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Karapetyan NH, Haroutiunian SG, Ananyan GV. Influence of Cu L-Histidinate Schiff Base Derivatives on Structural Features of Irradiated Rat's DNA. Cell Biochem Biophys 2024:10.1007/s12013-024-01368-9. [PMID: 38922498 DOI: 10.1007/s12013-024-01368-9] [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] [Accepted: 06/13/2024] [Indexed: 06/27/2024]
Abstract
A study of rats liver DNA damages under the influence of X-ray radiation at a dose of 6.5 Gy(LD60) was carried out. The radioprotective properties of newly synthesized Cu(II) L-Schiff Histidinate complexes were also studied. The survival of rats was determined over a 30-day period after exposure to X-rays without pretreatment and also after preadministration of Cu(II) L-Histidinate-Schiff base complexes. The structural defects of rat's liver DNA were detected at 3, 7, 14, and 30 days post-irradiation extracted. The results obtained revealed that irradiation with a 6.5Gy dose in the control group degraded the characteristics of rat liver DNA in comparison to healthy DNA. On all investigated experimental days, a decrease in the melting temperature (Tm), a widening of the melting interval (ΔT), and a decrease in hypochromicity (Δh) were observed in the DNA samples of irradiated animals compared to the norm. The rat's pretreatment by Cu(II) L-Histidinate complexes 1 or 24 hours prior to irradiation improved DNA characteristics. Electrophoretic studies of DNA were in good agreement with the melting data. Based on the study results, it can be concluded that Cu(II) L-Histidinate complexes exhibit radioprotective properties under the studied conditions and can protect DNA from damage.
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Affiliation(s)
- Nelli H Karapetyan
- Department of Molecular Physics, Yerevan State University, 1 Alex Manoogian St. 0025, Yerevan, Armenia.
| | - Samvel G Haroutiunian
- Department of Molecular Physics, Yerevan State University, 1 Alex Manoogian St. 0025, Yerevan, Armenia
| | - Gayane V Ananyan
- Department of Molecular Physics, Yerevan State University, 1 Alex Manoogian St. 0025, Yerevan, Armenia
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2
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Yudkina AV, Barmatov AE, Bulgakov NA, Boldinova EO, Shilkin ES, Makarova AV, Zharkov DO. Bypass of Abasic Site-Peptide Cross-Links by Human Repair and Translesion DNA Polymerases. Int J Mol Sci 2023; 24:10877. [PMID: 37446048 DOI: 10.3390/ijms241310877] [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: 04/30/2023] [Revised: 06/20/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023] Open
Abstract
DNA-protein cross-links remain the least-studied type of DNA damage. Recently, their repair was shown to involve proteolysis; however, the fate of the peptide remnant attached to DNA is unclear. Particularly, peptide cross-links could interfere with DNA polymerases. Apurinuic/apyrimidinic (AP) sites, abundant and spontaneously arising DNA lesions, readily form cross-links with proteins. Their degradation products (AP site-peptide cross-links, APPXLs) are non-instructive and should be even more problematic for polymerases. Here, we address the ability of human DNA polymerases involved in DNA repair and translesion synthesis (POLβ, POLλ, POLη, POLκ and PrimPOL) to carry out synthesis on templates containing AP sites cross-linked to the N-terminus of a 10-mer peptide (APPXL-I) or to an internal lysine of a 23-mer peptide (APPXL-Y). Generally, APPXLs strongly blocked processive DNA synthesis. The blocking properties of APPXL-I were comparable with those of an AP site, while APPXL-Y constituted a much stronger obstruction. POLη and POLκ demonstrated the highest bypass ability. DNA polymerases mostly used dNTP-stabilized template misalignment to incorporate nucleotides when encountering an APPXL. We conclude that APPXLs are likely highly cytotoxic and mutagenic intermediates of AP site-protein cross-link repair and must be quickly eliminated before replication.
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Affiliation(s)
- Anna V Yudkina
- SB RAS Institute of Chemical Biology and Fundamental Medicine, Novosibirsk 630090, Russia
| | - Alexander E Barmatov
- SB RAS Institute of Chemical Biology and Fundamental Medicine, Novosibirsk 630090, Russia
| | - Nikita A Bulgakov
- SB RAS Institute of Chemical Biology and Fundamental Medicine, Novosibirsk 630090, Russia
| | - Elizaveta O Boldinova
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow 123182, Russia
| | - Evgeniy S Shilkin
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow 123182, Russia
| | - Alena V Makarova
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow 123182, Russia
| | - Dmitry O Zharkov
- SB RAS Institute of Chemical Biology and Fundamental Medicine, Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk 630090, Russia
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3
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Natural and synthetic compounds for glioma treatment based on ROS-mediated strategy. Eur J Pharmacol 2023:175537. [PMID: 36871663 DOI: 10.1016/j.ejphar.2023.175537] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 01/08/2023] [Accepted: 01/23/2023] [Indexed: 03/06/2023]
Abstract
Glioma is the most frequent and most malignant tumor of the central nervous system (CNS),accounting for about 50% of all CNS tumor and approximately 80% of the malignant primary tumors in the CNS. Patients with glioma benefit from surgical resection, chemo- and radio-therapy. However these therapeutical strategies do not significantly improve the prognosis, nor increase survival rates owing to restricted drug contribution in the CNS and to the malignant characteristics of glioma. Reactive oxygen species (ROS) are important oxygen-containing molecules that regulate tumorigenesis and tumor progression. When ROS accumulates to cytotoxic levels, this can lead to anti-tumor effects. Multiple chemicals used as therapeutic strategies are based on this mechanism. They regulate intracellular ROS levels directly or indirectly, resulting in the inability of glioma cells to adapt to the damage induced by these substances. In the current review, we summarize the natural products, synthetic compounds and interdisciplinary techniques used for the treatment of glioma. Their possible molecular mechanisms are also presented. Some of them are also used as sensitizers: they modulate ROS levels to improve the outcomes of chemo- and radio-therapy. In addition, we summarize some new targets upstream or downstream of ROS to provide ideas for developing new anti-glioma therapies.
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4
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The 'stealth-bomber' paradigm for deciphering the tumour response to carbon-ion irradiation. Br J Cancer 2023; 128:1429-1438. [PMID: 36639527 PMCID: PMC10070470 DOI: 10.1038/s41416-022-02117-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 12/01/2022] [Accepted: 12/08/2022] [Indexed: 01/14/2023] Open
Abstract
Numerous studies have demonstrated the higher biological efficacy of carbon-ion irradiation (C-ions) and their ballistic precision compared with photons. At the nanometre scale, the reactive oxygen species (ROS) produced by radiation and responsible for the indirect effects are differentially distributed according to the type of radiation. Photon irradiation induces a homogeneous ROS distribution, whereas ROS remain condensed in clusters in the C-ions tracks. Based on this linear energy transfer-dependent differential nanometric ROS distribution, we propose that the higher biological efficacy and specificities of the molecular response to C-ions rely on a 'stealth-bomber' effect. When biological targets are on the trajectories of the particles, the clustered radicals in the tracks are responsible for a 'bomber' effect. Furthermore, the low proportion of ROS outside the tracks is not able to trigger the cellular mechanisms of defence and proliferation. The ability of C-ions to deceive the cellular defence of the cancer cells is then categorised as a 'stealth' effect. This review aims to classify the biological arguments supporting the paradigm of the 'stealth-bomber' as responsible for the biological superiority of C-ions compared with photons. It also explains how and why C-ions will always be more efficient for treating patients with radioresistant cancers than conventional radiotherapy.
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5
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Marignol L. Generation of Radioresistant Prostate Cancer Cells. Methods Mol Biol 2023; 2645:129-138. [PMID: 37202614 DOI: 10.1007/978-1-0716-3056-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The development of in vitro isogenic models of radioresistance through exposure to fractionated radiation is an increasingly used approach to investigate the mechanisms of radioresistance in cancer cells. Owing to the complex nature of the biological effect of ionizing radiation, the generation and validation of these models requires the careful consideration of radiation exposure protocols and cellular endpoints. This chapter presents a protocol we used to derive and characterize an isogenic model of radioresistant prostate cancer cells. This protocol may be applicable to other cancer cell lines.
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Affiliation(s)
- Laure Marignol
- Translational Radiobiology and Oncology Group, Applied Radiation Therapy Trinity Research Group, Trinity College Dublin, Dublin, Ireland.
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6
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Mansouri E, Mesbahi A, Hejazi MS, Montazersaheb S, Tarhriz V, Ghasemnejad T, Zarei M. Nanoscopic biodosimetry using plasmid DNA in radiotherapy with metallic nanoparticles. J Appl Clin Med Phys 2022; 24:e13879. [PMID: 36546569 PMCID: PMC9924121 DOI: 10.1002/acm2.13879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 09/08/2022] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
Nanoscopic lesions (complex damages), are the most lethal lesions for the cells. As nanoparticles have become increasingly popular in radiation therapy and the importance of analyzing nanoscopic dose enhancement has increased, a reliable tool for nanodosimetry has become indispensable. In this regard, the DNA plasmid is a widely used tool as a nanodosimetry probe in radiobiology and nano-radiosensitization studies. This approach is helpful for unraveling the radiosensitization role of nanoparticles in terms of physical and physicochemical effects and for quantifying radiation-induced biological damage. This review discusses the potential of using plasmid DNA assays for assessing the relative effects of nano-radiosensitizers, which can provide a theoretical basis for the development of nanoscopic biodosimetry and nanoparticle-based radiotherapy.
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Affiliation(s)
- Elham Mansouri
- Drug Applied Research CenterTabriz University of Medical SciencesTabrizIran
| | - Asghar Mesbahi
- Molecular Medicine Research CenterInstitute of BiomedicineTabriz University of Medical SciencesTabrizIran,Medical Physics DepartmentMedical SchoolTabriz University of Medical SciencesTabrizIran
| | - Mohammad Saied Hejazi
- Molecular Medicine Research CenterInstitute of BiomedicineTabriz University of Medical SciencesTabrizIran
| | - Soheila Montazersaheb
- Molecular Medicine Research CenterInstitute of BiomedicineTabriz University of Medical SciencesTabrizIran
| | - Vahideh Tarhriz
- Molecular Medicine Research CenterInstitute of BiomedicineTabriz University of Medical SciencesTabrizIran
| | - Tohid Ghasemnejad
- Molecular Medicine Research CenterInstitute of BiomedicineTabriz University of Medical SciencesTabrizIran
| | - Mojtaba Zarei
- Drug Applied Research CenterTabriz University of Medical SciencesTabrizIran
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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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8
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Yue W, Ma J, Xiao Y, Wang P, Gu X, Xie B, Li M. The Apoptotic Resistance of BRCA1-Deficient Ovarian Cancer Cells is Mediated by cAMP. Front Cell Dev Biol 2022; 10:889656. [PMID: 35517499 PMCID: PMC9065249 DOI: 10.3389/fcell.2022.889656] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 03/23/2022] [Indexed: 11/17/2022] Open
Abstract
Breast cancer type 1 susceptibility protein (BRCA1) is essential for homologous recombination repair of DNA double-strand breaks. Loss of BRCA1 is lethal to embryos due to extreme genomic instability and the activation of p53-dependent apoptosis. However, the apoptosis is resisted in BRCA1-deficient cancer cells even though their p53 is proficient. In this study, by analysis of transcriptome data of ovarian cancer patients bearing BRCA1 defects in TCGA database, we found that cAMP signaling pathway was significantly activated. Experimentally, we found that BRCA1 deficiency caused an increased expression of ADRB1, a transmembrane receptor that can promote the generation of cAMP. The elevated cAMP not only inhibited DNA damage-induced apoptosis through abrogating p53 accumulation, but also suppressed the proliferation of cytotoxic T lymphocytes by enhancing the expression of immunosuppressive factors DKK1. Inhibition of ADRB1 effectively killed cancer cells by abolishing the apoptotic resistance. These findings uncover a novel mechanism of apoptotic resistance in BRCA1-deficient ovarian cancer cells and point to a potentially new strategy for treating BRCA1-mutated tumors.
