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Karapetyan NH, Haroutiunian SG, Ananyan GV. Influence of Cu L-Histidinate Schiff Base Derivatives on Structural Features of Irradiated Rat's DNA. Cell Biochem Biophys 2024:10.1007/s12013-024-01368-9. [PMID: 38922498 DOI: 10.1007/s12013-024-01368-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2024] [Indexed: 06/27/2024]
Abstract
A study of rats liver DNA damages under the influence of X-ray radiation at a dose of 6.5 Gy(LD60) was carried out. The radioprotective properties of newly synthesized Cu(II) L-Schiff Histidinate complexes were also studied. The survival of rats was determined over a 30-day period after exposure to X-rays without pretreatment and also after preadministration of Cu(II) L-Histidinate-Schiff base complexes. The structural defects of rat's liver DNA were detected at 3, 7, 14, and 30 days post-irradiation extracted. The results obtained revealed that irradiation with a 6.5Gy dose in the control group degraded the characteristics of rat liver DNA in comparison to healthy DNA. On all investigated experimental days, a decrease in the melting temperature (Tm), a widening of the melting interval (ΔT), and a decrease in hypochromicity (Δh) were observed in the DNA samples of irradiated animals compared to the norm. The rat's pretreatment by Cu(II) L-Histidinate complexes 1 or 24 hours prior to irradiation improved DNA characteristics. Electrophoretic studies of DNA were in good agreement with the melting data. Based on the study results, it can be concluded that Cu(II) L-Histidinate complexes exhibit radioprotective properties under the studied conditions and can protect DNA from damage.
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Affiliation(s)
- Nelli H Karapetyan
- Department of Molecular Physics, Yerevan State University, 1 Alex Manoogian St. 0025, Yerevan, Armenia.
| | - Samvel G Haroutiunian
- Department of Molecular Physics, Yerevan State University, 1 Alex Manoogian St. 0025, Yerevan, Armenia
| | - Gayane V Ananyan
- Department of Molecular Physics, Yerevan State University, 1 Alex Manoogian St. 0025, Yerevan, Armenia
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2
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Sampadi B, Vermeulen S, Mišovic B, Boei JJ, Batth TS, Chang JG, Paulsen MT, Magnuson B, Schimmel J, Kool H, Olie CS, Everts B, Vertegaal ACO, Olsen JV, Ljungman M, Jeggo PA, Mullenders LHF, Vrieling H. Divergent Molecular and Cellular Responses to Low and High-Dose Ionizing Radiation. Cells 2022; 11:cells11233794. [PMID: 36497055 PMCID: PMC9739411 DOI: 10.3390/cells11233794] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Cancer risk after ionizing radiation (IR) is assumed to be linear with the dose; however, for low doses, definite evidence is lacking. Here, using temporal multi-omic systems analyses after a low (LD; 0.1 Gy) or a high (HD; 1 Gy) dose of X-rays, we show that, although the DNA damage response (DDR) displayed dose proportionality, many other molecular and cellular responses did not. Phosphoproteomics uncovered a novel mode of phospho-signaling via S12-PPP1R7, and large-scale dephosphorylation events that regulate mitotic exit control in undamaged cells and the G2/M checkpoint upon IR in a dose-dependent manner. The phosphoproteomics of irradiated DNA double-strand breaks (DSBs) repair-deficient cells unveiled extended phospho-signaling duration in either a dose-dependent (DDR signaling) or independent (mTOR-ERK-MAPK signaling) manner without affecting signal magnitude. Nascent transcriptomics revealed the transcriptional activation of genes involved in NRF2-regulated antioxidant defense, redox-sensitive ERK-MAPK signaling, glycolysis and mitochondrial function after LD, suggesting a prominent role for reactive oxygen species (ROS) in molecular and cellular responses to LD exposure, whereas DDR genes were prominently activated after HD. However, how and to what extent the observed dose-dependent differences in molecular and cellular responses may impact cancer development remain unclear, as the induction of chromosomal damage was found to be dose-proportional (10-200 mGy).
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Affiliation(s)
- Bharath Sampadi
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
- Correspondence: (B.S.); (H.V.)
| | - Sylvia Vermeulen
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Branislav Mišovic
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Jan J. Boei
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Tanveer S. Batth
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Science, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Jer-Gung Chang
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Michelle T. Paulsen
- Department of Radiation Oncology, Rogel Cancer Center and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Brian Magnuson
- Department of Radiation Oncology, Rogel Cancer Center and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Joost Schimmel
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Hanneke Kool
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Cyriel S. Olie
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Bart Everts
- Department of Parasitology, Leiden University Medical Center, 2333ZA Leiden, The Netherlands
| | - Alfred C. O. Vertegaal
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
| | - Jesper V. Olsen
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Science, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Mats Ljungman
- Department of Radiation Oncology, Rogel Cancer Center and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Penny A. Jeggo
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Leon H. F. Mullenders
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
- Department of Genetics, Research Institute of Environmental Medicine (RIeM), Nagoya University, Nagoya 464-8601, Japan
| | - Harry Vrieling
- Department of Human Genetics, Leiden University Medical Center, 2333ZC Leiden, The Netherlands
- Correspondence: (B.S.); (H.V.)
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3
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Xie L, Song Y, Petersen K, Solhaug KA, Lind OC, Brede DA, Salbu B, Tollefsen KE. Ultraviolet B modulates gamma radiation-induced stress responses in Lemna minor at multiple levels of biological organisation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 846:157457. [PMID: 35868377 DOI: 10.1016/j.scitotenv.2022.157457] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/01/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Elevated levels of ionizing and non-ionizing radiation may co-occur and pose cumulative hazards to biota. However, the combined effects and underlying toxicity mechanisms of different types of radiation in aquatic plants remain poorly understood. The present study aims to demonstrate how different combined toxicity prediction approaches can collectively characterise how chronic (7 days) exposure to ultraviolet B (UVB) radiation (0.5 W m-2) modulates gamma (γ) radiation (14.9, 19.5, 43.6 mGy h-1) induced stress responses in the macrophyte Lemna minor. A suite of bioassays was applied to quantify stress responses at multiple levels of biological organisation. The combined effects (no-enhancement, additivity, synergism, antagonism) were determined by two-way analysis of variance (2 W-ANOVA) and a modified Independent Action (IA) model. The toxicological responses and the potential causality between stressors were further visualised by a network of toxicity pathways. The results showed that γ-radiation or UVB alone induced oxidative stress and programmed cell death (PCD) as well as impaired oxidative phosphorylation (OXPHOS) and photosystem II (PSII) activity in L. minor. γ-radiation also activated antioxidant responses, DNA damage repair and chlorophyll metabolism, and inhibited growth at higher dose rates (≥20 mGy h-1). When co-exposed, UVB predominantly caused non-interaction (no-enhancement or additive) effects on γ-radiation-induced antioxidant gene expression, energy quenching in PSII and growth for all dose rates, whereas antagonistic effects were observed for lipid peroxidation, OXPHOS, PCD, oxidative stress, chlorophyll metabolism and genes involved in DNA damage responses. Synergistic effects were observed for changes in photochemical quenching and non-photochemical quenching, and up-regulation of antioxidant enzyme genes (GST) at one or more dose rates, while synergistic reproductive inhibition occurred at all three γ-radiation dose rates. The present study provides mechanistic knowledge, quantitative understanding and novel analytical strategies to decipher combined effects across levels of biological organisation, which should facilitate future cumulative hazard assessments of multiple stressors.
