1
|
Carrasco-Hernandez J, Ramos-Méndez J, Padilla-Rodal E, Avila-Rodriguez MA. Cellular lethal damage of 64Cu incorporated in mammalian genome evaluated with Monte Carlo methods. Front Med (Lausanne) 2023; 10:1253746. [PMID: 37841004 PMCID: PMC10575761 DOI: 10.3389/fmed.2023.1253746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023] Open
Abstract
Purpose Targeted Radionuclide Therapy (TRT) with Auger Emitters (AE) is a technique that allows targeting specific sites on tumor cells using radionuclides. The toxicity of AE is critically dependent on its proximity to the DNA. The aim of this study is to quantify the DNA damage and radiotherapeutic potential of the promising AE radionuclide copper-64 (64Cu) incorporated into the DNA of mammalian cells using Monte Carlo track-structure simulations. Methods A mammalian cell nucleus model with a diameter of 9.3 μm available in TOPAS-nBio was used. The cellular nucleus consisted of double-helix DNA geometrical model of 2.3 nm diameter surrounded by a hydration shell with a thickness of 0.16 nm, organized in 46 chromosomes giving a total of 6.08 giga base-pairs (DNA density of 14.4 Mbp/μm3). The cellular nucleus was irradiated with monoenergetic electrons and radiation emissions from several radionuclides including 111In, 125I, 123I, and 99mTc in addition to 64Cu. For monoenergetic electrons, isotropic point sources randomly distributed within the nucleus were modeled. The radionuclides were incorporated in randomly chosen DNA base pairs at two positions near to the central axis of the double-helix DNA model at (1) 0.25 nm off the central axis and (2) at the periphery of the DNA (1.15 nm off the central axis). For all the radionuclides except for 99mTc, the complete physical decay process was explicitly simulated. For 99mTc only total electron spectrum from published data was used. The DNA Double Strand Breaks (DSB) yield per decay from direct and indirect actions were quantified. Results obtained for monoenergetic electrons and radionuclides 111In, 125I, 123I, and 99mTc were compared with measured and calculated data from the literature for verification purposes. The DSB yields per decay incorporated in DNA for 64Cu are first reported in this work. The therapeutic effect of 64Cu (activity that led 37% cell survival after two cell divisions) was determined in terms of the number of atoms incorporated into the nucleus that would lead to the same DSBs that 100 decays of 125I. Simulations were run until a 2% statistical uncertainty (1 standard deviation) was achieved. Results The behavior of DSBs as a function of the energy for monoenergetic electrons was consistent with published data, the DSBs increased with the energy until it reached a maximum value near 500 eV followed by a continuous decrement. For 64Cu, when incorporated in the genome at evaluated positions (1) and (2), the DSB were 0.171 ± 0.003 and 0.190 ± 0.003 DSB/decay, respectively. The number of initial atoms incorporated into the genome (per cell) for 64Cu that would cause a therapeutic effect was estimated as 3,107 ± 28, that corresponds to an initial activity of 47.1 ± 0.4 × 10-3 Bq. Conclusion Our results showed that TRT with 64Cu has comparable therapeutic effects in cells as that of TRT with radionuclides currently used in clinical practice.
Collapse
Affiliation(s)
- Jhonatan Carrasco-Hernandez
- Departamento de Estructura de la Materia, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José Ramos-Méndez
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, United States
| | - Elizabeth Padilla-Rodal
- Departamento de Estructura de la Materia, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Miguel A. Avila-Rodriguez
- Unidad Radiofarmacia-Ciclotrón, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| |
Collapse
|
2
|
Kortylewicz ZP, Coulter DW, Han G, Baranowska-Kortylewicz J. Norepinephrine-Transporter-Targeted and DNA-Co-Targeted Theranostic Guanidines. J Med Chem 2020; 63:2051-2073. [PMID: 31268317 DOI: 10.1021/acs.jmedchem.9b00437] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
High risk neuroblastoma often recurs, even with aggressive treatments. Clinical evidence suggests that proliferative activities are predictive of poor outcomes. This report describes syntheses, characterization, and biological properties of theranostic guanidines that target norepinephrine transporter and undergo intracellular processing, and subsequently their catabolites are efficiently incorporated into DNA of proliferating neuroblastoma cells. Radioactive guanidines are synthesized from 5-radioiodo-2'-deoxyuridine, a molecular radiotherapy platform with clinically proven minimal toxicities and DNA-targeting properties. The transport of radioactive guanidines into neuroblastoma cells is active as indicated by the competitive suppression of cellular uptake by meta-iodobenzylguanidine. The rate of intracellular processing and DNA uptake is influenced by the agent's catabolic stability and cell population doubling times. The radiotoxicity is directly proportional to DNA uptake and duration of exposure. Biodistribution of 5-[125I]iodo-3'-O-(ε-guanidinohexanoyl)-2'-deoxyuridine in a mouse neuroblastoma model shows significant tumor retention of radioactivity. Neuroblastoma xenografts regress in response to the clinically achievable doses of this agent.