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Affiliation(s)
- Wei Yue
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology (Peking University Third Hospital), Beijing, China
| | - Jihong Ma
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology (Peking University Third Hospital), Beijing, China
| | - Yinan Xiao
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology (Peking University Third Hospital), Beijing, China
| | - Pan Wang
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology (Peking University Third Hospital), Beijing, China
| | - Xiaoyang Gu
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology (Peking University Third Hospital), Beijing, China
| | - Bingteng Xie
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Mo Li
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology (Peking University Third Hospital), Beijing, China
- *Correspondence: Mo Li,
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Formation of clustered DNA damage in vivo upon irradiation with ionizing radiation: Visualization and analysis with atomic force microscopy. Proc Natl Acad Sci U S A 2022; 119:e2119132119. [PMID: 35324325 PMCID: PMC9060515 DOI: 10.1073/pnas.2119132119] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
DNA damage causes loss of or alterations in genetic information, resulting in cell death or mutations. Ionizing radiations produce local, multiple DNA damage sites called clustered DNA damage. In this study, a complete protocol was established to analyze the damage complexity of clustered DNA damage, wherein damage-containing genomic DNA fragments were selectively concentrated via pulldown, and clustered DNA damage was visualized by atomic force microscopy. It was found that X-rays and Fe ion beams caused clustered DNA damage. Fe ion beams also produced clustered DNA damage with high complexity. Fe ion beam–induced complex DNA double-strand breaks (DSBs) containing one or more base lesion(s) near the DSB end were refractory to repair, implying their lethal effects. Clustered DNA damage is related to the biological effects of ionizing radiation. However, its precise yield and complexity (i.e., number of lesions per damaged site) in vivo remain unknown. To better understand the consequences of clustered DNA damage, a method was established to evaluate its yield and complexity in irradiated cells by atomic force microscopy. This was achieved by isolating and concentrating damaged DNA fragments from purified genomic DNA. It was found that X-rays and Fe ion beams caused clustered DNA damage in human TK6 cells, whereas Fenton's reagents did it less efficiently, highlighting clustered DNA damage as a signature of ionizing radiation. Moreover, Fe ion beams produced clustered DNA damage with high complexity. Remarkably, Fe ion beam–induced complex DNA double-strand breaks (DSBs) containing one or more base lesion(s) near the DSB end were refractory to repair, implying the lethal effect of complex DSBs.
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Matsuya Y, Kai T, Sato T, Ogawa T, Hirata Y, Yoshii Y, Parisi A, Liamsuwan T. Track-structure modes in particle and heavy ion transport code system (PHITS): application to radiobiological research. Int J Radiat Biol 2021; 98:148-157. [PMID: 34930091 DOI: 10.1080/09553002.2022.2013572] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
PURPOSE In radiation physics, Monte Carlo radiation transport simulations are powerful tools to evaluate the cellular responses after irradiation. When investigating such radiation-induced biological effects, it is essential to perform track structure simulations by explicitly considering each atomic interaction in liquid water at the sub-cellular and DNA scales. The Particle and Heavy-Ion Transport code System (PHITS) is a Monte Carlo code which enables to calculate track structure at DNA scale by employing the track-structure modes for electrons, protons and carbon ions. In this paper, we review the recent development status and future prospects of the track-structure modes in the PHITS code. CONCLUSIONS To date, the physical features of these modes have been verified using the available experimental data and Monte Carlo simulation results reported in literature. These track-structure modes can be used for calculating microdosimetric distributions to estimate cell survival and for estimating initial DNA damage yields. The use of PHITS track-structure mode is expected not only to clarify the underlying mechanisms of radiation effects but also to predict curative effects in radiation therapy. The results of PHITS simulations coupled with biophysical models will contribute to the radiobiological studies by precisely predicting radiation-induced biological effects based on the Monte Carlo approach.
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Affiliation(s)
- Yusuke Matsuya
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Japan
| | - Takeshi Kai
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Japan
| | - Tatsuhiko Sato
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Japan
| | - Tatsuhiko Ogawa
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Japan
| | - Yuho Hirata
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Japan
| | - Yuji Yoshii
- Central Institute of Isotope Science, Hokkaido University, Sapporo, Japan
| | - Alessio Parisi
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida
| | - Thiansin Liamsuwan
- Princess Srisavangavadhana College of Medicine, Chulabhorn Royal Academy, Bangkok, Thailand
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11
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Kacem H, Almeida A, Cherbuin N, Vozenin MC. Understanding the FLASH effect to unravel the potential of ultra-high dose rate irradiation. Int J Radiat Biol 2021; 98:506-516. [PMID: 34788193 DOI: 10.1080/09553002.2021.2004328] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
A reemergence of research implementing radiation delivery at ultra-high dose rates (UHDRs) has triggered intense interest in the radiation sciences and has opened a new field of investigation in radiobiology. Much of the promise of UHDR irradiation involves the FLASH effect, an in vivo biological response observed to maintain anti-tumor efficacy without the normal tissue complications associated with standard dose rates. The FLASH effect has been validated primarily, using intermediate energy electron beams able to deliver high doses (>7 Gy) in a very short period of time (<200 ms), but has also been found with photon and proton beams. The clinical implications of this new area of research are highly significant, as FLASH radiotherapy (FLASH-RT) has the potential to enhance the therapeutic index, opening new possibilities for eradicating radio-resistant tumors without toxicity. As pioneers in this field, our group has developed a multidisciplinary research team focused on investigating the mechanisms and clinical translation of the FLASH effect. Here, we review the field of UHDR, from the physico-chemical to the biological mechanisms.
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Affiliation(s)
- Houda Kacem
- Department of Oncology, Laboratory of Radiation Oncology, Radiation Oncology Service, CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Aymeric Almeida
- Department of Oncology, Laboratory of Radiation Oncology, Radiation Oncology Service, CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Nicolas Cherbuin
- Department of Medical Radiology, Institute of Radiation Physics, CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Marie-Catherine Vozenin
- Department of Oncology, Laboratory of Radiation Oncology, Radiation Oncology Service, CHUV, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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12
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Hsiao YY, Chen FH, Chan CC, Tsai CC. Monte Carlo Simulation of Double-Strand Break Induction and Conversion after Ultrasoft X-rays Irradiation. Int J Mol Sci 2021; 22:ijms222111713. [PMID: 34769142 PMCID: PMC8583805 DOI: 10.3390/ijms222111713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 12/26/2022] Open
Abstract
This paper estimates the yields of DNA double-strand breaks (DSBs) induced by ultrasoft X-rays and uses the DSB yields and the repair outcomes to evaluate the relative biological effectiveness (RBE) of ultrasoft X-rays. We simulated the yields of DSB induction and predicted them in the presence and absence of oxygen, using a Monte Carlo damage simulation (MCDS) software, to calculate the RBE. Monte Carlo excision repair (MCER) simulations were also performed to calculate the repair outcomes (correct repairs, mutations, and DSB conversions). Compared to 60Co γ-rays, the RBE values for ultrasoft X-rays (titanium K-shell, aluminum K-shell, copper L-shell, and carbon K-shell) for DSB induction were respectively 1.3, 1.9, 2.3, and 2.6 under aerobic conditions and 1.3, 2.1, 2.5, and 2.9 under a hypoxic condition (2% O2). The RBE values for enzymatic DSBs were 1.6, 2.1, 2.3, and 2.4, respectively, indicating that the enzymatic DSB yields are comparable to the yields of DSB induction. The synergistic effects of DSB induction and enzymatic DSB formation further facilitate cell killing and the advantage in cancer treatment.
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Affiliation(s)
- Ya-Yun Hsiao
- Department of Radiology, Chung Shan Medical University Hospital, Taichung 40201, Taiwan;
- Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung 40201, Taiwan
| | - Fang-Hsin Chen
- Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan 33302, Taiwan;
- Radiation Biology Research Center, Institute for Radiological Research, Chang Gung University, Taoyuan 33302, Taiwan
- Department of Radiation Oncology, Chang Gung Memorial Hospital-Linkou Branch, Taoyuan 33305, Taiwan
| | - Chun-Chieh Chan
- Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan
- Correspondence: (C.-C.C.); (C.-C.T.); Tel.: +886-4-22851549-222 (C.-C.T.)
| | - Ching-Chih Tsai
- Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan
- Correspondence: (C.-C.C.); (C.-C.T.); Tel.: +886-4-22851549-222 (C.-C.T.)
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13
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Kozmin SG, Eot-Houllier G, Reynaud-Angelin A, Gasparutto D, Sage E. Dissecting Highly Mutagenic Processing of Complex Clustered DNA Damage in Yeast Saccharomyces cerevisiae. Cells 2021; 10:cells10092309. [PMID: 34571958 PMCID: PMC8471780 DOI: 10.3390/cells10092309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 12/27/2022] Open
Abstract
Clusters of DNA damage, also called multiply damaged sites (MDS), are a signature of ionizing radiation exposure. They are defined as two or more lesions within one or two helix turns, which are created by the passage of a single radiation track. It has been shown that the clustering of DNA damage compromises their repair. Unresolved repair may lead to the formation of double-strand breaks (DSB) or the induction of mutation. We engineered three complex MDS, comprised of oxidatively damaged bases and a one-nucleotide (1 nt) gap (or not), in order to investigate the processing and the outcome of these MDS in yeast Saccharomyces cerevisiae. Such MDS could be caused by high linear energy transfer (LET) radiation. Using a whole-cell extract, deficient (or not) in base excision repair (BER), and a plasmid-based assay, we investigated in vitro excision/incision at the damaged bases and the mutations generated at MDS in wild-type, BER, and translesion synthesis-deficient cells. The processing of the studied MDS did not give rise to DSB (previously published). Our major finding is the extremely high mutation frequency that occurs at the MDS. The proposed processing of MDS is rather complex, and it largely depends on the nature and the distribution of the damaged bases relative to the 1 nt gap. Our results emphasize the deleterious consequences of MDS in eukaryotic cells.
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Affiliation(s)
- Stanislav G. Kozmin
- Institut Curie, PSL Research University Orsay, F-91405 Orsay, France; (G.E.-H.); (A.R.-A.)
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
- Correspondence: (S.G.K.); (E.S.)
| | - Gregory Eot-Houllier
- Institut Curie, PSL Research University Orsay, F-91405 Orsay, France; (G.E.-H.); (A.R.-A.)
