51
|
Saha J, Davis AJ. Unsolved mystery: the role of BRCA1 in DNA end-joining. JOURNAL OF RADIATION RESEARCH 2016; 57 Suppl 1:i18-i24. [PMID: 27170701 PMCID: PMC4990114 DOI: 10.1093/jrr/rrw032] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/11/2016] [Accepted: 02/19/2016] [Indexed: 06/05/2023]
Abstract
Heritable mutations in the tumor suppressor gene BRCA1 increase a woman's lifetime risk of developing breast and ovarian cancer. BRCA1's tumor suppressor function is directly linked to its myriad of functions in the cellular response to DNA double-strand breaks (DSBs). BRCA1 interacts with an extensive array of DNA damage responsive proteins and plays important roles in DSB repair, mediated by the homologous recombination pathway, and in the activation of cell cycle checkpoints. However, the role of BRCA1 in the other two DSB repair pathways, classical non-homologous end-joining (C-NHEJ) and alternative NHEJ (A-NHEJ), remains unclear. In this review, we will discuss the current literature on BRCA1's potential role(s) in modulating both C-NHEJ and A-NHEJ. We also present a model showing that BRCA1 contributes to genomic maintenance by promoting precise DNA repair across all cell cycle phases via the direct modulation of DNA end-joining.
Collapse
Affiliation(s)
- Janapriya Saha
- Department of Radiation Oncology, Division of Molecular Radiation Biology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390-9187, USA
| | - Anthony J Davis
- Department of Radiation Oncology, Division of Molecular Radiation Biology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390-9187, USA
| |
Collapse
|
52
|
Establishment of a γ-H2AX foci-based assay to determine biological dose of radon to red bone marrow in rats. Sci Rep 2016; 6:30018. [PMID: 27445126 PMCID: PMC4957115 DOI: 10.1038/srep30018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/27/2016] [Indexed: 11/30/2022] Open
Abstract
The biodosimetric information is critical for assessment of cancer risk in populations exposed to high radon. However, no tools are available for biological dose estimation following radon exposure. Here, we established a γ-H2AX foci-based assay to determine biological dose to red bone marrow (RBM) in radon-inhaled rats. After 1–3 h of in vitro radon exposure, a specific pattern of γ-H2AX foci, linear tracks with individual p-ATM and p-DNA-PKcs foci, was observed, and the yield of γ-H2AX foci and its linear tracks displayed a linear dose-response manner in both rat peripheral blood lymphocytes (PBLs) and bone-marrow lymphocytes (BMLs). When the cumulative doses of radon inhaled by rats reached 14, 30 and 60 working level months (WLM), the yields of three types of foci markedly increased in both PBLs and BMLs, and γ-H2AX foci-based dose estimates to RBM were 0.97, 2.06 and 3.94 mGy, respectively. Notably, BMLs displayed a more profound increase of three types of foci than PBLs, and the absorbed dose ratio between BMLs and PBLs was similar between rats exposed to 30 and 60 WLM of radon. Taken together, γ-H2AX foci quantitation in PBLs is able to estimate RBM-absorbed doses with the dose-response curve of γ-H2AX foci after in vitro radon exposure and the ratio of RBM- to PBL-absorbed doses in rats following radon exposure.
Collapse
|
53
|
Popp HD, Meyer M, Brendel S, Prinzhorn W, Naumann N, Weiss C, Seifarth W, Schoenberg SO, Hofmann WK, Henzler T, Fabarius A. Leukocyte DNA damage after reduced and conventional absorbed radiation doses using 3rd generation dual-source CT technology. Eur J Radiol Open 2016; 3:134-7. [PMID: 27437433 PMCID: PMC4939318 DOI: 10.1016/j.ejro.2016.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 06/22/2016] [Indexed: 01/10/2023] Open
Abstract
Purpose Computed tomography (CT) scans are an important source of ionizing irradiation (IR) in medicine that can induce a variety of DNA damage in human tissues. With technological improvements CT scans at reduced absorbed doses became feasible presumably lowering genotoxic side effects. Materials and methods For measuring DNA damage we performed γH2AX foci microscopy in peripheral blood mononuclear cells (PBMC) after exposure to reduced and conventional absorbed radiation doses using 3rd generation dual-source CT (DSCT) technology. Results CT scans performed at reduced absorbed doses of 3 mGy induced significant lower levels (p < 0.0001) of DNA damage (0.05 focus per cell ± 0.01 [mean ± standard error of mean]) at 5 min after IR compared to conventional absorbed doses of 15 mGy (0.30 focus per cell ± 0.03). With ongoing DNA repair background γH2AX foci levels (0.05 focus per cell) were approached at 24 h after CT with both protocols. Conclusion Our results provide evidence that reduced absorbed doses mediated by adjusted tube current in 3rd generation DSCT induce lower levels of DNA damage in PBMC compared to conventional absorbed doses suggesting a lower genotoxic risk for state-of-the-art tube current reduced CT protocols.
Collapse
Affiliation(s)
- Henning D Popp
- Department of Hematology and Oncology, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Mathias Meyer
- Institute of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Susanne Brendel
- Department of Hematology and Oncology, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Wiltrud Prinzhorn
- Department of Hematology and Oncology, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Nicole Naumann
- Department of Hematology and Oncology, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Christel Weiss
- Department of Statistical Analysis, Medical Faculty Mannheim of the University of Heidelberg, Ludolf-Krehl-Strasse 13-17, 68167 Mannheim, Germany
| | - Wolfgang Seifarth
- Department of Hematology and Oncology, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Stefan O Schoenberg
- Institute of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Wolf-K Hofmann
- Department of Hematology and Oncology, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Thomas Henzler
- Institute of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Alice Fabarius
- Department of Hematology and Oncology, Medical Faculty Mannheim of the University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| |
Collapse
|
54
|
Zhang XH, Hu XD, Zhao SY, Xie LH, Miao YJ, Li Q, Min R, Liu PD, Zhang HQ. Methemoglobin-Based Biological Dose Assessment for Human Blood. HEALTH PHYSICS 2016; 111:30-36. [PMID: 27218292 DOI: 10.1097/hp.0000000000000522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Methemoglobin is an oxidative form of hemoglobin in erythrocytes. The authors' aim was to develop a new biological dosimeter based on a methemoglobin assay. Methemoglobin in peripheral blood (of females or males) that was exposed to a Co source (0.20 Gy min) was quantified using an enzyme-linked immunosorbent assay. The dose range was 0.5-8.0 Gy. In a time-course experiment, the time points 0, 0.02, 1, 2, 3, 7, 15, 21, and 30 d after 4-Gy irradiation of heparinized peripheral blood were used. Methemoglobin levels in a lysed erythrocyte pellet from the irradiated blood of females and males increased with the increasing dose. Methemoglobin levels in female blood irradiated with γ-doses more than 4 Gy were significantly higher than those in male samples at the same doses. Two dose-response relations were fitted to the straight line: one is with the correlation coefficient of 0.98 for females, and the other is with the correlation coefficient of 0.99 for males. The lower limit of dose assessment based on methemoglobin is about 1 Gy. Methemoglobin levels in blood as a result of auto-oxidation increase after 7-d storage at -20 °C. The upregulation of methemoglobin induced by γ-radiation persists for ∼3 d. The absorbed doses that were estimated using the two dose-response relations were close to the actual doses. The results suggest that methemoglobin can be used as a rapid and accurate biological dosimeter for early assessment of absorbed γ-dose in human blood.
Collapse
Affiliation(s)
- Xiao-Hong Zhang
- *Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210006, P.R. China; †Clincal Laboratory, Jiangsu Province Hospital of Traditional Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China; ‡Division of Radiation Medicine, Department of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China; §Jiangsu Laboratory for Biomaterials and Devices, Southeast University, Nanjing 210018, P.R. China
| | | | | | | | | | | | | | | | | |
Collapse
|
55
|
Yashavarddhan MH, Shukla SK, Srivastava NN, Suar M, Dutta S, Kalita B, Ranjan R, Singh A, Bajaj S, Gupta ML. γH2AX formation kinetics in PBMCs of rabbits exposed to acute and fractionated radiation and attenuation of focus frequency through preadministration of a combination of podophyllotoxin and rutin hydrate. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:455-468. [PMID: 27338557 DOI: 10.1002/em.22027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 05/17/2016] [Accepted: 05/17/2016] [Indexed: 06/06/2023]
Abstract
DNA damage can be assessed by the quantitation of γH2AX foci that form at DSB sites. This study examines the generation and persistence of γH2AX foci, variability in foci size after acute and fractionated radiation exposure, and the effect of pretreatment with a safe radioprotective formulation termed G-003M on foci generation and persistence. G-003M contains a combination of podophyllotoxin and rutin hydrate, and was administered intramuscularly to rabbits 1 hr prior to Co(60) gamma irradiation. Rabbits were assigned to one of the following treatment groups: untreated, G-003M alone, irradiated (single dose 8 Gy, fractionated 2 Gy/day for 4 days or single dose 2 Gy) or G-003M preadministration followed by radiation exposure. Foci continuously persisted for a week in peripheral blood mononuclear cells of rabbits exposed to a single 8 Gy dose. However, the number of foci gradually decreased after reaching a maximum at 1 h. In rabbits exposed to fractionated radiation, foci detected 1 hr after the final exposure were significantly larger (P < 0.001) than in rabbits exposed to a single 8 Gy dose, but disappeared completely after 24 h. In both groups, foci reappeared on days 11-15 in terminally ill animals. G-003M pretreatment significantly (P < 0.05) attenuated the formation of γH2AX foci in all irradiated rabbits. This study reveals that γH2AX focus assessment could be used to confirm radiation exposure, that focus size reflects the type of radiation exposure (acute or fractionated), that the re-appearance of foci is a strong indicator of imminent death in animals, and that G-003M provides protection against radiation. Environ. Mol. Mutagen. 57:455-468, 2016. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- M H Yashavarddhan
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha 751024, India
| | - Sandeep K Shukla
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| | - Nitya N Srivastava
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha 751024, India
| | - Sangeeta Dutta
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| | - Bhargab Kalita
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| | - Rajiv Ranjan
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| | - Abhinav Singh
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| | - Sania Bajaj
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| | - Manju L Gupta
- Division of Radioprotective Drug Development Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, SK Mazumdar Marg, Delhi, 110054, India
| |
Collapse
|
56
|
Kummar S, Chen A, Gutierrez M, Pfister TD, Wang L, Redon C, Bonner WM, Yutzy W, Zhang Y, Kinders RJ, Ji J, Allen D, Covey JM, Eiseman JL, Holleran JL, Beumer JH, Rubinstein L, Collins J, Tomaszewski J, Parchment R, Pommier Y, Doroshow JH. Clinical and pharmacologic evaluation of two dosing schedules of indotecan (LMP400), a novel indenoisoquinoline, in patients with advanced solid tumors. Cancer Chemother Pharmacol 2016; 78:73-81. [PMID: 27169793 PMCID: PMC5199138 DOI: 10.1007/s00280-016-2998-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 02/25/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE Indenoisoquinolines are non-camptothecin topoisomerase I (TopI) inhibitors that overcome the limitations of camptothecins: chemical instability and camptothecin resistance. Two dosing schedules of the novel indenoisoquinoline, indotecan (LMP400), were evaluated in patients with advanced solid tumors. METHODS The maximum tolerated dose (MTD), toxicities, and pharmacokinetics of two indotecan drug administration schedules (daily for 5 days or weekly) were investigated. Modulation of TopI and the phosphorylation of histone H2AX (γH2AX) were assayed in tumor biopsies; γH2AX levels were also evaluated in circulating tumor cells (CTCs) and hair follicles to assess DNA damage response. RESULTS An MTD of 60 mg/m(2)/day was established for the daily regimen, compared to 90 mg/m(2) for the weekly regimen. The TopI response to drug showed target engagement in a subset of tumor biopsies. Pharmacokinetics profiles demonstrated a prolonged terminal half-life and tissue accumulation compared to topotecan. Dose-dependent decreases in total CTCs were measured in seven patients. Formation of γH2AX-positive foci in CTCs (day 3) and hair follicles (4-6 h) was observed following treatment. CONCLUSIONS We established the MTD of two dosing schedules for a novel TopI inhibitor, indotecan. Target engagement was demonstrated as Top1 downregulation and γH2AX response. No objective responses were observed on either schedule in this small patient cohort. The principal toxicity of both schedules was myelosuppression; no significant gastrointestinal problems were observed. Increased DNA damage response was observed in CTCs, hair follicles, and a subset of tumor biopsies.