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Affiliation(s)
- Li Xie
- Norwegian Institute for Water Research (NIVA), Section of Ecotoxicology and Risk Assessment, Økernveien 94, N-0349 Oslo, Norway; Norwegian University of Life Sciences (NMBU), Centre for Environmental Radioactivity, N-1432 Ås, Norway.
| | - You Song
- Norwegian Institute for Water Research (NIVA), Section of Ecotoxicology and Risk Assessment, Økernveien 94, N-0349 Oslo, Norway; Norwegian University of Life Sciences (NMBU), Centre for Environmental Radioactivity, N-1432 Ås, Norway
| | - Karina Petersen
- Norwegian Institute for Water Research (NIVA), Section of Ecotoxicology and Risk Assessment, Økernveien 94, N-0349 Oslo, Norway
| | - Knut Asbjørn Solhaug
- Norwegian University of Life Sciences (NMBU), Faculty of Environmental Sciences and Natural Resource Management (MINA), N-1432 Ås, Norway; Norwegian University of Life Sciences (NMBU), Centre for Environmental Radioactivity, N-1432 Ås, Norway
| | - Ole Christian Lind
- Norwegian University of Life Sciences (NMBU), Faculty of Environmental Sciences and Natural Resource Management (MINA), N-1432 Ås, Norway; Norwegian University of Life Sciences (NMBU), Centre for Environmental Radioactivity, N-1432 Ås, Norway
| | - Dag Anders Brede
- Norwegian University of Life Sciences (NMBU), Faculty of Environmental Sciences and Natural Resource Management (MINA), N-1432 Ås, Norway; Norwegian University of Life Sciences (NMBU), Centre for Environmental Radioactivity, N-1432 Ås, Norway
| | - Brit Salbu
- Norwegian University of Life Sciences (NMBU), Faculty of Environmental Sciences and Natural Resource Management (MINA), N-1432 Ås, Norway; Norwegian University of Life Sciences (NMBU), Centre for Environmental Radioactivity, N-1432 Ås, Norway
| | - Knut Erik Tollefsen
- Norwegian Institute for Water Research (NIVA), Section of Ecotoxicology and Risk Assessment, Økernveien 94, N-0349 Oslo, Norway; Norwegian University of Life Sciences (NMBU), Faculty of Environmental Sciences and Natural Resource Management (MINA), N-1432 Ås, Norway; Norwegian University of Life Sciences (NMBU), Centre for Environmental Radioactivity, N-1432 Ås, Norway.
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4
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Sampadi B, Mullenders LHF, Vrieling H. Low and high doses of ionizing radiation evoke discrete global (phospho)proteome responses. DNA Repair (Amst) 2022; 113:103305. [PMID: 35255311 DOI: 10.1016/j.dnarep.2022.103305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 02/02/2022] [Accepted: 02/22/2022] [Indexed: 12/16/2022]
Abstract
BACKGROUND Although cancer risk is assumed to be linear with ionizing radiation (IR) dose, it is unclear to what extent low doses (LD) of IR from medical and occupational exposures pose a cancer risk for humans. Improved mechanistic understanding of the signaling responses to LD may help to clarify this uncertainty. Here, we performed quantitative mass spectrometry-based proteomics and phosphoproteomics experiments, using mouse embryonic stem cells, at 0.5 h and 4 h after exposure to LD (0.1 Gy) and high doses (HD; 1 Gy) of IR. RESULTS The proteome remained relatively stable (29; 0.5% proteins responded), whereas the phosphoproteome changed dynamically (819; 7% phosphosites changed) upon irradiation. Dose-dependent alterations of 25 IR-responsive proteins were identified, with only four in common between LD and HD. Mitochondrial metabolic proteins and pathways responded to LD, whereas transporter proteins and mitochondrial uncoupling pathways responded to HD. Congruently, mitochondrial respiration increased after LD exposure but decreased after HD exposure. While the bulk of the phosphoproteome response to LD (76%) occurred already at 0.5 h, an equivalent proportion of the phosphosites responded to HD at both time points. Motif, kinome/phosphatome, kinase-substrate, and pathway analyses revealed a robust DNA damage response (DDR) activation after HD exposure but not after LD exposure. Instead, LD-irradiation induced (de)phosphorylation of kinases, kinase-substrates and phosphatases that predominantly respond to reactive oxygen species (ROS) production. CONCLUSION Our analyses identify discrete global proteome and phosphoproteome responses after LD and HD, uncovering novel proteins and protein (de)phosphorylation events involved in the dose-dependent ionizing radiation responses.
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Affiliation(s)
- Bharath Sampadi
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333ZC Leiden, The Netherlands.
| | - Leon H F Mullenders
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333ZC Leiden, The Netherlands; Department of Genetics, Research Institute of Environmental Medicine (RIeM), Nagoya University, Nagoya, Japan
| | - Harry Vrieling
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333ZC Leiden, The Netherlands.
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5
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The Chromatin Architectural Protein CTCF Is Critical for Cell Survival upon Irradiation-Induced DNA Damage. Int J Mol Sci 2022; 23:ijms23073896. [PMID: 35409255 PMCID: PMC8999573 DOI: 10.3390/ijms23073896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/26/2022] [Accepted: 03/29/2022] [Indexed: 02/05/2023] Open
Abstract
CTCF is a nuclear protein initially discovered for its role in enhancer-promoter insulation. It has been shown to play a role in genome architecture and in fact, its DNA binding sites are enriched at the borders of chromatin domains. Recently, we showed that depletion of CTCF impairs the DNA damage response to ionizing radiation. To investigate the relationship between chromatin domains and DNA damage repair, we present here clonogenic survival assays in different cell lines upon CTCF knockdown and ionizing irradiation. The application of a wide range of ionizing irradiation doses (0–10 Gy) allowed us to investigate the survival response through a biophysical model that accounts for the double-strand breaks’ probability distribution onto chromatin domains. We demonstrate that the radiosensitivity of different cell lines is increased upon lowering the amount of the architectural protein. Our model shows that the deficiency in the DNA repair ability is related to the changes in the size of chromatin domains that occur when different amounts of CTCF are present in the nucleus.
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Liu Q, Palomero L, Moore J, Guix I, Espín R, Aytés A, Mao JH, Paulovich AG, Whiteaker JR, Ivey RG, Iliakis G, Luo D, Chalmers AJ, Murnane J, Pujana MA, Barcellos-Hoff MH. Loss of TGFβ signaling increases alternative end-joining DNA repair that sensitizes to genotoxic therapies across cancer types. Sci Transl Med 2021; 13:eabc4465. [PMID: 33568520 PMCID: PMC8208885 DOI: 10.1126/scitranslmed.abc4465] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 12/07/2020] [Indexed: 12/17/2022]
Abstract
Among the pleotropic roles of transforming growth factor-β (TGFβ) signaling in cancer, its impact on genomic stability is least understood. Inhibition of TGFβ signaling increases use of alternative end joining (alt-EJ), an error-prone DNA repair process that typically functions as a "backup" pathway if double-strand break repair by homologous recombination or nonhomologous end joining is compromised. However, the consequences of this functional relationship on therapeutic vulnerability in human cancer remain unknown. Here, we show that TGFβ broadly controls the DNA damage response and suppresses alt-EJ genes that are associated with genomic instability. Mechanistically based TGFβ and alt-EJ gene expression signatures were anticorrelated in glioblastoma, squamous cell lung cancer, and serous ovarian cancer. Consistent with error-prone repair, more of the genome was altered in tumors classified as low TGFβ and high alt-EJ, and the corresponding patients had better outcomes. Pan-cancer analysis of solid neoplasms revealed that alt-EJ genes were coordinately expressed and anticorrelated with TGFβ competency in 16 of 17 cancer types tested. Moreover, regardless of cancer type, tumors classified as low TGFβ and high alt-EJ were characterized by an insertion-deletion mutation signature containing short microhomologies and were more sensitive to genotoxic therapy. Collectively, experimental studies revealed that loss or inhibition of TGFβ signaling compromises the DNA damage response, resulting in ineffective repair by alt-EJ. Translation of this mechanistic relationship into gene expression signatures identified a robust anticorrelation that predicts response to genotoxic therapies, thereby expanding the potential therapeutic scope of TGFβ biology.
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Affiliation(s)
- Qi Liu
- Department of Radiation Oncology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94143, USA
| | - Luis Palomero
- ProCURE, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona 08908, Catalonia, Spain
| | - Jade Moore
- Department of Radiation Oncology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94143, USA
| | - Ines Guix
- Department of Radiation Oncology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94143, USA
| | - Roderic Espín
- ProCURE, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona 08908, Catalonia, Spain
| | - Alvaro Aytés
- ProCURE, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona 08908, Catalonia, Spain
| | - Jian-Hua Mao
- Biological Systems and Engineering Division, Berkeley Biomedical Data Science Center, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Amanda G Paulovich
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Jeffrey R Whiteaker
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Richard G Ivey
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen, University Hospital Essen, Essen 45147, Germany
| | - Daxian Luo
- Institute of Medical Radiation Biology, University of Duisburg-Essen, University Hospital Essen, Essen 45147, Germany
| | - Anthony J Chalmers
- Institute of Cancer Sciences and Beatson West of Scotland Cancer Centre, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - John Murnane
- Department of Radiation Oncology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94143, USA
| | - Miquel Angel Pujana
- ProCURE, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona 08908, Catalonia, Spain.
| | - Mary Helen Barcellos-Hoff
- Department of Radiation Oncology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94143, USA.
