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Martin OA, Sykes PJ, Lavin M, Engels E, Martin RF. What's Changed in 75 Years of RadRes? - An Australian Perspective on Selected Topics. Radiat Res 2024; 202:309-327. [PMID: 38966925 DOI: 10.1667/rade-24-00037.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 05/09/2024] [Indexed: 07/06/2024]
Abstract
Several scientific themes are reviewed in the context of the 75-year period relevant to this special platinum issue of Radiation Research. Two criteria have been considered in selecting the scientific themes. One is the exposure of the associated research activity in the annual meetings of the Radiation Research Society (RRS) and in the publications of the Society's Journal, thus reflecting the interest of members of RRS. The second criteria is a focus on contributions from Australian members of RRS. The first theme is the contribution of radiobiology to radiation oncology, featuring two prominent Australian radiation oncologists, the late Rod Withers and his younger colleague, Lester Peters. Two other themes are also linked to radiation oncology; preclinical research aimed at developing experimental radiotherapy modalities, namely microbeam radiotherapy (MRT) and Auger endoradiotherapy. The latter has a long history, in contrast to MRT, especially in Australia, given that the associated medical beamline at the Australian Synchrotron in Melbourne only opened in 2011. Another theme is DNA repair, which has a trajectory parallel to the 75-year period of interest, given the birth of molecular biology in the 1950s. The low-dose radiobiology theme has a similar timeline, predominantly prompted by the nuclear era, which is also connected to the radioprotector theme, although radioprotectors also have a long-established potential utility in cancer radiotherapy. Finally, two themes are associated with biodosimetry. One is the micronucleus assay, highlighting the pioneering contribution from Michael Fenech in Adelaide, South Australia, and the other is the γ-H2AX assay and its widespread clinical applications.
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Affiliation(s)
- Olga A Martin
- Centre of Medical Radiation Physics (CMRP), University of Wollongong, Wollongong, NSW, Australia
| | - Pamela J Sykes
- College of Medicine and Public Health, Flinders University and Medical Centre, Bedford Park, SA, Australia
| | - Martin Lavin
- Centre for Clinical Research, University of Queensland, QSL, Brisbane, Australia
| | - Elette Engels
- Centre of Medical Radiation Physics (CMRP), University of Wollongong, Wollongong, NSW, Australia
- Australian Synchrotron, Australian Nuclear Science and Technology Organisation (ANSTO), Clayton, VIC, Australia
| | - Roger F Martin
- School of Chemistry, University of Melbourne, Parkville, VIC, Australia
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Anderson RF, Shinde SS, Andrau L, Leung B, Skene C, White JM, Lobachevsky PN, Martin RF. Chemical Repair of Radical Damage to the GC Base Pair by DNA-Bound Bisbenzimidazoles. J Phys Chem B 2024. [PMID: 38686959 DOI: 10.1021/acs.jpcb.4c01069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
The migration of an electron-loss center (hole) in calf thymus DNA to bisbenzimidazole ligands bound in the minor groove is followed by pulse radiolysis combined with time-resolved spectrophotometry. The initially observed absorption spectrum upon oxidation of DNA by the selenite radical is consistent with spin on cytosine (C), as the GC• pair neutral radical, followed by the spectra of oxidized ligands. The rate of oxidation of bound ligands increased with an increase in the ratio (r) ligands per base pair from 0.005 to 0.04. Both the rate of ligand oxidation and the estimated range of hole transfer (up to 30 DNA base pairs) decrease with the decrease in one-electron reduction potential between the GC• pair neutral radical of ca. 1.54 V and that of the ligand radicals (E0', 0.90-0.99 V). Linear plots of log of the rate of hole transfer versus r give a common intercept at r = 0 and a free energy change of 12.2 ± 0.3 kcal mol-1, ascribed to the GC• pair neutral radical undergoing a structural change, which is in competition to the observed hole transfer along DNA. The rate of hole transfer to the ligands at distance, R, from the GC• pair radical, k2, is described by the relationship k2 = k0 exp(constant/R), where k0 includes the rate constant for surmounting a small barrier.