- Institut de Génétique et Développement de Rennes, CNRS-UR1 UMR6290, Université Rennes-1, F-35043 Rennes, France
| | - Anne Reynaud-Angelin
- Institut Curie, PSL Research University Orsay, F-91405 Orsay, France; (G.E.-H.); (A.R.-A.)
| | - Didier Gasparutto
- CEA, CNRS IRIG/SyMMES-UMR5819, Université Grenoble Alpes, F-38054 Grenoble, France;
| | - Evelyne Sage
- Institut Curie, PSL Research University Orsay, F-91405 Orsay, France; (G.E.-H.); (A.R.-A.)
- CNRS UMR3347, INSERM U1021, Université Paris-Saclay, F-91405 Orsay, France
- Correspondence: (S.G.K.); (E.S.)
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14
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Obata Y, Nakaue H, Hirasaki K, Akimitsu N, Yokoya A. Expression of an X-Ray Irradiated EGFP-Expressing Plasmid Transfected into Nonirradiated Human Cells. Radiat Res 2021; 196:261-271. [PMID: 34237141 DOI: 10.1667/rr15399.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/11/2021] [Indexed: 11/03/2022]
Abstract
To investigate the repairability of X-ray induced DNA damage, particularly non-double-strand breaks in living cells, enhanced green fluorescent protein (EGFP)-expressing plasmids X-ray irradiated and then transfected into nonirradiated human cells, MCF7 and MCF10A. Live-cell imaging of EGFP fluorescence was performed to measure the efficiency of plasmid repair in cells. The number of EGFP-expressing cells significantly decreased with increasing X-ray dose for both cell lines. The obtained kinetic curves of EGFP expression indicating plasmid repair were quantitatively compared against algebraically calculated ones based on the values of the transfected plasmids that had been treated with nicking or restriction enzymes. Then, assuming a Poisson distribution of single-strand breaks (SSBs), the number of cells carrying these nicked plasmids that could express EGFP were estimated. Our experimental results revealed considerably fewer cells expressing EGFP compared to the expected values we had calculated. These results suggest that the lower proportion of cells expressing EGFP as a measure of plasmid repair was due not only to the complex chemical structures of termini created by SSBs compared to those created by enzyme treatments, but also that base lesions or AP sites proximately arising at the strand-break termini might compromise EGFP expression. These results emphasize that radiation-induced DNA breaks are less repairable than enzymatically induced DNA breaks, which is not apparent when using conventional gel electrophoresis assays of plasmid DNA.
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Affiliation(s)
- Yui Obata
- Graduate School of Science and Engineering, Ibaraki 310-8512, Japan.,Institute for Quantum Life Science, National Institutes of Quantum and Radiological Sciences, Tokai, Ibaraki 319-1106, Japan
| | - Hiroki Nakaue
- Graduate School of Science and Engineering, Ibaraki 310-8512, Japan.,Institute for Quantum Life Science, National Institutes of Quantum and Radiological Sciences, Tokai, Ibaraki 319-1106, Japan
| | - Keishiro Hirasaki
- College of Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | | | - Akinari Yokoya
- Graduate School of Science and Engineering, Ibaraki 310-8512, Japan.,Institute for Quantum Life Science, National Institutes of Quantum and Radiological Sciences, Tokai, Ibaraki 319-1106, Japan
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15
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Jia C, Wang Q, Yao X, Yang J. The Role of DNA Damage Induced by Low/High Dose Ionizing Radiation in Cell Carcinogenesis. EXPLORATORY RESEARCH AND HYPOTHESIS IN MEDICINE 2021; 000:000-000. [DOI: 10.14218/erhm.2021.00020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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16
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Chan CC, Hsiao YY. The Effects of Dimethylsulfoxide and Oxygen on DNA Damage Induction and Repair Outcomes for Cells Irradiated by 62 MeV Proton and 3.31 MeV Helium Ions. J Pers Med 2021; 11:jpm11040286. [PMID: 33917956 PMCID: PMC8068342 DOI: 10.3390/jpm11040286] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 04/06/2021] [Indexed: 12/12/2022] Open
Abstract
Reactive oxygen species (ROS) play an essential role in radiation-induced indirect actions. In terms of DNA damage, double strand breaks (DSBs) have the greatest effects on the repair of DNA damage, cell survival and transformation. This study evaluated the biological effects of the presence of ROS and oxygen on DSB induction and mutation frequency. The relative biological effectiveness (RBE) and oxygen enhancement ratio (OER) of 62 MeV therapeutic proton beams and 3.31 MeV helium ions were calculated using Monte Carlo damage simulation (MCDS) software. Monte Carlo excision repair (MCER) simulations were used to calculate the repair outcomes (mutation frequency). The RBE values of proton beams decreased to 0.75 in the presence of 0.4 M dimethylsulfoxide (DMSO) and then increases to 0.9 in the presence of 2 M DMSO while the RBE values of 3.31 MeV helium ions increased from 2.9 to 5.7 (0–2 M). The mutation frequency of proton beams also decreased from 0.008–0.065 to 0.004–0.034 per cell per Gy by the addition of 2 M DMSO, indicating that ROS affects both DSB induction and repair outcomes. These results show that the combined use of DMSO in normal tissues and an increased dose in tumor regions increases treatment efficiency.
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Affiliation(s)
- Chun-Chieh Chan
- Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan;
| | - Ya-Yun Hsiao
- Department of Radiology, Chung Shan Medical University Hospital, Taichung 40201, Taiwan
- Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung 40201, Taiwan
- Correspondence: ; Tel.: +886-4-24730022 (ext. 12010)
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17
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Zhang J, Zhang Y, Mo F, Patel G, Butterworth K, Shao C, Prise KM. The Roles of HIF-1α in Radiosensitivity and Radiation-Induced Bystander Effects Under Hypoxia. Front Cell Dev Biol 2021; 9:637454. [PMID: 33869184 PMCID: PMC8044822 DOI: 10.3389/fcell.2021.637454] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 02/19/2021] [Indexed: 12/13/2022] Open
Abstract
Radiation-induced bystander effects (RIBE) may have potential implications for radiotherapy, yet the radiobiological impact and underlying mechanisms in hypoxic tumor cells remain to be determined. Using two human tumor cell lines, hepatoma HepG2 cells and glioblastoma T98G cells, the present study found that under both normoxic and hypoxic conditions, increased micronucleus formation and decreased cell survival were observed in non-irradiated bystander cells which had been co-cultured with X-irradiated cells or treated with conditioned-medium harvested from X-irradiated cells. Although the radiosensitivity of hypoxic tumor cells was lower than that of aerobic cells, the yield of micronucleus induced in bystander cells under hypoxia was similar to that measured under normoxia indicating that RIBE is a more significant factor in overall radiation damage of hypoxic cells. When hypoxic cells were treated with dimethyl sulfoxide (DMSO), a scavenger of reactive oxygen species (ROS), or aminoguanidine (AG), an inhibitor of nitric oxide synthase (NOS), before and during irradiation, the bystander response was partly diminished. Furthermore, when only hypoxic bystander cells were pretreated with siRNA hypoxia-inducible factor-1α (HIF-1α), RIBE were decreased slightly but if irradiated cells were treated with siRNA HIF-1α, hypoxic RIBE decreased significantly. In addition, the expression of HIF-1α could be increased in association with other downstream effector molecules such as glucose transporter 1 (GLUT-1), vascular endothelial growth factor (VEGF), and carbonic anhydrase (CA9) in irradiated hypoxic cells. However, the expression of HIF-1α expression in bystander cells was decreased by a conditioned medium from isogenic irradiated cells. The current results showed that under hypoxic conditions, irradiated HepG2 and T98G cells showed reduced radiosensitivity by increasing the expression of HIF-1α and induced a syngeneic bystander effect by decreasing the expression of HIF-1α and regulating its downstream target genes in both the irradiated or bystander cells.
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Affiliation(s)
- Jianghong Zhang
- Institute of Radiation Medicine, Fudan University, Shanghai, China
| | - Yuhong Zhang
- Institute of Radiation Medicine, Fudan University, Shanghai, China
| | - Fang Mo
- Institute of Radiation Medicine, Fudan University, Shanghai, China
| | - Gaurang Patel
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| | - Karl Butterworth
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| | - Chunlin Shao
- Institute of Radiation Medicine, Fudan University, Shanghai, China
| | - Kevin M Prise
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
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18
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House NCM, Parasuram R, Layer JV, Price BD. Site-specific targeting of a light activated dCas9-KillerRed fusion protein generates transient, localized regions of oxidative DNA damage. PLoS One 2020; 15:e0237759. [PMID: 33332350 PMCID: PMC7746297 DOI: 10.1371/journal.pone.0237759] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/30/2020] [Indexed: 12/12/2022] Open
Abstract
DNA repair requires reorganization of the local chromatin structure to facilitate access to and repair of the DNA. Studying DNA double-strand break (DSB) repair in specific chromatin domains has been aided by the use of sequence-specific endonucleases to generate targeted breaks. Here, we describe a new approach that combines KillerRed, a photosensitizer that generates reactive oxygen species (ROS) when exposed to light, and the genome-targeting properties of the CRISPR/Cas9 system. Fusing KillerRed to catalytically inactive Cas9 (dCas9) generates dCas9-KR, which can then be targeted to any desired genomic region with an appropriate guide RNA. Activation of dCas9-KR with green light generates a local increase in reactive oxygen species, resulting in "clustered" oxidative damage, including both DNA breaks and base damage. Activation of dCas9-KR rapidly (within minutes) increases both γH2AX and recruitment of the KU70/80 complex. Importantly, this damage is repaired within 10 minutes of termination of light exposure, indicating that the DNA damage generated by dCas9-KR is both rapid and transient. Further, repair is carried out exclusively through NHEJ, with no detectable contribution from HR-based mechanisms. Surprisingly, sequencing of repaired DNA damage regions did not reveal any increase in either mutations or INDELs in the targeted region, implying that NHEJ has high fidelity under the conditions of low level, limited damage. The dCas9-KR approach for creating targeted damage has significant advantages over the use of endonucleases, since the duration and intensity of DNA damage can be controlled in "real time" by controlling light exposure. In addition, unlike endonucleases that carry out multiple cut-repair cycles, dCas9-KR produces a single burst of damage, more closely resembling the type of damage experienced during acute exposure to reactive oxygen species or environmental toxins. dCas9-KR is a promising system to induce DNA damage and measure site-specific repair kinetics at clustered DNA lesions.