Collapse
Affiliation(s)
- Zbigniew P Kortylewicz
- Department of Radiation Oncology, J. Bruce Henriksen Cancer Research Laboratories, University of Nebraska Medical Center, Omaha, Nebraska 68132-6850, United States
| | - Donald W Coulter
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, Nebraska 68132-2168, United States
| | - Guang Han
- Department of Radiation Oncology, J. Bruce Henriksen Cancer Research Laboratories, University of Nebraska Medical Center, Omaha, Nebraska 68132-6850, United States.,Department of Radiation Oncology, Hubei Cancer Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Janina Baranowska-Kortylewicz
- Department of Radiation Oncology, J. Bruce Henriksen Cancer Research Laboratories, University of Nebraska Medical Center, Omaha, Nebraska 68132-6850, United States
| |
Collapse
|
3
|
Schmitz S, Oskamp D, Pomplun E, Kriehuber R. Chromosome aberrations induced by the Auger electron emitter 125I. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 793:64-70. [DOI: 10.1016/j.mrgentox.2015.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 08/19/2015] [Indexed: 10/23/2022]
|
4
|
Kortylewicz ZP, Kimura Y, Inoue K, Mack E, Baranowska-Kortylewicz J. Radiolabeled cyclosaligenyl monophosphates of 5-iodo-2'-deoxyuridine, 5-iodo-3'-fluoro-2',3'-dideoxyuridine, and 3'-fluorothymidine for molecular radiotherapy of cancer: synthesis and biological evaluation. J Med Chem 2012; 55:2649-71. [PMID: 22339166 PMCID: PMC3328401 DOI: 10.1021/jm201482p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Targeted molecular radiotherapy opens unprecedented opportunities to eradicate cancer cells with minimal irradiation of normal tissues. Described in this study are radioactive cyclosaligenyl monophosphates designed to deliver lethal doses of radiation to cancer cells. These compounds can be radiolabeled with SPECT- and PET-compatible radionuclides as well as radionuclides suitable for Auger electron therapies. This characteristic provides an avenue for the personalized and comprehensive treatment strategy that comprises diagnostic imaging to identify sites of disease, followed by the targeted molecular radiotherapy based on the imaging results. The developed radiosynthetic methods produce no-carrier-added products with high radiochemical yield and purity. The interaction of these compounds with their target, butyrylcholinesterase, depends on the stereochemistry around the P atom. IC(50) values are in the nanomolar range. In vitro studies indicate that radiation doses delivered to the cell nucleus are sufficient to kill cells of several difficult to treat malignancies including glioblastoma and ovarian and colorectal cancers.
