to Particle Radiation-Induced Oxidative and Clustered DNA Damage. Front Cell Dev Biol 2022; 10:910440. [PMID: 35912116 PMCID: PMC9326100 DOI: 10.3389/fcell.2022.910440] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/21/2022] [Indexed: 12/03/2022] Open
Abstract
Exposure to environmental ionizing radiation is prevalent, with greatest lifetime doses typically from high Linear Energy Transfer (high-LET) alpha particles via the radioactive decay of radon gas in indoor air. Particle radiation is highly genotoxic, inducing DNA damage including oxidative base lesions and DNA double strand breaks. Due to the ionization density of high-LET radiation, the consequent damage is highly clustered wherein ≥2 distinct DNA lesions occur within 1–2 helical turns of one another. These multiply-damaged sites are difficult for eukaryotic cells to resolve either quickly or accurately, resulting in the persistence of DNA damage and/or the accumulation of mutations at a greater rate per absorbed dose, relative to lower LET radiation types. The proximity of the same and different types of DNA lesions to one another is challenging for DNA repair processes, with diverse pathways often confounding or interplaying with one another in complex ways. In this context, understanding the state of the higher order chromatin compaction and arrangements is essential, as it influences the density of damage produced by high-LET radiation and regulates the recruitment and activity of DNA repair factors. This review will summarize the latest research exploring the processes by which clustered DNA damage sites are induced, detected, and repaired in the context of chromatin.
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DNA Damage Clustering after Ionizing Radiation and Consequences in the Processing of Chromatin Breaks. Molecules 2022; 27:molecules27051540. [PMID: 35268641 PMCID: PMC8911773 DOI: 10.3390/molecules27051540] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 11/26/2022] Open
Abstract
Charged-particle radiotherapy (CPRT) utilizing low and high linear energy transfer (low-/high-LET) ionizing radiation (IR) is a promising cancer treatment modality having unique physical energy deposition properties. CPRT enables focused delivery of a desired dose to the tumor, thus achieving a better tumor control and reduced normal tissue toxicity. It increases the overall radiation tolerance and the chances of survival for the patient. Further improvements in CPRT are expected from a better understanding of the mechanisms governing the biological effects of IR and their dependence on LET. There is increasing evidence that high-LET IR induces more complex and even clustered DNA double-strand breaks (DSBs) that are extremely consequential to cellular homeostasis, and which represent a considerable threat to genomic integrity. However, from the perspective of cancer management, the same DSB characteristics underpin the expected therapeutic benefit and are central to the rationale guiding current efforts for increased implementation of heavy ions (HI) in radiotherapy. Here, we review the specific cellular DNA damage responses (DDR) elicited by high-LET IR and compare them to those of low-LET IR. We emphasize differences in the forms of DSBs induced and their impact on DDR. Moreover, we analyze how the distinct initial forms of DSBs modulate the interplay between DSB repair pathways through the activation of DNA end resection. We postulate that at complex DSBs and DSB clusters, increased DNA end resection orchestrates an increased engagement of resection-dependent repair pathways. Furthermore, we summarize evidence that after exposure to high-LET IR, error-prone processes outcompete high fidelity homologous recombination (HR) through mechanisms that remain to be elucidated. Finally, we review the high-LET dependence of specific DDR-related post-translational modifications and the induction of apoptosis in cancer cells. We believe that in-depth characterization of the biological effects that are specific to high-LET IR will help to establish predictive and prognostic signatures for use in future individualized therapeutic strategies, and will enhance the prospects for the development of effective countermeasures for improved radiation protection during space travel.
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Zhou Q, Howard ME, Tu X, Zhu Q, Denbeigh JM, Remmes NB, Herman MG, Beltran CJ, Yuan J, Greipp PT, Boughey JC, Wang L, Johnson N, Goetz MP, Sarkaria JN, Lou Z, Mutter RW. Inhibition of ATM Induces Hypersensitivity to Proton Irradiation by Upregulating Toxic End Joining. Cancer Res 2021; 81:3333-3346. [PMID: 33597272 PMCID: PMC8260463 DOI: 10.1158/0008-5472.can-20-2960] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 12/30/2020] [Accepted: 02/11/2021] [Indexed: 12/15/2022]
Abstract
Proton Bragg peak irradiation has a higher ionizing density than conventional photon irradiation or the entrance of the proton beam profile. Whether targeting the DNA damage response (DDR) could enhance vulnerability to the distinct pattern of damage induced by proton Bragg peak irradiation is currently unknown. Here, we performed genetic or pharmacologic manipulation of key DDR elements and evaluated DNA damage signaling, DNA repair, and tumor control in cell lines and xenografts treated with the same physical dose across a radiotherapy linear energy transfer spectrum. Radiotherapy consisted of 6 MV photons and the entrance beam or Bragg peak of a 76.8 MeV spot scanning proton beam. More complex DNA double-strand breaks (DSB) induced by Bragg peak proton irradiation preferentially underwent resection and engaged homologous recombination (HR) machinery. Unexpectedly, the ataxia-telangiectasia mutated (ATM) inhibitor, AZD0156, but not an inhibitor of ATM and Rad3-related, rendered cells hypersensitive to more densely ionizing proton Bragg peak irradiation. ATM inhibition blocked resection and shunted more DSBs to processing by toxic ligation through nonhomologous end-joining, whereas loss of DNA ligation via XRCC4 or Lig4 knockdown rescued resection and abolished the enhanced Bragg peak cell killing. Proton Bragg peak monotherapy selectively sensitized cell lines and tumor xenografts with inherent HR defects, and the repair defect induced by ATM inhibitor coadministration showed enhanced efficacy in HR-proficient models. In summary, inherent defects in HR or administration of an ATM inhibitor in HR-proficient tumors selectively enhances the relative biological effectiveness of proton Bragg peak irradiation. SIGNIFICANCE: Coadministration of an ATM inhibitor rewires DNA repair machinery to render cancer cells uniquely hypersensitive to DNA damage induced by the proton Bragg peak, which is characterized by higher density ionization.See related commentary by Nickoloff, p. 3156.
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Affiliation(s)
- Qin Zhou
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Xinyi Tu
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Qian Zhu
- Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Janet M Denbeigh
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Michael G Herman
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Chris J Beltran
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Jian Yuan
- Department of Oncology, Mayo Clinic, Rochester, Minnesota
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Patricia T Greipp
- Division of Laboratory Genetics and Genomics, Mayo Clinic, Rochester, Minnesota
| | - Judy C Boughey
- Department of Surgery, Mayo Clinic, Rochester, Minnesota
| | - Liewei Wang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Neil Johnson
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Matthew P Goetz
- Division of Medical Oncology, Mayo Clinic, Rochester, Minnesota
| | - Jann N Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Zhenkun Lou
- Department of Oncology, Mayo Clinic, Rochester, Minnesota.
