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Rampias T, Klinakis A. Using Sister Chromatid Exchange Assay to Detect Homologous Recombination Deficiency in Epigenetically Deregulated Urothelial Carcinoma Cells. Methods Mol Biol 2023; 2684:133-144. [PMID: 37410231 DOI: 10.1007/978-1-0716-3291-8_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023]
Abstract
Sister chromatid exchange (SCE) is the process of exchanging regions between two sister chromatids during DNA replication. Exchanges between replicated chromatids and their sisters can be visualized in cells when DNA synthesis in one chromatid is labelled by 5-bromo-2'-deoxyuridine (BrdU). Homologous recombination (HR) is considered as the principal mechanism responsible for the sister chromatid exchange (SCE) upon replication fork collapse, and therefore SCE frequency upon genotoxic conditions reflects the capacity of HR repair to respond to replication stress. During tumorigenesis, inactivating mutations or altered transcriptome can affect a plethora of epigenetic factors that participate in DNA repair processes, and there are an increasing number of reports which demonstrate a link between epigenetic deregulation in cancer and homologous recombination deficiency (HRD). Therefore, the SCE assay can provide valuable information regarding the HR functionality in tumors with epigenetic deficiencies. In this chapter, we provide a method to visualize SCEs. The technique outlined below is characterized by high sensitivity and specificity and has been successfully applied to human bladder cancer cell lines. In this context, this technique could be used to characterize the dynamics of HR repair in tumors with deregulated epigenome.
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Affiliation(s)
- Theodoros Rampias
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
| | - Apostolos Klinakis
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
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2
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Johnson AM, Bennett PV, Sanidad KZ, Hoang A, Jardine JH, Keszenman DJ, Wilson PF. Evaluation of Histone Deacetylase Inhibitors as Radiosensitizers for Proton and Light Ion Radiotherapy. Front Oncol 2021; 11:735940. [PMID: 34513712 PMCID: PMC8426582 DOI: 10.3389/fonc.2021.735940] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 07/29/2021] [Indexed: 12/23/2022] Open
Abstract
Significant opportunities remain for pharmacologically enhancing the clinical effectiveness of proton and carbon ion-based radiotherapies to achieve both tumor cell radiosensitization and normal tissue radioprotection. We investigated whether pretreatment with the hydroxamate-based histone deacetylase inhibitors (HDACi) SAHA (vorinostat), M344, and PTACH impacts radiation-induced DNA double-strand break (DSB) induction and repair, cell killing, and transformation (acquisition of anchorage-independent growth in soft agar) in human normal and tumor cell lines following gamma ray and light ion irradiation. Treatment of normal NFF28 primary fibroblasts and U2OS osteosarcoma, A549 lung carcinoma, and U87MG glioma cells with 5–10 µM HDACi concentrations 18 h prior to cesium-137 gamma irradiation resulted in radiosensitization measured by clonogenic survival assays and increased levels of colocalized gamma-H2AX/53BP1 foci induction. We similarly tested these HDACi following irradiation with 200 MeV protons, 290 MeV/n carbon ions, and 350 MeV/n oxygen ions delivered in the Bragg plateau region. Unlike uniform gamma ray radiosensitization, effects of HDACi pretreatment were unexpectedly cell type and ion species-dependent with C-12 and O-16 ion irradiations showing enhanced G0/G1-phase fibroblast survival (radioprotection) and in some cases reduced or absent tumor cell radiosensitization. DSB-associated foci levels were similar for proton-irradiated DMSO control and SAHA-treated fibroblast cultures, while lower levels of induced foci were observed in SAHA-pretreated C-12 ion-irradiated fibroblasts. Fibroblast transformation frequencies measured for all radiation types were generally LET-dependent and lowest following proton irradiation; however, both gamma and proton exposures showed hyperlinear transformation induction at low doses (≤25 cGy). HDACi pretreatments led to overall lower transformation frequencies at low doses for all radiation types except O-16 ions but generally led to higher transformation frequencies at higher doses (>50 cGy). The results of these in vitro studies cast doubt on the clinical efficacy of using HDACi as radiosensitizers for light ion-based hadron radiotherapy given the mixed results on their radiosensitization effectiveness and related possibility of increased second cancer induction.
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Affiliation(s)
- Alicia M Johnson
- Biology Department, Brookhaven National Laboratory, Upton, NY, United States
| | - Paula V Bennett
- Biology Department, Brookhaven National Laboratory, Upton, NY, United States
| | - Katherine Z Sanidad
- Biology Department, Brookhaven National Laboratory, Upton, NY, United States
| | - Anthony Hoang
- Biology Department, Brookhaven National Laboratory, Upton, NY, United States
| | - James H Jardine
- Biology Department, Brookhaven National Laboratory, Upton, NY, United States
| | - Deborah J Keszenman
- Biology Department, Brookhaven National Laboratory, Upton, NY, United States.,Laboratorio de Radiobiología Médica y Ambiental, Grupo de Biofisicoquímica, Centro Universitario Regional Litoral Norte, Universidad de la República (UdelaR), Salto, Uruguay
| | - Paul F Wilson
- Biology Department, Brookhaven National Laboratory, Upton, NY, United States.,Department of Radiation Oncology, University of California-Davis, Sacramento, CA, United States
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Cucinotta FA, Cacao E, Kim MHY, Saganti PB. Benchmarking risk predictions and uncertainties in the NSCR model of GCR cancer risks with revised low let risk coefficients. LIFE SCIENCES IN SPACE RESEARCH 2020; 27:64-73. [PMID: 34756232 DOI: 10.1016/j.lssr.2020.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/17/2020] [Accepted: 07/19/2020] [Indexed: 06/13/2023]
Abstract
We report on the contributions of model factors that appear in projection models to the overall uncertainty in cancer risks predictions for exposures to galactic cosmic ray (GCR) in deep space, including comparisons with revised low LET risks coefficients. Annual GCR exposures to astronauts at solar minimum are considered. Uncertainties in low LET risk coefficients, dose and dose-rate modifiers, quality factors (QFs), space radiation organ doses, non-targeted effects (NTE) and increased tumor lethality at high LET compared to low LET radiation are considered. For the low LET reference radiation parameters we use a revised assessment of excess relative risk (ERR) and excess additive risk (EAR) for radiation induced cancers in the Life-Span Study (LSS) of the Atomic bomb survivors that was recently reported, and also consider ERR estimates for males from the International Study of Nuclear Workers (INWORKS). For 45-y old females at mission age the risk of exposure induced death (REID) per year and 95% confidence intervals is predicted as 1.6% [0.71, 1.63] without QF uncertainties and 1.64% [0.69, 4.06] with QF uncertainties. However, fatal risk predictions increase to 5.83% [2.56, 9.7] based on a sensitivity study of the inclusion of non-targeted effects on risk predictions. For males a comparison using LSS or INWORKS lead to predictions of 1.24% [0.58, 3.14] and 2.45% [1.23, 5.9], respectively without NTEs. The major conclusion of our report is that high LET risk prediction uncertainties due to QFs parameters, NTEs, and possible increase lethality at high LET are dominant contributions to GCR uncertainties and should be the focus of space radiation research.
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Affiliation(s)
- Francis A Cucinotta
- Department of Health Physics and Diagnostic Sciences, University of Nevada, Las Vegas, NV, USA.
| | - Eliedonna Cacao
- Department of Health Physics and Diagnostic Sciences, University of Nevada, Las Vegas, NV, USA
| | - Myung-Hee Y Kim
- Physics Department, Prairie View A&M University, Prairie View TX, USA
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Ghasemi Z, Tahmasebi-Birgani MJ, Ghafari Novin A, Motlagh PE, Teimoori A, Ghadiri A, Pourghadamyari H, Sarli A, Khanbabaei H. Fractionated radiation promotes proliferation and radioresistance in bystander A549 cells but not in bystander HT29 cells. Life Sci 2020; 257:118087. [PMID: 32702442 DOI: 10.1016/j.lfs.2020.118087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/04/2020] [Accepted: 07/08/2020] [Indexed: 10/23/2022]
Abstract
AIMS Recent studies suggest that direct exposure of cells to fractionated radiotherapy might induce radioresistance. However, the effects of fractionated radiotherapy on the non-irradiated bystander cells remain unclear. We hypothesized that fractionated radiotherapy could enhance radioresistance and proliferation of bystander cells. MAIN METHODS Human tumor cell lines, including A549 and HT29 were irradiated (2 Gy per day). The irradiated cells (either A549 or HT29) were co-cultured with non-irradiated cells of the same line using transwell co-culture system. Tumor cell proliferation, radioresistance and apoptosis were measured using MTT assay, clonogenic survival assay and Annexin-V in bystander cells, respectively. In addition, activation of Chk1 (Ser 317), Chk2 (Thr 68) and Akt (Ser473) were measured via western blot. KEY FINDINGS Irradiated HT29 cells induced conventional bystander effects detected as modulation of clonogenic survival parameters (decreased area under curve, D10 and ED50 and increased α) and proliferation in recipient neighbors. While, irradiated A549 cells significantly enhanced the radioresistance and proliferation of bystander cells. These changes were accompanied with enhanced activation of Chk1, Chk2 and Akt in non-irradiated bystander A549 cells. Moreover, both bystander effects (damaging and protective) were mediated through secreted factors. SIGNIFICANCE These findings suggest that fractionated radiotherapy could promote proliferation and radioresistance of bystander cells probably through survival and proliferation pathways.