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Vukmirovic D, Seymour C, Mothersill C. Reprint of: Deciphering and simulating models of radiation genotoxicity with CRISPR/Cas9 systems. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 785:108318. [PMID: 32800271 DOI: 10.1016/j.mrrev.2020.108318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 11/16/2019] [Accepted: 01/15/2020] [Indexed: 10/24/2022]
Abstract
This short review explores the utility and applications of CRISPR/Cas9 systems in radiobiology. Specifically, in the context of experimentally simulating genotoxic effects of Ionizing Radiation (IR) to determine the contributions from DNA targets and 'Complex Double-Stranded Breaks' (complex DSBs) to the IR response. To elucidate this objective, this review considers applications of CRISPR/Cas9 on nuclear DNA targets to recognize the respective 'nucleocentric' response. The article also highlights contributions from mitochondrial DNA (mtDNA) - an often under-recognized target in radiobiology. This objective requires accurate experimental simulation of IR-like effects and parameters with the CRISPR/Cas9 systems. Therefore, the role of anti-CRISPR proteins in modulating enzyme activity to simulate dose rate - an important factor in radiobiology experiments is an important topic of this review. The applications of auxiliary domains on the Cas9 nuclease to simulate oxidative base damage and multiple stressor experiments are also topics of discussion. Ultimately, incorporation of CRISPR/Cas9 experiments into computational parameters in radiobiology models of IR damage and shortcomings to the technology are discussed as well. Altogether, the simulation of IR parameters and lack of damage to non-DNA targets in the CRISPR/Cas9 system lends this rapidly emerging tool as an effective model of IR induced DNA damage. Therefore, this literature review ultimately considers the relevance of complex DSBs to radiobiology with respect to using the CRISPR/Cas9 system as an effective experimental tool in models of IR induced effects.
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Affiliation(s)
- Dusan Vukmirovic
- McMaster University, Radiation Sciences Graduate Program, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada.
| | - Colin Seymour
- McMaster University, Department of Biology, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada.
| | - Carmel Mothersill
- McMaster University, Department of Biology, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada.
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Vukmirovic D, Seymour C, Mothersill C. Deciphering and simulating models of radiation genotoxicity with CRISPR/Cas9 systems. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 783:108298. [PMID: 32386748 DOI: 10.1016/j.mrrev.2020.108298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 11/16/2019] [Accepted: 01/15/2020] [Indexed: 10/25/2022]
Abstract
This short review explores the utility and applications of CRISPR/Cas9 systems in radiobiology. Specifically, in the context of experimentally simulating genotoxic effects of Ionizing Radiation (IR) to determine the contributions from DNA targets and 'Complex Double-Stranded Breaks' (complex DSBs) to the IR response. To elucidate this objective, this review considers applications of CRISPR/Cas9 on nuclear DNA targets to recognize the respective 'nucleocentric' response. The article also highlights contributions from mitochondrial DNA (mtDNA) - an often under-recognized target in radiobiology. This objective requires accurate experimental simulation of IR-like effects and parameters with the CRISPR/Cas9 systems. Therefore, the role of anti-CRISPR proteins in modulating enzyme activity to simulate dose rate - an important factor in radiobiology experiments is an important topic of this review. The applications of auxiliary domains on the Cas9 nuclease to simulate oxidative base damage and multiple stressor experiments are also topics of discussion. Ultimately, incorporation of CRISPR/Cas9 experiments into computational parameters in radiobiology models of IR damage and shortcomings to the technology are discussed as well. Altogether, the simulation of IR parameters and lack of damage to non-DNA targets in the CRISPR/Cas9 system lends this rapidly emerging tool as an effective model of IR induced DNA damage. Therefore, this literature review ultimately considers the relevance of complex DSBs to radiobiology with respect to using the CRISPR/Cas9 system as an effective experimental tool in models of IR induced effects.
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Affiliation(s)
- Dusan Vukmirovic
- McMaster University, Radiation Sciences Graduate Program, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada.
| | - Colin Seymour
- McMaster University, Department of Biology, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada.
| | - Carmel Mothersill
- McMaster University, Department of Biology, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada.
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Differential Repair Protein Recruitment at Sites of Clustered and Isolated DNA Double-Strand Breaks Produced by High-Energy Heavy Ions. Sci Rep 2020; 10:1443. [PMID: 31996740 PMCID: PMC6989695 DOI: 10.1038/s41598-020-58084-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/06/2020] [Indexed: 01/17/2023] Open
Abstract
DNA double-strand break (DSB) repair is crucial to maintain genomic stability. The fidelity of the repair depends on the complexity of the lesion, with clustered DSBs being more difficult to repair than isolated breaks. Using live cell imaging of heavy ion tracks produced at a high-energy particle accelerator we visualised simultaneously the recruitment of different proteins at individual sites of complex and simple DSBs in human cells. NBS1 and 53BP1 were recruited in a few seconds to complex DSBs, but in 40% of the isolated DSBs the recruitment was delayed approximately 5 min. Using base excision repair (BER) inhibitors we demonstrate that some simple DSBs are generated by enzymatic processing of base damage, while BER did not affect the complex DSBs. The results show that DSB processing and repair kinetics are dependent on the complexity of the breaks and can be different even for the same clastogenic agent.
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10
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Detection of DNA Double-Strand Breaks Using Pulsed-Field Gel Electrophoresis. Methods Mol Biol 2019. [PMID: 31473967 DOI: 10.1007/978-1-4939-9646-9_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
DNA is one of the most biologically important targets of exogenous and endogenous toxicants as well as carcinogens. Damage to DNA can be of different types (e.g., DNA adducts, DNA protein cross-links, single-strand breaks, oxidized bases, abasic sites, and double-strand breaks (DSBs)). DSBs are considered the most lethal form of DNA damage for eukaryotic cells, and if left unrepaired or misrepaired, can cause cell death, chromosome instability, and cancer. DSBs can arise in the cells through different sources and can be distinguished as endogenous or exogenous DSBs. Exogenous sources can be chemotherapeutic drugs, irradiation, and environmental chemicals. The endogenous causes of DNA DSBs in the cells are mainly reactive oxygen species and faulty repair of oxidative clustered DNA lesions. Qualitative and quantitative analysis of DNA DSBs is of utmost importance to understand physiologically relevant cellular processes as well as to investigate the genotoxic or clastogenic effects of toxicants. Pulsed-field gel electrophoresis (PFGE) is a widely used method for direct quantification of DNA DSBs. In this method, the cells exposed to DSB-inducing agents are embedded in the agarose blocks and lysed. These agarose blocks containing DNA are then run under multiple electric fields which are at 120° angle, to aid in the movement of large DNA strands. It gives a direct and specific measure of DSBs unlike the foci-based assays. This chapter provides a brief overview of the various commonly used approaches to analyze DNA DSBs and describes the theory, advantages and method of PFGE, for use in cells exposed to DNA DSB inducing agents.
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11
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Prediction of in vivo genotoxicity of lasiocarpine and riddelliine in rat liver using a combined in vitro-physiologically based kinetic modelling-facilitated reverse dosimetry approach. Arch Toxicol 2019; 93:2385-2395. [PMID: 31289892 DOI: 10.1007/s00204-019-02515-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 07/04/2019] [Indexed: 12/16/2022]
Abstract
Pyrrolizidine alkaloids (PAs) are naturally occurring genotoxic compounds, and PA-containing plants can pose a risk to humans through contaminated food sources and herbal products. Upon metabolic activation, PAs can form DNA adducts, DNA and protein cross links, chromosomal aberrations, micronuclei, and DNA double-strand breaks. These genotoxic effects may induce gene mutations and play a role in the carcinogenesis of PAs. This study aims to predict in vivo genotoxicity for two well-studied PAs, lasiocarpine and riddelliine, in rat using in vitro genotoxicity data and physiologically based kinetic (PBK) modelling-based reverse dosimetry. The phosphorylation of histone protein H2AX was used as a quantitative surrogate endpoint for in vitro genotoxicity of lasiocarpine and riddelliine in primary rat hepatocytes and human HepaRG cells. The in vitro concentration-response curves obtained from primary rat hepatocytes were subsequently converted to in vivo dose-response curves from which points of departure (PoDs) were derived that were compared to available in vivo genotoxicity data. The results showed that the predicted PoDs for lasiocarpine and riddelliine were comparable to in vivo genotoxicity data. It is concluded that this quantitative in vitro-in silico approach provides a method to predict in vivo genotoxicity for the large number of PAs for which in vivo genotoxicity data are lacking by integrating in vitro genotoxicity assays with PBK modelling-facilitated reverse dosimetry.