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Affiliation(s)
- Robert F Anderson
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Sujata S Shinde
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Laura Andrau
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Brenda Leung
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Colin Skene
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Jonathan M White
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Pavel N Lobachevsky
- Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne 3052, Australia
| | - Roger F Martin
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
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Lobachevsky P, Skene C, Munforte L, Smith A, White J, Martin RF. An approach to assessing the contribution of the high LET effect in strategies for Auger endoradiotherapy. Int J Radiat Biol 2023; 99:95-102. [PMID: 34519610 DOI: 10.1080/09553002.2021.1976862] [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: 01/13/2023]
Abstract
Purpose: The interest in exploiting Auger emitters in cancer therapy stems from their high linear energy transfer (LET)-type radiation damage to DNA. However, the design of Auger-emitter labeled vehicles that target the Auger cascade specifically to the DNA of tumour cells is challenging. Here we suggest a possible approach to evaluate tumour-targeting Auger-labeled conjugates by assessing the impact of a radioprotector known to be effective in protecting from low LET radiation, but not high LET radiation. Given some similarity between the energy spectrum of Auger electrons and that of secondary electrons from soft X-rays, we report the results of radioprotection experiments with 25 kVp X-rays. Materials and methods: Clonogenic survival curves for cultured human keratinocytes were established for three different irradiation conditions: 137Cs γ-rays, 25 kVp X-rays and 320 kVp X-rays, and the effect of including a new radioprotector, denoted "2PH", was investigated.Results: The extent of radioprotection by 2PH was comparable for all radiation conditions, although RBE was higher (about 1.7) for soft X-rays. Conclusions: Radioprotectors like 2PH will help to evaluate Auger endoradiotherapy strategies, by determining the relative contributions of the high-LET effects (not protected), compared to other components, such as Auger electrons not effectively targeted to DNA.
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Affiliation(s)
- Pavel Lobachevsky
- Peter MacCallum Cancer Centre, Parkville, Australia.,Advanced Analytical Technologies, Melbourne, Australia
| | - Colin Skene
- School of Chemistry and Bio21 Institute, The University of Melbourne, Parkville, Australia
| | | | - Andrea Smith
- Peter MacCallum Cancer Centre, Parkville, Australia
| | - Jonathan White
- School of Chemistry and Bio21 Institute, The University of Melbourne, Parkville, Australia
| | - Roger F Martin
- School of Chemistry and Bio21 Institute, The University of Melbourne, Parkville, Australia
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Razskazovskiy Y, Campbell EB, Cutright ZD, Thomas CS, Roginskaya M. One-electron oxidation of guanine derivatives: Detection of 2,5-diaminoimidazolone and novel guanine-guanine cross-links as major end products. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Martin OA, Martin RF. Cancer Radiotherapy: Understanding the Price of Tumor Eradication. Front Cell Dev Biol 2020; 8:261. [PMID: 32391355 PMCID: PMC7193305 DOI: 10.3389/fcell.2020.00261] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/27/2020] [Indexed: 12/15/2022] Open
Affiliation(s)
- Olga A Martin
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC, Australia
| | - Roger F Martin
- School of Chemistry, The University of Melbourne, Melbourne, VIC, Australia
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Anderson RF, Shinde SS, Maroz A, Reynisson J. The reduction potential of the slipped GC base pair in one-electron oxidized duplex DNA. Phys Chem Chem Phys 2020; 22:642-646. [PMID: 31822872 DOI: 10.1039/c9cp05544d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Redox equilibrium between the low potential aniline radical cation and the guanine in the GC base pair of duplex DNA has been established using pulse radiolysis. We relate the measurement of a radical one-electron reduction potential, E0', of 1.01 ± 0.03 V to the perturbation of the GC base pair to accommodate the neutral guanyl radical in an energetically more stable 'slipped' structure. The formation of the 'slipped' structure is exothermic by -11.4 kcal mol-1 as calculated by DFT, which is inline with our experimental results.