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Robert W Mutter
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
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Nickoloff JA. Toward Greater Precision in Cancer Radiotherapy. Cancer Res 2021; 81:3156-3157. [PMID: 34224374 DOI: 10.1158/0008-5472.can-21-0664] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 11/16/2022]
Abstract
The cellular DNA damage response (DDR) is a key factor in tumor suppression and tumor responses to genotoxic chemo- and radiotherapy. Master DDR regulators include three phosphatidyl inositol 3' kinase-related kinases (PIKK) called ATM, ATR, and the catalytic subunit of DNA-dependent protein kinase, DNA-PKcs. Among their many functions, PIKKs regulate repair of DNA double-strand breaks (DSB) by homologous recombination (HR) and nonhomologous end-joining (NHEJ). Ionizing radiation induces DSBs that are either widely dispersed and efficiently repaired, or clustered and poorly repaired by the dominant NHEJ pathway. The inefficient repair of clustered DSBs by NHEJ shifts repair toward the competing HR pathway. In this issue of Cancer Research, Zhou and colleagues revealed a novel synthetic lethal approach in which the greater dependency on HR to repair clustered DSBs induced by protons is exploited to enhance killing of tumor cells and tumor xenografts by suppressing HR with an ATM inhibitor or mutant BRCA1. This is an important step toward precision cancer radiotherapy.See related article by Zhou et al., p. 3333.
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Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado.
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12
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Harrell K, Day M, Smolikove S. Recruitment of MRE-11 to complex DNA damage is modulated by meiosis-specific chromosome organization. Mutat Res 2021; 822:111743. [PMID: 33975127 DOI: 10.1016/j.mrfmmm.2021.111743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/11/2021] [Accepted: 04/15/2021] [Indexed: 12/15/2022]
Abstract
DNA double-strand breaks (DSBs) are one of the most dangerous assaults on the genome, and yet their natural and programmed production are inherent to life. When DSBs arise close together they are particularly deleterious, and their repair may require an altered form of the DNA damage response. Our understanding of how clustered DSBs are repaired in the germline is unknown. Using laser microirradiation, we examine early events in the repair of clustered DSBs in germ cells within Caenorhabditis elegans. We use precise temporal resolution to show how the recruitment of MRE-11 to complex damage is regulated, and that clustered DNA damage can recruit proteins from various repair pathways. Abrogation of non-homologous end joining or COM-1 attenuates the recruitment of MRE-11 through distinct mechanisms. The synaptonemal complex plays both positive and negative regulatory roles in these mutant contexts. These findings indicate that MRE-11 is regulated by modifying its accessibility to chromosomes.
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Affiliation(s)
- Kailey Harrell
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA
| | - Madison Day
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA
| | - Sarit Smolikove
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA.
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13
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Nickoloff JA, Taylor L, Sharma N, Kato TA. Exploiting DNA repair pathways for tumor sensitization, mitigation of resistance, and normal tissue protection in radiotherapy. CANCER DRUG RESISTANCE (ALHAMBRA, CALIF.) 2021; 4:244-263. [PMID: 34337349 PMCID: PMC8323830 DOI: 10.20517/cdr.2020.89] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
More than half of cancer patients are treated with radiotherapy, which kills tumor cells by directly and indirectly inducing DNA damage, including cytotoxic DNA double-strand breaks (DSBs). Tumor cells respond to these threats by activating a complex signaling network termed the DNA damage response (DDR). The DDR arrests the cell cycle, upregulates DNA repair, and triggers apoptosis when damage is excessive. The DDR signaling and DNA repair pathways are fertile terrain for therapeutic intervention. This review highlights strategies to improve therapeutic gain by targeting DDR and DNA repair pathways to radiosensitize tumor cells, overcome intrinsic and acquired tumor radioresistance, and protect normal tissue. Many biological and environmental factors determine tumor and normal cell responses to ionizing radiation and genotoxic chemotherapeutics. These include cell type and cell cycle phase distribution; tissue/tumor microenvironment and oxygen levels; DNA damage load and quality; DNA repair capacity; and susceptibility to apoptosis or other active or passive cell death pathways. We provide an overview of radiobiological parameters associated with X-ray, proton, and carbon ion radiotherapy; DNA repair and DNA damage signaling pathways; and other factors that regulate tumor and normal cell responses to radiation. We then focus on recent studies exploiting DSB repair pathways to enhance radiotherapy therapeutic gain.
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Affiliation(s)
- Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
- Correspondence Address: Dr. Jac A. Nickoloff, Department of Environmental and Radiological Health Sciences, Colorado State University, 1681 Campus Delivery, Ft. Collins, CO 80523-1681, USA. E-mail:
| | - Lynn Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
| | - Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
| | - Takamitsu A. Kato
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
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14
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Tsai L, Lopezcolorado F, Bhargava R, Mendez-Dorantes C, Jahanshir E, Stark J. RNF8 has both KU-dependent and independent roles in chromosomal break repair. Nucleic Acids Res 2020; 48:6032-6052. [PMID: 32427332 PMCID: PMC7293022 DOI: 10.1093/nar/gkaa380] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/10/2020] [Accepted: 04/30/2020] [Indexed: 12/19/2022] Open
Abstract
Chromosomal double strand breaks (DSBs) can initiate several signaling events, such as ubiquitination, however the precise influence of such signaling on DSB repair outcomes remains poorly understood. With an RNA interference screen, we found that the E3 ubiquitin ligase RNF8 suppresses a deletion rearrangement mediated by canonical non-homologous end joining (C-NHEJ). We also found that RNF8 suppresses EJ without insertion/deletion mutations, which is a hallmark of C-NHEJ. Conversely, RNF8 promotes alternative EJ (ALT-EJ) events involving microhomology that is embedded from the edge of the DSB. These ALT-EJ events likely require limited end resection, whereas RNF8 is not required for single-strand annealing repair involving extensive end resection. Thus, RNF8 appears to specifically facilitate repair events requiring limited end resection, which we find is dependent on the DSB end protection factor KU. However, we also find that RNF8 is important for homology-directed repair (HDR) independently of KU, which appears linked to promoting PALB2 function. Finally, the influence of RNF8 on EJ is distinct from 53BP1 and the ALT-EJ factor, POLQ. We suggest that RNF8 mediates both ALT-EJ and HDR, but via distinct mechanisms, since only the former is dependent on KU.
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Affiliation(s)
- Linda Jillianne Tsai
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
| | | | - Ragini Bhargava
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
| | - Carlos Mendez-Dorantes
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
| | - Eva Jahanshir
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
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15
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Simpson SR, Hemphill WO, Hudson T, Perrino FW. TREX1 - Apex predator of cytosolic DNA metabolism. DNA Repair (Amst) 2020; 94:102894. [PMID: 32615442 DOI: 10.1016/j.dnarep.2020.102894] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 06/03/2020] [Indexed: 12/13/2022]
Abstract
The cytosolic Three prime Repair EXonuclease 1 (TREX1) is a powerful DNA-degrading enzyme required for clearing cytosolic DNA to prevent aberrant inflammation and autoimmunity. In the absence of TREX1 activity, cytosolic DNA pattern recognition receptors of the innate immune system are constitutively activated by undegraded TREX1 substrates. This triggers a chronic inflammatory response in humans expressing mutant TREX1 alleles, eliciting a spectrum of rare autoimmune diseases dependent on the nature of the mutation. The precise origins of cytosolic DNA targeted by TREX1 continue to emerge, but DNA emerging from the nucleus or taken up by the cell could represent potential sources. In this Review, we explore the biochemical and immunological data supporting the role of TREX1 in suppressing cytosolic DNA sensing, and discuss the possibility that TREX1 may contribute to maintenance of genome integrity.