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Affiliation(s)
- Zahra Ghasemi
- Department of Molecular Genetics, Faculty of Modern Sciences, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
| | | | - Arefeh Ghafari Novin
- Department of Medical Genetics, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Parisa Esmaili Motlagh
- Department of Molecular and Cell Biology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, General Campus, Tehran, Iran
| | - Ali Teimoori
- Department of Virology, Faculty of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran
| | - Ata Ghadiri
- Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Hossein Pourghadamyari
- Department of Clinical Biochemistry, Afzalipour School of Medicine, Kerman University of Medical Sciences, Kerman, Iran
| | - Abdolazim Sarli
- Department of Medical Genetics, Medical Science School, Tarbiat Modares University, Tehran, Iran
| | - Hashem Khanbabaei
- Department of Medical Physics, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
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Burdak-Rothkamm S, Rothkamm K. Radiation-induced bystander and systemic effects serve as a unifying model system for genotoxic stress responses. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 778:13-22. [DOI: 10.1016/j.mrrev.2018.08.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 12/19/2022]
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Exosome-packaged miR-1246 contributes to bystander DNA damage by targeting LIG4. Br J Cancer 2018; 119:492-502. [PMID: 30038324 PMCID: PMC6134031 DOI: 10.1038/s41416-018-0192-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 06/22/2018] [Accepted: 06/27/2018] [Indexed: 02/07/2023] Open
Abstract
Background An increasing number of studies have recently reported that
microRNAs packaged in exosomes contribute to multiple biological processes such as
cancer progression; however, little is known about their role in the development
of radiation-induced bystander effects. Methods The exosomes were isolated from the culture medium of BEP2D cells
with or without γ-ray irradiation by ultracentrifugation. To monitor DNA damage
and repair efficiency, the DNA double-strand break biomarker 53BP1 foci, comet,
micronuclei, expression of DNA repair genes and NHEJ repair activity were
detected. The miR-1246 targeting sequence of the DNA ligase 4 (LIG4) mRNA 3′UTR was assessed by luciferase reporter
vectors. Results miR-1246 was increased in exosomes secreted from 2 Gy-irradiated
BEP2D cells and inhibited the proliferation of nonirradiated cells. The miR-1246
mimic, exosomes from irradiated cells, and radiation-conditioned cell culture
medium increased the yields of 53BP1 foci, comet tail and micronuclei in
nonirradiated cells, and decreased NHEJ efficiency. miR-1246 downregulated LIG4
expression by directly targeting its 3′UTR. Conclusions Our findings demonstrate that miR-1246 packaged in exosomes could
act as a transfer messenger and contribute to DNA damage by directly repressing
the LIG4 gene. Exosomal miR-1246 may be a
critical predictor of and player in radiation-induced bystander DNA damage.
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Cucinotta FA, Cacao E. Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models. Sci Rep 2017; 7:1832. [PMID: 28500351 PMCID: PMC5431989 DOI: 10.1038/s41598-017-02087-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 04/06/2017] [Indexed: 11/09/2022] Open
Abstract
Cancer risk is an important concern for galactic cosmic ray (GCR) exposures, which consist of a wide-energy range of protons, heavy ions and secondary radiation produced in shielding and tissues. Relative biological effectiveness (RBE) factors for surrogate cancer endpoints in cell culture models and tumor induction in mice vary considerable, including significant variations for different tissues and mouse strains. Many studies suggest non-targeted effects (NTE) occur for low doses of high linear energy transfer (LET) radiation, leading to deviation from the linear dose response model used in radiation protection. Using the mouse Harderian gland tumor experiment, the only extensive data-set for dose response modelling with a variety of particle types (>4), for the first-time a particle track structure model of tumor prevalence is used to investigate the effects of NTEs in predictions of chronic GCR exposure risk. The NTE model led to a predicted risk 2-fold higher compared to a targeted effects model. The scarcity of data with animal models for tissues that dominate human radiation cancer risk, including lung, colon, breast, liver, and stomach, suggest that studies of NTEs in other tissues are urgently needed prior to long-term space missions outside the protection of the Earth's geomagnetic sphere.
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Nagasawa H, Lin YF, Kato TA, Brogan JR, Shih HY, Kurimasa A, Bedford JS, Chen BPC, Little JB. Coordination of the Ser2056 and Thr2609 Clusters of DNA-PKcs in Regulating Gamma Rays and Extremely Low Fluencies of Alpha-Particle Irradiation to G 0/G 1 Phase Cells. Radiat Res 2017; 187:259-267. [PMID: 28118114 DOI: 10.1667/rr14679.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The catalytic subunit of DNA dependent protein kinase (DNA-PKcs) and its kinase activity are critical for mediation of non-homologous end-joining (NHEJ) of DNA double-strand breaks (DSB) in mammalian cells after gamma-ray irradiation. Additionally, DNA-PKcs phosphorylations at the T2609 cluster and the S2056 cluster also affect DSB repair and cellular sensitivity to gamma radiation. Previously we reported that phosphorylations within these two regions affect not only NHEJ but also homologous recombination repair (HRR) dependent DSB repair. In this study, we further examine phenotypic effects on cells bearing various combinations of mutations within either or both regions. Effects studied included cell killing as well as chromosomal aberration induction after 0.5-8 Gy gamma-ray irradiation delivered to synchronized cells during the G0/G1 phase of the cell cycle. Blocking phosphorylation within the T2609 cluster was most critical regarding sensitization and depended on the number of available phosphorylation sites. It was also especially interesting that only one substitution of alanine in each of the two clusters separately abolished the restoration of wild-type sensitivity by DNA-PKcs. Similar patterns were seen for induction of chromosomal aberrations, reflecting their connection to cell killing. To study possible change in coordination between HRR and NHEJ directed repair in these DNA-PKcs mutant cell lines, we compared the induction of sister chromatid exchanges (SCEs) by very low fluencies of alpha particles with mutant cells defective in the HRR pathway that is required for induction of SCEs. Levels of true SCEs induced by very low fluence of alpha-particle irradiation normally seen in wild-type cells were only slightly decreased in the S2056 cluster mutants, but were completely abolished in the T2609 cluster mutants and were indistinguishable from levels seen in HRR deficient cells. Again, a single substitution in the S2056 together with a single substitution in the T2609 cluster abolished SCE formation and thus also effectively interferes with HRR.