Collapse
Affiliation(s)
- Shivaani Kummar
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Alice Chen
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Martin Gutierrez
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Thomas D Pfister
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Lihua Wang
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Christophe Redon
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - William M Bonner
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - William Yutzy
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Yiping Zhang
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Robert J Kinders
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Jiuping Ji
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Deborah Allen
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Joseph M Covey
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Julie L Eiseman
- Cancer Therapeutics Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Julianne L Holleran
- Cancer Therapeutics Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Jan H Beumer
- Cancer Therapeutics Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Larry Rubinstein
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Jerry Collins
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Joseph Tomaszewski
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA
| | - Ralph Parchment
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Yves Pommier
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - James H Doroshow
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 31 Center Drive, Room 3A44, Bethesda, MD, 20814, USA.
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| |
Collapse
|
57
|
Siva S, Lobachevsky P, MacManus MP, Kron T, Möller A, Lobb RJ, Ventura J, Best N, Smith J, Ball D, Martin OA. Radiotherapy for Non–Small Cell Lung Cancer Induces DNA Damage Response in Both Irradiated and Out-of-field Normal Tissues. Clin Cancer Res 2016; 22:4817-4826. [DOI: 10.1158/1078-0432.ccr-16-0138] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 05/11/2016] [Indexed: 11/16/2022]
|
58
|
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: 21] [Impact Index Per Article: 2.6] [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.
Collapse
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.
| |
Collapse
|
59
|
Lopez Perez R, Best G, Nicolay NH, Greubel C, Rossberger S, Reindl J, Dollinger G, Weber KJ, Cremer C, Huber PE. Superresolution light microscopy shows nanostructure of carbon ion radiation-induced DNA double-strand break repair foci. FASEB J 2016; 30:2767-76. [PMID: 27166088 DOI: 10.1096/fj.201500106r] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 04/12/2016] [Indexed: 12/13/2022]
Abstract
Carbon ion radiation is a promising new form of radiotherapy for cancer, but the central question about the biologic effects of charged particle radiation is yet incompletely understood. Key to this question is the understanding of the interaction of ions with DNA in the cell's nucleus. Induction and repair of DNA lesions including double-strand breaks (DSBs) are decisive for the cell. Several DSB repair markers have been used to investigate these processes microscopically, but the limited resolution of conventional microscopy is insufficient to provide structural insights. We have applied superresolution microscopy to overcome these limitations and analyze the fine structure of DSB repair foci. We found that the conventionally detected foci of the widely used DSB marker γH2AX (Ø 700-1000 nm) were composed of elongated subfoci with a size of ∼100 nm consisting of even smaller subfocus elements (Ø 40-60 nm). The structural organization of the subfoci suggests that they could represent the local chromatin structure of elementary DSB repair units at the DSB damage sites. Subfocus clusters may indicate induction of densely spaced DSBs, which are thought to be associated with the high biologic effectiveness of carbon ions. Superresolution microscopy might emerge as a powerful tool to improve our knowledge of interactions of ionizing radiation with cells.-Lopez Perez, R., Best, G., Nicolay, N. H., Greubel, C., Rossberger, S., Reindl, J., Dollinger, G., Weber, K.-J., Cremer, C., Huber, P. E. Superresolution light microscopy shows nanostructure of carbon ion radiation-induced DNA double-strand break repair foci.
Collapse
Affiliation(s)
- Ramon Lopez Perez
- Clinical Cooperation Unit and Molecular Radiation Oncology, German Cancer Research Center, Heidelberg University Hospital, Heidelberg, Germany; Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany;
| | - Gerrit Best
- Department of Ophthalmology, Heidelberg University Hospital, Heidelberg, Germany; Kirchhoff-Institute for Physics, Heidelberg University, Heidelberg, Germany
| | - Nils H Nicolay
- Clinical Cooperation Unit and Molecular Radiation Oncology, German Cancer Research Center, Heidelberg University Hospital, Heidelberg, Germany; Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Christoph Greubel
- Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg, Germany; and
| | - Sabrina Rossberger
- Kirchhoff-Institute for Physics, Heidelberg University, Heidelberg, Germany
| | - Judith Reindl
- Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg, Germany; and
| | - Günther Dollinger
- Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg, Germany; and
| | - Klaus-Josef Weber
- Clinical Cooperation Unit and Molecular Radiation Oncology, German Cancer Research Center, Heidelberg University Hospital, Heidelberg, Germany; Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Christoph Cremer
- Kirchhoff-Institute for Physics, Heidelberg University, Heidelberg, Germany; Superresolution Microscopy of Functional Nuclear Nanostructure, Institute of Molecular Biology, Mainz, Germany
| | - Peter E Huber
- Clinical Cooperation Unit and Molecular Radiation Oncology, German Cancer Research Center, Heidelberg University Hospital, Heidelberg, Germany; Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany;
| |
Collapse
|
60
|
γ-H2AX Kinetic Profile in Mouse Lymphocytes Exposed to the Internal Emitters Cesium-137 and Strontium-90. PLoS One 2015; 10:e0143815. [PMID: 26618801 PMCID: PMC4664397 DOI: 10.1371/journal.pone.0143815] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 11/10/2015] [Indexed: 11/19/2022] Open
Abstract
In the event of a dirty bomb scenario or an industrial nuclear accident, a significant dose of volatile radionuclides such as 137Cs and 90Sr may be dispersed into the atmosphere as a component of fallout and inhaled or ingested by hundreds and thousands of people. To study the effects of prolonged exposure to ingested radionuclides, we have performed long-term (30 day) internal-emitter mouse irradiations using soluble-injected 137CsCl and 90SrCl2 radioisotopes. The effect of ionizing radiation on the induction and repair of DNA double strand breaks (DSBs) in peripheral mouse lymphocytes in vivo was determined using the γ-H2AX biodosimetry marker. Using a serial sacrifice experimental design, whole-body radiation absorbed doses for 137Cs (0 to 10 Gy) and 90Sr (0 to 49 Gy) were delivered over 30 days following exposure to each radionuclide. The committed absorbed doses of the two internal emitters as a function of time post exposure were calculated based on their retention parameters and their derived dose coefficients for each specific sacrifice time. In order to measure the kinetic profile for γ-H2AX, peripheral blood samples were drawn at 5 specific timed dose points over the 30-day study period and the total γ-H2AX nuclear fluorescence per lymphocyte was determined using image analysis software. A key finding was that a significant γ-H2AX signal was observed in vivo several weeks after a single radionuclide exposure. A mechanistically-motivated model was used to analyze the temporal kinetics of γ-H2AX fluorescence. Exposure to either radionuclide showed two peaks of γ-H2AX: one within the first week, which may represent the death of mature, differentiated lymphocytes, and the second at approximately three weeks, which may represent the production of new lymphocytes from damaged progenitor cells. The complexity of the observed responses to internal irradiation is likely caused by the interplay between continual production and repair of DNA damage, cell cycle effects and apoptosis.
Collapse
|
61
|
Gould R, McFadden SL, Horn S, Prise KM, Doyle P, Hughes CM. Assessment of DNA double-strand breaks induced by intravascular iodinated contrast media followingin vitroirradiation andin vivo,during paediatric cardiac catheterization. CONTRAST MEDIA & MOLECULAR IMAGING 2015; 11:122-9. [DOI: 10.1002/cmmi.1671] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 08/10/2015] [Accepted: 09/17/2015] [Indexed: 01/01/2023]
Affiliation(s)
- Richard Gould
- Institute of Nursing and Health Research; Ulster University; Jordanstown Campus, Shore Road Newtownabbey BT37 OQB UK
| | - Sonyia L. McFadden
- Institute of Nursing and Health Research; Ulster University; Jordanstown Campus, Shore Road Newtownabbey BT37 OQB UK
| | - Simon Horn
- Centre for Cancer Research and Cell Biology; Queens University Belfast; 97 Lisburn Road Belfast BT9 7AE UK
| | - Kevin M. Prise
- Centre for Cancer Research and Cell Biology; Queens University Belfast; 97 Lisburn Road Belfast BT9 7AE UK
| | - Philip Doyle
- Regional Medical Physics Service, Belfast Health and Social Care Trust; Foster Green Hospital; 110 Saintfield Road Belfast BT8 6HD UK
| | - Ciara M. Hughes
- Institute of Nursing and Health Research; Ulster University; Jordanstown Campus, Shore Road Newtownabbey BT37 OQB UK
| |
Collapse
|
62
|
90Y-daclizumab, an anti-CD25 monoclonal antibody, provided responses in 50% of patients with relapsed Hodgkin's lymphoma. Proc Natl Acad Sci U S A 2015; 112:13045-50. [PMID: 26438866 DOI: 10.1073/pnas.1516107112] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite significant advances in the treatment of Hodgkin's lymphoma (HL), a significant proportion of patients will not respond or will subsequently relapse. We identified CD25, the IL-2 receptor alpha subunit, as a favorable target for systemic radioimmunotherapy of HL. The scientific basis for the clinical trial was that, although most normal cells with exception of Treg cells do not express CD25, it is expressed by a minority of Reed-Sternberg cells and by most polyclonal T cells rosetting around Reed-Sternberg cells. Forty-six patients with refractory and relapsed HL were evaluated with up to seven i.v. infusions of the radiolabeled anti-CD25 antibody (90)Y-daclizumab. (90)Y provides strong β emissions that kill tumor cells at a distance by a crossfire effect. In 46 evaluable HL patients treated with (90)Y-daclizumab there were 14 complete responses and nine partial responses; 14 patients had stable disease, and nine progressed. Responses were observed both in patients whose Reed-Sternberg cells expressed CD25 and in those whose neoplastic cells were CD25(-) provided that associated rosetting T cells expressed CD25. As assessed using phosphorylated H2AX (γ-H2AX) as a bioindicator of the effects of radiation exposure, predominantly nonmalignant cells in the tumor microenvironment manifested DNA damage, as reflected by increased expression of γ-H2AX. Toxicities were transient bone-marrow suppression and myelodysplastic syndrome in six patients who had not been evaluated with bone-marrow karyotype analyses before therapy. In conclusion, repeated (90)Y-daclizumab infusions directed predominantly toward nonmalignant T cells rosetting around Reed-Sternberg cells provided meaningful therapy for select HL patients.
Collapse
|
63
|
Johnston ML, Young EF, Shepard KL. Whole-blood immunoassay for γH2AX as a radiation biodosimetry assay with minimal sample preparation. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2015; 54:365-372. [PMID: 25935208 DOI: 10.1007/s00411-015-0595-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 04/16/2015] [Indexed: 06/04/2023]
Abstract
The current state of the art in high-throughput minimally invasive radiation biodosimetry involves the collection of samples in the field and analysis at a centralized facility. We have developed a simple biological immunoassay for radiation exposure that could extend this analysis out of the laboratory into the field. Such a forward placed assay would facilitate triage of a potentially exposed population. The phosphorylation and localization of the histone H2AX at double-stranded DNA breaks has already been proven to be an adequate surrogate assay for reporting DNA damage proportional to radiation dose. Here, we develop an assay for phosphorylated H2AX directed against minimally processed sample lysates. We conduct preliminary verification of H2AX phosphorylation using irradiated mouse embryo fibroblast cultures. Additional dosimetry is performed using human blood samples irradiated ex vivo. The assay reports H2AX phosphorylation in human blood samples in response to ionizing radiation over a range of 0-5 Gy in a linear fashion, without requiring filtering, enrichment, or purification of the blood sample.