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Affiliation(s)
- Sean R Simpson
- Department of Biochemistry, Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States
| | - Wayne O Hemphill
- Department of Biochemistry, Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States
| | - Teesha Hudson
- Department of Biochemistry, Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States
| | - Fred W Perrino
- Department of Biochemistry, Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States.
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16
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Cornforth MN. Occam's broom and the dirty DSB: cytogenetic perspectives on cellular response to changes in track structure and ionization density. Int J Radiat Biol 2020; 97:1099-1108. [PMID: 31971454 DOI: 10.1080/09553002.2019.1704302] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/30/2019] [Accepted: 11/11/2019] [Indexed: 12/19/2022]
Abstract
Given equal doses, it is well-known that densely ionizing radiations are more potent in causing a number of biological effects compared to sparsely ionizing radiations, such as x- or gamma rays. According to classical models of radiation action, this results from differences in the spatial distribution of lesions along charged particle tracks. In recent years investigators have been barraged with the alternative narrative that this is instead due to 'qualitative' differences in the types of molecular lesions that each type of radiation produces. The present review discusses, mainly from a cytogenetic perspective, the merits and shortcomings of these seemingly contradictory viewpoints. There may be a kernel of truth to the idea that qualitative differences in the types of molecular lesions produced at the nanometer level affect RBE/LET relationships, but to ignore the fact that such differences result from longer-range spatial distributions of lesions produced along charged particle tracks is an unjustifiably narrow stance tantamount to employing Occam's Broom. Not only are such spatial considerations indispensable in explaining the impact of ionization density upon higher-order biological endpoints, particularly chromosome aberrations, the explanations they provide render arguments based principally on the quality of IR damage largely superfluous.
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Affiliation(s)
- Michael N Cornforth
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, TX, USA
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17
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Nickoloff JA, Sharma N, Taylor L. Clustered DNA Double-Strand Breaks: Biological Effects and Relevance to Cancer Radiotherapy. Genes (Basel) 2020; 11:E99. [PMID: 31952359 PMCID: PMC7017136 DOI: 10.3390/genes11010099] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/08/2020] [Accepted: 01/14/2020] [Indexed: 01/03/2023] Open
Abstract
Cells manage to survive, thrive, and divide with high accuracy despite the constant threat of DNA damage. Cells have evolved with several systems that efficiently repair spontaneous, isolated DNA lesions with a high degree of accuracy. Ionizing radiation and a few radiomimetic chemicals can produce clustered DNA damage comprising complex arrangements of single-strand damage and DNA double-strand breaks (DSBs). There is substantial evidence that clustered DNA damage is more mutagenic and cytotoxic than isolated damage. Radiation-induced clustered DNA damage has proven difficult to study because the spectrum of induced lesions is very complex, and lesions are randomly distributed throughout the genome. Nonetheless, it is fairly well-established that radiation-induced clustered DNA damage, including non-DSB and DSB clustered lesions, are poorly repaired or fail to repair, accounting for the greater mutagenic and cytotoxic effects of clustered lesions compared to isolated lesions. High linear energy transfer (LET) charged particle radiation is more cytotoxic per unit dose than low LET radiation because high LET radiation produces more clustered DNA damage. Studies with I-SceI nuclease demonstrate that nuclease-induced DSB clusters are also cytotoxic, indicating that this cytotoxicity is independent of radiogenic lesions, including single-strand lesions and chemically "dirty" DSB ends. The poor repair of clustered DSBs at least in part reflects inhibition of canonical NHEJ by short DNA fragments. This shifts repair toward HR and perhaps alternative NHEJ, and can result in chromothripsis-mediated genome instability or cell death. These principals are important for cancer treatment by low and high LET radiation.
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Affiliation(s)
- Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA; (N.S.); (L.T.)
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18
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Scherthan H, Lee JH, Maus E, Schumann S, Muhtadi R, Chojowski R, Port M, Lassmann M, Bestvater F, Hausmann M. Nanostructure of Clustered DNA Damage in Leukocytes after In-Solution Irradiation with the Alpha Emitter Ra-223. Cancers (Basel) 2019; 11:cancers11121877. [PMID: 31779276 PMCID: PMC6966434 DOI: 10.3390/cancers11121877] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/22/2019] [Accepted: 11/23/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Cancer patients are increasingly treated with alpha-particle-emitting radiopharmaceuticals. At the subcellular level, alpha particles induce densely spaced ionizations and molecular damage. Induction of DNA lesions, especially clustered DNA double-strand breaks (DSBs), threatens a cell's survival. Currently, it is under debate to what extent the spatial topology of the damaged chromatin regions and the repair protein arrangements are contributing. METHODS Super-resolution light microscopy (SMLM) in combination with cluster analysis of single molecule signal-point density regions of DSB repair markers was applied to investigate the nano-structure of DNA damage foci tracks of Ra-223 in-solution irradiated leukocytes. RESULTS Alpha-damaged chromatin tracks were efficiently outlined by γ-H2AX that formed large (super) foci composed of numerous 60-80 nm-sized nano-foci. Alpha damage tracks contained 60-70% of all γ-H2AX point signals in a nucleus, while less than 30% of 53BP1, MRE11 or p-ATM signals were located inside γ-H2AX damage tracks. MRE11 and p-ATM protein fluorescent tags formed focal nano-clusters of about 20 nm peak size. There were, on average, 12 (± 9) MRE11 nanoclusters in a typical γ-H2AX-marked alpha track, suggesting a minimal number of MRE11-processed DSBs per track. Our SMLM data suggest regularly arranged nano-structures during DNA repair in the damaged chromatin domain.
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Affiliation(s)
- Harry Scherthan
- Bundeswehr Institute of Radiobiology, University of Ulm, Neuherbergstraße 11, 80937 München, Germany; (J.-H.L.); (E.M.); (R.M.); (M.P.)
- Correspondence: (H.S.); (M.H.); Tel.: +49-89-992692-2272 (H.S.); +49-6221-549824 (M.H.)
| | - Jin-Ho Lee
- Bundeswehr Institute of Radiobiology, University of Ulm, Neuherbergstraße 11, 80937 München, Germany; (J.-H.L.); (E.M.); (R.M.); (M.P.)
- Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany;
| | - Emanuel Maus
- Bundeswehr Institute of Radiobiology, University of Ulm, Neuherbergstraße 11, 80937 München, Germany; (J.-H.L.); (E.M.); (R.M.); (M.P.)
- Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany;
| | - Sarah Schumann
- Department of Nuclear Medicine, University of Würzburg, Oberdürrbacher Str. 6, 97080 Würzburg, Germany; (S.S.); (M.L.)
| | - Razan Muhtadi
- Bundeswehr Institute of Radiobiology, University of Ulm, Neuherbergstraße 11, 80937 München, Germany; (J.-H.L.); (E.M.); (R.M.); (M.P.)
| | - Robert Chojowski
- Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany;
| | - Matthias Port
- Bundeswehr Institute of Radiobiology, University of Ulm, Neuherbergstraße 11, 80937 München, Germany; (J.-H.L.); (E.M.); (R.M.); (M.P.)
| | - Michael Lassmann
- Department of Nuclear Medicine, University of Würzburg, Oberdürrbacher Str. 6, 97080 Würzburg, Germany; (S.S.); (M.L.)
| | - Felix Bestvater
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany;
| | - Michael Hausmann
- Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany;
- Correspondence: (H.S.); (M.H.); Tel.: +49-89-992692-2272 (H.S.); +49-6221-549824 (M.H.)
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19
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Abstract
Compromised detection of short DNA fragments can result in underestimation of radiation-induced clustered DNA damage. The fragments can be detected with atomic force microscopy (AFM), followed by image analysis to compute the length of plasmid molecules. Plasmid molecules imaged with AFM are represented by open or closed curves, possibly with crossings. For the analysis of such objects, a dedicated algorithm was developed, and its usability was demonstrated on the AFM images of plasmid pBR322 irradiated with 60Co gamma rays. The analysis of the set of the acquired AFM images revealed the presence of DNA fragments with lengths shorter than 300 base pairs that would have been neglected by a conventional detection method.
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20
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Processing-Challenges Generated by Clusters of DNA Double-Strand Breaks Underpin Increased Effectiveness of High-LET Radiation and Chromothripsis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1044:149-168. [DOI: 10.1007/978-981-13-0593-1_10] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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21
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Ozmen HK, Erdemci B, Askin S, Sezen O. Carnitine and Adiponectin Levels in Breast Cancer after Radiotherapy. Open Med (Wars) 2017; 12:189-194. [PMID: 28730178 PMCID: PMC5506391 DOI: 10.1515/med-2017-0028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/28/2017] [Indexed: 01/04/2023] Open
Abstract
In this study, serum carnitine (CRNT) and adiponectin (APN) levels and the correlation of these parameters in patients with breast cancer before and after treatment with radiotherapy (RT) were determined.
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Affiliation(s)
- Hilal Kiziltunc Ozmen
- Departments of Radiation Oncology, Ataturk University School of Medicine, 25240, Erzurum, Turkey
| | - Burak Erdemci
- Departments of Radiation Oncology, Ataturk University School of Medicine, 25240, Erzurum, Turkey
| | - Seda Askin
- Departments of Medical Biochemistry, Ataturk University School of Medicine, Erzurum, Turkey
| | - Orhan Sezen
- Departments of Radiation Oncology, Ataturk University School of Medicine, 25240, Erzurum, Turkey
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22
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Sage E, Shikazono N. Radiation-induced clustered DNA lesions: Repair and mutagenesis. Free Radic Biol Med 2017; 107:125-135. [PMID: 27939934 DOI: 10.1016/j.freeradbiomed.2016.12.008] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 12/05/2016] [Accepted: 12/07/2016] [Indexed: 12/18/2022]
Abstract
Clustered DNA lesions, also called Multiply Damaged Sites, is the hallmark of ionizing radiation. It is defined as the combination of two or more lesions, comprising strand breaks, oxidatively generated base damage, abasic sites within one or two DNA helix turns, created by the passage of a single radiation track. DSB clustered lesions associate DSB and several base damage and abasic sites in close vicinity, and are assimilated to complex DSB. Non-DSB clustered lesions comprise single strand break, base damage and abasic sites. At radiation with low Linear Energy Transfer (LET), such as X-rays or γ-rays clustered DNA lesions are 3-4 times more abundant than DSB. Their proportion and their complexity increase with increasing LET; they may represent a large part of the damage to DNA. Studies in vitro using engineered clustered DNA lesions of increasing complexity have greatly enhanced our understanding on how non-DSB clustered lesions are processed. Base excision repair is compromised, the observed hierarchy in the processing of the lesions within a cluster leads to the formation of SSB or DSB as repair intermediates and increases the lifetime of the lesions. As a consequence, the chances of mutation drastically increase. Complex DSB, either formed directly by irradiation or by the processing of non-DSB clustered lesions, are repaired by slow kinetics or left unrepaired and cause cell death or pass mitosis. In surviving cells, large deletions, translocations, and chromosomal aberrations are observed. This review details the most recent data on the processing of non-DSB clustered lesions and complex DSB and tends to demonstrate the high significance of these specific DNA damage in terms of genomic instability induction.
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Affiliation(s)
- Evelyne Sage
- Institut Curie, PSL Research University, CNRS, UMR3347, F-91405 Orsay, France.
| | - Naoya Shikazono
- Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, Kansai Photon Science Institute, 8-1-7 Umemidai, Kizugawa-Shi, Kyoto 619-0215, Japan.
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23
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Janowski E, Timofeeva O, Chasovskikh S, Goldberg M, Kim A, Banovac F, Pang D, Dritschilo A, Unger K. Yttrium-90 radioembolization for colorectal cancer liver metastases in KRAS wild-type and mutant patients: Clinical and ccfDNA studies. Oncol Rep 2016; 37:57-65. [PMID: 28004119 PMCID: PMC5355723 DOI: 10.3892/or.2016.5284] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/18/2016] [Indexed: 12/22/2022] Open
Abstract
Patients with unresectable, chemo-refractory colorectal cancer liver metastases (CRCLM) have limited local treatment options. We report our institutional experience on the efficacy of resin-based yttrium-90 (90Y) radioembolization for the treatment of CRCLM and our findings on associated circulating cell-free DNA (ccfDNA) studies. A total of 58 patients treated with 90Y for CRCLM at the Medstar Georgetown University Hospital had a median survival of 6 months [95% confidence interval (CI), 4.55–7.45 months] after treatment, with a 12-month survival rate of 33%. The median survival from treatment stratified by mutational status was longer in the wild-type (WT) as compared to the KRAS mutant patients at 7 vs. 5 months, but did not achieve statistical significance (p=0.059). Median tumor local control duration after 90Y treatment was 2 months (95% CI, 0.34–3.66 months) for the entire cohort and was longer in the WT vs. the mutant patients (2 vs. 1 month, respectively, p=0.088). Plasma was prospectively collected from a subset of 9 patients both before and after single lobe treatment, and ccfDNA concentration and fragmentation index (FI) were measured using quantitative PCR and atomic-force microscopy (AFM). In the WT and KRAS mutant patients, DNA FI was reduced from a median of 0.73–0.65 after treatment. A reduction in DNA FI after single lobe treatment was associated with an improved overall survival (p=0.046). Analysis by AFM of paired pre- and post-treatment samples from KRAS mutant and WT patients revealed a larger average decrease in fragment size in the WT patients (p=0.013). 90Y radioembolization extends local control for CRCLM, however, KRAS mutant tumors may be more radio-resistant to treatment. Changes in the FI of patients following treatment were noted and may be evaluated in a larger study for relevance as a biomarker of response.