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Affiliation(s)
- Hatsumi Nagasawa
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Yu-Fen Lin
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Takamitsu A Kato
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - John R Brogan
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Hung-Ying Shih
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Akihiro Kurimasa
- c Tohoku Medical and Pharmaceutical University, Sendai, Japan, 981-8558; and
| | - Joel S Bedford
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Benjamin P C Chen
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - John B Little
- d Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts 02115
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Ibahim MJ, Crosbie JC, Paiva P, Yang Y, Zaitseva M, Rogers PAW. An evaluation of novel real-time technology as a tool for measurement of radiobiological and radiation-induced bystander effects. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2016; 55:185-194. [PMID: 26994995 DOI: 10.1007/s00411-016-0641-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 02/29/2016] [Indexed: 06/05/2023]
Abstract
The xCELLigence real-time cell impedance system uses a non-invasive and label-free method to create a cell index that is a composite measure of cell proliferation. The aim of this study was to evaluate xCELLigence against clonogenic assay (gold standard) for measuring radiobiological effects and radiation-induced bystander effects (RIBE). A radiobiological study was conducted by irradiating EMT6.5, 4T1.2 and NMUMG cell lines with different radiation doses, while a RIBE study was done using transfer of conditioned media (CM) harvested from donor to the same type of recipient cell (EMT6.5, 4T1.2, NMUMG, HACAT and SW48). CM was harvested using two protocols which differed in the dose chosen and the exposure to the recipient cells. Results showed that xCELLigence measured a radiobiological effect which correlated with the clonogenic assay. For the RIBE study, no statistically significant differences were observed between xCELLigence or clonogenic survival in control or recipient cells incubated with CM in protocol one. However, there was a significant increase in cell index slope using CM from EMT-6.5 cells irradiated at 7.5 Gy compared with the control group under the second protocol. No other evidence of RIBE was detected by either xCELLigence or clonogenic assay. In conclusion, xCELLigence methods can measure radiobiological effects and the results correlate with clonogenic assay. We observed a lack of RIBE in all tested cell lines with the clonogenic assay; however, we observed a RIBE effect in EMT6.5 cells under one particular protocol that showed RIBE is cell type dependent, is not universally observed and can be detected in different assays.
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Affiliation(s)
- Mohammad Johari Ibahim
- Department of Obstetrics and Gynaecology, Royal Women's Hospital, University of Melbourne, Level 7, 20 Flemington Road, Parkville, VIC, 3052, Australia
- Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Jalan Hospital, 47000, Sungai Buloh, Selangor, Malaysia
| | - Jeffrey C Crosbie
- School of Applied Sciences, RMIT University, Melbourne, VIC, 3001, Australia
- William Buckland Radiotherapy Centre, Alfred Hospital, Melbourne, VIC, 3004, Australia
| | - Premila Paiva
- Department of Obstetrics and Gynaecology, Royal Women's Hospital, University of Melbourne, Level 7, 20 Flemington Road, Parkville, VIC, 3052, Australia
| | - Yuqing Yang
- Department of Obstetrics and Gynaecology, Royal Women's Hospital, University of Melbourne, Level 7, 20 Flemington Road, Parkville, VIC, 3052, Australia
| | - Marina Zaitseva
- Department of Obstetrics and Gynaecology, Royal Women's Hospital, University of Melbourne, Level 7, 20 Flemington Road, Parkville, VIC, 3052, Australia
| | - Peter A W Rogers
- Department of Obstetrics and Gynaecology, Royal Women's Hospital, University of Melbourne, Level 7, 20 Flemington Road, Parkville, VIC, 3052, Australia.
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Chang PY, Cucinotta FA, Bjornstad KA, Bakke J, Rosen CJ, Du N, Fairchild DG, Cacao E, Blakely EA. Harderian Gland Tumorigenesis: Low-Dose and LET Response. Radiat Res 2016; 185:449-60. [PMID: 27092765 DOI: 10.1667/rr14335.1] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Increased cancer risk remains a primary concern for travel into deep space and may preclude manned missions to Mars due to large uncertainties that currently exist in estimating cancer risk from the spectrum of radiations found in space with the very limited available human epidemiological radiation-induced cancer data. Existing data on human risk of cancer from X-ray and gamma-ray exposure must be scaled to the many types and fluences of radiations found in space using radiation quality factors and dose-rate modification factors, and assuming linearity of response since the shapes of the dose responses at low doses below 100 mSv are unknown. The goal of this work was to reduce uncertainties in the relative biological effect (RBE) and linear energy transfer (LET) relationship for space-relevant doses of charged-particle radiation-induced carcinogenesis. The historical data from the studies of Fry et al. and Alpen et al. for Harderian gland (HG) tumors in the female CB6F1 strain of mouse represent the most complete set of experimental observations, including dose dependence, available on a specific radiation-induced tumor in an experimental animal using heavy ion beams that are found in the cosmic radiation spectrum. However, these data lack complete information on low-dose responses below 0.1 Gy, and for chronic low-dose-rate exposures, and there are gaps in the LET region between 25 and 190 keV/μm. In this study, we used the historical HG tumorigenesis data as reference, and obtained HG tumor data for 260 MeV/u silicon (LET ∼70 keV/μm) and 1,000 MeV/u titanium (LET ∼100 keV/μm) to fill existing gaps of data in this LET range to improve our understanding of the dose-response curve at low doses, to test for deviations from linearity and to provide RBE estimates. Animals were also exposed to five daily fractions of 0.026 or 0.052 Gy of 1,000 MeV/u titanium ions to simulate chronic exposure, and HG tumorigenesis from this fractionated study were compared to the results from single 0.13 or 0.26 Gy acute titanium exposures. Theoretical modeling of the data show that a nontargeted effect model provides a better fit than the targeted effect model, providing important information at space-relevant doses of heavy ions.
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Affiliation(s)
- Polly Y Chang
- a Biosciences Division, SRI International, Menlo Park, California 94025;,b Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; and
| | - Francis A Cucinotta
- c Department of Health Physics and Diagnostic Sciences, University of Nevada, Las Vegas, Nevada 89154
| | - Kathleen A Bjornstad
- b Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; and
| | - James Bakke
- a Biosciences Division, SRI International, Menlo Park, California 94025
| | - Chris J Rosen
- a Biosciences Division, SRI International, Menlo Park, California 94025
| | - Nicholas Du
- b Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; and
| | - David G Fairchild
- b Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; and
| | - Eliedonna Cacao
- c Department of Health Physics and Diagnostic Sciences, University of Nevada, Las Vegas, Nevada 89154
| | - Eleanor A Blakely
- b Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; and
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11
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Calì B, Ceolin S, Ceriani F, Bortolozzi M, Agnellini AHR, Zorzi V, Predonzani A, Bronte V, Molon B, Mammano F. Critical role of gap junction communication, calcium and nitric oxide signaling in bystander responses to focal photodynamic injury. Oncotarget 2016; 6:10161-74. [PMID: 25868859 PMCID: PMC4496347 DOI: 10.18632/oncotarget.3553] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 02/14/2015] [Indexed: 12/02/2022] Open
Abstract
Ionizing and nonionizing radiation affect not only directly targeted cells but also surrounding “bystander” cells. The underlying mechanisms and therapeutic role of bystander responses remain incompletely defined. Here we show that photosentizer activation in a single cell triggers apoptosis in bystander cancer cells, which are electrically coupled by gap junction channels and support the propagation of a Ca2+ wave initiated in the irradiated cell. The latter also acts as source of nitric oxide (NO) that diffuses to bystander cells, in which NO levels are further increased by a mechanism compatible with Ca2+-dependent enzymatic production. We detected similar signals in tumors grown in dorsal skinfold chambers applied to live mice. Pharmacological blockade of connexin channels significantly reduced the extent of apoptosis in bystander cells, consistent with a critical role played by intercellular communication, Ca2+ and NO in the bystander effects triggered by photodynamic therapy.