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Affiliation(s)
- Nealia C. M. House
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, United States of America
| | - Ramya Parasuram
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, United States of America
| | - Jacob V. Layer
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, United States of America
| | - Brendan D. Price
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, United States of America
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19
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Radioprotective Effect of Flavonoids on Ionizing Radiation-Induced Brain Damage. Molecules 2020; 25:molecules25235719. [PMID: 33287417 PMCID: PMC7730479 DOI: 10.3390/molecules25235719] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/25/2020] [Accepted: 12/02/2020] [Indexed: 01/27/2023] Open
Abstract
Patients receiving brain radiotherapy may suffer acute or chronic side effects. Ionizing radiation induces the production of intracellular reactive oxygen species and pro-inflammatory cytokines in the central nervous system, leading to brain damage. Complementary Chinese herbal medicine therapy may reduce radiotherapy-induced side effects. Flavonoids are a class of natural products which can be extracted from Chinese herbal medicine and have been shown to have neuroprotective and radioprotective properties. Flavonoids are effective antioxidants and can also inhibit regulatory enzymes or transcription factors important for controlling inflammatory mediators, affect oxidative stress through interaction with DNA and enhance genomic stability. In this paper, radiation-induced brain damage and the relevant molecular mechanism were summarized. The radio-neuro-protective effect of flavonoids, i.e., antioxidant, anti-inflammatory and maintaining genomic stability, were then reviewed. We concluded that flavonoids treatment may be a promising complementary therapy to prevent radiotherapy-induced brain pathophysiological changes and cognitive impairment.
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20
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Ahumada-Flores S, Gómez Pando LR, Parra Cota FI, de la Cruz Torres E, Sarsu F, de Los Santos Villalobos S. Technical note: Gamma irradiation induces changes of phenotypic and agronomic traits in wheat (Triticum turgidum ssp. durum). Appl Radiat Isot 2020; 167:109490. [PMID: 33121892 DOI: 10.1016/j.apradiso.2020.109490] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 10/15/2020] [Accepted: 10/21/2020] [Indexed: 10/23/2022]
Abstract
WHEAT VAR CIRNO C2008 was irradiated with gamma rays at 100, 200, and 300 Gy. The irradiated plants obtained at 300 Gy (M1) showed a significant reduction (compared to M0 plants) in germination (i.e. 3.8% at day 5), survival percentage (48%), and plant height (63.3%). Thus, the Probit analysis showed an LD50 of 287.80 Gy. Besides, these irradiated plants, in the field, showed a significant increase (compared to M0 plants) in days to spike initiation (16 days), and maturation (14 days). On the other hand, in the field, fourteen chlorophyll mutants were found (at a different frequency) in the M2 generation, such as Albina, Anthocyanin, Chlorina, Maculata, Tigrina, Striata, Viridis, Viridoalbina, Alboviridis, Xantha, Xanthviridis, Xanthalba, Viridoxantha, and Orange stem. In addition, mutants with changes in agronomic and morphological traits were observed. This nuclear technique is an alternative to obtain promising mutant lines that can be used directly as a variety and/or as parental to transfer these traits to other varieties.
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Affiliation(s)
- Sergio Ahumada-Flores
- -Instituto Tecnológico de Sonora, 5 de Febrero 818 sur, 85000, Cd. Obregón, Sonora, Mexico
| | | | - Fannie Isela Parra Cota
- -Campo Experimental Norman E. Borlaug, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Norman E. Borlaug Km 12, 85000, Cd. Obregón, Sonora, Mexico
| | - Eulogio de la Cruz Torres
- -Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca S/N, La Marquesa, Ocoyoacac, Edo. México, C.P, 52750, Mexico
| | - Fatma Sarsu
- - Plant Breeding and Genetic Section, Joint FAO/IAEA Division, International Atomic Energy Agency, Vienna, Austria
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21
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Tambasco M, Pang G, Fuller L, Brescia EL, Mardirossian G. Impact of a 1.5 T magnetic field on DNA damage in MRI-guided HDR brachytherapy. Phys Med 2020; 76:85-91. [PMID: 32623225 DOI: 10.1016/j.ejmp.2020.06.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/16/2020] [Accepted: 06/23/2020] [Indexed: 12/23/2022] Open
Abstract
PURPOSE Some studies have suggested that the presence of a static magnetic field (SMF) during irradiation alters biological damage. Since MRI-guided radiotherapy is becoming increasingly common, we constructed a DNA-based detector to assess the effect of a 1.5 T SMF on DNA damage during high dose rate (HDR) brachytherapy irradiation. METHODS Block phantoms containing a small cavity for the placement of plasmid DNA (pBR322) samples were 3-D printed with biocompatible tissue equivalent material. The phantom was CT scanned and an HDR brachytherapy treatment plan was designed to deliver 20 Gy and 30 Gy doses to the DNA samples in the presence and absence of a 1.5 T SMF. Relative yields of single- and double-strand breaks (SSBs and DSBs, respectively) were computed from gel electrophoresis images of the DNA band intensities and averaged over sample sizes ranging from 12 to 30. Radiation dose was also measured in the presence and absence of the 1.5 T SMF using GafChromic™ EBT3 film placed in the coronal, sagittal, and axial planes. RESULTS The average yield of DNA with SSBs and DSBs in the presence and absence of the SMF showed no statistically significant differences (all p ≥ 0.17). Differences in the net optical densities of the EBT3 films for each plane were within experimental uncertainty, suggesting no dose difference in the presence and absence of the SMF. CONCLUSIONS HDR irradiation in the presence of the 1.5 T SMF did not alter dose deposition to the DNA cavity nor change SSB and DSB DNA damage.
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Affiliation(s)
- Mauro Tambasco
- Department of Physics, San Diego State University, San Diego, CA, USA.
| | - Geordi Pang
- Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
| | - Loni Fuller
- Department of Physics, San Diego State University, San Diego, CA, USA
| | - Erika L Brescia
- Department of Physics, San Diego State University, San Diego, CA, USA; Department of Medical Physics, Genesis Healthcare Partners, San Diego, CA, USA
| | - George Mardirossian
- Department of Medical Physics, Genesis Healthcare Partners, San Diego, CA, USA
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22
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Strand with mutagenic lesion is preferentially used as a template in the region of a bi-stranded clustered DNA damage site in Escherichia coli. Sci Rep 2020; 10:9737. [PMID: 32546758 PMCID: PMC7297740 DOI: 10.1038/s41598-020-66651-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 05/20/2020] [Indexed: 11/08/2022] Open
Abstract
The damaging potential of ionizing radiation arises largely from the generation of clustered DNA damage sites within cells. Previous studies using synthetic DNA lesions have demonstrated that models of clustered DNA damage exhibit enhanced mutagenic potential of the comprising lesions. However, little is known regarding the processes that lead to mutations in these sites, apart from the fact that base excision repair of lesions within the cluster is compromised. Unique features of the mutation frequencies within bi-stranded clusters have led researchers to speculate that the strand containing the mutagenic lesion is preferentially used as the template for DNA synthesis. To gain further insights into the processing of clustered DNA damage sites, we used a plasmid-based assay in E. coli cells. Our findings revealed that the strand containing a mutagenic lesion within a bi-stranded clustered DNA damage site is frequently used as the template. This suggests the presence of an, as yet unknown, strand synthesis process that is unrelated to base excision repair, and that this process plays an important role in mutagenesis. The length of the region of strand preference was found to be determined by DNA polymerase I.
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23
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Matsuya Y, Nakano T, Kai T, Shikazono N, Akamatsu K, Yoshii Y, Sato T. A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields. Int J Mol Sci 2020; 21:ijms21051701. [PMID: 32131419 PMCID: PMC7084883 DOI: 10.3390/ijms21051701] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 01/04/2023] Open
Abstract
Complex DNA damage, defined as at least two vicinal lesions within 10-20 base pairs (bp), induced after exposure to ionizing radiation, is recognized as fatal damage to human tissue. Due to the difficulty of directly measuring the aggregation of DNA damage at the nano-meter scale, many cluster analyses of inelastic interactions based on Monte Carlo simulation for radiation track structure in liquid water have been conducted to evaluate DNA damage. Meanwhile, the experimental technique to detect complex DNA damage has evolved in recent decades, so both approaches with simulation and experiment get used for investigating complex DNA damage. During this study, we propose a simplified cluster analysis of ionization and electronic excitation events within 10 bp based on track structure for estimating complex DNA damage yields for electron and X-ray irradiations. We then compare the computational results with the experimental complex DNA damage coupled with base damage (BD) measured by enzymatic cleavage and atomic force microscopy (AFM). The computational results agree well with experimental fractions of complex damage yields, i.e., single and double strand breaks (SSBs, DSBs) and complex BD, when the yield ratio of BD/SSB is assumed to be 1.3. Considering the comparison of complex DSB yields, i.e., DSB + BD and DSB + 2BD, between simulation and experimental data, we find that the aggregation degree of the events along electron tracks reflects the complexity of induced DNA damage, showing 43.5% of DSB induced after 70 kVp X-ray irradiation can be classified as a complex form coupled with BD. The present simulation enables us to quantify the type of complex damage which cannot be measured through in vitro experiments and helps us to interpret the experimental detection efficiency for complex BD measured by AFM. This simple model for estimating complex DNA damage yields contributes to the precise understanding of the DNA damage complexity induced after X-ray and electron irradiations.
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Affiliation(s)
- Yusuke Matsuya
- Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
- Correspondence:
| | - Toshiaki Nakano
- Department of Quantum life Science, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215, Japan
| | - Takeshi Kai
- Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
| | - Naoya Shikazono
- Department of Quantum life Science, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215, Japan
| | - Ken Akamatsu
- Department of Quantum life Science, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215, Japan
| | - Yuji Yoshii
- Central Institute of Isotope Science, Hokkaido University, Kita-15 Nishi-7, Kita-ku, Sapporo, Hokkaido 060-0815, Japan
| | - Tatsuhiko Sato
- Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
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24
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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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25
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Luo WR, Chen FH, Huang RJ, Chen YP, Hsiao YY. Effects of indirect actions and oxygen on relative biological effectiveness: estimate of DSB inductions and conversions induced by therapeutic proton beams. Int J Radiat Biol 2019; 96:187-196. [PMID: 31682784 DOI: 10.1080/09553002.2020.1688883] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Purpose: This study evaluated the DNA double strand breaks (DSBs) induced by indirect actions and its misrepairs to estimate the relative biological effectiveness (RBE) of proton beams.Materials and methods: From experimental data, DSB induction was evaluated in cells irradiated by 62 MeV proton beams in the presence of dimethylsulphoxide (DMSO) and under hypoxic conditions. The DNA damage yields for calculating the RBE were estimated using Monte Carlo Damage Simulation (MCDS) software. The repair outcomes (correct repairs, mutations and DSB conversions) were estimated using Monte Carlo Excision Repair (MCER) simulations.Results: The values for RBE of 62 MeV protons (LET = 1.051 keV/μm) for DSB induction and enzymatic DSB under aerobic condition (21% O2) was 1.02 and 0.94, respectively, as comparing to 60Co γ-rays (LET = 2.4 keV/μm). DMSO mitigated the inference of indirect action and reduced DSB induction to a greater extent when damaged by protons rather than γ-rays, resulting in a decreased RBE of 0.86. DMSO also efficiently prevented enzymatic DSB yields triggered by proton irradiation and reduced the RBE to 0.83. However, hypoxia (2% O2) produced a similar level of DSB induction with respect to the protons and γ-rays, with a comparable RBE of 1.02.Conclusions: The RBE values of proton beams estimated from DSB induction and enzymatic DSB decreased by 16% and 12%, respectively, in the presence of DMSO. Our findings indicate that the overall effects of DSB induction and enzymatic DSB could intensify the tumor killing, while alleviate normal tissue damage when indirect actions are effectively interrupted.
