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Binz RL, Tian E, Sadhukhan R, Zhou D, Hauer-Jensen M, Pathak R. Identification of novel breakpoints for locus- and region-specific translocations in 293 cells by molecular cytogenetics before and after irradiation. Sci Rep 2019; 9:10554. [PMID: 31332273 PMCID: PMC6646394 DOI: 10.1038/s41598-019-47002-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 06/24/2019] [Indexed: 12/19/2022] Open
Abstract
The human kidney embryonic 293 cell line (293 cells) is extensively used in biomedical and pharmaceutical research. These cells exhibit a number of numerical and structural chromosomal anomalies. However, the breakpoints responsible for these structural chromosomal rearrangements have not been comprehensively characterized. In addition, it is not known whether chromosomes with structural rearrangement are more sensitive to external toxic agents, such as ionizing radiation. We used G-banding, spectral karyotyping (SKY), and locus- and region-specific fluorescence in situ hybridization (FISH) probes designed in our lab or obtained from commercial vendor to address this gap. Our G-banding analysis revealed that the chromosome number varies from 66 to 71, with multiple rearrangements and partial additions and deletions. SKY analysis confirmed 3 consistent rearrangements, two simple and one complex in nature. Multicolor FISH analysis identified an array of breakpoints responsible for locus- and region-specific translocations. Finally, SKY analysis revealed that radio-sensitivity of structurally rearranged chromosomes is dependent on radiation dose. These findings will advance our knowledge in 293 cell biology and will enrich the understanding of radiation biology studies.
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Affiliation(s)
- Regina L Binz
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Erming Tian
- Myeloma Center, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Ratan Sadhukhan
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Daohong Zhou
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, USA.,Department of Pharmacodynamics, College of Pharmacy, Gainesville, FL, USA
| | - Martin Hauer-Jensen
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Rupak Pathak
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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Pathak R, Bachri A, Ghosh SP, Koturbash I, Boerma M, Binz RK, Sawyer JR, Hauer-Jensen M. The Vitamin E Analog Gamma-Tocotrienol (GT3) Suppresses Radiation-Induced Cytogenetic Damage. Pharm Res 2016; 33:2117-25. [PMID: 27216753 PMCID: PMC4967083 DOI: 10.1007/s11095-016-1950-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/13/2016] [Indexed: 01/24/2023]
Abstract
Purpose Ionizing radiation (IR) generates reactive oxygen species (ROS), which cause DNA double-strand breaks (DSBs) that are responsible for cytogenetic alterations. Because antioxidants are potent ROS scavengers, we determined whether the vitamin E isoform γ-tocotrienol (GT3), a radio-protective multifunctional dietary antioxidant, can suppress IR-induced cytogenetic damage. Methods We measured DSB formation in irradiated primary human umbilical vein endothelial cells (HUVECs) by quantifying the formation of γ-H2AX foci. Chromosomal aberrations (CAs) were analyzed in irradiated HUVECs and in the bone marrow cells of irradiated mice by conventional and fluorescence-based chromosome painting techniques. Gene expression was measured in HUVECs with quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Results GT3 pretreatment reduced DSB formation in HUVECS, and also decreased CAs in HUVECs and mouse bone marrow cells after irradiation. Moreover, GT3 increased expression of the DNA-repair gene RAD50 and attenuated radiation-induced RAD50 suppression. Conclusions GT3 attenuates radiation-induced cytogenetic damage, possibly by affecting RAD50 expression. GT3 should be explored as a therapeutic to reduce the risk of developing genetic diseases after radiation exposure.
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Affiliation(s)
- Rupak Pathak
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Biomed I, Suite 238, 4301 West Markham, Slot 522-3, Little Rock, Arkansas, 72205, USA.
| | - Abdel Bachri
- Department of Engineering and Engineering Physics, Southern Arkansas University, Magnolia, Arkansas, USA
| | - Sanchita P Ghosh
- Armed Forces Radiobiology Research Institute, USUHS, Bethesda, Maryland, USA
| | - Igor Koturbash
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Marjan Boerma
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Biomed I, Suite 238, 4301 West Markham, Slot 522-3, Little Rock, Arkansas, 72205, USA
| | - Regina K Binz
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Jeffrey R Sawyer
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Martin Hauer-Jensen
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Biomed I, Suite 238, 4301 West Markham, Slot 522-3, Little Rock, Arkansas, 72205, USA
- Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, USA
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Wu Y, Lee SH, Williamson EA, Reinert BL, Cho JH, Xia F, Jaiswal AS, Srinivasan G, Patel B, Brantley A, Zhou D, Shao L, Pathak R, Hauer-Jensen M, Singh S, Kong K, Wu X, Kim HS, Beissbarth T, Gaedcke J, Burma S, Nickoloff JA, Hromas RA. EEPD1 Rescues Stressed Replication Forks and Maintains Genome Stability by Promoting End Resection and Homologous Recombination Repair. PLoS Genet 2015; 11:e1005675. [PMID: 26684013 PMCID: PMC4684289 DOI: 10.1371/journal.pgen.1005675] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 10/26/2015] [Indexed: 12/13/2022] Open
Abstract
Replication fork stalling and collapse is a major source of genome instability leading to neoplastic transformation or cell death. Such stressed replication forks can be conservatively repaired and restarted using homologous recombination (HR) or non-conservatively repaired using micro-homology mediated end joining (MMEJ). HR repair of stressed forks is initiated by 5’ end resection near the fork junction, which permits 3’ single strand invasion of a homologous template for fork restart. This 5’ end resection also prevents classical non-homologous end-joining (cNHEJ), a competing pathway for DNA double-strand break (DSB) repair. Unopposed NHEJ can cause genome instability during replication stress by abnormally fusing free double strand ends that occur as unstable replication fork repair intermediates. We show here that the previously uncharacterized Exonuclease/Endonuclease/Phosphatase Domain-1 (EEPD1) protein is required for initiating repair and restart of stalled forks. EEPD1 is recruited to stalled forks, enhances 5’ DNA end resection, and promotes restart of stalled forks. Interestingly, EEPD1 directs DSB repair away from cNHEJ, and also away from MMEJ, which requires limited end resection