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Affiliation(s)
- Bianca Calì
- Foundation for Advanced Biomedical Research, Venetian Institute of Molecular Medicine, Padua, Italy.,University of Padua, Department of Surgery Oncology and Gastroenterology, Oncology and Immunology Section, Padua, Italy
| | - Stefano Ceolin
- University of Padua, Department of Physics and Astronomy, Padua, Italy
| | - Federico Ceriani
- Foundation for Advanced Biomedical Research, Venetian Institute of Molecular Medicine, Padua, Italy.,University of Padua, Department of Physics and Astronomy, Padua, Italy
| | - Mario Bortolozzi
- Foundation for Advanced Biomedical Research, Venetian Institute of Molecular Medicine, Padua, Italy.,University of Padua, Department of Physics and Astronomy, Padua, Italy
| | - Andrielly H R Agnellini
- Foundation for Advanced Biomedical Research, Venetian Institute of Molecular Medicine, Padua, Italy.,University of Padua, Department of Surgery Oncology and Gastroenterology, Oncology and Immunology Section, Padua, Italy
| | - Veronica Zorzi
- Foundation for Advanced Biomedical Research, Venetian Institute of Molecular Medicine, Padua, Italy.,University of Padua, Department of Physics and Astronomy, Padua, Italy
| | | | - Vincenzo Bronte
- Foundation for Advanced Biomedical Research, Venetian Institute of Molecular Medicine, Padua, Italy.,Verona University Hospital, Department of Pathology and Diagnostics, Immunology Section, Verona, Italy
| | | | - Fabio Mammano
- Foundation for Advanced Biomedical Research, Venetian Institute of Molecular Medicine, Padua, Italy.,University of Padua, Department of Physics and Astronomy, Padua, Italy.,Present address: CNR, Institute of Cell Biology and Neurobiology, Monterotondo (RM), Italy
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12
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Burtt JJ, Thompson PA, Lafrenie RM. Non-targeted effects and radiation-induced carcinogenesis: a review. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2016; 36:R23-R35. [PMID: 26910391 DOI: 10.1088/0952-4746/36/1/r23] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Exposure to ionising radiation is clearly associated with an increased risk of developing some types of cancer. However, the contribution of non-targeted effects to cancer development after exposure to ionising radiation is far less clear. The currently used cancer risk model by the international radiation protection community states that any increase in radiation exposure proportionately increases the risk of developing cancer. However, this stochastic cancer risk model does not take into account any contribution from non-targeted effects. Nor does it consider the possibility of a bystander mechanism in the induction of genomic instability. This paper reviews the available evidence to date for a possible role for non-targeted effects to contribute to cancer development after exposure to ionising radiation. An evolution in the understanding of the mechanisms driving non-targeted effects after exposure to ionising radiation is critical to determine the true contribution of non-targeted effects on the risk of developing cancer. Such an evolution will likely only be achievable through coordinated multidisciplinary teams combining several fields of study including: genomics, proteomics, cell biology, molecular epidemiology, and traditional epidemiology.
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Affiliation(s)
- Julie J Burtt
- Canadian Nuclear Safety Commission, 280 Slater Street, Ottawa, Ontario, K1P 5S9, Canada
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Fu J, Yuan D, Xiao L, Tu W, Dong C, Liu W, Shao C. The crosstalk between α-irradiated Beas-2B cells and its bystander U937 cells through MAPK and NF-κB signaling pathways. Mutat Res 2015; 783:1-8. [PMID: 26613333 DOI: 10.1016/j.mrfmmm.2015.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 12/19/2022]
Abstract
Although accumulated evidence suggests that α-particle irradiation induced bystander effect may relevant to lung injury and cancer risk assessment, the exact mechanisms are not yet elucidated. In the present study, a cell co-culture system was used to investigate the interaction between α-particle irradiated human bronchial epithelial cells (Beas-2B) and its bystander macrophage U937 cells. It was found that the cell co-culture amplified the detrimental effects of α-irradiation including cell viability decrease and apoptosis promotion on both irradiated cells and bystander cells in a feedback loop which was closely relevant to the activation of MAPK and NF-κB pathways in the bystander U937 cells. When these two pathways in U937 cells were disturbed by special pharmacological inhibitors before cell co-culture, it was found that a NF-κB inhibitor of BAY 11-7082 further enhanced the proliferation inhibition and apoptosis induction in bystander U937 cells, but MAPK inhibitors of SP600125 and SB203580 protected cells from viability loss and apoptosis and U0126 presented more beneficial effect on cell protection. For α-irradiated epithelial cells, the activation of NF-κB and MAPK pathways in U937 cells participated in detrimental cellular responses since the above inhibitors could largely attenuate cell viability loss and apoptosis of irradiated cells. Our results demonstrated that there are bilateral bystander responses between irradiated lung epithelial cells and macrophages through MAPK and NF-κB signaling pathways, which accounts for the enhancement of α-irradiation induced damage.
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Affiliation(s)
- Jiamei Fu
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China
| | - Dexiao Yuan
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China
| | - Linlin Xiao
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China
| | - Wenzhi Tu
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China
| | - Chen Dong
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China
| | - Weili Liu
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China
| | - Chunlin Shao
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China.
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Ghosh S, Ghosh A, Krishna M. Role of ATM in bystander signaling between human monocytes and lung adenocarcinoma cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 794:39-45. [PMID: 26653982 DOI: 10.1016/j.mrgentox.2015.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/05/2015] [Accepted: 10/20/2015] [Indexed: 12/14/2022]
Abstract
The response of a cell or tissue to ionizing radiation is mediated by direct damage to cellular components and indirect damage mediated by radiolysis of water. Radiation affects both irradiated cells and the surrounding cells and tissues. The radiation-induced bystander effect is defined by the presence of biological effects in cells that were not themselves in the field of irradiation. To establish the contribution of the bystander effect in the survival of the neighboring cells, lung carcinoma A549 cells were exposed to gamma-irradiation, 2Gy. The medium from the irradiated cells was transferred to non-irradiated A549 cells. Irradiated A549 cells as well as non-irradiated A549 cells cultured in the presence of medium from irradiated cells showed decrease in survival and increase in γ-H2AX and p-ATM foci, indicating a bystander effect. Bystander signaling was also observed between different cell types. Phorbol-12-myristate-13-acetate (PMA)-stimulated and gamma-irradiated U937 (human monocyte) cells induced a bystander response in non-irradiated A549 (lung carcinoma) cells as shown by decreased survival and increased γ-H2AX and p-ATM foci. Non-stimulated and/or irradiated U937 cells did not induce such effects in non-irradiated A549 cells. Since ATM protein was activated in irradiated cells as well as bystander cells, it was of interest to understand its role in bystander effect. Suppression of ATM with siRNA in A549 cells completely inhibited bystander effect in bystander A549 cells. On the other hand suppression of ATM with siRNA in PMA stimulated U937 cells caused only a partial inhibition of bystander effect in bystander A549 cells. These results indicate that apart from ATM, some additional factor may be involved in bystander effect between different cell types.
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Affiliation(s)
- Somnath Ghosh
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
| | - Anu Ghosh
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - Malini Krishna
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
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15
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Tang FR, Loke WK. Molecular mechanisms of low dose ionizing radiation-induced hormesis, adaptive responses, radioresistance, bystander effects, and genomic instability. Int J Radiat Biol 2014; 91:13-27. [DOI: 10.3109/09553002.2014.937510] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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16
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Lin YF, Nagasawa H, Little JB, Kato TA, Shih HY, Xie XJ, Wilson Jr. PF, Brogan JR, Kurimasa A, Chen DJ, Bedford JS, Chen BPC. Differential radiosensitivity phenotypes of DNA-PKcs mutations affecting NHEJ and HRR systems following irradiation with gamma-rays or very low fluences of alpha particles. PLoS One 2014; 9:e93579. [PMID: 24714417 PMCID: PMC3979685 DOI: 10.1371/journal.pone.0093579] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/04/2014] [Indexed: 12/03/2022] Open
Abstract
We have examined cell-cycle dependence of chromosomal aberration induction and cell killing after high or low dose-rate γ irradiation in cells bearing DNA-PKcs mutations in the S2056 cluster, the T2609 cluster, or the kinase domain. We also compared sister chromatid exchanges (SCE) production by very low fluences of α-particles in DNA-PKcs mutant cells, and in homologous recombination repair (HRR) mutant cells including Rad51C, Rad51D, and Fancg/xrcc9. Generally, chromosomal aberrations and cell killing by γ-rays were similarly affected by mutations in DNA-PKcs, and these mutant cells were more sensitive in G1 than in S/G2 phase. In G1-irradiated DNA-PKcs mutant cells, both chromosome- and chromatid-type breaks and exchanges were in excess than wild-type cells. For cells irradiated in late S/G2 phase, mutant cells showed very high yields of chromatid breaks compared to wild-type cells. Few exchanges were seen in DNA-PKcs-null, Ku80-null, or DNA-PKcs kinase dead mutants, but exchanges in excess were detected in the S2506 or T2609 cluster mutants. SCE induction by very low doses of α-particles is resulted from bystander effects in cells not traversed by α-particles. SCE seen in wild-type cells was completely abolished in Rad51C- or Rad51D-deficient cells, but near normal in Fancg/xrcc9 cells. In marked contrast, very high levels of SCEs were observed in DNA-PKcs-null, DNA-PKcs kinase-dead and Ku80-null mutants. SCE induction was also abolished in T2609 cluster mutant cells, but was only slightly reduced in the S2056 cluster mutant cells. Since both non-homologous end-joining (NHEJ) and HRR systems utilize initial DNA lesions as a substrate, these results suggest the possibility of a competitive interference phenomenon operating between NHEJ and at least the Rad51C/D components of HRR; the level of interaction between damaged DNA and a particular DNA-PK component may determine the level of interaction of such DNA with a relevant HRR component.