Collapse
Affiliation(s)
- Zbigniew P. Kortylewicz
- University of Nebraska Medical Center, Department of Radiation Oncology, J. Bruce Henrisken Cancer Research Laboratories, 986850 Nebraska Medical Center, Omaha, NE 68198-6850
| | - Yu Kimura
- University of Nebraska Medical Center, Department of Radiation Oncology, J. Bruce Henrisken Cancer Research Laboratories, 986850 Nebraska Medical Center, Omaha, NE 68198-6850
| | - Kotaro Inoue
- University of Nebraska Medical Center, Department of Radiation Oncology, J. Bruce Henrisken Cancer Research Laboratories, 986850 Nebraska Medical Center, Omaha, NE 68198-6850
| | - Elizabeth Mack
- University of Nebraska Medical Center, Department of Radiation Oncology, J. Bruce Henrisken Cancer Research Laboratories, 986850 Nebraska Medical Center, Omaha, NE 68198-6850
| | - Janina Baranowska-Kortylewicz
- University of Nebraska Medical Center, Department of Radiation Oncology, J. Bruce Henrisken Cancer Research Laboratories, 986850 Nebraska Medical Center, Omaha, NE 68198-6850
| |
Collapse
|
5
|
Morgenroth A, Vogg AT, Mottaghy FM, Schmaljohann J. Targeted endoradiotherapy using nucleotides. Methods 2011; 55:203-14. [PMID: 21782950 DOI: 10.1016/j.ymeth.2011.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/24/2011] [Accepted: 06/28/2011] [Indexed: 11/15/2022] Open
Abstract
Increased cellular proliferation is an integral part of the cancer phenotype. Hence, the sustained and continued demand on supply of DNA building blocks during the DNA replication presents a potential target for therapeutic intervention. For this propose, the α and Auger electron emitting nucleotides analogs are attractive for targeted endoradiotherapy, given that DNA of malignant cells is selectively addressed. This review summarizes development and preclinical and clinical studies of endoradiotherapeutic acting nucleoside analogs with a special focus on thymidine analogs.
Collapse
Affiliation(s)
- Agnieszka Morgenroth
- Department of Nuclear Medicine, University Hospital Aachen, RWTH, Pauwelsstraße 30, D-52074 Aachen, Germany.
| | | | | | | |
Collapse
|
6
|
Balagurumoorthy P, Chen K, Adelstein SJ, Kassis AI. Auger electron-induced double-strand breaks depend on DNA topology. Radiat Res 2008; 170:70-82. [PMID: 18582152 PMCID: PMC2829305 DOI: 10.1667/rr1072.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 02/09/2008] [Indexed: 11/03/2022]
Abstract
From a structural perspective, the factors controlling and the mechanisms underlying the toxic effects of ionizing radiation remain elusive. We have studied the consequences of superhelical/torsional stress on the magnitude and mechanism of DSBs induced by low-energy, short-range, high-LET Auger electrons emitted by (125)I, targeted to plasmid DNA by m-[(125)I]iodo-p-ethoxyHoechst 33342 ((125)IEH). DSB yields per (125)I decay for torsionally relaxed nicked (relaxed circular) and linear DNA (1.74+/-0.11 and 1.62+/-0.07, respectively) are approximately threefold higher than that for torsionally strained supercoiled DNA (0.52+/-0.02), despite the same affinity of all forms for (125)IEH. In the presence of DMSO, the DSB yield for the supercoiled form remains unchanged, whereas that for nicked and linear forms decreases to 1.05+/-0.07 and 0.76+/-0.03 per (125)I decay, respectively. DSBs in supercoiled DNA therefore result exclusively from direct mechanisms, and those in nicked and linear DNA, additionally, from hydroxyl radical-mediated indirect effects. Iodine-125 decays produce hydroxyl radicals along the tracks of Auger electrons in small isolated pockets around the decay site. We propose that relaxation of superhelical stress after radical attack could move a single-strand break lesion away from these pockets, thereby preventing further breaks in the complementary strand that could lead to DSBs.
Collapse
Affiliation(s)
| | - Kai Chen
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - S. James Adelstein
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Amin I. Kassis
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| |
Collapse
|
7
|
Balagurumoorthy P, Chen K, Bash RC, Adelstein SJ, Kassis AI. Mechanisms Underlying Production of Double-Strand Breaks in Plasmid DNA after Decay of125I-Hoechst. Radiat Res 2006; 166:333-44. [PMID: 16881734 DOI: 10.1667/rr3591.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Previously, the kinetics of strand break production by (125)I-labeled m-iodo-p-ethoxyHoechst 33342 ((125)IEH) in supercoiled (SC) plasmid DNA had demonstrated that approximately 1 DSB is produced per (125)I decay both in the presence and absence of the hydroxyl radical scavenger DMSO. In these experiments, an (125)IEH:DNA molar ratio of 42:1 was used. We now hypothesize that this DSB yield (but not the SSB yield) may be an overestimate due to subsequent decays occurring in any of the 41 (125)IEH molecules still bound to nicked (N) DNA. To test our hypothesis, (125)IEH was incubated with SC pUC19 plasmids ((125)IEH:DNA ratio of approximately 3:1) and the SSB and DSB yields were quantified after the decay of (125)I. As predicted, the number of DSBs produced per (125)I decay is one-half that reported previously ( approximately 0.5 compared to approximately 1, +/- DMSO) whereas the number of SSBs ( approximately 3/(125)I decay) is similar to that obtained previously ( approximately 90% are generated by OH radicals). Direct visualization by atomic force microscopy confirms formation of L and N DNA after (125)IEH decays in SC DNA and supports the strand break yields reported. These findings indicate that although SSB production is independent of the number of (125)IEH bound to DNA, the DSB yield can be augmented erroneously by (125)I decays occurring in N DNA. Further analysis indicates that 17% of SSBs and 100% of DSBs take place within the plasmid molecule in which an (125)IEH molecule decays, whereas 83% of SSBs are formed in neighboring plasmid DNA molecules.