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12
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Richter C, Marquardt S, Li F, Spitschak A, Murr N, Edelhäuser BAH, Iliakis G, Pützer BM, Logotheti S. Rewiring E2F1 with classical NHEJ via APLF suppression promotes bladder cancer invasiveness. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2019; 38:292. [PMID: 31287003 PMCID: PMC6615232 DOI: 10.1186/s13046-019-1286-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/20/2019] [Indexed: 12/29/2022]
Abstract
Background Bladder cancer progression has been associated with dysfunctional repair of double-strand breaks (DSB), a deleterious type of DNA lesions that fuel genomic instability. Accurate DSB repair relies on two distinct pathways, homologous recombination (HR) and classical non-homologous end-joining (c-NHEJ). The transcription factor E2F1 supports HR-mediated DSB repair and protects genomic stability. However, invasive bladder cancers (BC) display, in contrast to non-invasive stages, genomic instability despite their high E2F1 levels. Hence, E2F1 is either inefficient in controlling DSB repair in this setting, or rewires the repair apparatus towards alternative, error-prone DSB processing pathways. Methods RT-PCR and immunoblotting, in combination with bioinformatics tools were applied to monitor c-NHEJ factors status in high-E2F1-expressing, invasive BC versus low-E2F1-expressing, non-invasive BC. In vivo binding of E2F1 on target gene promoters was demonstrated by ChIP assays and E2F1 CRISPR-Cas9 knockdown. MIR888-dependent inhibition of APLF by E2F1 was demonstrated using overexpression and knockdown experiments, in combination with luciferase assays. Methylation status of MIR888 promoter was monitored by methylation-specific PCR. The changes in invasion potential and the DSB repair efficiency were estimated by Boyden chamber assays and pulse field electrophoresis, correspondingly. Results Herein, we show that E2F1 directly transactivates the c-NHEJ core factors Artemis, DNA-PKcs, ligase IV, NHEJ1, Ku70/Ku80 and XRCC4, but indirectly inhibits APLF, a chromatin modifier regulating c-NHEJ. Inhibition is achieved by miR-888-5p, a testis-specific, X-linked miRNA which, in normal tissues, is often silenced via promoter methylation. Upon hypomethylation in invasive BC cells, MIR888 is transactivated by E2F1 and represses APLF. Consequently, E2F1/miR-888/APLF rewiring is established, generating conditions of APLF scarcity that compromise proper c-NHEJ function. Perturbation of the E2F1/miR-888/APLF axis restores c-NHEJ and ameliorates cell invasiveness. Depletion of miR-888 can establish a ‘high E2F1/APLF/DCLRE1C’ signature, which was found to be particularly favorable for BC patient survival. Conclusion Suppression of the ‘out-of-context’ activity of miR-888 improves DSB repair and impedes invasiveness by restoring APLF. Electronic supplementary material The online version of this article (10.1186/s13046-019-1286-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Christin Richter
- Institute of Experimental Gene Therapy and Cancer Research, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany
| | - Stephan Marquardt
- Institute of Experimental Gene Therapy and Cancer Research, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany
| | - Fanghua Li
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Alf Spitschak
- Institute of Experimental Gene Therapy and Cancer Research, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany
| | - Nico Murr
- Institute of Experimental Gene Therapy and Cancer Research, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany
| | - Berdien A H Edelhäuser
- Institute of Experimental Gene Therapy and Cancer Research, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Brigitte M Pützer
- Institute of Experimental Gene Therapy and Cancer Research, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany. .,Department Life, Light and Matter of the Interdisciplinary Faculty at Rostock University, Rostock, Germany.
| | - Stella Logotheti
- Institute of Experimental Gene Therapy and Cancer Research, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany
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Abramenkovs A, Stenerlöw B. Removal of heat-sensitive clustered damaged DNA sites is independent of double-strand break repair. PLoS One 2018; 13:e0209594. [PMID: 30592737 PMCID: PMC6310273 DOI: 10.1371/journal.pone.0209594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 12/07/2018] [Indexed: 11/21/2022] Open
Abstract
DNA double-strand breaks (DSBs) are the most deleterious lesions that can arise in cells after ionizing radiation or radiometric drug treatment. In addition to prompt DSBs, DSBs may also be produced during repair, evolving from a clustered DNA damaged site, which is composed of two or more distinct lesions that are located within two helical turns. A specific type of cluster damage is the heat-sensitive clustered site (HSCS), which transforms into DSBs upon treatment at elevated temperatures. The actual lesions or mechanisms that mediate the HSCS transformation into DSBs are unknown. However, there are two possibilities; either these lesions are transformed into DSBs due to DNA lesion instability, e.g., transfer of HSCS into single-strand breaks (SSBs), or they are formed due to local DNA structure instability, e.g., DNA melting, where two SSBs on opposite strands meet and transform into a DSB. The importance of these processes in living cells is not understood, but they significantly affect estimates of DSB repair capacity. In this study, we show that HSCS removal in human cells is not affected by defects in DSB repair or inhibition of DSB repair. Under conditions where rejoining of prompt DSBs was almost completely inhibited, heat-sensitive DSBs were successfully rejoined, without resulting in increased DSB levels, indicating that HSCS do not transfer into DSB in cells under physiological conditions. Furthermore, analysis by atomic force microscopy suggests that prolonged heating of chromosomal DNA can induce structural changes that facilitate transformation of HSCS into DSB. In conclusion, the HSCS do not generate additional DSBs at physiological temperatures in human cells, and the repair of HSCS is independent of DSB repair.
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Affiliation(s)
- Andris Abramenkovs
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Bo Stenerlöw
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
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Jezkova L, Zadneprianetc M, Kulikova E, Smirnova E, Bulanova T, Depes D, Falkova I, Boreyko A, Krasavin E, Davidkova M, Kozubek S, Valentova O, Falk M. Particles with similar LET values generate DNA breaks of different complexity and reparability: a high-resolution microscopy analysis of γH2AX/53BP1 foci. NANOSCALE 2018; 10:1162-1179. [PMID: 29271466 DOI: 10.1039/c7nr06829h] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Biological effects of high-LET (linear energy transfer) radiation have received increasing attention, particularly in the context of more efficient radiotherapy and space exploration. Efficient cell killing by high-LET radiation depends on the physical ability of accelerated particles to generate complex DNA damage, which is largely mediated by LET. However, the characteristics of DNA damage and repair upon exposure to different particles with similar LET parameters remain unexplored. We employed high-resolution confocal microscopy to examine phosphorylated histone H2AX (γH2AX)/p53-binding protein 1 (53BP1) focus streaks at the microscale level, focusing on the complexity, spatiotemporal behaviour and repair of DNA double-strand breaks generated by boron and neon ions accelerated at similar LET values (∼135 keV μm-1) and low energies (8 and 47 MeV per n, respectively). Cells were irradiated using sharp-angle geometry and were spatially (3D) fixed to maximize the resolution of these analyses. Both high-LET radiation types generated highly complex γH2AX/53BP1 focus clusters with a larger size, increased irregularity and slower elimination than low-LET γ-rays. Surprisingly, neon ions produced even more complex γH2AX/53BP1 focus clusters than boron ions, consistent with DSB repair kinetics. Although the exposure of cells to γ-rays and boron ions eliminated a vast majority of foci (94% and 74%, respectively) within 24 h, 45% of the foci persisted in cells irradiated with neon. Our calculations suggest that the complexity of DSB damage critically depends on (increases with) the particle track core diameter. Thus, different particles with similar LET and energy may generate different types of DNA damage, which should be considered in future research.