Collapse
Affiliation(s)
- Matthew L Johnston
- Bialanx, Inc., 511 Avenue of the Americas, Suite 267, New York, NY, USA,
| | | | | |
Collapse
|
64
|
Siddiqui MS, François M, Fenech MF, Leifert WR. Persistent γH2AX: A promising molecular marker of DNA damage and aging. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 766:1-19. [PMID: 26596544 DOI: 10.1016/j.mrrev.2015.07.001] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 12/12/2022]
Abstract
One of the earliest cellular responses to DNA double strand breaks (DSBs) is the phosphorylation of the core histone protein H2AX (termed γH2AX). Persistent γH2AX is the level of γH2AX above baseline, measured at a given time-point beyond which DNA DSBs are normally expected to be repaired (usually persist for days to months). This review summarizes the concept of persistent γH2AX in the context of exogenous source induced DNA DSBs (e.g. ionizing radiation (IR), chemotherapeutic drugs, genotoxic agents), and endogenous γH2AX levels in normal aging and accelerated aging disorders. Summary of the current literature demonstrates the following (i) γH2AX persistence is a common phenomenon that occurs in humans and animals; (ii) nuclei retain persistent γH2AX foci for up to several months after IR exposure, allowing for retrospective biodosimetry; (iii) the combination of various radiosensitizing drugs with ionizing radiation exposure leads to persistent γH2AX response, thus enabling the potential for monitoring cancer patients' response to chemotherapy and radiotherapy as well as tailoring cancer treatments; (iv) persistent γH2AX accumulates in telomeric DNA and in cells undergoing cellular senescence; and (v) increased endogenous γH2AX levels may be associated with diseases of accelerated aging. In summary, measurement of persistent γH2AX could potentially be used as a marker of radiation biodosimetry, evaluating sensitivity to therapeutic genotoxins and radiotherapy, and exploring the association of unrepaired DNA DSBs on telomeres with diseases of accelerated aging.
Collapse
Affiliation(s)
- Mohammad Sabbir Siddiqui
- CSIRO Food and Nutrition Flagship, Genome Health and Healthy Aging, Adelaide, South Australia 5000, Australia; University of Adelaide, School of Agriculture, Food & Wine, Urrbrae, South Australia 5064, Australia
| | - Maxime François
- CSIRO Food and Nutrition Flagship, Genome Health and Healthy Aging, Adelaide, South Australia 5000, Australia
| | - Michael F Fenech
- CSIRO Food and Nutrition Flagship, Genome Health and Healthy Aging, Adelaide, South Australia 5000, Australia
| | - Wayne R Leifert
- CSIRO Food and Nutrition Flagship, Genome Health and Healthy Aging, Adelaide, South Australia 5000, Australia.
| |
Collapse
|
65
|
Rothkamm K, Barnard S, Moquet J, Ellender M, Rana Z, Burdak-Rothkamm S. DNA damage foci: Meaning and significance. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:491-504. [PMID: 25773265 DOI: 10.1002/em.21944] [Citation(s) in RCA: 237] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 02/13/2015] [Indexed: 06/04/2023]
Abstract
The discovery of DNA damage response proteins such as γH2AX, ATM, 53BP1, RAD51, and the MRE11/RAD50/NBS1 complex, that accumulate and/or are modified in the vicinity of a chromosomal DNA double-strand break to form microscopically visible, subnuclear foci, has revolutionized the detection of these lesions and has enabled studies of the cellular machinery that contributes to their repair. Double-strand breaks are induced directly by a number of physical and chemical agents, including ionizing radiation and radiomimetic drugs, but can also arise as secondary lesions during replication and DNA repair following exposure to a wide range of genotoxins. Here we aim to review the biological meaning and significance of DNA damage foci, looking specifically at a range of different settings in which such markers of DNA damage and repair are being studied and interpreted.
Collapse
Affiliation(s)
- Kai Rothkamm
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
- Department of Radiotherapy, Laboratory of Radiation Biology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Stephen Barnard
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Jayne Moquet
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Michele Ellender
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Zohaib Rana
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Susanne Burdak-Rothkamm
- Department of Cellular Pathology, Oxford University Hospitals, Headley Way, Headington, Oxford, United Kingdom
| |
Collapse
|
66
|
Piechowiak EI, Peter JFW, Kleb B, Klose KJ, Heverhagen JT. Intravenous Iodinated Contrast Agents Amplify DNA Radiation Damage at CT. Radiology 2015; 275:692-7. [DOI: 10.1148/radiol.14132478] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
67
|
Zahnreich S, Ebersberger A, Kaina B, Schmidberger H. Biodosimetry Based on γ-H2AX Quantification and Cytogenetics after Partial- and Total-Body Irradiation during Fractionated Radiotherapy. Radiat Res 2015; 183:432-46. [DOI: 10.1667/rr13911.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Sebastian Zahnreich
- Department of Radiation Oncology and Radiotherapy, University Medical Center Johannes Gutenberg University Mainz, 55131 Mainz, Germany
| | - Anne Ebersberger
- Department of Radiation Oncology and Radiotherapy, University Medical Center Johannes Gutenberg University Mainz, 55131 Mainz, Germany
| | - Bernd Kaina
- Department of Toxicology, University Medical Center Johannes Gutenberg University Mainz, 55131 Mainz, Germany
| | - Heinz Schmidberger
- Department of Radiation Oncology and Radiotherapy, University Medical Center Johannes Gutenberg University Mainz, 55131 Mainz, Germany
| |
Collapse
|
68
|
Barnard S, Ainsbury EA, Al-hafidh J, Hadjidekova V, Hristova R, Lindholm C, Monteiro Gil O, Moquet J, Moreno M, Rößler U, Thierens H, Vandevoorde C, Vral A, Wojewódzka M, Rothkamm K. The first gamma-H2AX biodosimetry intercomparison exercise of the developing European biodosimetry network RENEB. RADIATION PROTECTION DOSIMETRY 2015; 164:265-270. [PMID: 25118318 DOI: 10.1093/rpd/ncu259] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 07/18/2014] [Indexed: 06/03/2023]
Abstract
In the event of a mass casualty radiation incident, the gamma-H2AX foci assay could be a useful tool to estimate radiation doses received by individuals. The rapid processing time of blood samples of just a few hours and the potential for batch processing, enabling high throughput, make the assay ideal for early triage categorisation to separate the 'worried well' from the low and critically exposed by quantifying radiation-induced foci in peripheral blood lymphocytes. Within the RENEB framework, 8 European laboratories have taken part in the first European gamma-H2AX biodosimetry exercise, which consisted of a telescoring comparison of 200 circulated foci images taken from 8 samples, and a comparison of 10 fresh blood lymphocyte samples that were shipped overnight to participating labs 4 or 24 h post-exposure. Despite large variations between laboratories in the dose-response relationship for foci induction, the obtained results indicate that the network should be able to use the gamma-H2AX assay for rapidly identifying the most severely exposed individuals within a cohort who could then be prioritised for accurate chromosome dosimetry.
Collapse
Affiliation(s)
- S Barnard
- Public Health England, Centre for Radiation Chemical and Environmental Hazards, Chilton, UK
| | - E A Ainsbury
- Public Health England, Centre for Radiation Chemical and Environmental Hazards, Chilton, UK
| | - J Al-hafidh
- Public Health England, Centre for Radiation Chemical and Environmental Hazards, Chilton, UK
| | - V Hadjidekova
- National Centre of Radiobiology and Radiation Protection, Sofia, Bulgaria
| | - R Hristova
- National Centre of Radiobiology and Radiation Protection, Sofia, Bulgaria
| | - C Lindholm
- Radiation and Nuclear Safety Authority (STUK), Helsinki, Finland
| | - O Monteiro Gil
- Instituto Superior Técnico, Universidade de Lisboa, CTN, Grupo de Protecção e Segurança Radiológica, Bobadela-LRS, Portugal
| | - J Moquet
- Public Health England, Centre for Radiation Chemical and Environmental Hazards, Chilton, UK
| | - M Moreno
- Servicio Madrileño de Salud, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - U Rößler
- Bundesamt für Strahlenschutz, Oberschleissheim, Germany
| | - H Thierens
- Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
| | - C Vandevoorde
- Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
| | - A Vral
- Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
| | - M Wojewódzka
- Institute of Nuclear Chemistry and Technology, Center for Radiobiology and Biological Dosimetry, Warsaw, Poland
| | - K Rothkamm
- Public Health England, Centre for Radiation Chemical and Environmental Hazards, Chilton, UK
| |
Collapse
|
69
|
Turner HC, Shuryak I, Taveras M, Bertucci A, Perrier JR, Chen C, Elliston CD, Johnson GW, Smilenov LB, Amundson SA, Brenner DJ. Effect of dose rate on residual γ-H2AX levels and frequency of micronuclei in X-irradiated mouse lymphocytes. Radiat Res 2015; 183:315-24. [PMID: 25738897 DOI: 10.1667/rr13860.1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The biological risks associated with low-dose-rate (LDR) radiation exposures are not yet well defined. To assess the risk related to DNA damage, we compared the yields of two established biodosimetry end points, γ-H2AX and micronuclei (MNi), in peripheral mouse blood lymphocytes after prolonged in vivo exposure to LDR X rays (0.31 cGy/min) vs. acute high-dose-rate (HDR) exposure (1.03 Gy/min). C57BL/6 mice were total-body irradiated with 320 kVP X rays with doses of 0, 1.1, 2.2 and 4.45 Gy. Residual levels of total γ-H2AX fluorescence in lymphocytes isolated 24 h after the start of irradiation were assessed using indirect immunofluorescence methods. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to determine apoptotic cell frequency in lymphocytes sampled at 24 h. Curve fitting analysis suggested that the dose response for γ-H2AX yields after acute exposures could be described by a linear dependence. In contrast, a linear-quadratic dose-response shape was more appropriate for LDR exposure (perhaps reflecting differences in repair time after different LDR doses). Dose-rate sparing effects (P < 0.05) were observed at doses ≤2.2 Gy, such that the acute dose γ-H2AX and TUNEL-positive cell yields were significantly larger than the equivalent LDR yields. At the 4.45 Gy dose there was no difference in γ-H2AX expression between the two dose rates, whereas there was a two- to threefold increase in apoptosis in the LDR samples compared to the equivalent 4.45 Gy acute dose. Micronuclei yields were measured at 24 h and 7 days using the in vitro cytokinesis-blocked micronucleus (CBMN) assay. The results showed that MNi yields increased up to 2.2 Gy with no further increase at 4.45 Gy and with no detectable dose-rate effect across the dose range 24 h or 7 days post exposure. In conclusion, the γ-H2AX biomarker showed higher sensitivity to measure dose-rate effects after low-dose LDR X rays compared to MNi formation; however, confounding factors such as variable repair times post exposure, increased cell killing and cell cycle block likely contributed to the yields of MNi with accumulating doses of ionizing radiation.