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Affiliation(s)
- Robert F Anderson
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
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Burdak-Rothkamm S, Smith A, Lobachevsky P, Martin R, Prise KM. Radioprotection of targeted and bystander cells by methylproamine. Strahlenther Onkol 2014; 191:248-55. [PMID: 25245467 PMCID: PMC4338360 DOI: 10.1007/s00066-014-0751-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/02/2014] [Indexed: 11/25/2022]
Abstract
Introduction Radioprotective agents are of interest for application in radiotherapy for cancer and in public health medicine in the context of accidental radiation exposure. Methylproamine is the lead compound of a class of radioprotectors which act as DNA binding anti-oxidants, enabling the repair of transient radiation-induced oxidative DNA lesions. This study tested methylproamine for the radioprotection of both directly targeted and bystander cells. Methods T98G glioma cells were treated with 15 μM methylproamine and exposed to 137Cs γ-ray/X-ray irradiation and He2+ microbeam irradiation. Radioprotection of directly targeted cells and bystander cells was measured by clonogenic survival or γH2AX assay. Results Radioprotection of directly targeted T98G cells by methylproamine was observed for 137Cs γ-rays and X-rays but not for He2+ charged particle irradiation. The effect of methylproamine on the bystander cell population was tested for both X-ray irradiation and He2+ ion microbeam irradiation. The X-ray bystander experiments were carried out by medium transfer from irradiated to non-irradiated cultures and three experimental designs were tested. Radioprotection was only observed when recipient cells were pretreated with the drug prior to exposure to the conditioned medium. In microbeam bystander experiments targeted and nontargeted cells were co-cultured with continuous methylproamine treatment during irradiation and postradiation incubation; radioprotection of bystander cells was observed. Discussion and conclusion Methylproamine protected targeted cells from DNA damage caused by γ-ray or X-ray radiation but not He2+ ion radiation. Protection of bystander cells was independent of the type of radiation which the donor population received.
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Ranjan A, Kaur N, Tiwari V, Singh Y, Chaturvedi MM, Tandon V. 3,4-Dimethoxyphenyl Bis-benzimidazole Derivative, Mitigates Radiation-Induced DNA Damage. Radiat Res 2013; 179:647-62. [DOI: 10.1667/rr3246.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Atul Ranjan
- Department of Chemistry, University of Delhi, Delhi, India
| | - Navrinder Kaur
- Department of Chemistry, University of Delhi, Delhi, India
| | - Vinod Tiwari
- Department of Chemistry, University of Delhi, Delhi, India
| | - Yogendra Singh
- Institute of Genomics and Integrative Biology, Delhi, India
| | | | - Vibha Tandon
- Department of Chemistry, University of Delhi, Delhi, India
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Kaur N, Ranjan A, Tiwari V, Aneja R, Tandon V. DMA, a bisbenzimidazole, offers radioprotection by promoting NFκB transactivation through NIK/IKK in human glioma cells. PLoS One 2012; 7:e39426. [PMID: 22745752 PMCID: PMC3382165 DOI: 10.1371/journal.pone.0039426] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 05/21/2012] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Ionizing radiation (IR) exposure often occurs for human beings through occupational, medical, environmental, accidental and/or other sources. Thus, the role of radioprotector is essential to overcome the complex series of overlapping responses to radiation induced DNA damage. METHODS AND RESULTS Treatment of human glioma U87 cells with DMA (5- {4-methylpiperazin-1-yl}-2-[2'-(3, 4-dimethoxyphenyl)-5'-benzimidazolyl] in the presence or absence of radiation uncovered differential regulation of an array of genes and proteins using microarray and 2D PAGE techniques. Pathway construction followed by relative quantitation of gene expression of the identified proteins and their interacting partners led to the identification of MAP3K14 (NFκB inducing kinase, NIK) as the candidate gene affected in response to DMA. Subsequently, over expression and knock down of NIK suggested that DMA affects NFκB inducing kinase mediated phosphorylation of IKKα and IKKβ both alone and in the presence of ionizing radiation (IR). The TNF-α induced NFκB dependent luciferase reporter assay demonstrated 1.65, 2.26 and 3.62 fold increase in NFκB activation at 10, 25 and 50 µM DMA concentrations respectively, compared to control cells. This activation was further increased by 5.8 fold in drug + radiation (50 µM +8.5 Gy) treated cells in comparison to control. We observed 51% radioprotection in control siRNA transfected cells that attenuated to 15% in siRNA NIK treated U87 cells, irradiated in presence of DMA at 24 h. CONCLUSIONS Our studies show that NIK/IKK mediated NFκB activation is more intensified in cells over expressing NIK and treated with DMA, alone or in combination with ionizing radiation, indicating that DMA promotes NIK mediated NFκB signaling. This subsequently leads to the radioprotective effect exhibited by DMA.