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Affiliation(s)
- Lucie Jezkova
- Joint Institute for Nuclear Research, Dubna, Russia and University of Chemistry and Technology Prague, Prague, Czech Republic
- University of Chemistry and Technology Prague, Prague, Czech Republic
| | - Mariia Zadneprianetc
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Elena Kulikova
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | | | - Tatiana Bulanova
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Daniel Depes
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
| | - Iva Falkova
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
| | - Alla Boreyko
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Evgeny Krasavin
- Joint Institute for Nuclear Research, Dubna, Russia and Dubna State University, Dubna, Russia
- Dubna State University, Dubna, Russia
| | - Marie Davidkova
- Czech Academy of Sciences, Nuclear Physics Institute, Prague, Czech Republic
| | - Stanislav Kozubek
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
| | - Olga Valentova
- University of Chemistry and Technology Prague, Prague, Czech Republic
| | - Martin Falk
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic.
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15
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Sharma V, Collins LB, Chen TH, Herr N, Takeda S, Sun W, Swenberg JA, Nakamura J. Oxidative stress at low levels can induce clustered DNA lesions leading to NHEJ mediated mutations. Oncotarget 2018; 7:25377-90. [PMID: 27015367 PMCID: PMC5041911 DOI: 10.18632/oncotarget.8298] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 03/13/2016] [Indexed: 12/12/2022] Open
Abstract
DNA damage and mutations induced by oxidative stress are associated with various different human pathologies including cancer. The facts that most human tumors are characterized by large genome rearrangements and glutathione depletion in mice results in deletions in DNA suggest that reactive oxygen species (ROS) may cause gene and chromosome mutations through DNA double strand breaks (DSBs). However, the generation of DSBs at low levels of ROS is still controversial. In the present study, we show that H2O2 at biologically-relevant levels causes a marked increase in oxidative clustered DNA lesions (OCDLs) with a significant elevation of replication-independent DSBs. Although it is frequently reported that OCDLs are fingerprint of high-energy IR, our results indicate for the first time that H2O2, even at low levels, can also cause OCDLs leading to DSBs specifically in G1 cells. Furthermore, a reverse genetic approach revealed a significant contribution of the non-homologous end joining (NHEJ) pathway in H2O2-induced DNA repair & mutagenesis. This genomic instability induced by low levels of ROS may be involved in spontaneous mutagenesis and the etiology of a wide variety of human diseases like chronic inflammation-related disorders, carcinogenesis, neuro-degeneration and aging.
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Affiliation(s)
- Vyom Sharma
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Leonard B Collins
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Ting-Huei Chen
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Natalie Herr
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Wei Sun
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Jun Nakamura
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
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16
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Banerjee S, Chakraborty S, Jacinto MP, Paul MD, Balster MV, Greenberg MM. Probing Enhanced Double-Strand Break Formation at Abasic Sites within Clustered Lesions in Nucleosome Core Particles. Biochemistry 2016; 56:14-21. [PMID: 28005342 DOI: 10.1021/acs.biochem.6b01144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
DNA is rapidly cleaved under mild alkaline conditions at apyrimidinic/apurinic sites, but the half-life is several weeks in phosphate buffer (pH 7.5). However, abasic sites are ∼100-fold more reactive within nucleosome core particles (NCPs). Histone proteins catalyze the strand scission, and at superhelical location 1.5, the histone H4 tail is largely responsible for the accelerated cleavage. The rate constant for strand scission at an abasic site is enhanced further in a nucleosome core particle when it is part of a bistranded lesion containing a proximal strand break. Cleavage of this form results in a highly deleterious double-strand break. This acceleration is dependent upon the position of the abasic lesion in the NCP and its structure. The enhancement in cleavage rate at an apurinic/apyrimidinic site rapidly drops off as the distance between the strand break and abasic site increases and is negligible once the two forms of damage are separated by 7 bp. However, the enhancement of the rate of double-strand break formation increases when the size of the gap is increased from one to two nucleotides. In contrast, the cleavage rate enhancement at 2-deoxyribonolactone within bistranded lesions is more modest, and it is similar in free DNA and nucleosome core particles. We postulate that the enhanced rate of double-strand break formation at bistranded lesions containing apurinic/apyrimidinic sites within nucleosome core particles is a general phenomenon and is due to increased DNA flexibility.
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Affiliation(s)
- Samya Banerjee
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Supratim Chakraborty
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Marco Paolo Jacinto
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Michael D Paul
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Morgan V Balster
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
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17
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18
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Mladenova V, Mladenov E, Iliakis G. Novel Biological Approaches for Testing the Contributions of Single DSBs and DSB Clusters to the Biological Effects of High LET Radiation. Front Oncol 2016; 6:163. [PMID: 27446809 PMCID: PMC4923065 DOI: 10.3389/fonc.2016.00163] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/15/2016] [Indexed: 01/28/2023] Open
Abstract
The adverse biological effects of ionizing radiation (IR) are commonly attributed to the generation of DNA double-strand breaks (DSBs). IR-induced DSBs are generated by clusters of ionizations, bear damaged terminal nucleotides, and frequently comprise base damages and single-strand breaks in the vicinity generating a unique DNA damage-clustering effect that increases DSB "complexity." The number of ionizations in clusters of different radiation modalities increases with increasing linear energy transfer (LET), and is thought to determine the long-known LET-dependence of the relative biological effectiveness (RBE). Multiple ionizations may also lead to the formation of DSB clusters, comprising two or more DSBs that destabilize chromatin further and compromise overall processing. DSB complexity and DSB-cluster formation are increasingly considered in the development of mathematical models of radiation action, which are then "tested" by fitting available experimental data. Despite a plethora of such mathematical models the ultimate goal, i.e., the "a priori" prediction of the radiation effect, has not yet been achieved. The difficulty partly arises from unsurmountable difficulties in testing the fundamental assumptions of such mathematical models in defined biological model systems capable of providing conclusive answers. Recently, revolutionary advances in methods allowing the generation of enzymatic DSBs at random or in well-defined locations in the genome, generate unique testing opportunities for several key assumptions frequently fed into mathematical modeling - including the role of DSB clusters in the overall effect. Here, we review the problematic of DSB-cluster formation in radiation action and present novel biological technologies that promise to revolutionize the way we address the biological consequences of such lesions. We describe new ways of exploiting the I-SceI endonuclease to generate DSB-clusters at random locations in the genome and describe the possible utility of Zn-finger nucleases and of TALENs in generating DSBs at defined genomic locations. Finally, we describe ways to harness the revolution of CRISPR/Cas9 technology to advance our understanding of the biological effects of DSBs. Collectively, these approaches promise to improve the focus of mathematical modeling of radiation action by providing testing opportunities for key assumptions on the underlying biology. They are also likely to further strengthen interactions between experimental radiation biologists and mathematical modelers.
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Affiliation(s)
- Veronika Mladenova
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School , Essen , Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School , Essen , Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School , Essen , Germany
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19
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Cuaron JJ, Chang C, Lovelock M, Higginson DS, Mah D, Cahlon O, Powell S. Exponential Increase in Relative Biological Effectiveness Along Distal Edge of a Proton Bragg Peak as Measured by Deoxyribonucleic Acid Double-Strand Breaks. Int J Radiat Oncol Biol Phys 2016; 95:62-69. [PMID: 27084629 DOI: 10.1016/j.ijrobp.2016.02.018] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 02/01/2016] [Accepted: 02/03/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE To quantify the relative biological effectiveness (RBE) of the distal edge of the proton Bragg peak, using an in vitro assay of DNA double-strand breaks (DSBs). METHODS AND MATERIALS U2OS cells were irradiated within the plateau of a spread-out Bragg peak and at each millimeter position along the distal edge using a custom slide holder, allowing for simultaneous measurement of physical dose. A reference radiation signal was generated using photons. The DNA DSBs at 3 hours (to assess for early damage) and at 24 hours (to assess for residual damage and repair) after irradiation were measured using the γH2AX assay and quantified via flow cytometry. Results were confirmed with clonogenic survival assays. A detailed map of the RBE as a function of depth along the Bragg peak was generated using γH2AX measurements as a biological endpoint. RESULTS At 3 hours after irradiation, DNA DSBs were higher with protons at every point along the distal edge compared with samples irradiated with photons to similar doses. This effect was even more pronounced after 24 hours, indicating that the impact of DNA repair is less after proton irradiation relative to photons. The RBE demonstrated an exponential increase as a function of depth and was measured to be as high as 4.0 after 3 hours and as high as 6.0 after 24 hours. When the RBE-corrected dose was plotted as a function of depth, the peak effective dose was extended 2-3 mm beyond what would be expected with physical measurement. CONCLUSIONS We generated a highly comprehensive map of the RBE of the distal edge of the Bragg peak, using a direct assay of DNA DSBs in vitro. Our data show that the RBE of the distal edge increases with depth and is significantly higher than previously reported estimates.