Collapse
|
8
|
Elmroth K, Stenerlöw B. DNA-Incorporated125I Induces more than one Double-Strand Break per Decay in Mammalian Cells. Radiat Res 2005; 163:369-73. [PMID: 15799691 DOI: 10.1667/rr3339] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The Auger-electron emitter 125I releases cascades of 20 electrons per decay that deposit a great amount of local energy, and for DNA-incorporated 125I, approximately one DNA double-strand break (DSB) is produced close to the decay site. To investigate the potential of 125I to induce additional DSBs within adjacent chromatin structures in mammalian cells, we applied DNA fragment-size analysis based on pulsed-field gel electrophoresis (PFGE) of hamster V79-379A cells exposed to DNA-incorporated 125IdU. After accumulation of decays at -70 degrees C in the presence of 10% DMSO, there was a non-random distribution of DNA fragments with an excess of fragments <0.5 Mbp and the measured yield was 1.6 DSBs/decay. However, since these experiments were performed under high scavenging conditions (DMSO) that reduce indirect effects, the yield in cells exposed to 125IdU under physiological conditions would most likely be even higher. In contrast, using a conventional low-resolution assay without measurement of smaller DNA fragments, the yield was close to one DSB/decay. We conclude that a large fraction of the DSBs induced by DNA-incorporated 125I are nonrandomly distributed and that significantly more than one DSB/decay is induced in an intact cell. Thus, in addition to DSBs produced close to the decay site, DSBs may also be induced within neighboring chromatin fibers, releasing smaller DNA fragments that are not detected by conventional DSB assays.
Collapse
Affiliation(s)
- Kecke Elmroth
- Division of Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Uppsala University, Rudbeck Laboratory, SE-751 85 Uppsala, Sweden
| | | |
Collapse
|
9
|
Adelstein SJ, Kassis AI, Bodei L, Mariani G. Radiotoxicity of iodine-125 and other auger-electron-emitting radionuclides: background to therapy. Cancer Biother Radiopharm 2003; 18:301-16. [PMID: 12954118 DOI: 10.1089/108497803322285062] [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: 11/13/2022] Open
Abstract
Auger-electron cascades with their ability to deposit energy in extremely small volumes, typically in the range of cubic nanometers, have served as valuable probes of radiobiologic phenomena. Results from their experimental use form part of the evidence that nuclear DNA is the most radiosensitive cell element; that chromosomal aberrations and large scale double-strand breaks are correlated with reproductive survival; that neoplastic transformation and also mutagenesis are greatest at low doses with high specific ionization; and that, like high linear-energy-transfer radiation, Auger-electron cascades can lead to bystander effects. We have also learned that radiobiologic responses to Auger-electron emission are particularly sensitive to the site of decay, not only within the cell but also in the nucleus within the fine structure of chromatin.