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Affiliation(s)
- Navrinder Kaur
- Dr B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Atul Ranjan
- Department of Chemistry, University of Delhi, Delhi, India
| | - Vinod Tiwari
- Department of Chemistry, University of Delhi, Delhi, India
| | - Ritu Aneja
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Vibha Tandon
- Department of Chemistry, University of Delhi, Delhi, India
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Mah LJ, Orlowski C, Ververis K, Vasireddy RS, El-Osta A, Karagiannis TC. Evaluation of the efficacy of radiation-modifying compounds using γH2AX as a molecular marker of DNA double-strand breaks. Genome Integr 2011; 2:3. [PMID: 21261999 PMCID: PMC3037297 DOI: 10.1186/2041-9414-2-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 01/25/2011] [Indexed: 12/23/2022] Open
Abstract
Radiation therapy is a widely used therapeutic approach for cancer. To improve the efficacy of radiotherapy there is an intense interest in combining this modality with two broad classes of compounds, radiosensitizers and radioprotectors. These either enhance tumour-killing efficacy or mitigate damage to surrounding non-malignant tissue, respectively. Radiation exposure often results in the formation of DNA double-strand breaks, which are marked by the induction of H2AX phosphorylation to generate γH2AX. In addition to its essential role in DDR signalling and coordination of double-strand break repair, the ability to visualize and quantitate γH2AX foci using immunofluorescence microscopy techniques enables it to be exploited as an indicator of therapeutic efficacy in a range of cell types and tissues. This review will explore the emerging applicability of γH2AX as a marker for monitoring the effectiveness of radiation-modifying compounds.
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Affiliation(s)
- Li-Jeen Mah
- Epigenomic Medicine, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia.,Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia
| | - Christian Orlowski
- Epigenomic Medicine, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia.,Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia.,Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - Katherine Ververis
- Epigenomic Medicine, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia.,Department of Anatomy and Cell Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Raja S Vasireddy
- Epigenomic Medicine, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia.,Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia.,Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - Assam El-Osta
- Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia.,Department of Medicine, Monash University, Melbourne, Victoria, Australia.,Epigenomic Profiling Facility, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - Tom C Karagiannis
- Epigenomic Medicine, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia.,Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia
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Lobachevsky PN, Vasireddy RS, Broadhurst S, Sprung CN, Karagiannis TC, Smith AJ, Radford IR, McKay MJ, Martin RF. Protection by methylproamine of irradiated human keratinocytes correlates with reduction of DNA damage. Int J Radiat Biol 2010; 87:274-83. [PMID: 21087168 DOI: 10.3109/09553002.2011.530333] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The therapeutic ratio for ionising radiation treatment of tumour is a trade-off between normal tissue side-effects and tumour control. Application of a radioprotector to normal tissue can reduce side-effects. Here we study the effects of a new radioprotector on the cellular response to radiation. Methylproamine is a DNA-binding radioprotector which, on the basis of published pulse radiolysis studies, acts by repair of transient radiation-induced oxidative species on DNA. To substantiate this hypothesis, we studied protection by methylproamine at both clonogenic survival and radiation-induced DNA damage, assessed by γH2AX (histone 2AX phosphorylation at serine 139) focus formation endpoints. MATERIALS AND METHODS The human keratinocyte cell line FEP1811 was used to study clonogenic survival and yield of γH2AX foci following irradiation (¹³⁷Cs γ-rays) of cells exposed to various concentrations of methylproamine. Uptake of methylproamine into cell nuclei was measured in parallel. RESULTS The extent of radioprotection at the clonogenic survival endpoint increased with methylproamine concentration up to a maximum dose modification factor (DMF) of 2.0 at 10 μM. At least 0.1 fmole/nucleus of methylproamine is required to achieve a substantial level of radioprotection (DMF of 1.3) with maximum protection (DMF of 2.0) achieved at 0.23 fmole/nucleus. The γH2AX focus yield per cell nucleus 45 min after irradiation decreased with drug concentration with a DMF of 2.5 at 10 μM. CONCLUSIONS These results are consistent with the hypothesis that radioprotection by methylproamine is mediated by attenuation of the extent of initial DNA damage.
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Affiliation(s)
- Pavel N Lobachevsky
- Trescowthick Research Laboratories, Peter MacCallum Cancer Centre, St Andrew's Place, East Melbourne, Victoria 3002, Australia.