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Affiliation(s)
- Wei-Ren Luo
- Department of Radiology, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Fang-Hsin Chen
- Department of Medical Imaging and Radiological Sciences, Chang Gung University, Kweishan, Taiwan.,Radiation Biology Research Center, Institute for Radiological Research, Chang Gung University/Chang Gung Memorial Hospital, Taoyuan, Taiwan.,Department of Radiation Oncology, Chang Gung Memorial Hospital-Linkou Branch, Taoyuan, Taiwan
| | - Ren-Jing Huang
- Department of Radiology, Chung Shan Medical University Hospital, Taichung, Taiwan.,Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Yu-Pin Chen
- Department of Radiology, Taipei Manicipal Wan-Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Ya-Yun Hsiao
- Department of Radiology, Chung Shan Medical University Hospital, Taichung, Taiwan.,Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan
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26
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Cellular Stress Responses in Radiotherapy. Cells 2019; 8:cells8091105. [PMID: 31540530 PMCID: PMC6769573 DOI: 10.3390/cells8091105] [Citation(s) in RCA: 160] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/11/2019] [Accepted: 09/18/2019] [Indexed: 12/15/2022] Open
Abstract
Radiotherapy is one of the major cancer treatment strategies. Exposure to penetrating radiation causes cellular stress, directly or indirectly, due to the generation of reactive oxygen species, DNA damage, and subcellular organelle damage and autophagy. These radiation-induced damage responses cooperatively contribute to cancer cell death, but paradoxically, radiotherapy also causes the activation of damage-repair and survival signaling to alleviate radiation-induced cytotoxic effects in a small percentage of cancer cells, and these activations are responsible for tumor radio-resistance. The present study describes the molecular mechanisms responsible for radiation-induced cellular stress response and radioresistance, and the therapeutic approaches used to overcome radioresistance.
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Clustered DNA Damages induced by 0.5 to 30 eV Electrons. Int J Mol Sci 2019; 20:ijms20153749. [PMID: 31370253 PMCID: PMC6695612 DOI: 10.3390/ijms20153749] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 07/26/2019] [Accepted: 07/29/2019] [Indexed: 12/21/2022] Open
Abstract
Low-energy electrons (LEEs) of energies ≤30 eV are generated in large quantities by ionizing radiation. These electrons can damage DNA; particularly, they can induce the more detrimental clustered lesions in cells. This type of lesions, which are responsible for a large portion of the genotoxic stress generated by ionizing radiation, is described in the Introduction. The reactions initiated by the collisions of 0.5-30 eV electrons with oligonucleotides, duplex DNA, and DNA bound to chemotherapeutic platinum drugs are explained and reviewed in the subsequent sections. The experimental methods of LEE irradiation and DNA damage analysis are described with an emphasis on the detection of cluster lesions, which are considerably enhanced in DNA-Pt-drug complexes. Based on the energy dependence of damage yields and cross-sections, a mechanism responsible for the clustered lesions can be attributed to the capture of a single electron by the electron affinity of an excited state of a base, leading to the formation of transient anions at 6 and 10 eV. The initial capture is followed by electronic excitation of the base and dissociative attachment-at other DNA sites-of the electron reemitted from the temporary base anion. The mechanism is expected to be universal in the cellular environment and plays an important role in the formation of clustered lesions.
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Abramenkovs A, Stenerlöw B. Removal of heat-sensitive clustered damaged DNA sites is independent of double-strand break repair. PLoS One 2018; 13:e0209594. [PMID: 30592737 PMCID: PMC6310273 DOI: 10.1371/journal.pone.0209594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 12/07/2018] [Indexed: 11/21/2022] Open
Abstract
DNA double-strand breaks (DSBs) are the most deleterious lesions that can arise in cells after ionizing radiation or radiometric drug treatment. In addition to prompt DSBs, DSBs may also be produced during repair, evolving from a clustered DNA damaged site, which is composed of two or more distinct lesions that are located within two helical turns. A specific type of cluster damage is the heat-sensitive clustered site (HSCS), which transforms into DSBs upon treatment at elevated temperatures. The actual lesions or mechanisms that mediate the HSCS transformation into DSBs are unknown. However, there are two possibilities; either these lesions are transformed into DSBs due to DNA lesion instability, e.g., transfer of HSCS into single-strand breaks (SSBs), or they are formed due to local DNA structure instability, e.g., DNA melting, where two SSBs on opposite strands meet and transform into a DSB. The importance of these processes in living cells is not understood, but they significantly affect estimates of DSB repair capacity. In this study, we show that HSCS removal in human cells is not affected by defects in DSB repair or inhibition of DSB repair. Under conditions where rejoining of prompt DSBs was almost completely inhibited, heat-sensitive DSBs were successfully rejoined, without resulting in increased DSB levels, indicating that HSCS do not transfer into DSB in cells under physiological conditions. Furthermore, analysis by atomic force microscopy suggests that prolonged heating of chromosomal DNA can induce structural changes that facilitate transformation of HSCS into DSB. In conclusion, the HSCS do not generate additional DSBs at physiological temperatures in human cells, and the repair of HSCS is independent of DSB repair.
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Affiliation(s)
- Andris Abramenkovs
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Bo Stenerlöw
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
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Adachi M, Shimizu R, Shibazaki C, Satoh K, Fujiwara S, Arai S, Narumi I, Kuroki R. Extended structure of pleiotropic DNA repair‐promoting protein PprA from
Deinococcus radiodurans. FASEB J 2018; 33:3647-3658. [DOI: 10.1096/fj.201801506r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Motoyasu Adachi
- Tokai Quantum Beam Science CenterNational Institutes for QuantumRadiological Science and Technology Tokai Japan
| | - Rumi Shimizu
- Tokai Quantum Beam Science CenterNational Institutes for QuantumRadiological Science and Technology Tokai Japan
| | - Chie Shibazaki
- Tokai Quantum Beam Science CenterNational Institutes for QuantumRadiological Science and Technology Tokai Japan
| | - Katsuya Satoh
- Department of Radiation–Applied BiologyNational Institutes for Quantum and Radiological Science and Technology Takasaki Japan
| | - Satoru Fujiwara
- Tokai Quantum Beam Science CenterNational Institutes for QuantumRadiological Science and Technology Tokai Japan
| | - Shigeki Arai
- Tokai Quantum Beam Science CenterNational Institutes for QuantumRadiological Science and Technology Tokai Japan
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30
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Zhao HY, Lau KC, Garcia GA, Nahon L, Carniato S, Poisson L, Schwell M, Al-Mogren MM, Hochlaf M. Unveiling the complex vibronic structure of the canonical adenine cation. Phys Chem Chem Phys 2018; 20:20756-20765. [PMID: 29989120 DOI: 10.1039/c8cp02930j] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Adenine, a DNA base, exists as several tautomers and isomers that are closely lying in energy and that may form a mixture upon vaporization of solid adenine. Indeed, it is challenging to bring adenine into the gas phase, especially as a unique tautomer. The experimental conditions were tuned to prepare a jet-cooled canonical adenine (9H-adenine). This isolated DNA base was ionized by single VUV photons from a synchrotron beamline and the corresponding slow photoelectron spectrum was compared to ab initio computations of the neutral and ionic species. We report the vibronic structure of the X+ 2A'' (D0), A+ 2A' (D1) and B+ 2A'' (D2) electronic states of the 9H adenine cation, from the adiabatic ionization energy (AIE) up to AIE + 1.8 eV. Accurate AIEs are derived for the 9H-adenine (X[combining tilde] 1A') + hν → 9H-adenine+ (X+ 2A'', A+ 2A', B+ 2A'') + e- transitions. Close to the AIE, we fully assign the rich vibronic structure solely to the 9H-adenine (X 1A') + hν → 9H-adenine+ (X+ 2A'') transition. Importantly, we show that the lowest cationic electronic states of canonical adenine are coupled vibronically. The present findings are important for understanding the effects of ionizing radiation and the charge distribution on this elementary building block of life, at ultrafast, short, and long timescales.
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Affiliation(s)
- Hong Yan Zhao
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong
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31
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Shikazono N, Akamatsu K. Mutagenic potential of 8-oxo-7,8-dihydroguanine (8-oxoG) is influenced by nearby clustered lesions. Mutat Res 2018; 810:6-12. [PMID: 29870902 DOI: 10.1016/j.mrfmmm.2018.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/13/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
Ionizing radiation causes various different types of DNA damage. If not repaired, DNA damage can have detrimental effects. Previous studies indicate that the spatial distribution of DNA lesions induced by ionizing radiation is highly relevant to the ensuing biological effects. Clustered DNA damage, consisting of DNA lesions in close proximity, has been studied in detail, and has enhanced mutagenic potential depending on the configuration of the lesions. However, it is not known whether clustered DNA damage affects the mutagenic potential of a sufficiently separated, isolated lesion. Using synthetic damage constructs, we investigated the mutagenic potential of an isolated 8-oxo-7,8-dihydroguanine (8-oxoG) separated by at least 7 bp from other lesions. Under the spatial distribution of DNA lesions tested in the present study, neighboring clustered DNA lesions likely retarded the processing of the isolated 8-oxoG and resulted in enhanced mutation frequency. However, the enhanced mutagenic potential was dependent on which strand the isolated 8-oxoG was located. Our results indicate that the processing of a bi-stranded cluster could affect the mutagenic outcome of a nearby isolated lesion, separated up to ∼20 bp.
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Affiliation(s)
- Naoya Shikazono
- Department of Quantum life Science, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa-shi, Kyoto, 619-0215 Japan.
| | - Ken Akamatsu
- Department of Quantum life Science, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa-shi, Kyoto, 619-0215 Japan.
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32
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Teixeira ES, Uppulury K, Privett AJ, Stopera C, McLaurin PM, Morales JA. Electron Nuclear Dynamics Simulations of Proton Cancer Therapy Reactions: Water Radiolysis and Proton- and Electron-Induced DNA Damage in Computational Prototypes. Cancers (Basel) 2018; 10:E136. [PMID: 29734786 PMCID: PMC5977109 DOI: 10.3390/cancers10050136] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/22/2018] [Accepted: 04/28/2018] [Indexed: 11/16/2022] Open
Abstract
Proton cancer therapy (PCT) utilizes high-energy proton projectiles to obliterate cancerous tumors with low damage to healthy tissues and without the side effects of X-ray therapy. The healing action of the protons results from their damage on cancerous cell DNA. Despite established clinical use, the chemical mechanisms of PCT reactions at the molecular level remain elusive. This situation prevents a rational design of PCT that can maximize its therapeutic power and minimize its side effects. The incomplete characterization of PCT reactions is partially due to the health risks associated with experimental/clinical techniques applied to human subjects. To overcome this situation, we are conducting time-dependent and non-adiabatic computer simulations of PCT reactions with the electron nuclear dynamics (END) method. Herein, we present a review of our previous and new END research on three fundamental types of PCT reactions: water radiolysis reactions, proton-induced DNA damage and electron-induced DNA damage. These studies are performed on the computational prototypes: proton + H₂O clusters, proton + DNA/RNA bases and + cytosine nucleotide, and electron + cytosine nucleotide + H₂O. These simulations provide chemical mechanisms and dynamical properties of the selected PCT reactions in comparison with available experimental and alternative computational results.