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Affiliation(s)
- John J Cuaron
- Memorial Sloan Kettering Cancer Center, New York, New York.
| | - Chang Chang
- Texas Center for Proton Therapy, Irving, Texas
| | | | | | - Dennis Mah
- Procure Proton Therapy Center, Somerset, New Jersey
| | - Oren Cahlon
- Memorial Sloan Kettering Cancer Center, New York, New York
| | - Simon Powell
- Memorial Sloan Kettering Cancer Center, New York, New York
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20
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Cheng Y, Li F, Mladenov E, Iliakis G. The yield of DNA double strand breaks determined after exclusion of those forming from heat-labile lesions predicts tumor cell radiosensitivity to killing. Radiother Oncol 2015; 116:366-73. [PMID: 26303013 DOI: 10.1016/j.radonc.2015.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/10/2015] [Accepted: 08/03/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE The radiosensitivity to killing of tumor cells and in-field normal tissue are key determinants of radiotherapy response. In vitro radiosensitivity of tumor- and normal-tissue-derived cells often predicts radiation response, but high determination cost in time and resources compromise utility as routine response-predictor. Efforts to use induction or repair of DNA double-strand-breaks (DSBs) as surrogate-predictors of cell radiosensitivity to killing have met with limited success. Here, we re-visit this issue encouraged by our recent observations that ionizing radiation (IR) induces not only promptly-forming DSBs (prDSBs), but also DSBs developing after irradiation from the conversion to breaks of thermally-labile sugar-lesions (tlDSBs). MATERIALS AND METHODS We employ pulsed-field gel-electrophoresis and flow-cytometry protocols to measure total DSBs (tDSB=prDSB+tlDSBs) and prDSBs, as well as γH2AX and parameters of chromatin structure. RESULTS We report a fully unexpected and in many ways unprecedented correlation between yield of prDSBs and radiosensitivity to killing in a battery of ten tumor cell lines that is not matched by yields of tDSBs or γH2AX, and cannot be explained by simple parameters of chromatin structure. CONCLUSIONS We propose the introduction of prDSBs-yield as a novel and powerful surrogate-predictor of cell radiosensitivity to killing with potential for clinical application.
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Affiliation(s)
- Yanlei Cheng
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Germany
| | - Fanghua Li
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Germany.
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21
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Gustafsson AS, Hartman T, Stenerlöw B. Formation and repair of clustered damaged DNA sites in high LET irradiated cells. Int J Radiat Biol 2015; 91:820-6. [DOI: 10.3109/09553002.2015.1068463] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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22
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Tommasino F, Friedrich T, Jakob B, Meyer B, Durante M, Scholz M. Induction and Processing of the Radiation-Induced Gamma-H2AX Signal and Its Link to the Underlying Pattern of DSB: A Combined Experimental and Modelling Study. PLoS One 2015; 10:e0129416. [PMID: 26067661 PMCID: PMC4465900 DOI: 10.1371/journal.pone.0129416] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 05/10/2015] [Indexed: 12/23/2022] Open
Abstract
We present here an analysis of DSB induction and processing after irradiation with X-rays in an extended dose range based on the use of the γH2AX assay. The study was performed by quantitative flow cytometry measurements, since the use of foci counting would result in reasonable accuracy only in a limited dose range of a few Gy. The experimental data are complemented by a theoretical analysis based on the GLOBLE model. In fact, original aim of the study was to test GLOBLE predictions against new experimental data, in order to contribute to the validation of the model. Specifically, the γH2AX signal kinetics has been investigated up to 24 h after exposure to increasing photon doses between 2 and 500 Gy. The prolonged persistence of the signal at high doses strongly suggests dose dependence in DSB processing after low LET irradiation. Importantly, in the framework of our modelling analysis, this is related to a gradually increased fraction of DSB clustering at the micrometre scale. The parallel study of γH2AX dose response curves shows the onset of a pronounced saturation in two cell lines at a dose of about 20 Gy. This dose is much lower than expected according to model predictions based on the values usually adopted for the DSB induction yield (≈ 30 DSB/Gy) and for the γH2AX foci extension of approximately 2 Mbp around the DSB. We show and discuss how theoretical predictions and experimental findings can be in principle reconciled by combining an increased DSB induction yield with the assumption of a larger genomic extension for the single phosphorylated regions. As an alternative approach, we also considered in our model the possibility of a 3D spreading-mechanism of the H2AX phosphorylation around the induced DSB, and applied it to the analysis of both the aspects considered. Our results are found to be supportive for the basic assumptions on which GLOBLE is built. Apart from giving new insights into the H2AX phosphorylation process, experiments performed at high doses are of relevance in the context of radiation therapy, where hypo-fractionated schemes become increasingly popular.
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Affiliation(s)
- Francesco Tommasino
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
- * E-mail:
| | - Thomas Friedrich
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
| | - Burkhard Jakob
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
| | - Barbara Meyer
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Marco Durante
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
- Technische Universität Darmstadt, Institut für Festkörperphysik, Darmstadt, Germany
| | - Michael Scholz
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
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Li F, Cheng Y, Iliakis G. The contribution of thermally labile sugar lesions to DNA double-strand break formation in cells grown in the presence of BrdU. Int J Radiat Biol 2015; 91:312-20. [PMID: 25510257 DOI: 10.3109/09553002.2014.996260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Radiosensitization by bromodeoxyuridine (BrdU) is commonly attributed to an increase in the yield of double-strand breaks (DSB) in the DNA and an associated decrease in the reparability of these lesions. Radiation chemistry provides a mechanism for the increased yield of DSB through the generation, after bromine loss, of a highly reactive uracilyl radical that attacks the sugar moiety of the nucleotide to produce a single-strand break (SSB). The effects underpinning DSB repair inhibition remain, in contrast, incompletely characterized. A possible source of reduced reparability is a change in the nature or complexity of the DSB in BrdU-substituted DNA. Recent studies show that DSB-complexity or DSB-nature may also be affected by the presence within the cluster of thermally labile sugar lesions (TLSL) that break the DNA backbone only if they chemically evolve to SSB, a process thought to occur within the first hour post-irradiation. Since BrdU radiosensitization might be associated with increased yields and reduced reparability of DSB, we investigated whether BrdU underpins these effects by shifting the balance in the generation of TLSL. METHODS AND MATERIALS We employed asymmetric-field-inversion gel electrophoresis (AFIGE), a pulsed-field gel electrophoresis (PFGE) method to quantitate DSB in a battery of five cells lines grown in the presence of different concentrations of BrdU. We measured specifically the yields of promptly forming DSB (prDSB) using low temperature lysis protocols, and the yields of total DSB (tDSB = prDSB + tlDSB; tlDSB form after evolution to SSB of TLSL) using high temperature lysis protocols. RESULTS We report that incorporation of BrdU generates similar increases in the formation of tlDSB and prDSB, but variations are noted among the different cell lines tested. CONCLUSIONS The similar increase in the yields of tlDSB and prDSB in BrdU substituted DNA showed that shifts in the yields of these forms of lesions could not be invoked to explain BrdU radiosensitization.