Collapse
Affiliation(s)
- S James Adelstein
- Experimental Nuclear Medicine, Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | | | | | | |
Collapse
|
10
|
Sedelnikova OA, Rogakou EP, Panyutin IG, Bonner WM. Quantitative detection of (125)IdU-induced DNA double-strand breaks with gamma-H2AX antibody. Radiat Res 2002; 158:486-92. [PMID: 12236816 DOI: 10.1667/0033-7587(2002)158[0486:qdoiid]2.0.co;2] [Citation(s) in RCA: 484] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
When mammalian cells are exposed to ionizing radiation and other agents that introduce DSBs into DNA, histone H2AX molecules in megabase chromatin regions adjacent to the breaks become phosphorylated within minutes on a specific serine residue. An antibody to this phosphoserine motif of human H2AX (gamma-H2AX) demonstrates that gamma-H2AX molecules appear in discrete nuclear foci. To establish the quantitative relationship between the number of these foci and the number of DSBs, we took advantage of the ability of (125)I, when incorporated into DNA, to generate one DNA DSB per radioactive disintegration. SF-268 and HT-1080 cell cultures were grown in the presence of (125)IdU and processed immunocytochemically to determine the number of gamma-H2AX foci. The numbers of (125)IdU disintegrations per cell were measured by exposing the same immunocytochemically processed samples to a radiation-sensitive screen with known standards. Under appropriate conditions, the data yielded a direct correlation between the number of (125)I decays and the number of foci per cell, consistent with the assumptions that each (125)I decay yields a DNA DSB and each DNA DSB yields a visible gamma-H2AX focus. Based on these findings, we conclude that gamma-H2AX antibody may form the basis of a sensitive quantitative method for the detection of DNA DSBs in eukaryotic cells.
Collapse
Affiliation(s)
- Olga A Sedelnikova
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.
| | | | | | | |
Collapse
|
11
|
Abstract
The subcellular distribution and cytotoxicity of a DNA-binding ligand [125I]-Hoechst 33258 following incubation of K562 cells with the drug was investigated. The ability of a radical scavenger, dimethyl sulphoxide, to protect cells from the 125I-decay induced cell death was also studied. Three different concentrations and specific activities of the drug were used to provide different ligand : DNA binding ratios. The results demonstrated a trend toward improved delivery of the ligand to the nucleus and to chromatin at higher ligand concentrations, with concomitant increased sensitivity to 125I-decay induced cytotoxicity and decreased protection by dimethyl sulphoxide. This correlation of radiobiological parameters with subcellular drug distribution is consistent with the classical dogma that attributes cytotoxicity to DNA double-stranded breakage in the vicinity of the site of decay, where the high LET nature of the damage confers minimal sensitivity to radical scavenging.
Collapse
Affiliation(s)
- T C Karagiannis
- Trescowthick Research Laboratories, peter MacCallum Cancer Institute, Melbourne, Australia
| | | | | |
Collapse
|
12
|
Lobachevsky PN, Martin RF. Iodine-125 decay in a synthetic oligodeoxynucleotide. I. Fragment size distribution and evaluation of breakage probability. Radiat Res 2000; 153:263-70. [PMID: 10669547 DOI: 10.1667/0033-7587(2000)153[0263:idiaso]2.0.co;2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Lobachevsky, P. N. and Martin, R. F. Iodine-125 Decay in a Synthetic Oligodeoxynucleotide. I. Fragment Size Distribution and Evaluation of Breakage Probability. Incorporation of (125)I-dC into a defined location of a double-stranded oligodeoxynucleotide was used to investigate DNA breaks arising from decay of the Auger electron-emitting isotope. Samples of the oligodeoxynucleotide were also labeled with (32)P at either the 5' or 3' end of either the (125)I-dC-containing (so-called top) or opposite (bottom) strand and incubated in 20 mM phosphate buffer or the same buffer plus 2 M dimethylsulfoxide at 4 degrees C during 18-20 days. The (32)P-end-labeled fragments produced by (125)I decays were separated on denaturing polyacrylamide gels, and the (32)P activity in each fragment was determined by scintillation counting after elution of fragments from the gel. The relative fragment size distributions were then normalized on a per decay basis and converted to a distribution of single-strand break probabilities as a function of distance from the (125)I-dC. The results of three to five experiments for each of eight possible combinations of labels and incubation conditions are presented as a table showing the relative numbers of (32)P counts in different fragments as well as graphs of normalized fragment size distributions and probabilities of breakage. The average numbers of single-strand breaks per (125)I decay are 3. 3 and 3.7 in the top strand and 1.3 and 1.5 in the bottom strand with and without dimethylsulfoxide, respectively. Every (125)I decay event produces a break in the top strand, and breakage of the bottom strand occurs in 75-80% of the events. Thus a double-strand break is produced by (125)I decay with a probability of approximately 0.8.