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Affiliation(s)
- Erico S Teixeira
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA.
| | - Karthik Uppulury
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA.
| | - Austin J Privett
- Department of Chemistry and Biochemistry, Lipscomb University, Nashville, TN 37204, USA.
| | - Christopher Stopera
- Department of Chemistry and Industrial Hygiene, University of North Alabama, Florence, AL 35632, USA.
| | - Patrick M McLaurin
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA.
| | - Jorge A Morales
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA.
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33
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Effect of the track potential on the motion and energy flow of secondary electrons created from heavy-ion irradiation. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2018.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Liu W, Tan Z, Zhang L, Champion C. Investigation on the correlation between energy deposition and clustered DNA damage induced by low-energy electrons. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2018; 57:179-187. [PMID: 29335772 DOI: 10.1007/s00411-018-0730-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 01/10/2018] [Indexed: 06/07/2023]
Abstract
This study presents the correlation between energy deposition and clustered DNA damage, based on a Monte Carlo simulation of the spectrum of direct DNA damage induced by low-energy electrons including the dissociative electron attachment. Clustered DNA damage is classified as simple and complex in terms of the combination of single-strand breaks (SSBs) or double-strand breaks (DSBs) and adjacent base damage (BD). The results show that the energy depositions associated with about 90% of total clustered DNA damage are below 150 eV. The simple clustered DNA damage, which is constituted of the combination of SSBs and adjacent BD, is dominant, accounting for 90% of all clustered DNA damage, and the spectra of the energy depositions correlating with them are similar for different primary energies. One type of simple clustered DNA damage is the combination of a SSB and 1-5 BD, which is denoted as SSB + BD. The average contribution of SSB + BD to total simple clustered DNA damage reaches up to about 84% for the considered primary energies. In all forms of SSB + BD, the SSB + BD including only one base damage is dominant (above 80%). In addition, for the considered primary energies, there is no obvious difference between the average energy depositions for a fixed complexity of SSB + BD determined by the number of base damage, but average energy depositions increase with the complexity of SSB + BD. In the complex clustered DNA damage constituted by the combination of DSBs and BD around them, a relatively simple type is a DSB combining adjacent BD, marked as DSB + BD, and it is of substantial contribution (on average up to about 82%). The spectrum of DSB + BD is given mainly by the DSB in combination with different numbers of base damage, from 1 to 5. For the considered primary energies, the DSB combined with only one base damage contributes about 83% of total DSB + BD, and the average energy deposition is about 106 eV. However, the energy deposition increases with the complexity of clustered DNA damage, and therefore, the clustered DNA damage with high complexity still needs to be considered in the study of radiation biological effects, in spite of their small contributions to all clustered DNA damage.
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Affiliation(s)
- Wei Liu
- School of Electrical Engineering, Shandong University, Jinan, 250061, Shandong, People's Republic of China
- School of Information Science and Electrical Engineering, Shandong Jiaotong University, Jinan, 250357, People's Republic of China
| | - Zhenyu Tan
- School of Electrical Engineering, Shandong University, Jinan, 250061, Shandong, People's Republic of China.
| | - Liming Zhang
- Electric Power Research Institute of Tianjin Electric Power Corporation, Tianjin, 300384, People's Republic of China
| | - Christophe Champion
- Centre d'Etudes Nucléaires de Bordeaux Gradignan, Université de Bordeaux, CNRS/IN2P3, BP 120, 33175, Gradignan, France
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Zhan N, Li B, Xu X, Xu J, Hu S. Inhibition of FASN expression enhances radiosensitivity in human non-small cell lung cancer. Oncol Lett 2018. [PMID: 29541228 DOI: 10.3892/ol.2018.7896] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Fatty acid synthase (FASN) is the key enzyme required for the de novo synthesis of long-chain fatty acids. FASN has been observed to be overexpressed in the majority of cancer tissues, and its expression is associated with a poor prognosis, potentially mediated by resistance to drug or radiation. The present study investigated whether the downregulation of FASN in non-small cell lung cancer (NSCLC) may increase radiosensitivity. A lentiviral vector containing short hairpin RNA targeted to FASN (pSIH-H1-Puro-shFASN) was successfully constructed and transfected into A549 cells to knockdown the gene by RNA interference. pSIH-H1-Puro-shFASN was used as the experimental group, while pSIH-H1-Puro-shGFP was used as a control group. The mRNA expression levels of FASN were determined using quantitative polymerase chain reaction. In addition, cell proliferation was measured using cell counting kit-8 assay, and colony formation assay was performed to determine the radiosensitizing effect of FASN knockdown. The cell cycle distribution and apoptotic rates were analyzed using flow cytometry, while western blot analysis was used to assess the expression of DNA-dependent protein kinase catalytic subunit protein, which is associated with DNA double-strand break (DSB) repair. The results of the present study revealed that NSCLC cells are more sensitive to radiation following the knockdown of FASN. Furthermore, the increased radiosensitivity may be associated with increased proliferation, promotion of apoptosis and cell cycle arrest in the G2/M phase. Furthermore, downregulated FASN expression reduced the levels of DNA DSB repair-associated proteins following treatment with radiation. These results indicate that silencing FASN may sensitize NSCLC cells to radiation treatment. Therefore, FASN may be a potential novel therapeutic target to improve the response of NSCLCs to radiation therapy.
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Affiliation(s)
- Ning Zhan
- Department of Radiation Oncology, The Third Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Bin Li
- Department of Plastic Surgery, Nanfang Hospital of Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Xiangying Xu
- The Center Laboratory of Radiobiology, Institute of Cancer Prevention and Treatment of Heilongjiang Province, Harbin, Heilongjiang 150081, P.R. China
| | - Jianyu Xu
- Department of Radiation Oncology, The Third Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Songliu Hu
- Department of Radiation Oncology, The Third Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
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36
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Zhang H, Gattuso H, Dumont E, Cai W, Monari A, Chipot C, Dehez F. Accurate Estimation of the Standard Binding Free Energy of Netropsin with DNA. Molecules 2018; 23:molecules23020228. [PMID: 29370096 PMCID: PMC6017086 DOI: 10.3390/molecules23020228] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 01/14/2018] [Accepted: 01/19/2018] [Indexed: 12/12/2022] Open
Abstract
DNA is the target of chemical compounds (drugs, pollutants, photosensitizers, etc.), which bind through non-covalent interactions. Depending on their structure and their chemical properties, DNA binders can associate to the minor or to the major groove of double-stranded DNA. They can also intercalate between two adjacent base pairs, or even replace one or two base pairs within the DNA double helix. The subsequent biological effects are strongly dependent on the architecture of the binding motif. Discriminating between the different binding patterns is of paramount importance to predict and rationalize the effect of a given compound on DNA. The structural characterization of DNA complexes remains, however, cumbersome at the experimental level. In this contribution, we employed all-atom molecular dynamics simulations to determine the standard binding free energy of DNA with netropsin, a well-characterized antiviral and antimicrobial drug, which associates to the minor groove of double-stranded DNA. To overcome the sampling limitations of classical molecular dynamics simulations, which cannot capture the large change in configurational entropy that accompanies binding, we resort to a series of potentials of mean force calculations involving a set of geometrical restraints acting on collective variables.
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Affiliation(s)
- Hong Zhang
- Research Center for Analytical Sciences, College of Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Nankai University, Tianjin 300071, China.
| | - Hugo Gattuso
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), Université de Lorraine-Nancy, 54506 Vandoeuvre-lès-Nancy, France.
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), CNRS, 54506 Vandeouvre-lès-Nancy, France.
| | - Elise Dumont
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Laboratoire de Chimie, Université Claude Bernard Lyon 1, F-69342 Lyon, France.
| | - Wensheng Cai
- Research Center for Analytical Sciences, College of Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Nankai University, Tianjin 300071, China.
- Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China.
| | - Antonio Monari
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), Université de Lorraine-Nancy, 54506 Vandoeuvre-lès-Nancy, France.
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), CNRS, 54506 Vandeouvre-lès-Nancy, France.
| | - Christophe Chipot
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), Université de Lorraine-Nancy, 54506 Vandoeuvre-lès-Nancy, France.
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), CNRS, 54506 Vandeouvre-lès-Nancy, France.
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Champaign, Illinois, 54506 Vandeouvre-lès-Nancy, France.
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801, USA.
| | - François Dehez
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), Université de Lorraine-Nancy, 54506 Vandoeuvre-lès-Nancy, France.
- UMR 7019, Theoretical Physics and Chemistry Department (LPCT), CNRS, 54506 Vandeouvre-lès-Nancy, France.
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Champaign, Illinois, 54506 Vandeouvre-lès-Nancy, France.
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Jezkova L, Zadneprianetc M, Kulikova E, Smirnova E, Bulanova T, Depes D, Falkova I, Boreyko A, Krasavin E, Davidkova M, Kozubek S, Valentova O, Falk M. Particles with similar LET values generate DNA breaks of different complexity and reparability: a high-resolution microscopy analysis of γH2AX/53BP1 foci. NANOSCALE 2018; 10:1162-1179. [PMID: 29271466 DOI: 10.1039/c7nr06829h] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Biological effects of high-LET (linear energy transfer) radiation have received increasing attention, particularly in the context of more efficient radiotherapy and space exploration. Efficient cell killing by high-LET radiation depends on the physical ability of accelerated particles to generate complex DNA damage, which is largely mediated by LET. However, the characteristics of DNA damage and repair upon exposure to different particles with similar LET parameters remain unexplored. We employed high-resolution confocal microscopy to examine phosphorylated histone H2AX (γH2AX)/p53-binding protein 1 (53BP1) focus streaks at the microscale level, focusing on the complexity, spatiotemporal behaviour and repair of DNA double-strand breaks generated by boron and neon ions accelerated at similar LET values (∼135 keV μm-1) and low energies (8 and 47 MeV per n, respectively). Cells were irradiated using sharp-angle geometry and were spatially (3D) fixed to maximize the resolution of these analyses. Both high-LET radiation types generated highly complex γH2AX/53BP1 focus clusters with a larger size, increased irregularity and slower elimination than low-LET γ-rays. Surprisingly, neon ions produced even more complex γH2AX/53BP1 focus clusters than boron ions, consistent with DSB repair kinetics. Although the exposure of cells to γ-rays and boron ions eliminated a vast majority of foci (94% and 74%, respectively) within 24 h, 45% of the foci persisted in cells irradiated with neon. Our calculations suggest that the complexity of DSB damage critically depends on (increases with) the particle track core diameter. Thus, different particles with similar LET and energy may generate different types of DNA damage, which should be considered in future research.