Collapse
Affiliation(s)
- H C Turner
- Center for Radiological Research, Columbia University Medical Center, New York, New York 10032
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
70
|
Jossé R, Martin SE, Guha R, Ormanoglu P, Pfister TD, Reaper PM, Barnes CS, Jones J, Charlton P, Pollard JR, Morris J, Doroshow JH, Pommier Y. ATR inhibitors VE-821 and VX-970 sensitize cancer cells to topoisomerase i inhibitors by disabling DNA replication initiation and fork elongation responses. Cancer Res 2014; 74:6968-79. [PMID: 25269479 PMCID: PMC4252598 DOI: 10.1158/0008-5472.can-13-3369] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Camptothecin and its derivatives, topotecan and irinotecan, are specific topoisomerase I (Top1) inhibitors and potent anticancer drugs killing cancer cells by producing replication-associated DNA double-strand breaks, and the indenoisoquinoline LMP-400 (indotecan) is a novel Top1 inhibitor in clinical trial. To develop novel drug combinations, we conducted a synthetic lethal siRNA screen using a library that targets nearly 7,000 human genes. Depletion of ATR, the main transducer of replication stress, came as a top candidate gene for camptothecin synthetic lethality. Validation studies using ATR siRNA and the ATR inhibitor VE-821 confirmed marked antiproliferative synergy with camptothecin and even greater synergy with LMP-400. Single-cell analyses and DNA fiber combing assays showed that VE-821 abrogates the S-phase replication elongation checkpoint and the replication origin-firing checkpoint induced by camptothecin and LMP-400. As expected, the combination of Top1 inhibitors with VE-821 inhibited the phosphorylation of ATR and Chk1; however, it strongly induced γH2AX. In cells treated with the combination, the γH2AX pattern changed over time from the well-defined Top1-induced damage foci to an intense peripheral and diffuse nuclear staining, which could be used as response biomarker. Finally, the clinical derivative of VE-821, VX-970, enhanced the in vivo tumor response to irinotecan without additional toxicity. A key implication of our work is the mechanistic rationale and proof of principle it provides to evaluate the combination of Top1 inhibitors with ATR inhibitors in clinical trials.
Collapse
Affiliation(s)
- Rozenn Jossé
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Scott E Martin
- Division of Pre-Clinical Innovation, National Center for Advancing Translational Sciences (NCATS), NIH, Rockville, Maryland
| | - Rajarshi Guha
- Division of Pre-Clinical Innovation, National Center for Advancing Translational Sciences (NCATS), NIH, Rockville, Maryland
| | - Pinar Ormanoglu
- Division of Pre-Clinical Innovation, National Center for Advancing Translational Sciences (NCATS), NIH, Rockville, Maryland
| | - Thomas D Pfister
- Laboratory of Human Toxicology and Pharmacology, Applied/Developmental Research Directorate, Leidos Biomedical Research, Inc, National Laboratory for Cancer Research, Frederick, Maryland
| | - Philip M Reaper
- Vertex Pharmaceuticals (Europe) Ltd, Abingdon, Oxfordshire, United Kingdom
| | | | - Julie Jones
- Vertex Pharmaceuticals (Europe) Ltd, Abingdon, Oxfordshire, United Kingdom
| | - Peter Charlton
- Vertex Pharmaceuticals (Europe) Ltd, Abingdon, Oxfordshire, United Kingdom
| | - John R Pollard
- Vertex Pharmaceuticals (Europe) Ltd, Abingdon, Oxfordshire, United Kingdom
| | - Joel Morris
- Drug Synthesis and Chemistry Branch, Division of Cancer Treatment, Division of Cancer Treatment and Diagnosis (DTP-DCTD), NCI-NIH, Bethesda, Maryland
| | - James H Doroshow
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland. Drug Synthesis and Chemistry Branch, Division of Cancer Treatment, Division of Cancer Treatment and Diagnosis (DTP-DCTD), NCI-NIH, Bethesda, Maryland
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland.
| |
Collapse
|
71
|
Thomas A, Rajan A, Szabo E, Tomita Y, Carter CA, Scepura B, Lopez-Chavez A, Lee MJ, Redon CE, Frosch A, Peer CJ, Chen Y, Piekarz R, Steinberg SM, Trepel JB, Figg WD, Schrump DS, Giaccone G. A phase I/II trial of belinostat in combination with cisplatin, doxorubicin, and cyclophosphamide in thymic epithelial tumors: a clinical and translational study. Clin Cancer Res 2014; 20:5392-402. [PMID: 25189481 PMCID: PMC4216756 DOI: 10.1158/1078-0432.ccr-14-0968] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE This phase I/II study sought to determine the safety and maximum tolerated dose (MTD) of a novel schedule of belinostat, a histone deacetylase inhibitor (HDAC) administered before and in combination with cisplatin (P), doxorubicin (A), and cyclophosphamide (C) in thymic epithelial tumors (TET). Antitumor activity, pharmacokinetics, and biomarkers of response were also assessed. EXPERIMENTAL DESIGN Patients with advanced, unresectable TET received increasing doses of belinostat as a continuous intravenous infusion over 48 hours with chemotherapy in 3-week cycles. In phase II, belinostat at the MTD was used. RESULTS Twenty-six patients were enrolled (thymoma, 12; thymic carcinoma, 14). Dose-limiting toxicities at 2,000 mg/m(2) belinostat were grade 3 nausea and diarrhea and grade 4 neutropenia and thrombocytopenia, respectively, in two patients. Twenty-four patients were treated at the MTD of 1,000 mg/m(2) with chemotherapy (P, 50 mg/m(2) on day 2; A, 25 mg/m(2) on days 2 and 3; C, 500 mg/m(2) on day 3). Objective response rates in thymoma and thymic carcinoma were 64% (95% confidence interval, 30.8%-89.1%) and 21% (4.7%-50.8%), respectively. Modulation of pharmacodynamic markers of HDAC inhibition and declines in regulatory T cell (Treg) and exhausted CD8(+) T-cell populations were observed. Decline in Tregs was associated with response (P = 0.0041) and progression-free survival (P = 0.021). Declines in TIM3(+) CD8(+) T cells were larger in responders than nonresponders (P = 0.049). CONCLUSION This study identified the MTD of belinostat in combination with PAC and indicates that the combination is active and feasible in TETs. Immunomodulatory effects on Tregs and TIM3(+) CD8(+) T cells warrant further study.
Collapse
Affiliation(s)
- Anish Thomas
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Arun Rajan
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Eva Szabo
- Division of Cancer Prevention, National Cancer Institute, NIH, Bethesda, Maryland
| | - Yusuke Tomita
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Corey A Carter
- Department of Hematology and Oncology, Walter Reed National Military Medical Center, Bethesda, Maryland
| | - Barbara Scepura
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Ariel Lopez-Chavez
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Min-Jung Lee
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Christophe E Redon
- Laboratory of Molecular Pharmacology, National Cancer Institute, NIH, Bethesda, Maryland
| | - Ari Frosch
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Cody J Peer
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Yuanbin Chen
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Richard Piekarz
- Cancer Therapy Evaluation Program, National Cancer Institute, NIH, Bethesda, Maryland
| | - Seth M Steinberg
- Biostatistics and Data Management Section, National Cancer Institute, NIH, Bethesda, Maryland
| | - Jane B Trepel
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - William D Figg
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - David S Schrump
- Thoracic Surgery Section, Thoracic and Gastrointestinal Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Giuseppe Giaccone
- Medical Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland.
| |
Collapse
|
72
|
Bazan JG, Chang P, Balog R, D'Andrea A, Shaler T, Lin H, Lee S, Harrison T, Shura L, Schoen L, Knox SJ, Cooper DE. Novel Human Radiation Exposure Biomarker Panel Applicable for Population Triage. Int J Radiat Oncol Biol Phys 2014; 90:612-9. [DOI: 10.1016/j.ijrobp.2014.05.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 05/22/2014] [Accepted: 05/27/2014] [Indexed: 11/30/2022]
|
73
|
Ha CT, Li XH, Fu D, Moroni M, Fisher C, Arnott R, Srinivasan V, Xiao M. Circulating interleukin-18 as a biomarker of total-body radiation exposure in mice, minipigs, and nonhuman primates (NHP). PLoS One 2014; 9:e109249. [PMID: 25290447 PMCID: PMC4188589 DOI: 10.1371/journal.pone.0109249] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/04/2014] [Indexed: 12/21/2022] Open
Abstract
We aim to develop a rapid, easy-to-use, inexpensive and accurate radiation dose-assessment assay that tests easily obtained samples (e.g., blood) to triage and track radiological casualties, and to evaluate the radioprotective and therapeutic effects of radiation countermeasures. In the present study, we evaluated the interleukin (IL)-1 family of cytokines, IL-1β, IL-18 and IL-33, as well as their secondary cytokines’ expression and secretion in CD2F1 mouse bone marrow (BM), spleen, thymus and serum in response to γ-radiation from sublethal to lethal doses (5, 7, 8, 9, 10, or 12 Gy) at different time points using the enzyme-linked immune sorbent assay (ELISA), immunoblotting, and cytokine antibody array. Our data identified increases of IL-1β, IL-18, and/or IL-33 in mouse thymus, spleen and BM cells after total-body irradiation (TBI). However, levels of these cytokines varied in different tissues. Interestingly, IL-18 but not IL-1β or IL-33 increased significantly (2.5–24 fold) and stably in mouse serum from day 1 after TBI up to 13 days in a radiation dose-dependent manner. We further confirmed our finding in total-body γ-irradiated nonhuman primates (NHPs) and minipigs, and demonstrated that radiation significantly enhanced IL-18 in serum from NHPs 2–4 days post-irradiation and in minipig plasma 1–3 days post-irradiation. Finally, we compared circulating IL-18 with the well known hematological radiation biomarkers lymphocyte and neutrophil counts in blood of mouse, minipigs and NHPs and demonstrated close correlations between these biomarkers in response to radiation. Our results suggest that the elevated levels of circulating IL-18 after radiation proportionally reflect radiation dose and severity of radiation injury and may be used both as a potential biomarker for triage and also to track casualties after radiological accidents as well as for therapeutic radiation exposure.
Collapse
Affiliation(s)
- Cam T. Ha
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Xiang-Hong Li
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Dadin Fu
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Maria Moroni
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Carolyn Fisher
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Robert Arnott
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Venkataraman Srinivasan
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Mang Xiao
- Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- * E-mail:
| |
Collapse
|
74
|
Siva S, Callahan J, Kron T, Martin OA, MacManus MP, Ball DL, Hicks RJ, Hofman MS. A prospective observational study of Gallium-68 ventilation and perfusion PET/CT during and after radiotherapy in patients with non-small cell lung cancer. BMC Cancer 2014; 14:740. [PMID: 25277150 PMCID: PMC4192760 DOI: 10.1186/1471-2407-14-740] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 09/25/2014] [Indexed: 12/25/2022] Open
Abstract
Background Non-small cell lung cancer (NSCLC) accounts for 85% of lung cancers, and is the leading cause of cancer deaths. Radiation therapy (RT), alone or in combination with chemotherapy, is the standard of care for curative intent treatment of patients with locally advanced or inoperable NSCLC. The ability to intensify treatment to achieve a better chance for cure is limited by the risk of injury to the surrounding lung. Methods/Design This is a prospective observational study of 60 patients with NSCLC receiving curative intent RT. Independent human ethics board approval was received from the Peter MacCallum Cancer Centre ethics committee. In this research, Galligas and Gallium-68 macroaggregated albumin (MAA) positron emission tomography (PET) imaging will be used to measure ventilation (V) and perfusion (Q) in the lungs. This is combined with computed tomography (CT) and both performed with a four dimensional (4D) technique that tracks respiratory motion. This state-of-the-art scan has superior resolution, accuracy and quantitative ability than previous techniques. The primary objective of this research is to observe changes in ventilation and perfusion secondary to RT as measured by 4D V/Q PET/CT. Additionally, we plan to model personalised RT plans based on an individual’s lung capacity. Increasing radiation delivery through areas of poorly functioning lung may enable delivery of larger, more effective doses to tumours without increasing toxicity. By performing a second 4D V/Q PET/CT scan during treatment, we plan to simulate biologically adapted RT depending on the individual’s accumulated radiation injury. Tertiary aims of the study are assess the prognostic significance of a novel combination of clinical, imaging and serum biomarkers in predicting for the risk of lung toxicity. These biomarkers include spirometry, 18 F-Fluorodeoxyglucose PET/CT, gamma-H2AX signals in hair and lymphocytes, as well as assessment of blood cytokines. Discussion By correlating these biomarkers to toxicity outcomes, we aim to identify those patients early who will not tolerate RT intensification during treatment. This research is an essential step leading towards the design of future biologically adapted radiotherapy strategies to mitigate the risk of lung injury during dose escalation for patients with locally advanced lung cancer. Trials registration Universal Trial Number (UTN) U1111-1138-4421.