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Affiliation(s)
- E Janowski
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - O Timofeeva
- Department of Oncology, Georgetown University, Washington, DC, USA
| | - S Chasovskikh
- Department of Oncology, Georgetown University, Washington, DC, USA
| | - M Goldberg
- Department of Oncology, Georgetown University, Washington, DC, USA
| | - A Kim
- Department of Interventional Radiology, Georgetown University Hospital, Washington, DC, USA
| | - F Banovac
- Department of Interventional Radiology, Vanderbilt University Hospital, Nashville, TN, USA
| | - D Pang
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - A Dritschilo
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - K Unger
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
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24
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Lorat Y, Timm S, Jakob B, Taucher-Scholz G, Rübe CE. Clustered double-strand breaks in heterochromatin perturb DNA repair after high linear energy transfer irradiation. Radiother Oncol 2016; 121:154-161. [PMID: 27637859 DOI: 10.1016/j.radonc.2016.08.028] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/05/2016] [Accepted: 08/18/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND PURPOSE High linear energy transfer (LET) radiotherapy offers superior dose conformity and biological effectiveness compared with low-LET radiotherapy, representing a promising alternative for radioresistant tumours. A prevailing hypothesis is that energy deposition along the high-LET particle trajectories induces DNA lesions that are more complex and clustered and therefore more challenging to repair. The precise molecular mechanisms underlying the differences in radiobiological effects between high-LET and low-LET radiotherapies remain unclear. MATERIAL AND METHODS Human fibroblasts were irradiated with high-LET carbon ions or low-LET photons. At 0.5h and 5h post exposure, the DNA-damage pattern in the chromatin ultrastructure was visualised using gold-labelled DNA-repair factors. The induction and repair of single-strand breaks, double-strand breaks (DSBs), and clustered lesions were analysed in combination with terminal dUTP nick-end labelling of DNA breaks. RESULTS High-LET irradiation induced clustered lesions with multiple DSBs along ion trajectories predominantly in heterochromatic regions. The cluster size increased over time, suggesting inefficient DSB repair. Low-LET irradiation induced many isolated DSBs throughout the nucleus, most of which were efficiently rejoined. CONCLUSIONS The clustering of DSBs in heterochromatin following high-LET irradiation perturbs efficient DNA repair, leading to greater biological effectiveness of high-LET irradiation versus that of low-LET irradiation.
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Affiliation(s)
- Yvonne Lorat
- Department of Radiation Oncology, Saarland University, Homburg/Saar, Germany
| | - Sara Timm
- Department of Radiation Oncology, Saarland University, Homburg/Saar, Germany
| | - Burkhard Jakob
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Gisela Taucher-Scholz
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Claudia E Rübe
- Department of Radiation Oncology, Saarland University, Homburg/Saar, Germany.
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25
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Mladenova V, Mladenov E, Iliakis G. Novel Biological Approaches for Testing the Contributions of Single DSBs and DSB Clusters to the Biological Effects of High LET Radiation. Front Oncol 2016; 6:163. [PMID: 27446809 PMCID: PMC4923065 DOI: 10.3389/fonc.2016.00163] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/15/2016] [Indexed: 01/28/2023] Open
Abstract
The adverse biological effects of ionizing radiation (IR) are commonly attributed to the generation of DNA double-strand breaks (DSBs). IR-induced DSBs are generated by clusters of ionizations, bear damaged terminal nucleotides, and frequently comprise base damages and single-strand breaks in the vicinity generating a unique DNA damage-clustering effect that increases DSB "complexity." The number of ionizations in clusters of different radiation modalities increases with increasing linear energy transfer (LET), and is thought to determine the long-known LET-dependence of the relative biological effectiveness (RBE). Multiple ionizations may also lead to the formation of DSB clusters, comprising two or more DSBs that destabilize chromatin further and compromise overall processing. DSB complexity and DSB-cluster formation are increasingly considered in the development of mathematical models of radiation action, which are then "tested" by fitting available experimental data. Despite a plethora of such mathematical models the ultimate goal, i.e., the "a priori" prediction of the radiation effect, has not yet been achieved. The difficulty partly arises from unsurmountable difficulties in testing the fundamental assumptions of such mathematical models in defined biological model systems capable of providing conclusive answers. Recently, revolutionary advances in methods allowing the generation of enzymatic DSBs at random or in well-defined locations in the genome, generate unique testing opportunities for several key assumptions frequently fed into mathematical modeling - including the role of DSB clusters in the overall effect. Here, we review the problematic of DSB-cluster formation in radiation action and present novel biological technologies that promise to revolutionize the way we address the biological consequences of such lesions. We describe new ways of exploiting the I-SceI endonuclease to generate DSB-clusters at random locations in the genome and describe the possible utility of Zn-finger nucleases and of TALENs in generating DSBs at defined genomic locations. Finally, we describe ways to harness the revolution of CRISPR/Cas9 technology to advance our understanding of the biological effects of DSBs. Collectively, these approaches promise to improve the focus of mathematical modeling of radiation action by providing testing opportunities for key assumptions on the underlying biology. They are also likely to further strengthen interactions between experimental radiation biologists and mathematical modelers.
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Affiliation(s)
- Veronika Mladenova
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School , Essen , Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School , Essen , Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School , Essen , Germany
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Pang D, Chasovskikh S, Rodgers JE, Dritschilo A. Short DNA Fragments Are a Hallmark of Heavy Charged-Particle Irradiation and May Underlie Their Greater Therapeutic Efficacy. Front Oncol 2016; 6:130. [PMID: 27376024 PMCID: PMC4901041 DOI: 10.3389/fonc.2016.00130] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/16/2016] [Indexed: 11/13/2022] Open
Abstract
Growing interest in proton and heavy ion therapy has reinvigorated research into the fundamental biological mechanisms underlying the therapeutic efficacy of charged-particle radiation. To improve our understanding of the greater biological effectiveness of high-LET radiations, we have investigated DNA double-strand breaks (DSBs) following exposure of plasmid DNA to low-LET Co-60 gamma photon and electron irradiation and to high-LET Beryllium and Argon ions with atomic force microscopy. The sizes of DNA fragments following radiation exposure were individually measured to construct fragment size distributions from which the DSB per DNA molecule and DSB spatial distributions were derived. We report that heavy charged particles induce a significantly larger proportion of short DNA fragments in irradiated DNA molecules, reflecting densely and clustered damage patterns of high-LET energy depositions. We attribute the enhanced short DNA fragmentation following high-LET radiations as an important determinant of the observed, enhanced biological effectiveness of high-LET irradiations.