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Affiliation(s)
- Fanghua Li
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School , Essen , Germany
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Holley AK, Miao L, St Clair DK, St Clair WH. Redox-modulated phenomena and radiation therapy: the central role of superoxide dismutases. Antioxid Redox Signal 2014; 20:1567-89. [PMID: 24094070 PMCID: PMC3942704 DOI: 10.1089/ars.2012.5000] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
SIGNIFICANCE Ionizing radiation is a vital component in the oncologist's arsenal for the treatment of cancer. Approximately 50% of all cancer patients will receive some form of radiation therapy as part of their treatment regimen. DNA is considered the major cellular target of ionizing radiation and can be damaged directly by radiation or indirectly through reactive oxygen species (ROS) formed from the radiolysis of water, enzyme-mediated ROS production, and ROS resulting from altered aerobic metabolism. RECENT ADVANCES ROS are produced as a byproduct of oxygen metabolism, and superoxide dismutases (SODs) are the chief scavengers. ROS contribute to the radioresponsiveness of normal and tumor tissues, and SODs modulate the radioresponsiveness of tissues, thus affecting the efficacy of radiotherapy. CRITICAL ISSUES Despite its prevalent use, radiation therapy suffers from certain limitations that diminish its effectiveness, including tumor hypoxia and normal tissue damage. Oxygen is important for the stabilization of radiation-induced DNA damage, and tumor hypoxia dramatically decreases radiation efficacy. Therefore, auxiliary therapies are needed to increase the effectiveness of radiation therapy against tumor tissues while minimizing normal tissue injury. FUTURE DIRECTIONS Because of the importance of ROS in the response of normal and cancer tissues to ionizing radiation, methods that differentially modulate the ROS scavenging ability of cells may prove to be an important method to increase the radiation response in cancer tissues and simultaneously mitigate the damaging effects of ionizing radiation on normal tissues. Altering the expression or activity of SODs may prove valuable in maximizing the overall effectiveness of ionizing radiation.
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Affiliation(s)
- Aaron K Holley
- 1 Graduate Center for Toxicology, University of Kentucky , Lexington, Kentucky
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Khoury L, Zalko D, Audebert M. Validation of high-throughput genotoxicity assay screening using γH2AX in-cell western assay on HepG2 cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2013; 54:737-746. [PMID: 24105934 DOI: 10.1002/em.21817] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 07/19/2013] [Accepted: 08/13/2013] [Indexed: 06/02/2023]
Abstract
In vitro genotoxicity tests used in regulatory toxicology studies are sensitive, but the occurrence of irrelevant positive results is high compared with carcinogenicity studies in rodents. Current in vitro genotoxicity tests are also often limited by relatively low throughput. The aim of this study was to validate an in vitro genotoxic assay in a 96-well plate format that allows the simultaneous examination of cytotoxicity and genotoxicity. The test is based on the quantification of the phosphorylation of the histone H2AX (γH2AX), which reflects a global genotoxic insult, using the In-Cell Western technique. The assay was evaluated on HepG2 cells by testing a list of 61 compounds recommended by the European Center for the Validation of Alternative Methods (ECVAM), whose genotoxic potential has already been characterized. The γH2AX assay on HepG2 cell line was highly sensitive: 75% of the genotoxic compounds gave a positive result, and specific: 90-100% of nongenotoxic compounds gave negative results. Compared with the micronucleus genotoxicity assay using the same cell line and test compounds, the γH2AX assay was more sensitive and specific. In sum, the high-throughput γH2AX assay described here can accurately detect simultaneously the genotoxic and the cytotoxic potential of compounds with different modes of mutagenic action, notably those who required metabolic activation. The use of this assay in the early discovery phase of drug development may prove to be a valuable way to assess the genotoxic potential of xenobiotics.
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Affiliation(s)
- Laure Khoury
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, F-31027, Toulouse, France; Université de Toulouse, INPT, UPS, UMR1331, F-31062, Toulouse, France
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Moscariello M, Iliakis G. Effects of chromatin decondensation on alternative NHEJ. DNA Repair (Amst) 2013; 12:972-81. [DOI: 10.1016/j.dnarep.2013.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 07/25/2013] [Accepted: 08/16/2013] [Indexed: 11/25/2022]
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Plante I, Ponomarev AL, Cucinotta FA. Calculation of the energy deposition in nanovolumes by protons and HZE particles: geometric patterns of initial distributions of DNA repair foci. Phys Med Biol 2013; 58:6393-405. [PMID: 23999659 DOI: 10.1088/0031-9155/58/18/6393] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The biological effects of high-linear energy transfer (LET) radiation are different from those caused by low-LET radiation due to the difference in the patterns of energy deposition in cells. In this work, we studied the role of the track structure in the spatial distribution of radiation-induced double-strand breaks (DSBs). In the first part, the irradiation of a cubic volume of 12 µm of side by 300 MeV protons (LET ∼0.3 keV µm(-1)) and by 1 GeV/amu iron ion particles (LET∼150 keV µm(-1)) was simulated with the Monte Carlo code RITRACKS (relativistic ion tracks) and the dose was calculated in voxels of different sizes. In the second part, dose calculations were combined with chromosomes simulated by a random walk (RW) model to assess the formation of DSBs. The number of DSBs was calculated as a function of the dose and particle fluence for 1 GeV protons, 293 MeV/u carbon, and 1 GeV/u iron particles. Finally, the DSB yield was obtained as a function of the LET for protons, helium, and carbon. In general, the number and distribution of calculated DSBs were similar to experimental DNA repair foci data. From this study, we concluded that a stochastic model combining nanoscopic dose calculations and chromosomes simulated by RWs is a useful approach to study radiation-induced DSBs.
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Affiliation(s)
- Ianik Plante
- Division of Space Life Sciences, Universities Space Research Association, 3600 Bay Area Blvd, Houston, TX 77058 USA.
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Georgakilas AG, O'Neill P, Stewart RD. Induction and Repair of Clustered DNA Lesions: What Do We Know So Far? Radiat Res 2013; 180:100-109. [DOI: 10.1667/rr3041.1] [Citation(s) in RCA: 213] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Schipler A, Iliakis G. DNA double-strand-break complexity levels and their possible contributions to the probability for error-prone processing and repair pathway choice. Nucleic Acids Res 2013; 41:7589-605. [PMID: 23804754 PMCID: PMC3763544 DOI: 10.1093/nar/gkt556] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Although the DNA double-strand break (DSB) is defined as a rupture in the double-stranded DNA molecule that can occur without chemical modification in any of the constituent building blocks, it is recognized that this form is restricted to enzyme-induced DSBs. DSBs generated by physical or chemical agents can include at the break site a spectrum of base alterations (lesions). The nature and number of such chemical alterations define the complexity of the DSB and are considered putative determinants for repair pathway choice and the probability that errors will occur during this processing. As the pathways engaged in DSB processing show distinct and frequently inherent propensities for errors, pathway choice also defines the error-levels cells opt to accept. Here, we present a classification of DSBs on the basis of increasing complexity and discuss how complexity may affect processing, as well as how it may cause lethal or carcinogenic processing errors. By critically analyzing the characteristics of DSB repair pathways, we suggest that all repair pathways can in principle remove lesions clustering at the DSB but are likely to fail when they encounter clusters of DSBs that cause a local form of chromothripsis. In the same framework, we also analyze the rational of DSB repair pathway choice.
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Affiliation(s)
- Agnes Schipler
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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Singh SK, Bencsik-Theilen A, Mladenov E, Jakob B, Taucher-Scholz G, Iliakis G. Reduced contribution of thermally labile sugar lesions to DNA double strand break formation after exposure to heavy ions. Radiat Oncol 2013; 8:77. [PMID: 23547740 PMCID: PMC3627621 DOI: 10.1186/1748-717x-8-77] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 03/22/2013] [Indexed: 11/10/2022] Open
Abstract
In cells exposed to low linear energy transfer (LET) ionizing-radiation (IR),
double-strand-breaks (DSBs) form within clustered-damage-sites (CDSs) from
lesions disrupting the DNA sugar-phosphate backbone. It is commonly assumed that
all DSBs form promptly and are immediately detected by the cellular
DNA-damage-response (DDR) apparatus. However, there is evidence that the pool of
DSBs detected by physical methods, such as pulsed-field gel electrophoresis
(PFGE), comprises not only promptly forming DSBs (prDSBs) but also DSBs
developing during lysis at high temperatures from thermally-labile sugar-lesions
(TLSLs). We recently demonstrated that conversion of TLSLs to DNA breaks and
ultimately to DSBs also occurs in cells during the first hour of
post-irradiation incubation at physiological temperatures. Thus, TLSL-dependent
DSBs (tlDSBs) are not an avoidable technique-related artifact, but a reality the
cell always faces. The biological consequences of tlDSBs and the dependence of
their formation on LET require in-depth investigation. Heavy-ions (HI) are a
promising high-LET radiation modality used in cancer treatment. HI are also
encountered in space and generate serious radiation protection problems to
prolonged space missions. Here, we study, therefore, the effect of HI on the
yields of tlDSBs and prDSBs. We report a reduction in the yield of tlDBSs
stronger than that earlier reported for neutrons, and with pronounced cell line
dependence. We conclude that with increasing LET the complexity of CDSs
increases resulting in a commensurate increase in the yield prDSBs and a
decrease in tlDSBs. The consequences of these effects to the relative biological
effectiveness are discussed.