Collapse
Affiliation(s)
- Shankar Siva
- Division of Radiation Oncology and Cancer Imaging, St Andrews Place, East Melbourne 3002, Australia.
| | | | | | | | | | | | | | | |
Collapse
|
75
|
Halm BM, Franke AA, Lai JF, Turner HC, Brenner DJ, Zohrabian VM, DiMauro R. γ-H2AX foci are increased in lymphocytes in vivo in young children 1 h after very low-dose X-irradiation: a pilot study. Pediatr Radiol 2014; 44:1310-7. [PMID: 24756254 PMCID: PMC4175172 DOI: 10.1007/s00247-014-2983-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/30/2013] [Accepted: 03/23/2014] [Indexed: 01/21/2023]
Abstract
BACKGROUND Computed tomography (CT) is an imaging modality involving ionizing radiation. The presence of γ-H2AX foci after low to moderate ionizing radiation exposure has been demonstrated; however it is unknown whether very low ionizing radiation exposure doses from CT exams can induce γ-H2AX formation in vivo in young children. OBJECTIVE To test whether very low ionizing radiation doses from CT exams can induce lymphocytic γ-H2AX foci (phosphorylated histones used as a marker of DNA damage) formation in vivo in young children. MATERIALS AND METHODS Parents of participating children signed a consent form. Blood samples from three children (ages 3-21 months) undergoing CT exams involving very low blood ionizing radiation exposure doses (blood doses of 0.22-1.22 mGy) were collected immediately before and 1 h post CT exams. Isolated lymphocytes were quantified for γ-H2AX foci by a technician blinded to the radiation status and dose of the patients. Paired t-tests and regression analyses were performed with significance levels set at P < 0.05. RESULTS We observed a dose-dependent increase in γ-H2AX foci post-CT exams (P = 0.046) among the three children. Ionizing radiation exposure doses led to a linear increase of foci per cell in post-CT samples (102% between lowest and highest dose). CONCLUSION We found a significant induction of γ-H2AX foci in lymphocytes from post-CT samples of three very young children. When possible, CT exams should be limited or avoided by possibly applying non-ionizing radiation exposure techniques such as US or MRI.
Collapse
Affiliation(s)
- Brunhild M Halm
- University of Hawaii Cancer Center, 1236 Lauhala St., Honolulu, HI, 96813, USA,
| | | | | | | | | | | | | |
Collapse
|
76
|
Gerić M, Gajski G, Garaj-Vrhovac V. γ-H2AX as a biomarker for DNA double-strand breaks in ecotoxicology. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 105:13-21. [PMID: 24780228 DOI: 10.1016/j.ecoenv.2014.03.035] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 03/27/2014] [Accepted: 03/29/2014] [Indexed: 06/03/2023]
Abstract
The visualisation of DNA damage response proteins enables the indirect measurement of DNA damage. Soon after the occurrence of a DNA double-strand break (DSB), the formation of γ-H2AX histone variants is to be expected. This review is focused on the potential use of the γ-H2AX foci assay in assessing the genotoxicity of environmental contaminants including cytostatic pharmaceuticals, since standard methods may not be sensitive enough to detect the damaging effect of low environmental concentrations of such drugs. These compounds are constantly released into the environment, potentially representing a threat to water quality, aquatic organisms, and, ultimately, human health. Our review of the literature revealed that this method could be used in the biomonitoring and risk assessment of aquatic systems affected by wastewater from the production, usage, and disposal of cytostatic pharmaceuticals.
Collapse
Affiliation(s)
- Marko Gerić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia
| | - Goran Gajski
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia
| | - Vera Garaj-Vrhovac
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia.
| |
Collapse
|
77
|
Min XY, Zhang XH, Zhou QP, Hu XD, Liu PD, Zhang HQ. Development of serum zinc as a biological dosimeter in mice. Int J Radiat Biol 2014; 90:909-13. [PMID: 24827851 DOI: 10.3109/09553002.2014.922718] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To develop a new biological dosimeter based on serum zinc concentration. MATERIALS AND METHODS Male mice (8 weeks old) were exposed to different doses (0, 1.0, 2.0, 4.0, or 8.0 Gy) of gamma rays from a (60)Co source. Blood was then collected from the orbital area of these mice, and the serum zinc concentration was detected using the 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol colorimetric method. The data were analyzed using one-way analysis of variance. RESULTS The serum zinc concentration in the irradiated mice decreased with increasing dose. Two dose-response relationships fitted to the linear quadratic curve were obtained: One immediately after exposure (y = 0.010x(2) - 0.133x + 0.663, r = 0.983) and the other on the seventh day after exposure (y = 0.008x(2) - 0.127x + 0.695, r = 0.990). The serum zinc concentration continued to decrease until 21 days after exposure. The absorbed doses estimated using both dose-response relationships were close to the actual doses. CONCLUSIONS Serum zinc is a quick, effective, and sensitive biomarker for early biological doses assessment of mice irradiated by gamma radiation.
Collapse
Affiliation(s)
- Xuan-Yu Min
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics , Nanjing , P. R. China
| | | | | | | | | | | |
Collapse
|
78
|
Griffiths NM, Coudert S, Wilk JC, Renault D, Angulo JF, Van der Meeren A. Combined drug and surgery treatment of plutonium-contaminated wounds: indications obtained using a rodent model. HEALTH PHYSICS 2014; 106:638-644. [PMID: 24776894 DOI: 10.1097/hp.0000000000000088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
There is an important requirement following accidental actinide contamination of wounds to limit the dissemination and retention of such alpha-emitting radionuclides. To reduce wound and systemic contamination, treatment approaches include chelation therapy with or without wound excision. However, it has been hypothesized that wound excision could lead to increased contaminant release and systemic organ retention. This study in the rat addresses this question. Anesthetized rats were contaminated with plutonium nitrate following wounding by deep incision of hind leg muscle. Excision of tissue at the contaminated site was performed 7 d later with or without Diethylene Triamine Pentaacetic Acid (DTPA) treatment (30 μmol kg⁻¹ i.v.). Pu urinary excretion was then measured for a further 3 d, and animals were euthanized at 14 d after contamination. Tissue samples were evaluated for Pu activity and histology. At 7 d after contamination, around 50% of the initial activity remained at the wound site. An average of 16% of this activity was then removed by surgery. Surgery alone resulted in increased urinary excretion, suggesting release from the wound site, but no subsequent increases in organ retention (bone, liver) were observed at 14 d. Indeed, organ Pu activity was slightly reduced. The combination of surgery and DTPA or DTPA treatment alone was much more effective than excision alone as shown by the markedly increased urinary Pu excretion and decreased tissue levels. This is the first report in an experimental rodent model of resection of Pu-contaminated wound. Urinary excretion data provide evidence for the release of activity as a result of surgery, but this does not appear to lead to further Pu organ retention. However, a combination of prior DTPA treatment with wound excision is particularly effective.
Collapse
Affiliation(s)
- Nina M Griffiths
- *Laboratoire de RadioToxicologie, CEA/DSV/iRCM, Bruyères le Châtel, 91297 ARPAJON, France
| | | | | | | | | | | |
Collapse
|
79
|
Matsuya Y, Ohtsubo Y, Tsutsumi K, Sasaki K, Yamazaki R, Date H. Quantitative estimation of DNA damage by photon irradiation based on the microdosimetric-kinetic model. JOURNAL OF RADIATION RESEARCH 2014; 55:484-93. [PMID: 24515253 PMCID: PMC4014172 DOI: 10.1093/jrr/rrt222] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 12/12/2013] [Accepted: 12/13/2013] [Indexed: 05/23/2023]
Abstract
The microdosimetric-kinetic (MK) model is one of the models that can describe the fraction of cells surviving after exposure to ionizing radiation. In the MK model, there are specific parameters, k and yD, where k is an inherent parameter to represent the number of potentially lethal lesions (PLLs) and yD indicates the dose-mean lineal energy in keV/μm. Assuming the PLLs to be DNA double-strand breaks (DSBs), the rate equations are derived for evaluating the DSB number in the cell nucleus. In this study, we estimated the ratio of DSBs for two types of photon irradiation (6 MV and 200 kVp X-rays) in Chinese hamster ovary (CHO-K1) cells and human non-small cell lung cancer (H1299) cells by observing the surviving fraction. The estimated ratio was then compared with the ratio of γ-H2AX foci using immunofluorescent staining. For making a comparison of the number of DSBs among a variety of radiation energy cases, we next utilized the survival data in the literature for both cells exposed to other photon types, such as (60)Co γ-rays, (137)Cs γ-rays and 100 kVp X-rays. The ratio of DSBs based on the MK model with conventional data was consistent with the ratio of γ-H2AX foci numbers, confirming that the γ-H2AX focus is indicative of DSBs. It was also shown that the larger yD is, the larger the DSB number is. These results suggest that k and yD represent the characteristics of the surviving fraction and the biological effects for photon irradiation.
Collapse
Affiliation(s)
- Yusuke Matsuya
- Graduate School of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo 060-0812, Japan
| | - Yosuke Ohtsubo
- Hokkaido PWFAC Sapporo-Kosei General Hospital, Kita-3 Higashi-8, Chuo-ku, Sapporo 060-0033, Japan
| | - Kaori Tsutsumi
- Faculty of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo 060-0812, Japan
| | - Kohei Sasaki
- Graduate School of Engineering, Kyoto University, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8530, Japan
| | - Rie Yamazaki
- Graduate School of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo 060-0812, Japan
| | - Hiroyuki Date
- Faculty of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo 060-0812, Japan
| |
Collapse
|
80
|
Wang Z, Hu H, Hu M, Zhang X, Wang Q, Qiao Y, Liu H, Shen L, Zhou P, Chen Y. Ratio of γ-H2AX level in lymphocytes to that in granulocytes detected using flow cytometry as a potential biodosimeter for radiation exposure. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2014; 53:283-290. [PMID: 24687842 DOI: 10.1007/s00411-014-0530-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 02/24/2014] [Indexed: 06/03/2023]
Abstract
This study aims to assess utilisation of the ratio of γ-H2AX in lymphocytes to that in granulocytes (RL/G of γ-H2AX) in blood as a rapid method for population triage and dose estimation during large-scale radiation emergencies. Blood samples from healthy volunteers exposed to 0-10 Gy of (60)Co irradiation were collected. The samples were cultured for 0-24 h and then analysed using flow cytometry to measure the levels of γ-H2AX in lymphocytes and granulocytes. The basal RL/G levels of γ-H2AX in healthy human blood, the response of RL/G of γ-H2AX to ionising radiation and its relationship with doses, time intervals after exposure and individual differences were also analysed. The level of γ-H2AX in lymphocytes increased in a dose-dependent manner after irradiation, whereas the level in granulocytes was not affected. A linear dose-effect relationship with low inter-experimental and inter-individual variations was observed. The RL/G of γ-H2AX may be used as a biomarker for population triage and dose estimation during large-scale radiation emergencies if blood samples can be collected within 24 h.