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Affiliation(s)
- Dalong Pang
- Radiation Medicine, Georgetown University Medical Center , Washington, DC , USA
| | - Sergey Chasovskikh
- Radiation Medicine, Georgetown University Medical Center , Washington, DC , USA
| | - James E Rodgers
- Radiation Oncology, Medstar Franklin Square Medical Center , Rosedale, MD , USA
| | - Anatoly Dritschilo
- Radiation Medicine, Georgetown University Medical Center , Washington, DC , USA
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Sridharan DM, Asaithamby A, Blattnig SR, Costes SV, Doetsch PW, Dynan WS, Hahnfeldt P, Hlatky L, Kidane Y, Kronenberg A, Naidu MD, Peterson LE, Plante I, Ponomarev AL, Saha J, Snijders AM, Srinivasan K, Tang J, Werner E, Pluth JM. Evaluating biomarkers to model cancer risk post cosmic ray exposure. LIFE SCIENCES IN SPACE RESEARCH 2016; 9:19-47. [PMID: 27345199 PMCID: PMC5613937 DOI: 10.1016/j.lssr.2016.05.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/11/2016] [Indexed: 06/06/2023]
Abstract
Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing biomarkers and to evaluate the potential for biomarkers to inform models of post exposure cancer risk. Because cellular stress response pathways to space radiation and environmental carcinogens share common nodes, biomarker-driven risk models may be broadly applicable for estimating risks for other carcinogens.
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Affiliation(s)
| | | | - Steve R Blattnig
- Langley Research Center, Langley Research Center (LaRC), VA, United States
| | - Sylvain V Costes
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | | | | | | | - Lynn Hlatky
- CCSB-Tufts School of Medicine, Boston, MA, United States
| | - Yared Kidane
- Wyle Science, Technology & Engineering Group, Houston, TX, United States
| | - Amy Kronenberg
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Mamta D Naidu
- CCSB-Tufts School of Medicine, Boston, MA, United States
| | - Leif E Peterson
- Houston Methodist Research Institute, Houston, TX, United States
| | - Ianik Plante
- Wyle Science, Technology & Engineering Group, Houston, TX, United States
| | - Artem L Ponomarev
- Wyle Science, Technology & Engineering Group, Houston, TX, United States
| | - Janapriya Saha
- UT Southwestern Medical Center, Dallas, TX, United States
| | | | | | - Jonathan Tang
- Exogen Biotechnology, Inc., Berkeley, CA, United States
| | | | - Janice M Pluth
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
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Schipler A, Mladenova V, Soni A, Nikolov V, Saha J, Mladenov E, Iliakis G. Chromosome thripsis by DNA double strand break clusters causes enhanced cell lethality, chromosomal translocations and 53BP1-recruitment. Nucleic Acids Res 2016; 44:7673-90. [PMID: 27257076 PMCID: PMC5027484 DOI: 10.1093/nar/gkw487] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 05/19/2016] [Indexed: 01/04/2023] Open
Abstract
Chromosome translocations are hallmark of cancer and of radiation-induced cell killing, reflecting joining of incongruent DNA-ends that alter the genome. Translocation-formation requires DNA end-joining mechanisms and incompletely characterized, permissive chromatin conditions. We show that chromatin destabilization by clusters of DNA double-strand-breaks (DSBs) generated by the I-SceI meganuclease at multiple, appropriately engineered genomic sites, compromises c-NHEJ and markedly increases cell killing and translocation-formation compared to single-DSBs. Translocation-formation from DSB-clusters utilizes Parp1 activity, implicating alt-EJ in their formation. Immunofluorescence experiments show that single-DSBs and DSB-clusters uniformly provoke the formation of single γ-H2AX foci, suggesting similar activation of early DNA damage response (DDR). Live-cell imaging also shows similar single-focus recruitment of the early-response protein MDC1, to single-DSBs and DSB-clusters. Notably, the late DDR protein, 53BP1 shows in live-cell imaging strikingly stronger recruitment to DSB-clusters as compared to single-DSBs. This is the first report that chromatin thripsis, in the form of engineered DSB-clusters, compromises first-line DSB-repair pathways, allowing alt-EJ to function as rescuing-backup. DSB-cluster-formation is indirectly linked to the increased biological effectiveness of high ionization-density radiations, such as the alpha-particles emitted by radon gas or the heavy-ions utilized in cancer therapy. Our observations provide the first direct mechanistic explanation for this long-known effect.
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Affiliation(s)
- Agnes Schipler
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Veronika Mladenova
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Vladimir Nikolov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Janapriya Saha
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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Carante MP, Altieri S, Bortolussi S, Postuma I, Protti N, Ballarini F. Modeling radiation-induced cell death: role of different levels of DNA damage clustering. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2015; 54:305-316. [PMID: 25956821 DOI: 10.1007/s00411-015-0601-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/28/2015] [Indexed: 06/04/2023]
Abstract
Some open questions on the mechanisms underlying radiation-induced cell death were addressed by a biophysical model, focusing on DNA damage clustering and its consequences. DNA "cluster lesions" (CLs) were assumed to produce independent chromosome fragments that, if created within a micrometer-scale threshold distance (d), can lead to chromosome aberrations following mis-rejoining; in turn, certain aberrations (dicentrics, rings and large deletions) were assumed to lead to clonogenic cell death. The CL yield and d were the only adjustable parameters. The model, implemented as a Monte Carlo code called BIophysical ANalysis of Cell death and chromosome Aberrations (BIANCA), provided simulated survival curves that were directly compared with experimental data on human and hamster cells exposed to photons, protons, α-particles and heavier ions including carbon and iron. d = 5 μm, independent of radiation quality, and CL yields in the range ~2-20 CLs Gy(-1) cell(-1), depending on particle type and energy, led to good agreement between simulations and data. This supports the hypothesis of a pivotal role of DNA cluster damage at sub-micrometric scale, modulated by chromosome fragment mis-rejoining at micrometric scale. To investigate the features of such critical damage, the CL yields were compared with experimental or theoretical yields of DNA fragments of different sizes, focusing on the base-pair scale (related to the so-called local clustering), the kbp scale ("regional clustering") and the Mbp scale, corresponding to chromatin loops. Interestingly, the CL yields showed better agreement with kbp fragments rather than bp fragments or Mbp fragments; this suggests that also regional clustering, in addition to other clustering levels, may play an important role, possibly due to its relationship with nucleosome organization in the chromatin fiber.
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Affiliation(s)
- M P Carante
- Physics Department, University of Pavia, Via Bassi 6, 27100, Pavia, Italy
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Pachnerová Brabcová K, Sihver L, Yasuda N, Matuo Y, Stěpán V, Davídková M. Clustered DNA damage on subcellular level: effect of scavengers. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2014; 53:705-712. [PMID: 25034012 DOI: 10.1007/s00411-014-0557-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/08/2014] [Indexed: 06/03/2023]
Abstract
Clustered DNA damages are induced by ionizing radiation, particularly of high linear energy transfer (LET). Compared to isolated DNA damage sites, their biological effects can be more severe. We investigated a clustered DNA damage induced by high LET radiation (C 290 MeV u(-1) and Fe 500 MeV u(-1)) in pBR322 plasmid DNA. The plasmid is dissolved in pure water or in aqueous solution of one of the three scavengers (coumarin-3-carboxylic acid, dimethylsulfoxide, and glycylglycine). The yield of double strand breaks (DSB) induced in the DNA plasmid-scavenger system by heavy ion radiation was found to decrease with increasing scavenging capacity due to reaction with hydroxyl radical, linearly with high correlation coefficients. The yield of non-DSB clusters was found to occur twice as much as the DSB. Their decrease with increasing scavenging capacity had lower linear correlation coefficients. This indicates that the yield of non-DSB clusters depends on more factors, which are likely connected to the chemical properties of individual scavengers.