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Abstract
Radiation leaves a fairly characteristic footprint in biological materials, but this is rapidly all but obliterated by the canonical biological responses to the radiation damage. The innate immune recognition systems that sense "danger" through direct radiation damage and through associated collateral damage set in motion a chain of events that, in a tissue compromised by radiation, often unwittingly result in oscillating waves of molecular and cellular responses as tissues attempt to heal. Understanding "nature's whispers" that inform on these processes will lead to novel forms of intervention targeted more precisely towards modifying them in an appropriate and timely fashion so as to improve the healing process and prevent or mitigate the development of acute and late effects of normal tissue radiation damage, whether it be accidental, as a result of a terrorist incident, or of therapeutic treatment of cancer. Here we attempt to discuss some of the non-free radical scavenging mechanisms that modify radiation responses and comment on where we see them within a conceptual framework of an evolving radiation-induced lesion.
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Affiliation(s)
- Kwanghee Kim
- Department of Radiation Oncology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - William H. McBride
- Department of Radiation Oncology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095, USA
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Sprung CN, Vasireddy RS, Karagiannis TC, Loveridge SJ, Martin RF, McKay MJ. Methylproamine protects against ionizing radiation by preventing DNA double-strand breaks. Mutat Res 2010; 692:49-52. [PMID: 20732333 DOI: 10.1016/j.mrfmmm.2010.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 08/11/2010] [Accepted: 08/13/2010] [Indexed: 05/29/2023]
Abstract
PURPOSE The majority of cancer patients will receive radiotherapy (RT), therefore, investigations into advances of this modality are important. Conventional RT dose intensities are limited by adverse responses in normal tissues and a primary goal is to ameliorate adverse normal tissue effects. The aim of these experiments is to further our understanding regarding the mechanism of radioprotection by the DNA minor groove binder, methylproamine, in a cellular context at the DNA level. MATERIALS AND METHODS We used immunocytochemical methods to measure the accumulation of phosphorylated H2AX (γH2AX) foci following ionizing radiation (IR) in patient-derived lymphoblastoid cells exposed to methylproamine. Furthermore, we performed pulsed field gel electrophoresis DNA damage and repair assays to directly interrogate the action of methylproamine on DNA in irradiated cells. RESULTS We found that methylproamine-treated cells had fewer γH2AX foci after IR compared to untreated cells. Also, the presence of methylproamine decreased the amount of lower molecular weight DNA entering the gel as shown by the pulsed field gel electrophoresis assay. CONCLUSIONS These results suggest that methylproamine acts by preventing the formation of DNA double-strand breaks (dsbs) and support the hypothesis that radioprotection by methylproamine is mediated, at least in part, by decreasing initial DNA damage.
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Affiliation(s)
- Carl N Sprung
- Division of Research, Peter MacCallum Cancer Centre, St. Andrews Pl. Melbourne, 8006 Victoria, Australia.
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Mishra K, Bhardwaj R, Chaudhury NK. Netropsin, a Minor Groove Binding Ligand: A Potential Radioprotective Agent. Radiat Res 2009; 172:698-705. [DOI: 10.1667/rr1815.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Shinde SS, Maroz A, Hay MP, Anderson RF. One-electron reduction potential of the neutral guanyl radical in the GC base pair of duplex DNA. J Am Chem Soc 2009; 131:5203-7. [PMID: 19320486 DOI: 10.1021/ja8087339] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The one-electron oxidation of guanine in the GC base pair of DNA has been investigated using pulse radiolysis combined with DFT calculations. Reaction of benzotriazinyl radicals with DNA results in the formation of the neutral guanyl radical and redox equilibria. The one-electron reduction potential, E(7), of the neutral guanyl radical in the GC base pair is determined for the first time as 1.22 +/- 0.02 V, from both absorption and kinetic data.