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Affiliation(s)
- Yu-Fen Lin
- Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Hatsumi Nagasawa
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - John B. Little
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Takamitsu A. Kato
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Hung-Ying Shih
- Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Xian-Jin Xie
- Department of Clinical Sciences, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Paul F. Wilson Jr.
- Department of Biosciences, Brookhaven National Laboratory, Upton, New York, United States of America
| | - John R. Brogan
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Akihiro Kurimasa
- Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Tottori, Japan
| | - David J. Chen
- Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Joel S. Bedford
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Benjamin P. C. Chen
- Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
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Varès G, Wang B, Tanaka K, Kakimoto A, Eguchi-Kasai K, Nenoi M. Mutagenic adaptive response to high-LET radiation in human lymphoblastoid cells exposed to low doses of heavy-ion radiation. Mutat Res 2011; 712:49-54. [PMID: 21540043 DOI: 10.1016/j.mrfmmm.2011.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 04/06/2011] [Accepted: 04/14/2011] [Indexed: 05/30/2023]
Abstract
Adaptive response (AR) and bystander effect are two important phenomena involved in biological responses to low doses of ionizing radiation (IR). Furthermore, there is a strong interest in better understanding the biological effects of high-LET radiation. We previously demonstrated the ability of low doses of X-rays to induce an AR to challenging heavy-ion radiation [8]. In this study, we assessed in vitro the ability of priming low doses (0.01Gy) of heavy-ion radiation to induce a similar AR to a subsequent challenging dose (1-4Gy) of high-LET IR (carbon-ion: 20 and 40keV/μm, neon-ion: 150keV/μm) in TK6, AHH-1 and NH32 cells. Our results showed that low doses of high-LET radiation can induce an AR characterized by lower mutation frequencies at hypoxanthine-guanine phosphoribosyl transferase locus and faster DNA repair kinetics, in cells expressing p53.
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Affiliation(s)
- Guillaume Varès
- Radiation Risk Reduction Research Program, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan.
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18
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Rajendran S, Harrison SH, Thomas RA, Tucker JD. The role of mitochondria in the radiation-induced bystander effect in human lymphoblastoid cells. Radiat Res 2010; 175:159-71. [PMID: 21268709 DOI: 10.1667/rr2296.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cells without intact mitochondrial DNA have been shown to lack the bystander effect, which is an energy-dependent process. We hypothesized that cells harboring mutations in mitochondrial genes responsible for ATP synthesis would show a decreased bystander effect compared to normal cells. Radiation-induced bystander effects were analyzed in two normal and four mitochondrial mutant human lymphoblastoid cells. Medium from previously irradiated cells (conditioned medium) was transferred to unirradiated cells from the respective cell lines and evaluated for the bystander effect using the cytokinesis-block micronucleus assay. Unlike normal cells that were used as a control, mitochondrial mutant cells neither generated nor responded to the bystander signals. The bystander effect was inhibited in normal cells by adding the mitochondrial inhibitors rotenone and oligomycin to the culture medium. Time-controlled blocking of the bystander effect by inhibitors was found to occur either for prolonged exposure to the inhibitor prior to irradiation with an immediate and subsequent removal of the inhibitors or immediate post-application of the inhibitor. Adding the inhibitors just prior to irradiation and removing them immediately after irradiation was uneventful. Fully functional mitochondrial metabolic capability may therefore be essential for the bystander effect.
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Affiliation(s)
- Sountharia Rajendran
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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19
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Cogan N, Baird DM, Phillips R, Crompton LA, Caldwell MA, Rubio MA, Newson R, Lyng F, Case CP. DNA damaging bystander signalling from stem cells, cancer cells and fibroblasts after Cr(VI) exposure and its dependence on telomerase. Mutat Res 2010; 683:1-8. [PMID: 19800897 DOI: 10.1016/j.mrfmmm.2009.09.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/23/2009] [Accepted: 09/24/2009] [Indexed: 01/29/2023]
Abstract
The bystander effect is a feature of low dose radiation exposure and is characterized by a signaling process from irradiated cells to non irradiated cells, which causes DNA and chromosome damage in these 'nearest neighbour' cells. Here we show that a low and short dose of Cr(VI) can induce stem cells, cancer cells and fibroblasts to chronically secrete bystander signals, which cause DNA damage in neighboring cells. The Cr(VI) induced bystander signaling depended on the telomerase status of either cell. Telomerase negative fibroblasts were able to receive DNA damaging signals from telomerase positive or negative fibroblasts or telomerase positive cancer cells. However telomerase positive fibroblasts were resistant to signals from Cr(VI) exposed telomerase positive fibroblasts or cancer cells. Human embryonic stem cells, with positive Oct4 staining as a marker of pluripotency, showed no significant increase of DNA damage from adjacent Cr and mitomycin C exposed fibroblasts whilst those cells that were negatively stained did. This selectivity of DNA damaging bystander signaling could be an important consideration in developing therapies against cancer and in the safety and effectiveness of tissue engineering and transplantation using stem cells.
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Affiliation(s)
- Nicola Cogan
- Bristol Implant Research Centre, University of Bristol, Bristol, UK
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20
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Burdak-Rothkamm S, Prise KM. New molecular targets in radiotherapy: DNA damage signalling and repair in targeted and non-targeted cells. Eur J Pharmacol 2009; 625:151-5. [PMID: 19835868 DOI: 10.1016/j.ejphar.2009.09.068] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 09/10/2009] [Accepted: 09/23/2009] [Indexed: 12/28/2022]
Abstract
Ionising radiation plays a key role in therapy due to its ability to directly induce DNA damage, in particular DNA double-strand breaks leading to cell death. Cells have multiple repair pathways which attempt to maintain genomic stability. DNA repair proteins have become key targets for therapy, using small molecule inhibitors, in combination with radiation and or chemotherapeutic agents as a means of enhancing cell killing. Significant advances in our understanding of the response of cells to radiation exposures has come from the observation of non-targeted effects where cells respond via mechanisms other than those which are a direct consequence of energy-dependent DNA damage. Typical of these is bystander signalling where cells respond to the fact that their neighbours have been irradiated. Bystander cells show a DNA damage response which is distinct from directly irradiated cells. In bystander cells, ATM- and Rad3-related (ATR) protein kinase-dependent signalling in response to stalled replication forks is an early event in the DNA damage response. The ATM protein kinase is activated downstream of ATR in bystander cells. This offers the potential for differential approaches for the modulation of bystander and direct effects with repair inhibitors which may impact on the response of tumours and on the protection of normal tissues during radiotherapy.
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Affiliation(s)
- Susanne Burdak-Rothkamm
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
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21
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Zhang Y, Zhou J, Baldwin J, Held KD, Prise KM, Redmond RW, Liber HL. Ionizing radiation-induced bystander mutagenesis and adaptation: quantitative and temporal aspects. Mutat Res 2009; 671:20-5. [PMID: 19695271 DOI: 10.1016/j.mrfmmm.2009.08.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 08/05/2009] [Accepted: 08/10/2009] [Indexed: 01/08/2023]
Abstract
This work explores several quantitative aspects of radiation-induced bystander mutagenesis in WTK1 human lymphoblast cells. Gamma-irradiation of cells was used to generate conditioned medium containing bystander signals, and that medium was transferred onto naïve recipient cells. Kinetic studies revealed that it required up to 1h to generate sufficient signal to induce the maximal level of mutations at the thymidine kinase locus in the bystander cells receiving the conditioned medium. Furthermore, it required at least 1h of exposure to the signal in the bystander cells to induce mutations. Bystander signal was fairly stable in the medium, requiring 12-24h to diminish. Medium that contained bystander signal was rendered ineffective by a 4-fold dilution; in contrast a greater than 20-fold decrease in the cell number irradiated to generate a bystander signal was needed to eliminate bystander-induced mutagenesis. This suggested some sort of feedback inhibition by bystander signal that prevented the signaling cells from releasing more signal. Finally, an ionizing radiation-induced adaptive response was shown to be effective in reducing bystander mutagenesis; in addition, low levels of exposure to bystander signal in the transferred medium induced adaptation that was effective in reducing mutations induced by subsequent gamma-ray exposures.