Collapse
Affiliation(s)
- Zhidong Wang
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing, 100850, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
81
|
Brengues M, Liu D, Korn R, Zenhausern F. Method for validating radiobiological samples using a linear accelerator. EPJ TECHNIQUES AND INSTRUMENTATION 2014; 1:2. [PMID: 25485227 PMCID: PMC4257133 DOI: 10.1140/epjti2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 12/20/2013] [Indexed: 06/04/2023]
Abstract
There is an immediate need for rapid triage of the population in case of a large scale exposure to ionizing radiation. Knowing the dose absorbed by the body will allow clinicians to administer medical treatment for the best chance of recovery for the victim. In addition, today's radiotherapy treatment could benefit from additional information regarding the patient's sensitivity to radiation before starting the treatment. As of today, there is no system in place to respond to this demand. This paper will describe specific procedures to mimic the effects of human exposure to ionizing radiation creating the tools for optimization of administered radiation dosimetry for radiotherapy and/or to estimate the doses of radiation received accidentally during a radiation event that could pose a danger to the public. In order to obtain irradiated biological samples to study ionizing radiation absorbed by the body, we performed ex-vivo irradiation of human blood samples using the linear accelerator (LINAC). The LINAC was implemented and calibrated for irradiating human whole blood samples. To test the calibration, a 2 Gy test run was successfully performed on a tube filled with water with an accuracy of 3% in dose distribution. To validate our technique the blood samples were ex-vivo irradiated and the results were analyzed using a gene expression assay to follow the effect of the ionizing irradiation by characterizing dose responsive biomarkers from radiobiological assays. The response of 5 genes was monitored resulting in expression increase with the dose of radiation received. The blood samples treated with the LINAC can provide effective irradiated blood samples suitable for molecular profiling to validate radiobiological measurements via the gene-expression based biodosimetry tools.
Collapse
Affiliation(s)
- Muriel Brengues
- />Center for Applied NanoBioscience and Medicine, The University of Arizona College of Medicine, 425 N. 5th Street, Phoenix, AZ 85004 USA
| | - David Liu
- />Scottsdale Healthcare, Scottsdale Clinical Research Institute, 10510 N. 92nd Street, Scottsdale, AZ 85258 USA
| | - Ronald Korn
- />Scottsdale Healthcare, Scottsdale Clinical Research Institute, 10510 N. 92nd Street, Scottsdale, AZ 85258 USA
| | - Frederic Zenhausern
- />Center for Applied NanoBioscience and Medicine, The University of Arizona College of Medicine, 425 N. 5th Street, Phoenix, AZ 85004 USA
- />Scottsdale Healthcare, Scottsdale Clinical Research Institute, 10510 N. 92nd Street, Scottsdale, AZ 85258 USA
| |
Collapse
|
82
|
Forrester HB, Sprung CN. Intragenic controls utilizing radiation-induced alternative transcript regions improves gene expression biodosimetry. Radiat Res 2014; 181:314-23. [PMID: 24625097 DOI: 10.1667/rr13501.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ionizing-radiation exposure can be life threatening if given to the whole body. In addition, whole body radiation exposure can affect large numbers of people such as after a nuclear reactor accident, a nuclear explosion or a radiological terrorist attack. In these cases, an accurate biodosimeter is essential for triage management. One of the problems for biodosimetry in general is the interindividual variation before and after exposure, which can make it challenging to assign an accurate dose. To begin to address this challenge, lymphocyte cell lines were exposed to 0, 1, 2 and 5 Gy ionizing radiation from a ¹³⁷Cs source at a dose rate of 0.6 Gy/min. Alternative transcripts with regions showing large differential responses to ionizing radiation were determined from exon array data. Gene expression analysis was then performed on isolated mRNA using qRT-PCR with normalization to intergenic (PGK1, GAPDH) and novel intragenic regions for candidate radiation-responsive genes, PPM1D and MDM2. Our studies show that the use of a cis-associated expression reference improved the potential dose prediction approximately 2.3-8.3 fold and provided an advantage for dose prediction compared to distantly or trans-located control ionizing radiation nonresponsive genes. This approach also provides an alternative gene expression normalization method to potentially reduce interindividual variations when untreated basal gene expression levels are unavailable. Using associated noninduced regions of ionizing radiation-induced genes provides a way to estimate basal gene expression in the irradiated sample. This strategy can be utilized as a biodosimeter on its own or to enhance other gene expression candidates for biodosimetry. This normalization strategy may also be generally applicable for other quantitative PCR strategies where normalization is required for a particular response.
Collapse
Affiliation(s)
- Helen B Forrester
- Centre for Innate Immunity and Infectious Diseases, MIMR-PHI Institute of Medical Research and Monash University, Victoria, Australia
| | | |
Collapse
|
83
|
Lamkowski A, Forcheron F, Agay D, Ahmed EA, Drouet M, Meineke V, Scherthan H. DNA damage focus analysis in blood samples of minipigs reveals acute partial body irradiation. PLoS One 2014; 9:e87458. [PMID: 24498326 PMCID: PMC3911974 DOI: 10.1371/journal.pone.0087458] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 12/27/2013] [Indexed: 11/18/2022] Open
Abstract
Radiation accidents frequently involve acute high dose partial body irradiation leading to victims with radiation sickness and cutaneous radiation syndrome that implements radiation-induced cell death. Cells that are not lethally hit seek to repair ionizing radiation (IR) induced damage, albeit at the expense of an increased risk of mutation and tumor formation due to misrepair of IR-induced DNA double strand breaks (DSBs). The response to DNA damage includes phosphorylation of histone H2AX in the vicinity of DSBs, creating foci in the nucleus whose enumeration can serve as a radiation biodosimeter. Here, we investigated γH2AX and DNA repair foci in peripheral blood lymphocytes of Göttingen minipigs that experienced acute partial body irradiation (PBI) with 49 Gy (±6%) Co-60 γ-rays of the upper lumbar region. Blood samples taken 4, 24 and 168 hours post PBI were subjected to γ-H2AX, 53BP1 and MRE11 focus enumeration. Peripheral blood lymphocytes (PBL) of 49 Gy partial body irradiated minipigs were found to display 1–8 DNA damage foci/cell. These PBL values significantly deceed the high foci numbers observed in keratinocyte nuclei of the directly γ-irradiated minipig skin regions, indicating a limited resident time of PBL in the exposed tissue volume. Nonetheless, PBL samples obtained 4 h post IR in average contained 2.2% of cells displaying a pan-γH2AX signal, suggesting that these received a higher IR dose. Moreover, dispersion analysis indicated partial body irradiation for all 13 minipigs at 4 h post IR. While dose reconstruction using γH2AX DNA repair foci in lymphocytes after in vivo PBI represents a challenge, the DNA damage focus assay may serve as a rapid, first line indicator of radiation exposure. The occurrence of PBLs with pan-γH2AX staining and of cells with relatively high foci numbers that skew a Poisson distribution may be taken as indicator of acute high dose partial body irradiation, particularly when samples are available early after IR exposure.
Collapse
Affiliation(s)
- Andreas Lamkowski
- Institut für Radiobiologie der Bundeswehr in Verb. mit der Universität Ulm, München, Germany
| | - Fabien Forcheron
- Institut de Recherche Biomédicale des Armées (IRBA), Bretigny sur Orge, France
| | - Diane Agay
- Institut de Recherche Biomédicale des Armées (IRBA), Bretigny sur Orge, France
| | - Emad A. Ahmed
- Institut für Radiobiologie der Bundeswehr in Verb. mit der Universität Ulm, München, Germany
| | - Michel Drouet
- Institut de Recherche Biomédicale des Armées (IRBA), Bretigny sur Orge, France
| | - Viktor Meineke
- Institut für Radiobiologie der Bundeswehr in Verb. mit der Universität Ulm, München, Germany
| | - Harry Scherthan
- Institut für Radiobiologie der Bundeswehr in Verb. mit der Universität Ulm, München, Germany
- * E-mail:
| |
Collapse
|
84
|
Sakai H, Fujigaki H, Mazur SJ, Appella E. Wild-type p53-induced phosphatase 1 (Wip1) forestalls cellular premature senescence at physiological oxygen levels by regulating DNA damage response signaling during DNA replication. Cell Cycle 2014; 13:1015-29. [PMID: 24552809 DOI: 10.4161/cc.27920] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Wip1 (protein phosphatase Mg(2+)/Mn(2+)-dependent 1D, Ppm1d) is a nuclear serine/threonine protein phosphatase that is induced by p53 following the activation of DNA damage response (DDR) signaling. Ppm1d(-/-) mouse embryonic fibroblasts (MEFs) exhibit premature senescence under conventional culture conditions; however, little is known regarding the role of Wip1 in regulating cellular senescence. In this study, we found that even at a representative physiological concentration of 3% O2, Ppm1d(-/-) MEFs underwent premature cellular senescence that depended on the functional activation of p53. Interestingly, Ppm1d(-/-) MEFs showed increased H2AX phosphorylation levels without increased levels of reactive oxygen species (ROS) or DNA base damage compared with wild-type (Wt) MEFs, suggesting a decreased threshold for DDR activation or sustained DDR activation during recovery. Notably, the increased H2AX phosphorylation levels observed in Ppm1d(-/-) MEFs were primarily associated with S-phase cells and predominantly dependent on the activation of ATM. Moreover, these same phenotypes were observed when Wt and Ppm1d(-/-) MEFs were either transiently or chronically exposed to low levels of agents that induce replication-mediated double-stranded breaks. These findings suggest that Wip1 prevents the induction of cellular senescence at physiological oxygen levels by attenuating DDR signaling in response to endogenous double-stranded breaks that form during DNA replication.
Collapse
Affiliation(s)
- Hiroyasu Sakai
- Laboratory of Cell Biology; National Cancer Institute; National Institutes of Health; Bethesda, MD USA
| | - Hidetsugu Fujigaki
- Laboratory of Cell Biology; National Cancer Institute; National Institutes of Health; Bethesda, MD USA
| | - Sharlyn J Mazur
- Laboratory of Cell Biology; National Cancer Institute; National Institutes of Health; Bethesda, MD USA
| | - Ettore Appella
- Laboratory of Cell Biology; National Cancer Institute; National Institutes of Health; Bethesda, MD USA
| |
Collapse
|
85
|
Zhang XH, Min XY, Wang AL, Lou ZC, Zhang YN, Hu XD, Zhang HQ. Development of serum copper-based biological dosimetry in whole body gamma irradiation of mice. HEALTH PHYSICS 2013; 105:351-355. [PMID: 23982611 DOI: 10.1097/hp.0b013e31829aea95] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A new biological dosimeter based on serum copper has been developed. Serum copper in mice subjected to a 60Co source at a dose rate of 0.5 Gy min-1 was detected using the bis(cyclohexanone) oxaldihydrazone colorimetric method. The dose range was from 0.5–7 Gy. The results demonstrate that serum copper decreases with increasing dose. A linear dose response is obtained. The detection limit based on serum copper is the same as that with the lower limit of dose assessment; i.e., about 1 Gy. The decrease in serum copper continues until the 28th day after gamma radiation. The absorbed doses in mice assessed using the linear curve are close to “blind” doses of 4 and 6 Gy. Therefore, serum copper is a quick, simple, and accurate biomarker for early assessment of radiation exposure of mice in the range of 0.5–7 Gy.