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Affiliation(s)
- Lucie Jezkova
- Joint Institute for Nuclear Research, Dubna, Russia and University of Chemistry and Technology Prague, Prague, Czech Republic
- University of Chemistry and Technology Prague, Prague, Czech Republic
| | - Mariia Zadneprianetc
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Elena Kulikova
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | | | - Tatiana Bulanova
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Daniel Depes
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
| | - Iva Falkova
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
| | - Alla Boreyko
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Evgeny Krasavin
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Marie Davidkova
- Czech Academy of Sciences, Nuclear Physics Institute, Prague, Czech Republic
| | - Stanislav Kozubek
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
| | - Olga Valentova
- University of Chemistry and Technology Prague, Prague, Czech Republic
| | - Martin Falk
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
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38
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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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39
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Exploring water radiolysis in proton cancer therapy: Time-dependent, non-adiabatic simulations of H+ + (H2O)1-6. PLoS One 2017; 12:e0174456. [PMID: 28376128 PMCID: PMC5380356 DOI: 10.1371/journal.pone.0174456] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 03/09/2017] [Indexed: 11/23/2022] Open
Abstract
To elucidate microscopic details of proton cancer therapy (PCT), we apply the simplest-level electron nuclear dynamics (SLEND) method to H+ + (H2O)1-6 at ELab = 100 keV. These systems are computationally tractable prototypes to simulate water radiolysis reactions—i.e. the PCT processes that generate the DNA-damaging species against cancerous cells. To capture incipient bulk-water effects, ten (H2O)1-6 isomers are considered, ranging from quasi-planar/multiplanar (H2O)1-6 to “smallest-drop” prism and cage (H2O)6 structures. SLEND is a time-dependent, variational, non-adiabatic and direct method that adopts a nuclear classical-mechanics description and an electronic single-determinantal wavefunction in the Thouless representation. Short-time SLEND/6-31G* (n = 1–6) and /6-31G** (n = 1–5) simulations render cluster-to-projectile 1-electron-transfer (1-ET) total integral cross sections (ICSs) and 1-ET probabilities. In absolute quantitative terms, SLEND/6-31G* 1-ET ICS compares satisfactorily with alternative experimental and theoretical results only available for n = 1 and exhibits almost the same accuracy of the best alternative theoretical result. SLEND/6-31G** overestimates 1-ET ICS for n = 1, but a comparable overestimation is also observed with another theoretical method. An investigation on H+ + H indicates that electron direct ionization (DI) becomes significant with the large virtual-space quasi-continuum in large basis sets; thus, SLEND/6-31G** 1-ET ICS is overestimated by DI contributions. The solution to this problem is discussed. In relative quantitative terms, both SLEND/6-31* and /6-31G** 1-ET ICSs precisely fit into physically justified scaling formulae as a function of the cluster size; this indicates SLEND’s suitability for predicting properties of water clusters with varying size. Long-time SLEND/6-31G* (n = 1–4) simulations predict the formation of the DNA-damaging radicals H, OH, O and H3O. While “smallest-drop” isomers are included, no early manifestations of bulk water PCT properties are observed and simulations with larger water clusters will be needed to capture those effects. This study is the largest SLEND investigation on water radiolysis to date.
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Chen Z, Lau KC, Garcia GA, Nahon L, Božanić DK, Poisson L, Al-Mogren MM, Schwell M, Francisco JS, Bellili A, Hochlaf M. Identifying Cytosine-Specific Isomers via High-Accuracy Single Photon Ionization. J Am Chem Soc 2016; 138:16596-16599. [DOI: 10.1021/jacs.6b10413] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Ziyong Chen
- Department
of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong
| | - Kai-Chung Lau
- Department
of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong
| | - Gustavo A. Garcia
- Synchrotron SOLEIL, L’orme des
Merisiers, Saint-Aubin
- BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Laurent Nahon
- Synchrotron SOLEIL, L’orme des
Merisiers, Saint-Aubin
- BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Dušan K. Božanić
- Synchrotron SOLEIL, L’orme des
Merisiers, Saint-Aubin
- BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Lionel Poisson
- LIDYL,
CEA, CNRS, Université Paris-Saclay, CEA Saclay, F-91191 Gif-sur-Yvette, France
| | - Muneerah Mogren Al-Mogren
- Chemistry
Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia
| | - Martin Schwell
- Laboratoire
Interuniversitaire des Systèmes Atmosphériques (LISA),
UMR 7583 CNRS, Universités Paris-Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil, France
| | - Joseph S. Francisco
- Department
of Chemistry, University of Nebraska-Lincoln. 433 Hamilton Hall, Lincoln, Nebraska 68588-0304, United States
| | - Ayad Bellili
- Laboratoire
Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est. 5 bd Descartes, 77454 Marne-la-Vallée, France
| | - Majdi Hochlaf
- Laboratoire
Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est. 5 bd Descartes, 77454 Marne-la-Vallée, France
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Shiraishi I, Shikazono N, Suzuki M, Fujii K, Yokoya A. Efficiency of radiation-induced base lesion excision and the order of enzymatic treatment. Int J Radiat Biol 2016; 93:295-302. [PMID: 27707033 DOI: 10.1080/09553002.2017.1239849] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To clarify whether initial base excision repair processes at clustered DNA damage sites comprising multiple base lesions affect subsequent excision processes via the formation of additional strand breaks by glycosylase and apurinic/apyrimidinic (AP) endonuclease base excision enzymes. MATERIALS AND METHODS Plasmid DNA (pUC18) as a model DNA molecule was exposed to high-linear-energy-transfer (LET) ionizing radiation (He2+ or C6+ ions) or low-LET ionizing radiation (X-rays) under various conditions to produce varied radical-scavenging effects. pUC18 was then treated sequentially or simultaneously with two bacterial base excision enzymes (glycosylases), namely, endonuclease III and formamidopyrimidine-DNA glycosylase, which convert pyrimidine (or abasic [AP] site) and purine (or AP site) lesions to single-strand breaks (SSB), respectively. Yields of additional SSB or double-strand breaks (DSB) as digestion products were examined after changing the order of enzymatic treatment. RESULTS There were few differences among the enzymatic treatments, indicating that treatment order did not affect the final yields of additional SSB or DSB formed by glycosylase activity. This suggests that of the total damage, the fraction of clustered damage sites with a persistent base lesion dependent on the order of glycosylase treatment was insignificant if present. CONCLUSION Base lesion clusters induced by high- or low-LET radiation appear three or more base pairs apart, and are promptly converted to a DSB by glycosylase, regardless of the order of enzymatic treatment.
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Affiliation(s)
- Iyo Shiraishi
- a Department of Environmental Sciences, Faculty of Science , Ibaraki University , Mito , Ibaraki , Japan.,b Tokai Quantum Beam Science Center, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology , Tokai-mura , Ibaraki , Japan
| | - Naoya Shikazono
- c Department of Quantum Beam Life Science , Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology , Kyoto, Kizugawa-shi , Japan
| | - Masao Suzuki
- d Department of Basic Medical Sciences for Radiation Damages , National Institute of Radiological Sciences, National Institutes of Quantum and Radiological Science and Technology , Chiba , Japan
| | - Kentaro Fujii
- b Tokai Quantum Beam Science Center, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology , Tokai-mura , Ibaraki , Japan
| | - Akinari Yokoya
- a Department of Environmental Sciences, Faculty of Science , Ibaraki University , Mito , Ibaraki , Japan.,b Tokai Quantum Beam Science Center, Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology , Tokai-mura , Ibaraki , Japan
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Choofong S, Cloutier P, Sanche L, Wagner JR. Base Release and Modification in Solid-Phase DNA Exposed to Low-Energy Electrons. Radiat Res 2016; 186:520-530. [PMID: 27802110 DOI: 10.1667/rr14476.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ionization generates a large number of secondary low-energy electrons (LEEs) with a most probable energy of approximately 10 eV, which can break DNA bonds by dissociative electron attachment (DEA) and lead to DNA damage. In this study, we investigated radiation damage to dry DNA induced by X rays (1.5 keV) alone on a glass substrate or X rays combined with extra LEEs (average energy of 5.8 eV) emitted from a tantalum (Ta) substrate under an atmosphere of N2 and standard ambient conditions of temperature and pressure. The targets included calf-thymus DNA and double-stranded synthetic oligonucleotides. We developed analytical methods to measure the release of non-modified DNA bases from DNA and the formation of several base modifications by LC-MS/MS with isotopic dilution for precise quantification. The results show that the yield of non-modified bases as well as base modifications increase by 20-30% when DNA is deposited on a Ta substrate compared to that on a glass substrate. The order of base release (Gua > Ade > Thy ∼ Cyt) agrees well with several theoretical studies indicating that Gua is the most susceptible site toward sugar-phosphate cleavage. The formation of DNA damage by LEEs is explained by DEA leading to the release of non-modified bases involving the initial cleavage of N1-C1', C3'-O3' or C5'-O5' bonds. The yield of base modifications was lower than the release of non-modified bases. The main LEE-induced base modifications include 5,6-dihydrothymine (5,6-dHT), 5,6-dihydrouracil (5-dHU), 5-hydroxymethyluracil (5-HmU) and 5-formyluracil (5-ForU). The formation of base modifications by LEEs can be explained by DEA and cleavage of the C-H bond of the methyl group of Thy (giving 5-HmU and 5-ForU) and by secondary reactions of H atoms and hydride anions that are generated by primary LEE reactions followed by subsequent reaction with Cyt and Thy (giving 5,6-dHU and 5,6-dHT).
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Affiliation(s)
- Surakarn Choofong
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Pierre Cloutier
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Léon Sanche
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - J Richard Wagner
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Gattuso H, Durand E, Bignon E, Morell C, Georgakilas AG, Dumont E, Chipot C, Dehez F, Monari A. Repair Rate of Clustered Abasic DNA Lesions by Human Endonuclease: Molecular Bases of Sequence Specificity. J Phys Chem Lett 2016; 7:3760-3765. [PMID: 27612215 DOI: 10.1021/acs.jpclett.6b01692] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In the present contribution, the interaction between damaged DNA and repair enzymes is examined by means of molecular dynamics simulations. More specifically, we consider clustered abasic DNA lesions processed by the primary human apurinic/apyrimidinic (AP) endonuclease, APE1. Our results show that, in stark contrast with the corresponding bacterial endonucleases, human APE1 imposes strong geometrical constraints on the DNA duplex. As a consequence, the level of recognition and, hence, the repair rate is higher. Important features that guide the DNA/protein interactions are the presence of an extended positively charged region and of a molecular tweezers that strongly constrains DNA. Our results are on very good agreement with the experimentally determined repair rate of clustered abasic lesions. The lack of repair for one particular arrangement of the two abasic sites is also explained considering the peculiar destabilizing interaction between the recognition region and the second lesion, resulting in a partial opening of the molecular tweezers and, thus, a less stable complex. This contribution cogently establishes the molecular bases for the recognition and repair of clustered DNA lesions by means of human endonucleases.