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Affiliation(s)
- Sujata S Shinde
- Department of Chemistry and Auckland Cancer Society Research Centre, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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Tawar U, Bansal S, Shrimal S, Singh M, Tandon V. Nuclear condensation and free radical scavenging: a dual mechanism of bisbenzimidazoles to modulate radiation damage to DNA. Mol Cell Biochem 2007; 305:221-33. [PMID: 17619948 DOI: 10.1007/s11010-007-9546-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Accepted: 06/21/2007] [Indexed: 10/23/2022]
Abstract
The complexing of histones with DNA and the resulting condensation of chromatin protects mammalian cell, from radiation-induced strand breakage. In the present study, benzimidazoles DMA and TBZ showed marked radioprotection through drug-induced compaction of chromatin and direct quenching of free radicals generated by radiation. The mammalian cells were incubated with 100 microM concentration of DMA and TBZ and irradiated at 5 Gy; both the ligands showed nuclei condensation suggesting a probable mechanism to protect DNA from radiation damage. The bisubstituted analogs of Hoechst 33342 are found to be better free radical scavengers and protect DNA against radiation-induced damage at a lower concentration than the parent molecule. Both the ligands also quenched free radicals in isolated free radical system suggesting their dual mode of action against radiation-induced damage to DNA. Molecules binding to the chromatin alter gene expression, whereas in this study both the ligands have not shown any profound effect on the nucleosome assembly and gene expression in vitro and in vivo. Both ligands afford a 2-fold protection by altering DNA structure as well as through direct free radical quenching in bulk solution in comparison to the parent ligand, which acts only through quenching of free radicals.
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Affiliation(s)
- Urmila Tawar
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, 110007, India
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Görner H. Direct and Sensitized Photoprocesses of Bis-benzimidazole Dyes and the Effects of Surfactants and DNA¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2001)0730339daspob2.0.co2] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Arora R, Gupta D, Chawla R, Sagar R, Sharma A, Kumar R, Prasad J, Singh S, Samanta N, Sharma RK. Radioprotection by plant products: present status and future prospects. Phytother Res 2005; 19:1-22. [PMID: 15799007 DOI: 10.1002/ptr.1605] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The development of radioprotective agents has been the subject of intense research in view of their potential for use within a radiation environment, such as space exploration, radiotherapy and even nuclear war. However, no ideal, safe synthetic radioprotectors are available to date, so the search for alternative sources, including plants, has been on going for several decades. In Ayurveda, the traditional Indian system of medicine, several plants have been used to treat free radical-mediated ailments and, therefore, it is logical to expect that such plants may also render some protection against radiation damage. A systematic screening approach can provide leads to identifying potential new candidate drugs from plant sources, for mitigation of radiation injury. This article reviews some of the most promising plants, and their bioactive principles, that are widely used in traditional systems of medicine, and which have rendered significant radioprotection in both in vitro and in vivo model systems. Plants and their constituents with pharmacological activities that may be relevant to amelioration of radiation-mediated damage, including antiemetic, antiinflammatory, antioxidant, cell proliferative, wound healing and haemopoietic stimulatories are also discussed.
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Affiliation(s)
- Rajesh Arora
- Division of Radiopharmaceuticals and Radiation Biology, Institute of Nuclear Medicine and Allied Sciences, Defence Research and Development Organization, Brig. SK Mazumdar Road, Delhi-110 054, India
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19
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Ly A, Tran NQ, Sullivan K, Bandong SL, Milligan JR. Involvement of proton transfer in the reductive repair of DNA guanyl radicals by aniline derivatives. Org Biomol Chem 2005; 3:917-23. [PMID: 15731879 DOI: 10.1039/b418681h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The most easily oxidized sites in DNA are the guanine bases, and major intermediates produced by the direct effect of ionizing radiation (ionization of the DNA itself) are electron deficient guanine species. By means of a radiation chemical method (gamma-irradiation of aqueous thiocyanate), we are able to produce these guanyl radicals in dilute aqueous solutions of plasmid DNA where the direct effect would otherwise be negligible. Stable modified guanine products are formed from these radicals. They can be detected in the plasmid conversion to strand breaks after a post-irradiation incubation with a DNA base excision endonuclease enzyme. If aniline compounds are also present, the yield of modified guanines is strongly attenuated. The mechanism responsible for this effect is electron donation from the aniline compound to the guanyl radical, and it is possible to derive rate constants for this reaction. Aniline compounds bearing electron withdrawing groups (e.g., 4-CF3) were found to be less reactive than those bearing electron donating groups (e.g., 4-CH3). At physiological pH values, the reduction of a guanyl radical involves the transfer of a proton as well as of an electron. The mild dependence of the rate constant on the driving force suggests that the electron is not transferred before the proton. Although the source of the proton is unclear, our observations emphasize the importance of an accompanying proton transfer in the reductive repair of oxidative damage to guanine bases which are located in a biologically active double stranded plasmid DNA substrate.