Collapse
Affiliation(s)
- P N Lobachevsky
- Molecular Radiation Biology, Trescowthick Research Laboratories, Peter MacCallum Cancer Institute, Melbourne, Australia
| | | |
Collapse
|
13
|
Lobachevsky PN, Martin RF. Iodine-125 decay in a synthetic oligodeoxynucleotide. II. The role of auger electron irradiation compared to charge neutralization in DNA breakage. Radiat Res 2000; 153:271-8. [PMID: 10669548 DOI: 10.1667/0033-7587(2000)153[0271:idiaso]2.0.co;2] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Lobachevsky, P. N. and Martin, R. F. Iodine-125 Decay in a Synthetic Oligodeoxynucleotide. II. The Role of Auger Electron Irradiation Compared to Charge Neutralization in DNA Breakage. The dramatic chemical and biological effects of the decay of DNA-incorporated (125)I stem from two consequences of the Auger electron cascades associated with the decay of the isotope: high local deposition of radiation energy from short-range Auger electrons, and neutralization of the multiply charged tellurium atom. We have analyzed the extensive data reported in the companion paper (Radiat. Res. 153, 000-000, 2000), in which DNA breakage was measured after (125)I decay in a 41-bp oligoDNA. The experimental data collected under scavenging conditions (2 M dimethylsulfoxide) were deconvoluted into two components denoted as radiation and nonradiation, the former being attributed to energy deposition by Auger electrons. The contribution of the components was estimated by adopting various assumptions, the principal one being that DNA breakage due to the radiation mechanism is dependent on the distance between the decaying (125)I atom and the cleaved deoxyribosyl unit, while the nonradiation mechanism, associated with neutralization of the multiply charged tellurium atom, contributes equally at corresponding nucleotides starting from the (125)I-incorporating nucleotide. Comparison of the experimental data sets collected under scavenging and nonscavenging (without dimethylsulfoxide) conditions was used to estimate the radiation-scavengeable component. Our analysis showed that the nonradiation component plays the major role in causing breakage within 4-5 nucleotides from the site of (125)I incorporation and produces about 50% of all single-stranded breaks. This overall result is consistent with the relative amounts of energy associated with Auger electrons and the charged tellurium atom. However, the nonradiation component accounts for almost four times more breaks in the top strand, to which the (125)I is bound covalently, than in the bottom strand, thus suggesting an important role of covalent bonds in the energy transfer from the charged tellurium atom. The radiation component dominates at the distances beyond 8-9 nucleotides, and 36% of the radiation-induced breaks are scavengeable.
Collapse
Affiliation(s)
- P N Lobachevsky
- Molecular Radiation Biology, Trescowthick Research Laboratories, Peter MacCallum Cancer Institute, Melbourne, Australia
| | | |
Collapse
|
14
|
Abstract
Radionuclide decay by electron capture and/or internal conversion is accompanied by complex atomic vacancy cascades and emission of low-energy electrons, resulting in a highly charged daughter atom and a high density of electron irradiation in the immediate vicinity of the decay site. The molecular and cellular consequences of such decay events include DNA strand breaks, mutations, chromosome aberrations, malignant transformation, division delay, and cell death. Damage to cells depends largely on the intracellular location of the radionuclide. Decays outside the cell nucleus produce low-LET-type radiation effects (RBE approximately 1). In contrast, decays in DNA cause pronounced high-LET-type effects (RBE approximately 7-9). However, recent studies suggest that even for DNA-associated Auger emitters cell damage can be modified to resemble the pattern observed with low-LET radiations. These findings indicate that the molecular and cellular mechanism(s) responsible for the cytotoxic effects of Auger emitters remain obscure.