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Affiliation(s)
- Ying Zhang
- Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA
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22
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Chakraborty A, Held KD, Prise KM, Liber HL, Redmond RW. Bystander effects induced by diffusing mediators after photodynamic stress. Radiat Res 2009; 172:74-81. [PMID: 19580509 DOI: 10.1667/rr1669.1] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The bystander effect, whereby cells that are not traversed by ionizing radiation exhibit various responses when in proximity to irradiated cells, is well documented in the field of radiation biology, Here we demonstrate that considerable bystander responses are also observed after photodynamic stress using the membrane-localizing dye deuteroporphyrin (DP). Using cells of a WTK1 human lymphoblastoid cell line in suspension and a transwell insert system that precludes contact between targeted and bystander cells, we have shown that the bystander signaling is mediated by diffusing species. The extranuclear localization of the photosensitizer used suggests that primary DNA damage is not the trigger for initiating these bystander responses, which include elevated oxidative stress, DNA damage (micronucleus formation), mutagenesis and decreased clonogenic survival. In addition, oxidative stress in the bystander population was reduced by the presence of the membrane antioxidant vitamin E in the targeted cells, suggesting that lipid peroxidation may play a key role in mediating these bystander effects. The fluence responses for these bystander effects are non-linear, with larger effects seen at lower fluences and toxicity to the target cell population. Hence, when considering outcomes of photodynamic action in cells and tissue, bystander effects may be significant, especially at sublethal fluences.
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Affiliation(s)
- Asima Chakraborty
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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23
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Rubio N, Rajadurai A, Held KD, Prise KM, Liber HL, Redmond RW. Real-time imaging of novel spatial and temporal responses to photodynamic stress. Free Radic Biol Med 2009; 47:283-90. [PMID: 19409981 DOI: 10.1016/j.freeradbiomed.2009.04.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 04/21/2009] [Accepted: 04/24/2009] [Indexed: 01/06/2023]
Abstract
Cells subjected to various forms of stress have been shown to induce bystander responses in nontargeted cells, thus extending the stress response to a larger population. However, the mechanism(s) of bystander responses remains to be clearly identified, particularly for photodynamic stress. Oxidative stress and cell viability were studied on the spatial and temporal levels after photodynamic targeting of a subpopulation of EMT6 murine mammary cancer cells in a multiwell plate by computerized time-lapse fluorescence microscopy. In the targeted population a dose-dependent loss of cell viability was observed in accordance with increased oxidative stress. This was accompanied by increased oxidative stress in bystander populations but on different time scales, reaching a maximum more rapidly in targeted cells. Treatment with extracellular catalase, or the NADPH oxidase inhibitor diphenyleneiodinium, decreased production of reactive oxygen species (ROS) in both populations. These effects are ascribed to photodynamic activation of NADPH-oxidase in the targeted cells, resulting in a rapid burst of ROS formation with hydrogen peroxide acting as the signaling molecule responsible for initiation of these photodynamic bystander responses. The consequences of increased oxidative stress in bystander cells should be considered in the overall framework of photodynamic stress.
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Affiliation(s)
- Noemi Rubio
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
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24
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Kanasugi Y, Hamada N, Wada S, Funayama T, Sakashita T, Kakizaki T, Kobayashi Y, Takakura K. Role of DNA-PKcs in the bystander effect after low- or high-LET irradiation. Int J Radiat Biol 2009; 83:73-80. [PMID: 17357428 DOI: 10.1080/09553000601121116] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE To investigate the role of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) in the medium-mediated bystander effect for chromosomal aberrations induced by low-linear energy transfer (LET) X-rays and high-LET heavy ions in normal human fibroblast cells. MATERIALS AND METHODS The recipient cells were treated for 12 h with conditioned medium, which was harvested from donor cells at 24 h after exposure to 10 Gy of soft X-rays (5 keV/microm) and 20Ne ions (437 keV/microm), followed by analyses of chromosome aberrations in recipient cells with premature chromosome condensation methods. To examine the role of DNA-PKcs and nitric oxide (NO), cells were treated with its inhibitor LY294002 (LY) and its scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (c-PTIO), respectively. RESULTS Increased frequency of chromosome aberrations in recipient cells treated with conditioned medium from irradiated but not from un-irradiated donor cells was observed which was independent of radiation type. Bystander induction of chromosome aberrations in recipient cells was mitigated when donor cells were treated with LY before irradiation and with c-PTIO after irradiation, and was enhanced when recipient cells were treated with LY before treatment of recipient cells with conditioned medium from irradiated donor cells. CONCLUSION Irradiated normal human cells secrete NO and other molecules which in turn transmit radiation signals to unirradiated bystander cells, leading to the induction of bystander chromosome aberrations partially repairable by DNA-PKcs-mediated DNA damage repair machinery, such as non-homologous end-joining repair pathways.
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Affiliation(s)
- Yuichi Kanasugi
- Physics Department, International Christian University, Tokyo, Japan
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25
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Asur RS, Thomas RA, Tucker JD. Chemical induction of the bystander effect in normal human lymphoblastoid cells. Mutat Res 2009; 676:11-6. [PMID: 19486859 DOI: 10.1016/j.mrgentox.2009.02.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 02/24/2009] [Accepted: 02/25/2009] [Indexed: 11/30/2022]
Abstract
Many studies investigating the bystander effect have used ionizing radiation to evaluate this phenomenon, whereas very few have determined whether genotoxic chemicals are also capable of inducing this effect. Here, we show that two such chemicals, mitomycin C, a bifunctional alkylating agent and phleomycin, a glycopeptide antibiotic of the bleomycin family, cause normal human B lymphoblastoid cells to produce media soluble factors that induce a bystander effect in unexposed cells. Ionizing radiation was used in parallel experiments to verify the existence of the bystander effect in these cells. Micronuclei in Cytochalasin B-blocked binucleated cells were used as the endpoint. Conditioned media obtained from cells exposed to mitomycin C induced a 1.5-3 fold increase, while conditioned media from phleomycin induced a 1.5-4 fold increase, and conditioned media from irradiated cells induced a 2-8 fold increase in micronuclei. We conclude that the bystander effect is not restricted to ionizing radiation, suggesting it may be a part of a general cellular stress response.
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Affiliation(s)
- Rajalakshmi S Asur
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202-3917, USA
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26
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Matsumoto H, Tomita M, Otsuka K, Hatashita M. A new paradigm in radioadaptive response developing from microbeam research. JOURNAL OF RADIATION RESEARCH 2009; 50 Suppl A:A67-A79. [PMID: 19346687 DOI: 10.1269/jrr.09003s] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A classic paradigm in radiation biology asserts that all radiation effects on cells, tissues and organisms are due to the direct action of radiation on living tissue. Using this model, possible risks from exposure to low dose ionizing radiation (below 100 mSv) are estimated by extrapolating from data obtained after exposure to higher doses of radiation, using a linear non-threshold model (LNT model). However, the validity of using this dose-response model is controversial because evidence accumulated over the past decade has indicated that living organisms, including humans, respond differently to low dose/low dose-rate radiation than they do to high dose/high dose-rate radiation. These important responses to low dose/low dose-rate radiation are the radiation-induced adaptive response, the bystander response, low-dose hypersensitivity, and genomic instability. The mechanisms underlying these responses often involve biochemical and molecular signals generated in response to targeted and non-targeted events. In order to define and understand the bystander response to provide a basis for the understanding of non-targeted events and to elucidate the mechanisms involved, recent sophisticated research has been conducted with X-ray microbeams and charged heavy particle microbeams, and these studies have produced many new observations. Based on these observations, associations have been suggested to exist between the radioadaptive and bystander responses. The present review focuses on these two phenomena, and summarizes observations supporting their existence, and discusses the linkage between them in light of recent results obtained from experiments utilizing microbeams.
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Affiliation(s)
- Hideki Matsumoto
- Division of Oncology, Biomedical Imaging Research Center, University of Fukui, 23-3 Matsuoka-Shimoaitsuki, Eiheiji-cho, Fukui 910-1193, Japan.