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Affiliation(s)
- Anne Ly
- Department of Radiology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0610, USA
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21
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Martin RF, Broadhurst S, Reum ME, Squire CJ, Clark GR, Lobachevsky PN, White JM, Clark C, Sy D, Spotheim-Maurizot M, Kelly DP. In Vitro Studies with Methylproamine. Cancer Res 2004; 64:1067-70. [PMID: 14871839 DOI: 10.1158/0008-5472.can-03-2423] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
New analogues of the minor groove binding ligand Hoechst 33342 have been investigated in an attempt to improve radioprotective activity. The synthesis, DNA binding, and in vitro radioprotective properties of methylproamine, the most potent derivative, are reported. Experiments with V79 cells have shown that methylproamine is approximately 100-fold more potent than the classical aminothiol radioprotector WR1065. The crystal structures of methylproamine and proamine complexes with the dodecamer d(CGCGAATTCGCG)(2) confirm that the new analogues also are minor groove binders. It is proposed that the DNA-bound methylproamine ligand acts as a reducing agent by an electron transfer mechanism, repairing transient radiation-induced oxidizing species on DNA.
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Affiliation(s)
- Roger F Martin
- Trescowthick Research Laboratories, Peter MacCallum Cancer Centre, Melbourne, Australia
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22
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Kakkar R, Garg R, Suruchi. Theoretical studies on the mechanism of radioprotection by Hoechst 33258 derivatives. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.theochem.2003.10.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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23
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Milligan JR, Aguilera JA, Ly A, Tran NQ, Hoang O, Ward JF. Repair of oxidative DNA damage by amino acids. Nucleic Acids Res 2003; 31:6258-63. [PMID: 14576314 PMCID: PMC275458 DOI: 10.1093/nar/gkg816] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Guanyl radicals, the product of the removal of a single electron from guanine, are produced in DNA by the direct effect of ionizing radiation. We have produced guanyl radicals in DNA by using the single electron oxidizing agent (SCN)2-, itself derived from the indirect effect of ionizing radiation via thiocyanate scavenging of OH. We have examined the reactivity of guanyl radicals in plasmid DNA with the six most easily oxidized amino acids cysteine, cystine, histidine, methionine, tryptophan and tyrosine and also simple ester and amide derivatives of them. Cystine and histidine derivatives are unreactive. Cysteine, methionine, tyrosine and particularly tryptophan derivatives react to repair guanyl radicals in plasmid DNA with rate constants in the region of approximately 10(5), 10(5), 10(6) and 10(7) dm3 mol(-1) s(-1), respectively. The implication is that amino acid residues in DNA binding proteins such as histones might be able to repair by an electron transfer reaction the DNA damage produced by the direct effect of ionizing radiation or by other oxidative insults.
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Affiliation(s)
- J R Milligan
- Department of Radiology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0610, USA.
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Nair CK, Parida DK, Nomura T. Radioprotectors in radiotherapy. JOURNAL OF RADIATION RESEARCH 2001; 42:21-37. [PMID: 11393887 DOI: 10.1269/jrr.42.21] [Citation(s) in RCA: 297] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- C K Nair
- Radiation Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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25
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Lyubimova NV, Coultas PG, Yuen K, Martin RF. In vivo radioprotection of mouse brain endothelial cells by Hoechst 33342. Br J Radiol 2001; 74:77-82. [PMID: 11227782 DOI: 10.1259/bjr.74.877.740077] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Radiation-induced loss of mouse brain endothelial cells has been examined in mice given an intravenous injection of the DNA-binding radioprotector Hoechst 33342 (80 mg kg-1). At the time of irradiation, 10 min after injection, Hoechst fluorescence in the brain was confined to the endothelial cells. Endothelial cell density was measured using a histochemical fluorescence technique that had been used previously to monitor post-irradiation changes in endothelial cell density in rat brain, in which it was shown that a sensitive subpopulation comprising about 15% of the endothelial cells was lost within 24 h of radiation exposure. The present study shows a similar dose-response for the control mice, with depletion of the sensitive subpopulation to 85% being almost complete after a dose of 2.5 Gy gamma-rays. However, in mice irradiated 10 min after Hoechst 33342 administration, doses between 12 Gy and 20 Gy were required to ablate these cells. The kinetics of cell loss and the rather large dose modification factor suggests that Hoechst 33342 may be suppressing an apoptotic response in this subpopulation. Whatever the mechanism involved, Hoechst 33342 clearly provides substantial protection against early radiation-induced endothelial cell loss. Further studies are necessary to determine the extent to which this initial protection translates into an improved long-term survival of the "protected" cells and, especially, to see whether this endothelial cell protection can ameliorate the later consequences of central nervous system irradiation, namely necrosis and paralysis.