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31
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Lan YY, Londoño D, Bouley R, Rooney MS, Hacohen N. Dnase2a deficiency uncovers lysosomal clearance of damaged nuclear DNA via autophagy. Cell Rep 2014; 9:180-192. [PMID: 25284779 DOI: 10.1016/j.celrep.2014.08.074] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 07/30/2014] [Accepted: 08/28/2014] [Indexed: 12/22/2022] Open
Abstract
Deficiencies in DNA-degrading nucleases lead to accumulation of self DNA and induction of autoimmunity in mice and in monogenic and polygenic human diseases. However, the sources of DNA and the mechanisms that trigger immunity remain unclear. We analyzed mice deficient for the lysosomal nuclease Dnase2a and observed elevated levels of undegraded DNA in both phagocytic and nonphagocytic cells. In nonphagocytic cells, the excess DNA originated from damaged DNA in the nucleus based on colocalization studies, live-cell imaging, and exacerbation by DNA-damaging agents. Removal of damaged DNA by Dnase2a required nuclear export and autophagy-mediated delivery of the DNA to lysosomes. Finally, DNA was found to accumulate in Dnase2a(-/-) or autophagy-deficient cells and induce inflammation via the Sting cytosolic DNA-sensing pathway. Our results reveal a cell-autonomous process for removal of damaged nuclear DNA with implications for conditions with elevated DNA damage, such as inflammation, cancer, and chemotherapy.
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Affiliation(s)
- Yuk Yuen Lan
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 415 Main Street, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Diana Londoño
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, 149 13(th) Street, Charlestown, MA 02129, USA
| | - Richard Bouley
- Center for Systems Biology, Program in Membrane Biology and Nephrology Division, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Michael S Rooney
- Broad Institute, 415 Main Street, Cambridge, MA 02142, USA; Harvard/MIT Division of Health Sciences and Technology, Cambridge, MA 02139, USA
| | - Nir Hacohen
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 415 Main Street, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
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The repair of environmentally relevant DNA double strand breaks caused by high linear energy transfer irradiation – No simple task. DNA Repair (Amst) 2014; 17:64-73. [DOI: 10.1016/j.dnarep.2014.01.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/10/2014] [Accepted: 01/24/2014] [Indexed: 01/03/2023]
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Mouliere F, El Messaoudi S, Pang D, Dritschilo A, Thierry AR. Multi-marker analysis of circulating cell-free DNA toward personalized medicine for colorectal cancer. Mol Oncol 2014; 8:927-41. [PMID: 24698732 DOI: 10.1016/j.molonc.2014.02.005] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 01/27/2014] [Accepted: 02/12/2014] [Indexed: 12/14/2022] Open
Abstract
Development of a Q-PCR-based assay for the high-performance analysis of circulating cell-free DNA (ccfDNA) requires good knowledge of its structure and size. In this work, we present the first visual determination of ccfDNA by Atomic Force Microscopy (AFM) on plasma samples from colorectal cancer (CRC) patients and healthy donors. In addition to the examination of fragment size distribution profile as performed by Q-PCR, this analysis confirms that ccfDNA is highly fragmented and that more than 80% of ccfDNA fragments in CRC plasma are below 145 bp. We adapted an Allele-Specific Blocker (ASB) Q-PCR to small ccfDNA fragments to determine simultaneously the total ccfDNA concentration, the presence of point mutation, the proportion of mutated allele, and a ccfDNA integrity index. The data validated analytically these four parameters in 124 CRC clinical samples and 71 healthy individuals. The multi-marker method, termed Intplex, enables sensitive and specific non-invasive analysis of tumor ccfDNA, which has great potential in terms of cost, quality control, and easy implementation in every clinical center laboratory.
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Affiliation(s)
- Florent Mouliere
- Institut de Recherche en Cancérologie de Montpellier, U896 Inserm, Montpellier, France
| | - Safia El Messaoudi
- Institut de Recherche en Cancérologie de Montpellier, U896 Inserm, Montpellier, France
| | - Dalong Pang
- Department of Radiation Oncology, Lombardi Cancer Center, Georgetown University, Washington DC, USA
| | - Anatoly Dritschilo
- Department of Radiation Oncology, Lombardi Cancer Center, Georgetown University, Washington DC, USA
| | - Alain R Thierry
- Institut de Recherche en Cancérologie de Montpellier, U896 Inserm, Montpellier, France.
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Zhou X, Zhang X, Xie Y, Tanaka K, Wang B, Zhang H. DNA-PKcs inhibition sensitizes cancer cells to carbon-ion irradiation via telomere capping disruption. PLoS One 2013; 8:e72641. [PMID: 24013362 PMCID: PMC3754927 DOI: 10.1371/journal.pone.0072641] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Accepted: 07/11/2013] [Indexed: 11/18/2022] Open
Abstract
Heavy-ion irradiation induces a higher frequency of DNA double strand breaks (DSBs) which must be properly repaired. Critical shortening of telomeres can trigger DNA damage responses such as DSBs. Telomeres are very sensitive to oxidative stress such as ionizing radiation. The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is the central component in the non-homologous end joining (NHEJ) repair complex and participates in telomere maintenance. Therefore, it is expected to enhance the cell killing effect of heavy-ion irradiation via DNA-PKcs inhibition. To test this hypothesis, cellular radiosensitivity was measured by the clonal genetic assay. DNA damage repair was relatively quantified by long PCR. Apoptosis was quantified by flow-cytometric analysis of annexin V/PI double staining, and senescence was analyzed by galactosidase activity. Telomere length was semi-quantified by real-time PCR. P53 and p21 expression was determined by western blotting. Our data demonstrated that MCF-7 and HeLa cells with DNA-PKcs inhibition were more susceptible to carbon-ion irradiation than Those without DNA-PKcs inhibition. Even though NHEJ was inhibited by the DNA-PKcs specific inhibitor, NU7026, most DNA damage induced by carbon-ion irradiation was repaired within 24 hours after irradiation in both cell lines. However, potential lethal damage repair (PLDR) could not restore cellular inactivation in DNA-PKcs inhibited cells. MCF-7 cells showed extensive senescence and accelerated telomere length reduction, while HeLa cells underwent significant apoptosis after irradiation with NU7026 incubation. In addition, both cell lines with shorter telomere were more susceptible to carbon-ion radiation. Our current data suggested that DNA-PKcs inhibition could enhance cellular sensitivity to carbon-ion radiation via disturbing its functional role in telomere end protection. The combination of DNA-PKcs inhibition and carbon-ion irradiation may be an efficient method of heavy-ion therapy.