Collapse
Affiliation(s)
- Xiao-hong Zhang
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210006, PR China
| | | | | | | | | | | | | |
Collapse
|
86
|
Willitzki A, Lorenz S, Hiemann R, Guttek K, Goihl A, Hartig R, Conrad K, Feist E, Sack U, Schierack P, Heiserich L, Eberle C, Peters V, Roggenbuck D, Reinhold D. Fully automated analysis of chemically induced γH2AX foci in human peripheral blood mononuclear cells by indirect immunofluorescence. Cytometry A 2013; 83:1017-26. [DOI: 10.1002/cyto.a.22350] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 07/26/2013] [Indexed: 12/16/2022]
Affiliation(s)
- Annika Willitzki
- Institute of Molecular and Clinical Immunology; Otto-von-Guericke-University; Magdeburg Germany
| | | | - Rico Hiemann
- Faculty of Sciences; Brandenburg Technical University Cottbus-Senftenberg; Senftenberg Germany
| | - Karina Guttek
- Institute of Molecular and Clinical Immunology; Otto-von-Guericke-University; Magdeburg Germany
| | - Alexander Goihl
- Institute of Molecular and Clinical Immunology; Otto-von-Guericke-University; Magdeburg Germany
| | - Roland Hartig
- Institute of Molecular and Clinical Immunology; Otto-von-Guericke-University; Magdeburg Germany
| | - Karsten Conrad
- Institute of Immunology; Technical University Dresden; Dresden Germany
| | - Eugen Feist
- Department of Rheumatology and Clinical Immunology; Charité-Universitätsmedizin; Berlin Germany
| | - Ulrich Sack
- Institute of Clinical Immunology, Medical Faculty; University of Leipzig; Germany
| | - Peter Schierack
- Faculty of Sciences; Brandenburg Technical University Cottbus-Senftenberg; Senftenberg Germany
| | | | | | | | - Dirk Roggenbuck
- Medipan GmbH; Dahlewitz/Berlin Germany
- Faculty of Sciences; Brandenburg Technical University Cottbus-Senftenberg; Senftenberg Germany
| | - Dirk Reinhold
- Institute of Molecular and Clinical Immunology; Otto-von-Guericke-University; Magdeburg Germany
| |
Collapse
|
87
|
Rothkamm K, Horn S, Scherthan H, Rössler U, De Amicis A, Barnard S, Kulka U, Lista F, Meineke V, Braselmann H, Beinke C, Abend M. Laboratory intercomparison on the γ-H2AX foci assay. Radiat Res 2013; 180:149-55. [PMID: 23883318 DOI: 10.1667/rr3238.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The focus of the study is an intercomparison of laboratories' dose-assessment performances using the γ-H2AX foci assay as a diagnostic triage tool for rapid individual radiation dose assessment. Homogenously X-irradiated (240 kVp, 1 Gy/min) blood samples for establishing calibration data (0.25-4 Gy) as well as blinded test samples (0.1-6.4 Gy) were incubated at 37°C for 2 and 24 h (repair time) and sent to the participants. The foci assay was performed according to protocols individually established in participating laboratories and therefore varied. The time taken to report dose estimates was documented for each laboratory. Additional information concerning laboratory organization/characteristics as well as assay performance was collected. The mean absolute difference (MAD) of estimated doses relative to the actual doses was calculated and radiation doses were merged into four triage categories reflecting clinical relevance to calculate accuracy, sensitivity and specificity. First γ-H2AX based dose estimates were reported 7 h after sample receipt. Estimates were similarly accurate for 2 and 24 h repair times, providing scope for its use in the early phase of a radiation exposure incident. Equal accuracy was achieved by scoring 20, 30, 40 or 50 cells per sample. However, MAD values of 0.5-0.7 Gy and 1.3-1.7 Gy divided the data sets into two groups, driven mainly by the considerable differences in foci yields between calibration and blind samples. Foci yields also varied dramatically between laboratories, highlighting reproducibility issues as an important caveat of the foci assay. Nonetheless, foci counts could distinguish high- and low-dose samples in all data sets and binary dose categories of clinical significance could be discriminated with satisfactory accuracy (mean 84%, ±0.03 SEM). Overall, the results suggest that the γ-H2AX assay is a useful tool for rapidly screening individuals for significant exposures that occurred up to at least 24 h earlier, and may help to prioritize cytogenetic dosimetry follow-up.
Collapse
Affiliation(s)
- K Rothkamm
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
88
|
Evaluation of the gamma-H2AX assay for radiation biodosimetry in a swine model. Int J Mol Sci 2013; 14:14119-35. [PMID: 23880859 PMCID: PMC3742235 DOI: 10.3390/ijms140714119] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Revised: 06/18/2013] [Accepted: 06/25/2013] [Indexed: 02/07/2023] Open
Abstract
There is a paucity of large animal models to study both the extent and the health risk of ionizing radiation exposure in humans. One promising candidate for such a model is the minipig. Here, we evaluate the minipig for its potential in γ-H2AX-based biodosimetry after exposure to ionizing radiation using both Cs137 and Co60 sources. γ-H2AX foci were enumerated in blood lymphocytes and normal fibroblasts of human and porcine origin after ex vivo γ-ray irradiation. DNA double-strand break repair kinetics in minipig blood lymphocytes and fibroblasts, based on the γ-H2AX assay, were similar to those observed in their human counterparts. To substantiate the similarity observed between the human and minipig we show that minipig fibroblast radiosensitivity was similar to that observed with human fibroblasts. Finally, a strong γ-H2AX induction was observed in blood lymphocytes following minipig total body irradiation. Significant responses were detected 3 days after 1.8 Gy and 1 week after 3.8 and 5 Gy with residual γ-H2AX foci proportional to the initial radiation doses. These findings show that the Gottingen minipig provides a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans.
Collapse
|
89
|
Zhang XH, Lou ZC, Wang AL, Hu XD, Zhang HQ. Development of Serum Iron as a Biological Dosimeter in Mice. Radiat Res 2013; 179:684-9. [DOI: 10.1667/rr3142.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
90
|
Manual versus automated γ-H2AX foci analysis across five European laboratories: can this assay be used for rapid biodosimetry in a large scale radiation accident? Mutat Res 2013; 756:170-3. [PMID: 23648320 DOI: 10.1016/j.mrgentox.2013.04.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 04/21/2013] [Indexed: 01/12/2023]
Abstract
The identification of severely exposed individuals and reassurance of the 'worried well' are of prime importance for initial triage following a large scale radiation accident. We aim to develop the γ-H2AX foci assay into a rapid biomarker tool for use in accidents. Here, five laboratories established a standard operating procedure and analysed 100 ex vivo γ-irradiated, 4 or 24h incubated and overnight-shipped lymphocyte samples from four donors to generate γ-H2AX reference data, using manual and/or automated foci scoring strategies. In addition to acute, homogeneous exposures to 0, 1, 2 and 4Gy, acute simulated partial body (4Gy to 50% of cells) and protracted exposures (4Gy over 24h) were analysed. Data from all laboratories could be satisfactorily fitted with linear dose response functions. Average yields observed at 4h post exposure were 2-4 times higher than at 24h and varied considerably between laboratories. Automated scoring caused larger uncertainties than manual scoring and was unable to identify partial exposures, which were detectable in manually scored samples due to their overdispersed foci distributions. Protracted exposures were detectable but doses could not be accurately estimated with the γ-H2AX assay. We conclude that the γ-H2AX assay may be useful for rapid triage following a recent acute radiation exposure. The potentially higher speed and convenience of automated relative to manual foci scoring needs to be balanced against its compromised accuracy and inability to detect partial body exposures. Regular re-calibration or inclusion of reference samples may be necessary to ensure consistent results between laboratories or over long time periods.
Collapse
|
91
|
Vasilyev SA, Kubes M, Markova E, Belyaev I. DNA damage response in CD133 + stem/progenitor cells from umbilical cord blood: low level of endogenous foci and high recruitment of 53BP1. Int J Radiat Biol 2013. [PMID: 23206244 DOI: 10.3109/09553002.2013.754555] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
UNLABELLED Abstract Purpose: Human hematopoietic stem cells (HSC) are thought to be a major target of radiation-induced leukemogenesis and also provide a relevant cellular model for assessing cancer risk. Cluster of designation 133+ (CD133+) is a marker found in human progenitor and hematopoietic stem cells. Our study examined the repair of radiation-induced DNA double-strand breaks (DSB) in CD133 + umbilical cord blood cells (UCBC). MATERIALS AND METHODS After γ-irradiation, endogenous and induced DSB were evaluated in CD133 + UCBC, CD133 - UCBC and peripheral blood lymphocytes (PBL) in terms of phosphorylated histone 2A family member X (γH2AX) and tumor suppressor p53 binding protein 1 (53BP1) foci. RESULTS We found that repair signaling in CD133 + UCBC is different from CD133 - UCBC and PBL. These differences include lower endogenous DSB levels and higher 53BP1 recruitment. CONCLUSIONS Our data, together with a recent report on radiation-induced γH2AX and 53BP1 foci in CD34 + cells, indicate enhanced DNA repair capacity in HSC as compared to mature lymphocytes.
Collapse
Affiliation(s)
- Stanislav A Vasilyev
- Laboratory of Molecular Genetics, Cancer Research Institute, Bratislava, Slovak Republic
| | | | | | | |
Collapse
|
92
|
Ivashkevich A, Redon CE, Nakamura AJ, Martin RF, Martin OA. Use of the γ-H2AX assay to monitor DNA damage and repair in translational cancer research. Cancer Lett 2012; 327:123-33. [PMID: 22198208 PMCID: PMC3329565 DOI: 10.1016/j.canlet.2011.12.025] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/11/2011] [Accepted: 12/14/2011] [Indexed: 12/30/2022]
Abstract
Formation of γ-H2AX in response to DNA double stranded breaks (DSBs) provides the basis for a sensitive assay of DNA damage in human biopsies. The review focuses on the application of γ-H2AX-based methods to translational studies to monitor the clinical response to DNA targeted therapies such as some forms of chemotherapy, external beam radiotherapy, radionuclide therapy or combinations thereof. The escalating attention on radiation biodosimetry has also highlighted the potential of the assay including renewed efforts to assess the radiosensitivity of prospective radiotherapy patients. Finally the γ-H2AX response has been suggested as a basis for an in vivo imaging modality.
Collapse
Affiliation(s)
- Alesia Ivashkevich
- Laboratory of Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Christophe E. Redon
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, USA
| | - Asako J. Nakamura
- Department of Anatomy and Cell Biology, Osaka Medical College, Osaka, Japan
| | - Roger F. Martin
- Laboratory of Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Olga A. Martin
- Laboratory of Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne, Australia
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia
| |
Collapse
|
93
|
New platform technology for comprehensive serological diagnostics of autoimmune diseases. Clin Dev Immunol 2012; 2012:284740. [PMID: 23316252 PMCID: PMC3536031 DOI: 10.1155/2012/284740] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 11/16/2012] [Indexed: 12/22/2022]
Abstract
Antibody assessment is an essential part in the serological diagnosis of autoimmune diseases. However, different diagnostic strategies have been proposed for the work up of sera in particular from patients with systemic autoimmune rheumatic disease (SARD). In general, screening for SARD-associated antibodies by indirect immunofluorescence (IIF) is followed by confirmatory testing covering different assay techniques. Due to lacking automation, standardization, modern data management, and human bias in IIF screening, this two-stage approach has recently been challenged by multiplex techniques particularly in laboratories with high workload. However, detection of antinuclear antibodies by IIF is still recommended to be the gold standard method for antibody screening in sera from patients with suspected SARD. To address the limitations of IIF and to meet the demand for cost-efficient autoantibody screening, automated IIF methods employing novel pattern recognition algorithms for image analysis have been introduced recently. In this respect, the AKLIDES technology has been the first commercially available platform for automated interpretation of cell-based IIF testing and provides multiplexing by addressable microbead immunoassays for confirmatory testing. This paper gives an overview of recently published studies demonstrating the advantages of this new technology for SARD serology.