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Affiliation(s)
- Hugo Gattuso
- Université de Lorraine-Nancy , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
- CNRS , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
| | - Elodie Durand
- Université de Lorraine-Nancy , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
- CNRS , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
| | - Emmanuelle Bignon
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1 , Laboratoire de Chimie, F-69342 Lyon, France
- Université de Lyon , Institut des Sciences Analytiques UMR 5280, CNRS, Université de Lyon 1, ENS Lyon 5 rue de la Doua, F-69100 Villeurbanne, France
| | - Christophe Morell
- Université de Lyon , Institut des Sciences Analytiques UMR 5280, CNRS, Université de Lyon 1, ENS Lyon 5 rue de la Doua, F-69100 Villeurbanne, France
| | - Alexandros G Georgakilas
- DNA damage laboratory, Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens (NTUA) , Zografou, Athens 15780, Greece
| | - Elise Dumont
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1 , Laboratoire de Chimie, F-69342 Lyon, France
| | - Christophe Chipot
- Université de Lorraine-Nancy , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
- CNRS , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
- Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801, United States
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign
| | - François Dehez
- Université de Lorraine-Nancy , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
- CNRS , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign
| | - Antonio Monari
- Université de Lorraine-Nancy , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
- CNRS , Theory-Modeling-Simulation SRSMC, 54000 Vandoeuvre-lès-Nancy, France
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Takahashi M, Akamatsu K, Shikazono N. A polymerization-based method to construct a plasmid containing clustered DNA damage and a mismatch. Anal Biochem 2016; 510:129-135. [PMID: 27449134 DOI: 10.1016/j.ab.2016.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 10/21/2022]
Abstract
Exposure of biological materials to ionizing radiation often induces clustered DNA damage. The mutagenicity of clustered DNA damage can be analyzed with plasmids carrying a clustered DNA damage site, in which the strand bias of a replicating plasmid (i.e., the degree to which each of the two strands of the plasmid are used as the template for replication of the plasmid) can help to clarify how clustered DNA damage enhances the mutagenic potential of comprising lesions. Placement of a mismatch near a clustered DNA damage site can help to determine the strand bias, but present plasmid-based methods do not allow insertion of a mismatch at a given site in the plasmid. Here, we describe a polymerization-based method for constructing a plasmid containing clustered DNA lesions and a mismatch. The presence of a DNA lesion and a mismatch in the plasmid was verified by enzymatic treatment and by determining the relative abundance of the progeny plasmids derived from each of the two strands of the plasmid.
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Affiliation(s)
- Momoko Takahashi
- Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, Japan
| | - Ken Akamatsu
- Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, Japan
| | - Naoya Shikazono
- Quantum Beam Science Research Directorate, National Institutes of Quantum and Radiological Science and Technology, Japan.
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Zálešák J, Constant JF, Jourdan M. Nuclear Magnetic Resonance Solution Structure of DNA Featuring Clustered 2'-Deoxyribonolactone and 8-Oxoguanine Lesions. Biochemistry 2016; 55:3899-906. [PMID: 27322640 DOI: 10.1021/acs.biochem.6b00396] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ionizing radiation, free radicals, and reactive oxygen species produce hundreds of different DNA lesions. Clustered lesions are typical for ionizing radiation. They compromise the efficiency of the base excision repair (BER) pathway, and as a consequence, they are much more toxic and mutagenic than isolated lesions. Despite their biological relevance, e.g., in cancer radiotherapy and accidental exposure, they are not very well studied from a structural point of view, and while insights provided by structural studies contribute to the understanding of the repair process, only three nuclear magnetic resonance (NMR) studies of DNA containing clusters of lesions were reported. Herein, we report the first NMR solution structure of two DNAs containing a bistranded cluster with the 2'-deoxyribonolactone and 8-oxoguanine lesions. Both DNA duplexes feature a 2'-deoxyribonolactone site in the middle of the sequence of one strand and differ by the relative position of the 8-oxoguanine, staggered 3' or 5' side on the complementary strand at a three-nucleotide distance. Depending on its relative position, the repair of the 8-oxoguanine lesion by the base excision repair protein Fpg is either almost complete or inhibited. We found that the structures of the two DNAs containing a bistranded cluster of two lesions are similar and do not deviate very much from the standard B-form. As no obvious structural deformations were observed between the two duplexes, we concluded that the differences in Fpg activity are not due to differences in their global conformation.
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Affiliation(s)
- Jan Zálešák
- Universite Grenoble Alpes , DCM UMR 5250, F-38000 Grenoble, France.,CNRS , DCM UMR 5250, F-38000 Grenoble, France
| | - Jean-François Constant
- Universite Grenoble Alpes , DCM UMR 5250, F-38000 Grenoble, France.,CNRS , DCM UMR 5250, F-38000 Grenoble, France
| | - Muriel Jourdan
- Universite Grenoble Alpes , DCM UMR 5250, F-38000 Grenoble, France.,CNRS , DCM UMR 5250, F-38000 Grenoble, France
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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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End-processing nucleases and phosphodiesterases: An elite supporting cast for the non-homologous end joining pathway of DNA double-strand break repair. DNA Repair (Amst) 2016; 43:57-68. [PMID: 27262532 DOI: 10.1016/j.dnarep.2016.05.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 05/05/2016] [Indexed: 11/20/2022]
Abstract
Nonhomologous end joining (NHEJ) is an error-prone DNA double-strand break repair pathway that is active throughout the cell cycle. A substantial fraction of NHEJ repair events show deletions and, less often, insertions in the repair joints, suggesting an end-processing step comprising the removal of mismatched or damaged nucleotides by nucleases and other phosphodiesterases, as well as subsequent strand extension by polymerases. A wide range of nucleases, including Artemis, Metnase, APLF, Mre11, CtIP, APE1, APE2 and WRN, are biochemically competent to carry out such double-strand break end processing, and have been implicated in NHEJ by at least circumstantial evidence. Several additional DNA end-specific phosphodiesterases, including TDP1, TDP2 and aprataxin are available to resolve various non-nucleotide moieties at DSB ends. This review summarizes the biochemical specificities of these enzymes and the evidence for their participation in the NHEJ pathway.
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Manova V, Gruszka D. DNA damage and repair in plants - from models to crops. FRONTIERS IN PLANT SCIENCE 2015; 6:885. [PMID: 26557130 PMCID: PMC4617055 DOI: 10.3389/fpls.2015.00885] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Accepted: 10/05/2015] [Indexed: 05/17/2023]
Abstract
The genomic integrity of every organism is constantly challenged by endogenous and exogenous DNA-damaging factors. Mutagenic agents cause reduced stability of plant genome and have a deleterious effect on development, and in the case of crop species lead to yield reduction. It is crucial for all organisms, including plants, to develop efficient mechanisms for maintenance of the genome integrity. DNA repair processes have been characterized in bacterial, fungal, and mammalian model systems. The description of these processes in plants, in contrast, was initiated relatively recently and has been focused largely on the model plant Arabidopsis thaliana. Consequently, our knowledge about DNA repair in plant genomes - particularly in the genomes of crop plants - is by far more limited. However, the relatively small size of the Arabidopsis genome, its rapid life cycle and availability of various transformation methods make this species an attractive model for the study of eukaryotic DNA repair mechanisms and mutagenesis. Moreover, abnormalities in DNA repair which proved to be lethal for animal models are tolerated in plant genomes, although sensitivity to DNA damaging agents is retained. Due to the high conservation of DNA repair processes and factors mediating them among eukaryotes, genes and proteins that have been identified in model species may serve to identify homologous sequences in other species, including crop plants, in which these mechanisms are poorly understood. Crop breeding programs have provided remarkable advances in food quality and yield over the last century. Although the human population is predicted to "peak" by 2050, further advances in yield will be required to feed this population. Breeding requires genetic diversity. The biological impact of any mutagenic agent used for the creation of genetic diversity depends on the chemical nature of the induced lesions and on the efficiency and accuracy of their repair. More recent targeted mutagenesis procedures also depend on host repair processes, with different pathways yielding different products. Enhanced understanding of DNA repair processes in plants will inform and accelerate the engineering of crop genomes via both traditional and targeted approaches.
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Affiliation(s)
- Vasilissa Manova
- Department of Molecular Genetics, Institute of Plant Physiology and Genetics, Bulgarian Academy of SciencesSofia
| | - Damian Gruszka
- Department of Genetics, Faculty of Biology and Environment Protection, University of SilesiaKatowice, Poland
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Mion G, Gianferrara T, Bergamo A, Gasser G, Pierroz V, Rubbiani R, Vilar R, Leczkowska A, Alessio E. Phototoxic Activity and DNA Interactions of Water-Soluble Porphyrins and Their Rhenium(I) Conjugates. ChemMedChem 2015; 10:1901-14. [PMID: 26332425 DOI: 10.1002/cmdc.201500288] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/13/2015] [Indexed: 12/12/2022]
Abstract
In the search for alternative photosensitizers for use in photodynamic therapy (PDT), herein we describe two new water-soluble porphyrins, a neutral fourfold-symmetric compound and a +3-charged tris-methylpyridinium derivative, in which either four or one [1,4,7]-triazacyclononane (TACN) units are connected to the porphyrin macrocycle through a hydrophilic linker; we also report their corresponding tetracationic Re(I) conjugates. The in vitro (photo)toxic effects of the compounds toward the human cell lines HeLa (cervical cancer), H460M2 (non-small-cell lung carcinoma), and HBL-100 (non-tumorigenic epithelial cells) are reported. Three of the compounds are not cytotoxic in the dark up to 100 μm, and the fourfold-symmetric couple revealed very good phototoxic indexes (PIs). The intracellular localization of all derivatives was studied in HeLa cells by confocal fluorescence microscopy. Although low nuclear localization was observed for some of them, it still prompted us to investigate their capacity to bind both quadruplex and duplex DNA; we observed significant selectivity in the tris-methylpyridinium derivatives for G-quadruplex interactions.
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Affiliation(s)
- Giuliana Mion
- Department of Chemical & Pharmaceutical Sciences, Università degli Studi di Trieste, P.le Europa 1, 34127, Trieste, Italy
| | - Teresa Gianferrara
- Department of Chemical & Pharmaceutical Sciences, Università degli Studi di Trieste, P.le Europa 1, 34127, Trieste, Italy.
| | - Alberta Bergamo
- Callerio Foundation Onlus, Via A. Fleming 22-31, 34127, Trieste, Italy
| | - Gilles Gasser
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Vanessa Pierroz
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Riccardo Rubbiani
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Ramon Vilar
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK.
| | - Anna Leczkowska
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK
| | - Enzo Alessio
- Department of Chemical & Pharmaceutical Sciences, Università degli Studi di Trieste, P.le Europa 1, 34127, Trieste, Italy
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Vyšín L, Pachnerová Brabcová K, Štěpán V, Moretto-Capelle P, Bugler B, Legube G, Cafarelli P, Casta R, Champeaux JP, Sence M, Vlk M, Wagner R, Štursa J, Zach V, Incerti S, Juha L, Davídková M. Proton-induced direct and indirect damage of plasmid DNA. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2015; 54:343-352. [PMID: 26007308 DOI: 10.1007/s00411-015-0605-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 05/15/2015] [Indexed: 06/04/2023]
Abstract
Clustered DNA damage induced by 10, 20 and 30 MeV protons in pBR322 plasmid DNA was investigated. Besides determination of strand breaks, additional lesions were detected using base excision repair enzymes. The plasmid was irradiated in dry form, where indirect radiation effects were almost fully suppressed, and in water solution containing only minimal residual radical scavenger. Simultaneous irradiation of the plasmid DNA in the dry form and in the solution demonstrated the contribution of the indirect effect as prevalent. The damage composition slightly differed when comparing the results for liquid and dry samples. The obtained data were also subjected to analysis concerning different methodological approaches, particularly the influence of irradiation geometry, models used for calculation of strand break yields and interpretation of the strand breaks detected with the enzymes. It was shown that these parameters strongly affect the results.
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Affiliation(s)
- Luděk Vyšín
- Institute of Physics CAS, Na Slovance 1999/2, 182 21, Prague, Czech Republic
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