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27
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Frankenberg D, Greif KD, Beverung W, Langner F, Giesen U. The role of nonhomologous end joining and homologous recombination in the clonogenic bystander effects of mammalian cells after exposure to counted 10 MeV protons and 4.5 MeV alpha-particles of the PTB microbeam. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2008; 47:431-438. [PMID: 18688633 DOI: 10.1007/s00411-008-0187-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Accepted: 07/15/2008] [Indexed: 05/26/2023]
Abstract
We have studied the dependence of clonogenic bystander effects on defects in the pathways of DNA double-strand break (DSB) repair and on linear energy transfer (LET). The single-ion microbeam of the Physikalisch-Technische Bundesanstalt (PTB) was used to irradiate parental Chinese hamster ovary cells or derivatives deficient in nonhomologous end joining (NHEJ) or homologous recombination (HR) in the G1-phase of the cell cycle. Cell nuclei were targeted with 10 MeV protons (LET = 4.7 keV/microm) or 4.5 MeV alpha-particles (LET = 100 keV/microm). During exposure, the cells were confluent, allowing signal transfer through both gap junctions and diffusion. When all cell nuclei were targeted with 10 MeV protons, approximately exponential survival curves were obtained for all three cell lines. When only 10% of all cell nuclei were targeted, a significant bystander effect was observed for parental and HR-deficient cells, but not for NHEJ-deficient cells. For all three cell lines, the survival data after exposure of all cell nuclei to 4.5 MeV alpha-particles could be fitted by exponential curves. When only 10% of all cell nuclei were targeted, significant bystander effects were obtained for parental and HR-deficient cells, whereas for NHEJ-deficient cells a small, but significant, bystander effect was observed only at higher doses. The data suggest that bystander cell killing is a consequence of un- or misrejoined DSB which occur in bystander cells during the S-phase as a result of the processing of oxidative bistranded DNA lesions. The relative contributions of NHEJ and HR to the repairing of DSB in the late S/G2-phase may affect clonogenic bystander effects.
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Affiliation(s)
- Dieter Frankenberg
- Department 6.4, Ion Accelerators and Reference Radiation Fields, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
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Oncogenic bystander radiation effects in Patched heterozygous mouse cerebellum. Proc Natl Acad Sci U S A 2008; 105:12445-50. [PMID: 18711141 DOI: 10.1073/pnas.0804186105] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The central dogma of radiation biology, that biological effects of ionizing radiation are a direct consequence of DNA damage occurring in irradiated cells, has been challenged by observations that genetic/epigenetic changes occur in unexposed "bystander cells" neighboring directly-hit cells, due to cell-to-cell communication or soluble factors released by irradiated cells. To date, the vast majority of these effects are described in cell-culture systems, while in vivo validation and assessment of biological consequences within an organism remain uncertain. Here, we describe the neonatal mouse cerebellum as an accurate in vivo model to detect, quantify, and mechanistically dissect radiation-bystander responses. DNA double-strand breaks and apoptotic cell death were induced in bystander cerebellum in vivo. Accompanying these genetic events, we report bystander-related tumor induction in cerebellum of radiosensitive Patched-1 (Ptch1) heterozygous mice after x-ray exposure of the remainder of the body. We further show that genetic damage is a critical component of in vivo oncogenic bystander responses, and provide evidence supporting the role of gap-junctional intercellular communication (GJIC) in transmission of bystander signals in the central nervous system (CNS). These results represent the first proof-of-principle that bystander effects are factual in vivo events with carcinogenic potential, and implicate the need for re-evaluation of approaches currently used to estimate radiation-associated health risks.
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29
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DNA-PKcs and ATM influence generation of ionizing radiation-induced bystander signals. Oncogene 2008; 27:6761-9. [DOI: 10.1038/onc.2008.276] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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30
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Zhang Y, Zhou J, Held KD, Redmond RW, Prise KM, Liber HL. Deficiencies of double-strand break repair factors and effects on mutagenesis in directly gamma-irradiated and medium-mediated bystander human lymphoblastoid cells. Radiat Res 2008; 169:197-206. [PMID: 18220473 DOI: 10.1667/rr1189.1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 10/02/2007] [Indexed: 11/03/2022]
Abstract
Using RNA interference techniques to knock down key proteins in two major double-strand break (DSB) repair pathways (DNA-PKcs for nonhomologous end joining, NHEJ, and Rad54 for homologous recombination, HR), we investigated the influence of DSB repair factors on radiation mutagenesis at the autosomal thymidine kinase (TK) locus both in directly irradiated cells and in unirradiated bystander cells. We also examined the role of p53 (TP53) in these processes by using cells of three human lymphoblastoid cell lines from the same donor but with differing p53 status (TK6 is p53 wild-type, NH32 is p53 null, and WTK1 is p53 mutant). Our results indicated that p53 status did not affect either the production of radiation bystander mutagenic signals or the response to these signals. In directly irradiated cells, knockdown of DNA-PKcs led to an increased mutant fraction in WTK1 cells and decreased mutant fractions in TK6 and NH32 cells. In contrast, knockdown of DNA-PKcs led to increased mutagenesis in bystander cells regardless of p53 status. In directly irradiated cells, knockdown of Rad54 led to increased induced mutant fractions in WTK1 and NH32 cells, but the knockdown did not affect mutagenesis in p53 wild-type TK6 cells. In all cell lines, Rad54 knockdown had no effect on the magnitude of bystander mutagenesis. Studies with extracellular catalase confirmed the involvement of H2O2 in bystander signaling. Our results demonstrate that DSB repair factors have different roles in mediating mutagenesis in irradiated and bystander cells.
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Affiliation(s)
- Ying Zhang
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA.
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31
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Hamada N, Ni M, Funayama T, Sakashita T, Kobayashi Y. Temporally distinct response of irradiated normal human fibroblasts and their bystander cells to energetic heavy ions. Mutat Res 2008; 639:35-44. [PMID: 18082226 DOI: 10.1016/j.mrfmmm.2007.11.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 10/19/2007] [Accepted: 11/02/2007] [Indexed: 05/25/2023]
Abstract
Ionizing radiation-induced bystander effects have been documented for a multitude of endpoints such as mutations, chromosome aberrations and cell death, which arise in nonirradiated bystander cells having received signals from directly irradiated cells; however, energetic heavy ion-induced bystander response is incompletely characterized. To address this, we employed precise microbeams of carbon and neon ions for targeting only a very small fraction of cells in confluent fibroblast cultures. Conventional broadfield irradiation was conducted in parallel to see the effects in irradiated cells. Exposure of 0.00026% of cells led to nearly 10% reductions in the clonogenic survival and twofold rises in the apoptotic incidence regardless of ion species. Whilst apoptotic frequency increased with time up to 72 h postirradiation in irradiated cells, its frequency escalated up to 24h postirradiation but declined at 48 h postirradiation in bystander cells, indicating that bystander cells exhibit transient commitment to apoptosis. Carbon- and neon-ion microbeam irradiation similarly caused almost twofold increments in the levels of serine 15-phosphorylated p53 proteins, irrespective of whether 0.00026, 0.0013 or 0.0066% of cells were targeted. Whereas the levels of phosphorylated p53 were elevated and remained unchanged at 2h and 6h postirradiation in irradiated cells, its levels rose at 6h postirradiation but not at 2h postirradiation in bystander cells, suggesting that bystander cells manifest delayed p53 phosphorylation. Collectively, our results indicate that heavy ions inactivate clonogenic potential of bystander cells, and that the time course of the response to heavy ions differs between irradiated and bystander cells. These induced bystander responses could be a defensive mechanism that minimizes further expansion of aberrant cells.