Collapse
Affiliation(s)
- K G Hofer
- Institute of Molecular Biophysics, Florida State University, Tallahassee 32306, USA
| |
Collapse
|
15
|
Adelstein SJ, Kassis AI. Strand breaks in plasmid DNA following positional changes of Auger-electron-emitting radionuclides. Acta Oncol 1996; 35:797-801. [PMID: 9004755 DOI: 10.3109/02841869609104029] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The purpose of our studies is to elucidate the kinetics of DNA strand breaks caused by low-energy Auger electron emitters in close proximity to DNA. Previously we have studied the DNA break yields in plasmids after the decay of indium-111 bound to DNA or free in solution. In this work, we compare the DNA break yields in supercoiled DNA of iodine-125 decaying close to DNA following DNA intercalation, minor-groove binding, or surface binding, and at a distance from DNA. Supercoiled DNA, stored at 4 degrees C to accumulate radiation dose from the decay of 125I, was then resolved by gel electrophoresis into supercoiled, nicked circular, and linear forms, representing undamaged DNA, single-strand breaks, and double-strand breaks respectively. DNA-intercalated or groove-bound 125I is more effective than surface-bound radionuclide or 125I free in solution. The hydroxyl radical scavenger DMSO protects against damage by 125I free in solution but has minimal effect on damage by groove-bound 125I.
Collapse
Affiliation(s)
- S J Adelstein
- Harvard Medical School, Department of Radiology, Boston, MA, USA
| | | |
Collapse
|
16
|
Scherberg N, Bloch I, Gardner P. Site-specific incorporation of [125I]iododeoxyuridine into DNA. INTERNATIONAL JOURNAL OF RADIATION APPLICATIONS AND INSTRUMENTATION. PART A, APPLIED RADIATION AND ISOTOPES 1992; 43:923-7. [PMID: 1321102 DOI: 10.1016/0883-2889(92)90157-a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A procedure for the incorporation of [125I]IdU into specific sites in DNA is described. The approach depends upon attachment of radioiododeoxyuridine to a controlled pore glass support which is then used for automated synthesis of an oligomer. The resulting oligomer, containing a terminal 3'[125I]iododeoxyuridine, is used as a primer during DNA synthesis catalyzed by the Taq polymerase employing thermal cycling. The product formed includes the radioiodonucleotide at a single internal site determined by the length of the oligomer.
Collapse
Affiliation(s)
- N Scherberg
- University of Chicago Hospitals and Clinics, IL
| | | | | |
Collapse
|
17
|
Larson D, Bodell WJ, Ling C, Phillips TL, Schell M, Shrieve D, Troxel T. Auger electron contribution to bromodeoxyuridine cellular radiosensitization. Int J Radiat Oncol Biol Phys 1989; 16:171-6. [PMID: 2912939 DOI: 10.1016/0360-3016(89)90025-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Halogenated thymidine analogs become incorporated into the DNA of proliferating cells during S-phase and may be used clinically to radiosensitize tumors that are otherwise poorly responsive to radiation. Although radiosensitization has been studied for years, mechanisms of radiosensitization are poorly understood. One possible mechanism involves the release of short range, high-LET, Auger electrons following photoelectric absorption of an X ray by the K-shell of the incorporated halogen. Such absorption occurs only with X ray energies slightly greater than the K-shell binding energy. We report the results of an experiment designed to measure this effect, in which cultured monolayers of Chinese hamster V79 cells, with 32% replacement of thymidine by bromodeoxyuridine (BUdR), were exposed to monoenergetic X rays just below (13.450 KeV) or above (13.490 KeV) the K-edge (13.475 KeV) of bromine. Enhancement ratios calculated in five different ways were slightly increased (3-12%) above the K-edge compared to below. However, only a calculation using a linear-quadratic fit to the data and a surviving fraction of 0.01 demonstrated a statistically significant increased enhancement ratio (12%) above the K-edge. We conclude that Auger electrons produced following photoelectric absorption of X rays by the K-shell of bromine contribute minimally to observed BUdR cellular radiosensitization.
Collapse
Affiliation(s)
- D Larson
- Department of Radiation Oncology, University of California, San Francisco 94143
| | | | | | | | | | | | | |
Collapse
|
18
|
Nath R, Bongiorni P, Rockwell S. Enhancement of IUdR radiosensitization by low energy photons. Int J Radiat Oncol Biol Phys 1987; 13:1071-9. [PMID: 3597150 DOI: 10.1016/0360-3016(87)90047-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effect of the photon energy on the radiosensitization produced by iododeoxyuridine (IUdR) was examined using Chinese hamster cells in vitro. Radiosensitization by IUdR was considerably higher for 60 keV photons from 241Am sources than for the 860 keV photons (average energy) from 226Ra sources, under continuous low dose rate conditions applicable to intracavitary brachytherapy (a dose rate of 0.57 Gy/hr). Also, IUdR radiosensitization was higher for 250 kV X rays than for 4 MV X rays under the acute exposure conditions used in external beam radiation therapy (dose rates of 1 to 2 Gy/min). These data support the hypothesis that photons with energies just greater than 32.2 keV, the K-absorption edge of iodine, are more effective in causing cell damage than are photons of other energies, because their absorption results in the production of Auger electron cascades and therefore in the production of high linear energy transfer (LET) radiations.