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Affiliation(s)
- Satyendra K Singh
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Hufelandstr 55, Essen, 45122, Germany
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Cis-9,trans-11-conjugated linoleic acid affects lipid raft composition and sensitizes human colorectal adenocarcinoma HT-29 cells to X-radiation. Biochim Biophys Acta Gen Subj 2012; 1830:2233-42. [PMID: 23116821 DOI: 10.1016/j.bbagen.2012.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 09/29/2012] [Accepted: 10/18/2012] [Indexed: 11/21/2022]
Abstract
BACKGROUND Investigations concerned the mechanism of HT-29 cells radiosensitization by cis-9,trans-11-conjugated linoleic acid (c9,t11-CLA), a natural component of human diet with proven antitumor activity. METHODS The cells were incubated for 24h with 70μM c9,t11-CLA and then X-irradiated. The following methods were used: gas chromatography (incorporation of the CLA isomer), flow cytometry (cell cycle), cloning (survival), Western blotting (protein distribution in membrane fractions), and pulse-field gel electrophoresis (rejoining of DNA double-strand breaks). In parallel, DNA-PK activity, γ-H2AX foci numbers and chromatid fragmentation were estimated. Gene expression was analysed by RT-PCR and chromosomal aberrations by the mFISH method. Nuclear accumulation of the EGF receptor (EGFR) was monitored by ELISA. RESULTS AND CONCLUSIONS C9,t11-CLA sensitized HT-29 cells to X-radiation. This effect was not due to changes in cell cycle progression or DNA-repair-related gene expression. Post-irradiation DSB rejoining was delayed, corresponding with the insufficient DNA-PK activation, although chromosomal aberration frequencies did not increase. Distributions of cholesterol and caveolin-1 in cellular membrane fractions changed. The nuclear EGFR translocation, necessary to increase the DNA-PK activity in response to oxidative stress, was blocked. We suppose that c9,t11-CLA modified the membrane structure, thus disturbing the intracellular EGFR transport and the EGFR-dependent pro-survival signalling, both functionally associated with lipid raft properties. GENERAL SIGNIFICANCE The results point to the importance of the cell membrane interactions with the nucleus after injury inflicted by X -rays. Compounds like c9,t11-CLA, that specifically alter membrane properties, could be used to develop new anticancer strategies.
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Singh SK, Wu W, Stuschke M, Bockisch A, Iliakis G. Reduced contribution of thermally-labile sugar lesions to DNA double-strand break formation after exposure to neutrons. Radiat Res 2012; 178:581-90. [PMID: 23088767 DOI: 10.1667/rr2996.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In cells exposed to ionizing radiation, double-strand breaks (DSBs) form within clustered damage sites from lesions disrupting the DNA sugar-phosphate backbone. It is commonly assumed that DSBs form promptly and are immediately detected and processed by the cellular DNA damage response apparatus. However, DSBs also form by delayed chemical conversion of thermally-labile sugar lesions (TLSL) to breaks. We recently reported that conversion of thermally-labile sugar lesions to breaks occurs in cells maintained at physiological temperatures. Here, we investigate the influence of radiation quality on the formation of thermally-labile sugar lesions dependent DSBs. We show that, although the yields of total DSBs are very similar after exposure to neutrons and X rays, the yields of thermally-labile sugar lesions dependent DSBs from neutrons are decreased in comparison to that from X rays. Thus, the yields of prompt DSBs for neutrons are greater than for X rays. Notably, after neutron irradiation the decreased yield of thermally-labile sugar lesion dependent DSBs is strongly cell line dependent, likely reflecting subtle differences in DNA organization. We propose that the higher ionization density of neutrons generates with higher probability prompt DSBs within ionization clusters and renders the ensuing chemical evolution of thermally-labile sugar lesions inconsequential to DNA integrity. Modification of thermally-labile sugar lesion evolution may define novel radiation protection strategies aiming at decreasing DSB formation by chemically preserving thermally-labile sugar lesions until other DSB contributing lesions within the clustered damage site are removed by non-DSB repair pathways.
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Affiliation(s)
- Satyendra K Singh
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
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Romei C, Fugazzola L, Puxeddu E, Frasca F, Viola D, Muzza M, Moretti S, Nicolosi ML, Giani C, Cirello V, Avenia N, Rossi S, Vitti P, Pinchera A, Elisei R. Modifications in the papillary thyroid cancer gene profile over the last 15 years. J Clin Endocrinol Metab 2012; 97:E1758-65. [PMID: 22745248 DOI: 10.1210/jc.2012-1269] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Evidence for an increased prevalence of BRAF(V600E) mutations has been documented in recent decades. The aim of this study was to evaluate the prevalence of both RET/PTC rearrangements and BRAF(V600E) mutations in an Italian cohort of papillary thyroid carcinoma (PTC) patients followed at the Endocrine Units of Pisa, Milano, and Perugia from 1996-2010. PATIENTS AND METHODS In total, 401 PTC patients were examined and grouped according to the time of surgery: group 1, 1996-2000; group 2, 2001-2005; and group 3, 2006-2010. Patients were analyzed for clinical, pathological, and molecular features. In parallel, the molecular characteristics of 459 PTC from Sicily were studied. RESULTS The genetic profiles of the three groups were significantly different (P < 0.0001). In particular, the frequency of RET/PTC rearrangements decreased from 1996-2010, occurring in 33 of 100 (33%) of the patients in group 1, 26 of 148 (17%) in group 2, and 15 of 153 (9.8%) in group 3. The incidence of BRAF(V600E) mutations increased over the same period, from 28% in group 1 (28 of 100) to 48.9% in group 2 (73 of 148) and 58.1% in group 3 (89 of 153). A consistent increase in BRAF(V600E) prevalence was observed in the Sicilian group (P < 0.0001). Moreover, a statistically significant increase in the mean age at diagnosis and decrease in tumor size over the study period was observed. CONCLUSION The genetic profile of PTC changed over the last 15 yr, with a significant decrease in the prevalence of RET/PTC rearrangements and an increase in BRAF(V600E) mutations. In addition, the mean age at diagnosis increased and tumor size decreased over the study period.
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Affiliation(s)
- Cristina Romei
- Department of Endocrinology and Metabolism and World Health Organization Collaborating Center for the Study and Treatment of Thyroid Diseases and Other Endocrine and Metabolic Disorders, University of Pisa, 56124 Pisa, Italy
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Hayman TJ, Williams ES, Jamal M, Shankavaram UT, Camphausen K, Tofilon PJ. Translation initiation factor eIF4E is a target for tumor cell radiosensitization. Cancer Res 2012; 72:2362-72. [PMID: 22397984 DOI: 10.1158/0008-5472.can-12-0329] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A core component in the cellular response to radiation occurs at the level of translational control of gene expression. Because a critical element in translation control is the availability of the initiation factor eIF4E, which selectively enhances the cap-dependent translation of mRNAs, we investigated a regulatory role for eIF4E in cellular radiosensitivity. eIF4E silencing enhanced the radiosensitivity of tumor cell lines but not normal cells. Similarly, pharmacologic inhibition of eIF4E with ribavirin also enhanced tumor cell radiosensitivity. eIF4E attenuation did not affect cell-cycle phase distribution or radiation-induced apoptosis, but it delayed the dispersion of radiation-induced γH2AX foci and increased the frequency of radiation-induced mitotic catastrophe. Radiation did not affect 4E-BP1 phosphorylation or cap-complex formation but it increased eIF4E binding to more than 1,000 unique transcripts including many implicated in DNA replication, recombination, and repair. Taken together, our findings suggest that eIF4E represents a logical therapeutic target to increase tumor cell radiosensitivity.
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Affiliation(s)
- Thomas J Hayman
- University of South Florida Morsani College of Medicine, Tampa, Florida, USA
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