Collapse
|
94
|
Pernot E, Hall J, Baatout S, Benotmane MA, Blanchardon E, Bouffler S, El Saghire H, Gomolka M, Guertler A, Harms-Ringdahl M, Jeggo P, Kreuzer M, Laurier D, Lindholm C, Mkacher R, Quintens R, Rothkamm K, Sabatier L, Tapio S, de Vathaire F, Cardis E. Ionizing radiation biomarkers for potential use in epidemiological studies. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2012; 751:258-286. [DOI: 10.1016/j.mrrev.2012.05.003] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 05/04/2012] [Accepted: 05/28/2012] [Indexed: 02/07/2023]
|
95
|
Johnson CH, Patterson AD, Krausz KW, Kalinich JF, Tyburski JB, Kang DW, Luecke H, Gonzalez FJ, Blakely WF, Idle JR. Radiation metabolomics. 5. Identification of urinary biomarkers of ionizing radiation exposure in nonhuman primates by mass spectrometry-based metabolomics. Radiat Res 2012; 178:328-40. [PMID: 22954391 DOI: 10.1667/rr2950.1] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Mass spectrometry-based metabolomics has previously demonstrated utility for identifying biomarkers of ionizing radiation exposure in cellular, mouse and rat in vivo radiation models. To provide a valuable link from small laboratory rodents to humans, γ-radiation-induced urinary biomarkers were investigated using a nonhuman primate total-body-irradiation model. Mass spectrometry-based metabolomics approaches were applied to determine whether biomarkers could be identified, as well as the previously discovered rodent biomarkers of γ radiation. Ultra-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry analysis was carried out on a time course of clean-catch urine samples collected from nonhuman primates (n = 6 per cohort) exposed to sham, 1.0, 3.5, 6.5 or 8.5 Gy doses of (60)Co γ ray (∼0.55 Gy/min) ionizing radiation. By multivariate data analysis, 13 biomarkers of radiation were discovered: N-acetyltaurine, isethionic acid, taurine, xanthine, hypoxanthine, uric acid, creatine, creatinine, tyrosol sulfate, 3-hydroxytyrosol sulfate, tyramine sulfate, N-acetylserotonin sulfate, and adipic acid. N-Acetyltaurine, isethionic acid, and taurine had previously been identified in rats, and taurine and xanthine in mice after ionizing radiation exposure. Mass spectrometry-based metabolomics has thus successfully revealed and verified urinary biomarkers of ionizing radiation exposure in the nonhuman primate for the first time, which indicates possible mechanisms for ionizing radiation injury.
Collapse
Affiliation(s)
- Caroline H Johnson
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
96
|
Redon CE, Weyemi U, Parekh PR, Huang D, Burrell AS, Bonner WM. γ-H2AX and other histone post-translational modifications in the clinic. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1819:743-56. [PMID: 22430255 PMCID: PMC3371125 DOI: 10.1016/j.bbagrm.2012.02.021] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 02/23/2012] [Accepted: 02/28/2012] [Indexed: 12/27/2022]
Abstract
Chromatin is a dynamic complex of DNA and proteins that regulates the flow of information from genome to end product. The efficient recognition and faithful repair of DNA damage, particularly double-strand damage, is essential for genomic stability and cellular homeostasis. Imperfect repair of DNA double-strand breaks (DSBs) can lead to oncogenesis. The efficient repair of DSBs relies in part on the rapid formation of foci of phosphorylated histone H2AX (γ-H2AX) at each break site, and the subsequent recruitment of repair factors. These foci can be visualized with appropriate antibodies, enabling low levels of DSB damage to be measured in samples obtained from patients. Such measurements are proving useful to optimize treatments involving ionizing radiation, to assay in vivo the efficiency of various drugs to induce DNA damage, and to help diagnose patients with a variety of syndromes involving elevated levels of γ-H2AX. We will survey the state of the art of utilizing γ-H2AX in clinical settings. We will also discuss possibilities with other histone post-translational modifications. The ability to measure in vivo the responses of individual patients to particular drugs and/or radiation may help optimize treatments and improve patient care. This article is part of a Special Issue entitled: Chromatin in time and space.
Collapse
Affiliation(s)
- Christophe E. Redon
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Urbain Weyemi
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Palak R. Parekh
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Dejun Huang
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD, 20892, USA
- School of Life Sciences, Lanzhou University, China
| | - Allison S. Burrell
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD, 20892, USA
- Molecular Medicine Program, Institute of Biomedical Sciences, The George Washington University
| | - William M. Bonner
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| |
Collapse
|
97
|
Luo Y, Hossain M, Wang C, Qiao Y, Ma L, Su M. On-chip radiation biodosimetry with three-dimensional microtissues. Analyst 2012; 137:3441-4. [PMID: 22701873 DOI: 10.1039/c2an35046g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper reports an image-based, on-chip microtissue radiation biodosimeter that can simultaneously monitor radiation responses of multiple mammalian cell types. The microtissue chip is fabricated by molding molten agarose gel onto microfabricated patterns to form microwells, and seeding a variety of cell suspensions into different microwells inside the agarose gel. The camera of a mobile phone is used to collect images of an array of microtissues, and the color changes of microtissues upon X-ray irradiation allow accurate determination of cell death, which is related to radiation dose. The images can be transferred wirelessly, allowing the biodosimeter to be used for convenient and field deployable monitoring of radiation exposure.
Collapse
Affiliation(s)
- Yang Luo
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, USA
| | | | | | | | | | | |
Collapse
|
98
|
Kiang JG, Garrison BR, Burns TM, Zhai M, Dews IC, Ney PH, Cary LH, Fukumoto R, Elliott TB, Ledney GD. Wound trauma alters ionizing radiation dose assessment. Cell Biosci 2012; 2:20. [PMID: 22686656 PMCID: PMC3469379 DOI: 10.1186/2045-3701-2-20] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 06/11/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Wounding following whole-body γ-irradiation (radiation combined injury, RCI) increases mortality. Wounding-induced increases in radiation mortality are triggered by sustained activation of inducible nitric oxide synthase pathways, persistent alteration of cytokine homeostasis, and increased susceptibility to bacterial infection. Among these factors, cytokines along with other biomarkers have been adopted for biodosimetric evaluation and assessment of radiation dose and injury. Therefore, wounding could complicate biodosimetric assessments. RESULTS In this report, such confounding effects were addressed. Mice were given 60Co γ-photon radiation followed by skin wounding. Wound trauma exacerbated radiation-induced mortality, body-weight loss, and wound healing. Analyses of DNA damage in bone-marrow cells and peripheral blood mononuclear cells (PBMCs), changes in hematology and cytokine profiles, and fundamental clinical signs were evaluated. Early biomarkers (1 d after RCI) vs. irradiation alone included significant decreases in survivin expression in bone marrow cells, enhanced increases in γ-H2AX formation in Lin+ bone marrow cells, enhanced increases in IL-1β, IL-6, IL-8, and G-CSF concentrations in blood, and concomitant decreases in γ-H2AX formation in PBMCs and decreases in numbers of splenocytes, lymphocytes, and neutrophils. Intermediate biomarkers (7 - 10 d after RCI) included continuously decreased γ-H2AX formation in PBMC and enhanced increases in IL-1β, IL-6, IL-8, and G-CSF concentrations in blood. The clinical signs evaluated after RCI were increased water consumption, decreased body weight, and decreased wound healing rate and survival rate. Late clinical signs (30 d after RCI) included poor survival and wound healing. CONCLUSION Results suggest that confounding factors such as wounding alters ionizing radiation dose assessment and agents inhibiting these responses may prove therapeutic for radiation combined injury and reduce related mortality.
Collapse
Affiliation(s)
- Juliann G Kiang
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
- Department of Radiation Biology, Uniformed Services University of The Health Sciences, Bethesda, MD 20814, USA
- Department of Medicine, Uniformed Services University of The Health Sciences, Bethesda, MD 20814, USA
| | - Bradley R Garrison
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - True M Burns
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - Min Zhai
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - Ian C Dews
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - Patrick H Ney
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - Lynnette H Cary
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - Risaku Fukumoto
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - Thomas B Elliott
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| | - G David Ledney
- Radiation Combined Injury Program, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA
| |
Collapse
|
99
|
Quanz M, Herbette A, Sayarath M, de Koning L, Dubois T, Sun JS, Dutreix M. Heat shock protein 90α (Hsp90α) is phosphorylated in response to DNA damage and accumulates in repair foci. J Biol Chem 2012; 287:8803-15. [PMID: 22270370 DOI: 10.1074/jbc.m111.320887] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
DNA damage triggers a complex signaling cascade involving a multitude of phosphorylation events. We found that the threonine 7 (Thr-7) residue of heat shock protein 90α (Hsp90α) was phosphorylated immediately after DNA damage. The phosphorylated Hsp90α then accumulated at sites of DNA double strand breaks and formed repair foci with slow kinetics, matching the repair kinetics of complex DNA damage. The phosphorylation of Hsp90α was dependent on phosphatidylinositol 3-kinase-like kinases, including the DNA-dependent protein kinase (DNA-PK) in particular. DNA-PK plays an essential role in the repair of DNA double strand breaks by nonhomologous end-joining and in the signaling of DNA damage. It is also present in the cytoplasm of the cell and has been suggested to play a role in cytoplasmic signaling pathways. Using stabilized double-stranded DNA molecules to activate DNA-PK, we showed that an active DNA-PK complex could be assembled in the cytoplasm, resulting in phosphorylation of the cytoplasmic pool of Hsp90α. In vivo, reverse phase protein array data for tumors revealed that basal levels of Thr-7-phosphorylated Hsp90α were correlated with phosphorylated histone H2AX levels. The Thr-7 phosphorylation of the ubiquitously produced and secreted Hsp90α may therefore serve as a surrogate biomarker of DNA damage. These findings shed light on the interplay between central DNA repair enzymes and an essential molecular chaperone.
Collapse
Affiliation(s)
- Maria Quanz
- Institut Curie, CNRS UMR3347, INSERM U1021, Université Paris-Sud 11, Centre Universitaire, Orsay, France.
| | | | | | | | | | | | | |
Collapse
|
100
|
Zheng Z, Ng WL, Zhang X, Olson JJ, Hao C, Curran WJ, Wang Y. RNAi-mediated targeting of noncoding and coding sequences in DNA repair gene messages efficiently radiosensitizes human tumor cells. Cancer Res 2012; 72:1221-8. [PMID: 22237628 DOI: 10.1158/0008-5472.can-11-2785] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Human tumor cell death during radiotherapy is caused mainly by ionizing radiation (IR)-induced DNA double-strand breaks (DSB), which are repaired by either homologous recombination repair (HRR) or nonhomologous end-joining (NHEJ). Although siRNA-mediated knockdown of DNA DSB repair genes can sensitize tumor cells to IR, this approach is limited by inefficiencies of gene silencing. In this study, we show that combining an artificial miRNA (amiR) engineered to target 3'-untranslated regions of XRCC2 (an HRR factor) or XRCC4 (an NHEJ factor) along with an siRNA to target the gene coding region can improve silencing efficiencies to achieve more robust radiosensitization than a single approach alone. Mechanistically, the combinatorial knockdown decreased targeted gene expression through both a reduction in mRNA stability and a blockade to mRNA translation. Together, our findings establish a general method of gene silencing that is more efficient and particularly suited for suppressing genes that are difficult to downregulate by amiR- or siRNA-based methods alone.
Collapse
Affiliation(s)
- Zhiming Zheng
- Department of Neurosurgery, Provincial Hospital affiliated to Shandong University, Shandong University, Jinan, China
| | | | | | | | | | | | | |
Collapse
|