Collapse
|
19
|
Ritter MA. The radiotoxicity of iodine-125 in ataxia telangiectasia fibroblasts. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 652:151-9. [PMID: 7213729 DOI: 10.1016/0005-2787(81)90218-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Normal and ataxia telangiectasia fibroblast strains were labeled with 3H- or 125I-labelled iododeoxyuridine, were stored at -75 degrees C to accumulate damage, and were thawed for survival assays. X-ray survival of frozen, unlabeled cells was also determined. The ataxia telangiectasia strains were about twice as sensitive as normal (based upon survival curve slopes) when irradiated with X-rays or 3H decays under frozen conditions. Accumulated 125I decays, while about 13 times more toxic than 3H decays, also killed ataxia telangiectasia cells about twice as efficiently as normal cells. These results indicate that a large proportion of 125I-induced damage--at least 50%--is subject to repair in normal cells. In addition, they suggest that ataxia telangiectasia cells less capably repair a lesion that is induced in common by X-rays and 125I, but in larger porportion by the latter--probably a DNA double-strand break.
Collapse
|
20
|
Abstract
The DNA in Chinese hamster cells was labeled first for 3 h with [3H]TdR and then for 3 h with [125I]UdR. Chromatin was extracted, frozen, and stored at -30 degrees C until 1.0 X 10(17) and 1.25 X 10(17) disintegrations/g of labeled DNA occurred for 125I and 3H respectively. Velocity sedimentation of chromatin (DNA with associated chromosomal proteins) in neutral sucrose gradients indicated that the localized energy from the 125I disintegrations, which gave about 1 double-strand break/disintegration plus an additional 1.3 single strand breaks, selectively fragmented the [125I] chromatin into pieces smaller than the [3H] chromatin. In other words, 125I disintegrations caused much more localized damage in the chromatin labeled with 125I than in the chromatin labeled with 3H, and fragments induced in DNA by 125I disintegrations were not held together by the associated chromosomal proteins. Use of this 125I technique for studying chromosomal proteins associated with different regions in the cellular DNA is discussed. For these studies, the number of disintegrations required for fragmenting DNA molecules of different sizes is illustrated.
Collapse
|
21
|
Krasin F, Person S, Ley RD, Hutchinson F. DNA crosslinks, single-strand breaks and effects on bacteriophage T4 survival from tritium decay of (2-3H)adenine, (8-3H)adenine and (8-3H)guanine. J Mol Biol 1976; 101:197-209. [PMID: 772217 DOI: 10.1016/0022-2836(76)90372-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
22
|
Microdosimetery of Auger Electrons. Radiat Res 1975. [DOI: 10.1016/b978-0-12-523350-7.50055-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
23
|
Painter RB, Young BR, Burk HJ. Non-repairable strand breaks induced by 125I incorporated into mammalian DNA. Proc Natl Acad Sci U S A 1974; 71:4836-8. [PMID: 4531021 PMCID: PMC433992 DOI: 10.1073/pnas.71.12.4836] [Citation(s) in RCA: 45] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
When (125)I is incorporated into Chinese hamster DNA (via (125)I-labeled iododeoxyuridine) and the cells are stored at 77 degrees K, the resulting decays of the isotope cause 4 to 5 breaks/single-strand per disintegration. On the average, about 50% of these breaks are repaired. In contrast, under the same conditions of storage and in the same range of total strand breaks/cell, 70-100% of the breaks induced by x-radiation are repaired. Thus, the extreme toxicity of (125)I when incorporated into DNA is correlated with the unrepaired breaks caused by decay of this isotope. These results suggest that unrepaired DNA strand breaks may be important in cell killing after treatments which damage DNA.
Collapse
|