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Affiliation(s)
- Nobuyuki Hamada
- Department of Quantum Biology, Division of Bioregulatory Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
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Nagasawa H, Wilson PF, Chen DJ, Thompson LH, Bedford JS, Little JB. Low doses of alpha particles do not induce sister chromatid exchanges in bystander Chinese hamster cells defective in homologous recombination. DNA Repair (Amst) 2008; 7:515-22. [DOI: 10.1016/j.dnarep.2007.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Accepted: 11/21/2007] [Indexed: 11/17/2022]
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Schöllnberger H, Mitchel REJ, Redpath JL, Crawford-Brown DJ, Hofmann W. Detrimental and protective bystander effects: a model approach. Radiat Res 2007; 168:614-26. [PMID: 17973556 PMCID: PMC3088356 DOI: 10.1667/rr0742.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Accepted: 07/04/2007] [Indexed: 11/03/2022]
Abstract
This work integrates two important cellular responses to low doses, detrimental bystander effects and apoptosis-mediated protective bystander effects, into a multistage model for chromosome aberrations and in vitro neoplastic transformation: the State-Vector Model. The new models were tested on representative data sets that show supralinear or U-shaped dose responses. The original model without the new low-dose features was also tested for consistency with LNT-shaped dose responses. Reductions of in vitro neoplastic transformation frequencies below the spontaneous level have been reported after exposure of cells to low doses of low-LET radiation. In the current study, this protective effect is explained with bystander-induced apoptosis. An important data set that shows a low-dose detrimental bystander effect for chromosome aberrations was successfully fitted by additional terms within the cell initiation stage. It was found that this approach is equivalent to bystander-induced clonal expansion of initiated cells. This study is an important step toward a comprehensive model that contains all essential biological mechanisms that can influence dose-response curves at low doses.
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Affiliation(s)
- H Schöllnberger
- Department of Materials Engineering and Physics and Biophysics, University of Salzburg, Salzburg, Austria.
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Hamada N, Matsumoto H, Hara T, Kobayashi Y. Intercellular and intracellular signaling pathways mediating ionizing radiation-induced bystander effects. JOURNAL OF RADIATION RESEARCH 2007; 48:87-95. [PMID: 17327686 DOI: 10.1269/jrr.06084] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A rapidly growing body of experimental evidence indicates that ionizing radiation induces biological effects in non-irradiated bystander cells that have received signals from adjacent or distant irradiated cells. This phenomenon, which has been termed the ionizing radiation-induced bystander effect, challenges the long-standing paradigm that radiation traversal through the nucleus of a cell is a prerequisite to elicit genetic damage or a biological response. Bystander effects have been observed in a number of experimental systems, and cells whose nucleus or cytoplasm is irradiated exert bystander responses. Bystander cells manifest a multitude of biological consequences, such as genetic and epigenetic changes, alterations in gene expression, activation of signal transduction pathways, and delayed effects in their progeny. Several mediating mechanisms have been proposed. These involve gap junction-mediated intercellular communication, secreted soluble factors, oxidative metabolism, plasma membrane-bound lipid rafts, and calcium fluxes. This paper reviews briefly the current knowledge of the bystander effect with a focus on proposed mechanisms. The potential benefit of bystander effects to cancer radiotherapy will also be discussed.
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Affiliation(s)
- Nobuyuki Hamada
- Department of Quantum Biology, Division of Bioregulatory Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan.
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Abstract
Radiation-induced bystander effects refer to those responses occurring in cells that were not subject to energy deposition events following ionizing radiation. These bystander cells may have been neighbors of irradiated cells, or physically separated but subject to soluble secreted signals from irradiated cells. Bystander effects have been observed in vitro and in vivo and for various radiation qualities. In tribute to an old friend and colleague, Anthony V. Carrano, who would have said "well what are the critical questions that should be addressed, and so what?", we review the evidence for non-targeted radiation-induced bystander effects with emphasis on prevailing questions in this rapidly developing research field, and the potential significance of bystander effects in evaluating the detrimental health effects of radiation exposure.
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Affiliation(s)
- William F Morgan
- Radiation Oncology Research Laboratory, and Marlene and Stewart Greenebaum Cancer Center, BRB 7-011, University of Maryland, Baltimore, MD 21201-1509, USA.
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Little JB. Lauriston S. Taylor lecture: nontargeted effects of radiation: implications for low-dose exposures. HEALTH PHYSICS 2006; 91:416-26. [PMID: 17033451 DOI: 10.1097/01.hp.0000232847.23192.3e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Traditional thinking has been that the biological effects of ionizing radiation occur in irradiated cells as a consequence of the DNA damage they incur. This implies that (1) biological effects occur only in irradiated cells, (2) radiation traversal through the nucleus of the cell is a prerequisite to produce a biological response, and (3) DNA is the target molecule in the cell. Evidence has been emerging, however, for non-DNA targeted effects of radiation; that is, effects including mutations, chromosomal aberrations, and changes in gene expression that occur in cells that in themselves receive no radiation exposure. Two of these phenomena will be described in this paper. The first is radiation-induced genomic instability whereby biological effects, including elevated frequencies of mutations and chromosomal aberrations, arise in the distant descendants of irradiated cells. The second phenomenon has been termed the "bystander effect," whereby in a mixed population of irradiated and nonirradiated cells, biological effects arise in those cells that receive no radiation exposure. The damage signals are transmitted from cell to cell through gap junction channels, and the genetic effects observed in bystander cells appear to result from an upregulation of oxidative stress. The possible influence of these nontargeted effects of radiation on the response to low-dose exposures is discussed.
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Affiliation(s)
- John B Little
- Harvard School of Public Health, Center for Radiation Sciences and Environmental Health, 665 Huntington Avenue, Boston, MA 02115, USA.
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Hinz JM, Tebbs RS, Wilson PF, Nham PB, Salazar EP, Nagasawa H, Urbin SS, Bedford JS, Thompson LH. Repression of mutagenesis by Rad51D-mediated homologous recombination. Nucleic Acids Res 2006; 34:1358-68. [PMID: 16522646 PMCID: PMC1390685 DOI: 10.1093/nar/gkl020] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Homologous recombinational repair (HRR) restores chromatid breaks arising during DNA replication and prevents chromosomal rearrangements that can occur from the misrepair of such breaks. In vertebrates, five Rad51 paralogs are identified that contribute in a nonessential but critical manner to HRR proficiency. We constructed and characterized a knockout of the paralog Rad51D in widely studied CHO cells. The rad51d mutant (clone 51D1) displays sensitivity to a diverse spectrum of induced DNA damage including γ-rays, ultraviolet (UV)-C radiation, and methyl methanesulfonate (MMS), indicating the broad relevance of HRR to genotoxicity. Spontaneous chromatid breaks/gaps and isochromatid breaks are elevated 3- to 12-fold, but the chromosome number distribution remains unchanged. Most importantly, 51D1 cells exhibit a 12-fold-increased rate of hprt mutation, as well as 4- to 10-fold increased rates of gene amplification at the dhfr and CAD loci, respectively. Xrcc3 irs1SF cells from the same parental CHO line show similarly elevated mutagenesis at these three loci. Collectively, these results confirm the a priori expectation that HRR acts in an error-free manner to repress three classes of genetic alterations (chromosomal aberrations, loss of gene function and increased gene expression), all of which are associated with carcinogenesis.
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Affiliation(s)
| | | | - Paul F. Wilson
- Department of Environmental and Radiological Health Sciences Colorado State UniversityFort Collins, CO 80523, USA
| | | | | | - Hatsumi Nagasawa
- Department of Environmental and Radiological Health Sciences Colorado State UniversityFort Collins, CO 80523, USA
| | | | - Joel S. Bedford
- Department of Environmental and Radiological Health Sciences Colorado State UniversityFort Collins, CO 80523, USA
| | - Larry H. Thompson
- To whom correspondence should be addressed. Tel: +1 925 422 5658; Fax: +1 925 422 2099;
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Schöllnberger H, Mitchel REJ, Crawford-Brown DJ, Hofmann W. A model for the induction of chromosome aberrations through direct and bystander mechanisms. RADIATION PROTECTION DOSIMETRY 2006; 122:275-81. [PMID: 17166875 PMCID: PMC3088355 DOI: 10.1093/rpd/ncl433] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A state vector model (SVM) for chromosome aberrations and neoplastic transformation has been adapted to describe detrimental bystander effects. The model describes initiation (formation of translocations) and promotion (clonal expansion and loss of contact inhibition of initiated cells). Additional terms either in the initiation model or in the rate of clonal expansion of initiated cells, describe detrimental bystander effects for chromosome aberrations as reported in the scientific literature. In the present study, the SVM with bystander effects is tested on a suitable dataset. In addition to the simulation of non-linear effects, a classical dataset for neoplastic transformation in C3H 10T1/2 cells after alpha particle irradiation is used to show that the model without bystander features can also describe LNT-like dose responses. A published model for bystander induced neoplastic transformation was adapted for chromosome aberration induction and used to compare the results obtained with the different models.
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Affiliation(s)
- H Schöllnberger
- Department of Material Sciences, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria.
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