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Affiliation(s)
- N V Lyubimova
- Trescowthick Research Laboratories, Peter MacCallum Cancer Institute, St Andrews Place, Melbourne, Victoria 3000, Australia
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Anderson RF, Amarasinghe C, Fisher LJ, Mak WB, Packer JE. Reduction in free-radical-induced DNA strand breaks and base damage through fast chemical repair by flavonoids. Free Radic Res 2000; 33:91-103. [PMID: 10826925 DOI: 10.1080/10715760000300651] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This paper provides evidence that dietary flavonoids can repair a range of oxidative radical damages on DNA, and thus give protection against radical-induced strand breaks and base alterations. We have irradiated dilute aqueous solutions of plasmid DNA in the absence and presence of flavonoids (F) in a "constant *OH radical scavenging environment", k of 1.5 x 10(7) s(-1) by decreasing the concentration of TRIS buffer in relation to the concentration of added flavonoids. We have shown that the flavonoids can reduce the incidence of single-strand breaks in double-stranded DNA as well as residual base damage (assayed as additional single-strand breaks upon post-irradiation incubation with endonucleases) with dose modification factors of up to 2.0+/-0.2 at [F] < 100 microM by a mechanism other than through direct scavenging of *OH radicals. Pulse radiolysis measurements support the mechanism of electron transfer or H* atom transfer from the flavonoids to free radical sites on DNA which result in the fast chemical repair of some of the oxidative damage on DNA resulting from *OH radical attack. These in vitro assays point to a possible additional role for antioxidants in reducing DNA damage.
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Affiliation(s)
- R F Anderson
- Department of Chemistry, The University of Auckland, New Zealand.
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Messer A, Carpenter K, Forzley K, Buchanan J, Yang S, Razskazovskii Y, Cai Z, Sevilla MD. Electron Spin Resonance Study of Electron Transfer Rates in DNA: Determination of the Tunneling Constant β for Single-Step Excess Electron Transfer. J Phys Chem B 2000. [DOI: 10.1021/jp993550w] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrea Messer
- Department of Chemistry, Oakland University, Rochester, Michigan 48309
| | | | - Kristen Forzley
- Department of Chemistry, Oakland University, Rochester, Michigan 48309
| | - John Buchanan
- Department of Chemistry, Oakland University, Rochester, Michigan 48309
| | - Shen Yang
- Department of Chemistry, Oakland University, Rochester, Michigan 48309
| | | | - Zhongli Cai
- Department of Chemistry, Oakland University, Rochester, Michigan 48309
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28
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Ali MM, Symons MC, Taiwo FA, Patterson LH. Effects of AQ4N and its reduction product on radiation-mediated DNA strand breakage. Chem Biol Interact 1999; 123:1-10. [PMID: 10597898 DOI: 10.1016/s0009-2797(99)00097-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Supercoiled plasmid pBR322 DNA was irradiated in phosphate buffer by 60Co gamma-rays at a dose rate 19.26 Gy/min and total dose of 10 Gy in the presence of a bioreductive antitumour prodrug namely 1,4-bis [¿2-(dimethylamino-N-oxide)ethyl¿ amino] 5, 8-dihydroxyanthracene-9,10-dione (AQ4N) and its DNA affinic reduction product 1,4-bis[¿2(dimethylamino)ethyl¿ amino] 5,8-dihydroxyanthracene-9,10-dione (AQ4) under air and nitrogen. AQ4N and AQ4 were found to protect against radiation-induced plasmid single and double strand breakage as assessed by agarose gel electrophoresis. The differences between the two agents, and between atmospheres of air or nitrogen were negligible. It was also found that the protection efficiencies of the compounds were pH dependent and showed maximum protection at pH 6. These results indicate that protection of DNA by AQ4 and AQ4N against radiation damage is an indirect effect since both agents are equally effective despite major differences in their DNA affinity. It is likely that radiation-induced phosphate buffer radicals are intercepted by AQ4 and AQ4N in a pH-dependent process.
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Affiliation(s)
- M M Ali
- Institute of Nuclear Science and Technology, Atomic Energy Research Establishment, Dhaka, Bangladesh
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