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Affiliation(s)
- Xin Zhou
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
| | - Xin Zhang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
| | - Yi Xie
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
| | - Kaoru Tanaka
- Radiation Risk Reduction Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
| | - Bing Wang
- Radiation Risk Reduction Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
| | - Hong Zhang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
- * E-mail:
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35
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Ozmen HK, Askın S. Lecithin: cholesterol acyltransferase and na(+)-k(+)-ATPase activity in patients with breast cancer. J Breast Cancer 2013; 16:159-63. [PMID: 23843847 PMCID: PMC3706860 DOI: 10.4048/jbc.2013.16.2.159] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/15/2013] [Indexed: 12/05/2022] Open
Abstract
Purpose The aim of this study was to determine whether plasma lecithin:cholesterol acyltransferase (pLCAT) and erythrocyte membrane Na+-K+-ATPase ase (emNaKATPs) activity have a correlation in breast cancer. This study compared these parameters at time points before and after treatment with radiotherapy. Methods The levels of pLCAT and emNaKATPs were assessed in 30 patients with breast carcinoma and 20 control subjects. While emNaKATPs was measured with spectrophotometric method, pLCAT levels was measured using a specific enzyme-linked immunosorbent assay. Results pLCAT levels, both before and after radiotherapy, were found to be decreased in breast cancer patients than in the controls groups (p<0.001 and p<0.001, respectively). Also, pLCAT levels after radiotherapy were found to be decreased in breast cancer patients than the pLCAT levels before radiotherapy (p<0.001). The emNaKATPs activity were higher in the control group than in the breast cancer patients before/after radiotherapy (RT) (p<0.001 and p<0.001, respectively). At the same time, emNaKATPs activity before RT was higher in the breast cancer patients than emNaKATPs activity after RT (p<0.001). There was a significant correlation between pLCAT and emNaKATPs activity in breast cancer patients receiving radiotherapy (r=0.63, p<0.001), but no correlation between in breast cancer patients before RT and control group (r=0.023, p>0.05). Conclusion The results of the present study demonstrated that decreased pLCAT and emNaKATPs activity levels in breast cancer patients after/before RT than control group. In addition, decreased emNaKATPs activity in breast cancer patients receiving radiotherapy may be due to decreased pLCAT concentrations and RT beam. In our opinion, altered activities of pLCAT and emNaKATPs are linked to the treatment effect of radiotherapy. These data may clarify the development of cell membrane dysfunction and lipid metabolism in breast cancer patients receiving radiotherapy.
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Affiliation(s)
- Hilal Kiziltunç Ozmen
- Department of Radiation Oncology, Ataturk University School of Medicine, Erzurum, Turkey
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36
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Schipler A, Iliakis G. DNA double-strand-break complexity levels and their possible contributions to the probability for error-prone processing and repair pathway choice. Nucleic Acids Res 2013; 41:7589-605. [PMID: 23804754 PMCID: PMC3763544 DOI: 10.1093/nar/gkt556] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Although the DNA double-strand break (DSB) is defined as a rupture in the double-stranded DNA molecule that can occur without chemical modification in any of the constituent building blocks, it is recognized that this form is restricted to enzyme-induced DSBs. DSBs generated by physical or chemical agents can include at the break site a spectrum of base alterations (lesions). The nature and number of such chemical alterations define the complexity of the DSB and are considered putative determinants for repair pathway choice and the probability that errors will occur during this processing. As the pathways engaged in DSB processing show distinct and frequently inherent propensities for errors, pathway choice also defines the error-levels cells opt to accept. Here, we present a classification of DSBs on the basis of increasing complexity and discuss how complexity may affect processing, as well as how it may cause lethal or carcinogenic processing errors. By critically analyzing the characteristics of DSB repair pathways, we suggest that all repair pathways can in principle remove lesions clustering at the DSB but are likely to fail when they encounter clusters of DSBs that cause a local form of chromothripsis. In the same framework, we also analyze the rational of DSB repair pathway choice.
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Affiliation(s)
- Agnes Schipler
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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37
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Bajinskis A, Olsson G, Harms-Ringdahl M. The indirect effect of radiation reduces the repair fidelity of NHEJ as verified in repair deficient CHO cell lines exposed to different radiation qualities and potassium bromate. Mutat Res 2011; 731:125-32. [PMID: 22207102 DOI: 10.1016/j.mrfmmm.2011.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 12/02/2011] [Accepted: 12/13/2011] [Indexed: 10/14/2022]
Abstract
The complexity of DNA lesions induced by ionizing radiation is mainly dependent on radiation quality, where the indirect action of radiation may contribute to different extent depending on the type of radiation under study. The effect of indirect action of radiation can be investigated by using agents that induce oxidative DNA damage or by applying free radical scavengers. The aim of this study was to investigate the role of the indirect effect of radiation for the repair fidelity of non-homologous end-joining (NHEJ), homologous recombination repair (HRR) and base excision repair (BER) when DNA damage of different complexity was induced by gamma radiation, alpha particles or from base damages (8-oxo-dG) induced by potassium bromate (KBrO(3)). CHO cells lines deficient in XRCC3 (HRR) irs1SF, XRCC7 (NHEJ) V3-3 and XRCC1 (BER) EM9 were irradiated in the absence or presence of the free radical scavenger dimethyl sulfoxide (DMSO). The endpoints investigated included rate of cell proliferation by the DRAG assay, clonogenic cell survival and the level of primary DNA damage by the comet assay. The results revealed that the indirect effect of low-LET radiation significantly reduced the repair fidelity of both NHEJ and HRR pathways. For high-LET radiation the indirect effect of radiation also significantly reduced the repair fidelity for the repair deficient cell lines. The results suggest further that the repair fidelity of the error prone NHEJ repair pathway is more impaired by the indirect effect of high-LET radiation relative to the other repair pathways studied. The response to bromate observed for the two DSB repair deficient cell lines strongly support earlier studies that bromate induces complex DNA damages. The significantly reduced repair fidelity of irs1SF and V3-3 suggests that NHEJ as well as HRR are needed for the repair, and that complex DSBs are formed after bromate exposure.
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Affiliation(s)
- Ainars Bajinskis
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
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Khan HA, Alhomida AS. A review of the logistic role of L-carnitine in the management of radiation toxicity and radiotherapy side effects. J Appl Toxicol 2011; 31:707-13. [PMID: 21818761 DOI: 10.1002/jat.1716] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 06/10/2011] [Accepted: 06/10/2011] [Indexed: 02/05/2023]
Abstract
Radiation therapy is a key modality in the treatment of different cancer types. Fatigue is the most common side effect of radiotherapy, while others include nausea, hair loss, skin irritation, anemia, infertility, cardiovascular disease, cognitive impairment and even the development of second cancers. Studies in experimental animals have shown protective effects of carnitine against exposure of various organs to ionizing radiation, whereas carnitine deficiency is known to enhance radiation-induced toxicity. This report summarizes the recent literature on the adverse effects of radiotherapy and the impact of radiation on carnitine homeostasis. Although some studies have demonstrated the prophylactic benefits of carnitine against the toxic effects of chemotherapy, the role of carnitine in the prognosis and management of cancer patients receiving radiotherapy is not clear and needs to be explored.
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Affiliation(s)
- Haseeb Ahmad Khan
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia.
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