for initiation. EEPD1 is also required for proper ATR and CHK1 phosphorylation, and formation of gamma-H2AX, RAD51 and phospho-RPA32 foci. Consistent with a direct role in stalled replication fork cleavage, EEPD1 is a 5’ overhang nuclease in an obligate complex with the end resection nuclease Exo1 and BLM. EEPD1 depletion causes nuclear and cytogenetic defects, which are made worse by replication stress. Depleting 53BP1, which slows cNHEJ, fully rescues the nuclear and cytogenetic abnormalities seen with EEPD1 depletion. These data demonstrate that genome stability during replication stress is maintained by EEPD1, which initiates HR and inhibits cNHEJ and MMEJ. The cell itself damages its own DNA throughout the cell cycle as a result of oxidative metabolism, and this damage creates barriers for replication fork progression. Thus, DNA replication is not a smooth and continuous process, but rather one of stalls and restarts. Therefore, proper replication fork restart is crucial to maintain the integrity of the cell’s genome, and preventing its own death or immortalization. To restart after stalling, the replication fork subverts a DNA repair pathway termed homologous recombination. Using any other pathway for fork repair will result in an unstable genome. How the homologous recombination repair pathway is initiated at the replication fork is not well defined. In this study we demonstrate the previously uncharacterized EEPD1 protein is a novel gatekeeper for the initiation of this fork repair pathway. EEPD1 promotes 5’ end resection, the initial step of homologous recombination, which also prevents alternative fork repair pathways that lead to unstable chromosomes. Thus, EEPD1 protects the integrity of the cell genome by promoting the safe homologous recombination fork repair pathway.
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Affiliation(s)
- Yuehan Wu
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Suk-Hee Lee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Elizabeth A. Williamson
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Brian L. Reinert
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Ju Hwan Cho
- Department of Radiation Oncology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, United States of America
| | - Fen Xia
- Department of Radiation Oncology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, United States of America
| | - Aruna Shanker Jaiswal
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Gayathri Srinivasan
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Bhavita Patel
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Alexis Brantley
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Daohong Zhou
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Lijian Shao
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Rupak Pathak
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Martin Hauer-Jensen
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Sudha Singh
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
| | - Kimi Kong
- Department of Craniofacial Regeneration, College of Dental Medicine, Columbia University, New York, New York, United States of America
| | - Xaiohua Wu
- Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California, United States of America
| | - Hyun-Suk Kim
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Timothy Beissbarth
- Department of Medical Statistics, and General, Visceral, and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Jochen Gaedcke
- Department of Medical Statistics, and General, Visceral, and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Sandeep Burma
- Department of Radiation Oncology, University of Texas Southwestern, Dallas, Texas, United States of America
| | - Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail: (JAN); (RAH)
| | - Robert A. Hromas
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, Florida, United States of America
- * E-mail: (JAN); (RAH)
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You Y, Wen R, Pathak R, Li A, Li W, St Clair D, Hauer-Jensen M, Zhou D, Liang Y. Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway. Cell Death Dis 2014; 5:e1493. [PMID: 25341047 PMCID: PMC4237263 DOI: 10.1038/cddis.2014.443] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/04/2014] [Accepted: 09/08/2014] [Indexed: 11/09/2022]
Abstract
Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy.
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Affiliation(s)
- Y You
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - R Wen
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - R Pathak
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - A Li
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | - W Li
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - D St Clair
- Gratuate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
| | - M Hauer-Jensen
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - D Zhou
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Y Liang
- 1] Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA [2] Gratuate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
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Abstract
Chromosomal translocations are common contributors to malignancy, yet little is known about the precise molecular mechanisms by which they are generated. Sequencing translocation junctions in acute leukemias revealed that the translocations were likely mediated by a DNA double-strand break repair pathway termed nonhomologous end-joining (NHEJ). There are major 2 types of NHEJ: (1) the classical pathway initiated by the Ku complex, and (2) the alternative pathway initiated by poly ADP-ribose polymerase 1 (PARP1). Recent reports suggest that classical NHEJ repair components repress translocations, whereas alternative NHEJ components were required for translocations. The rate-limiting step for initiation of alternative NHEJ is the displacement of the Ku complex by PARP1. Therefore, we asked whether PARP1 inhibition could prevent chromosomal translocations in 3 translocation reporter systems. We found that 2 PARP1 inhibitors or repression of PARP1 protein expression strongly repressed chromosomal translocations, implying that PARP1 is essential for this process. Finally, PARP1 inhibition also reduced both ionizing radiation-generated and VP16-generated translocations in 2 cell lines. These data define PARP1 as a critical mediator of chromosomal translocations and raise the possibility that oncogenic translocations occurring after high-dose chemotherapy or radiation could be prevented by treatment with a clinically available PARP1 inhibitor.
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Abstract
BACKGROUND In vitro RBE values for various high LET radiation types have been determined for many different cell types. Occasionally it is criticized that RBE for a given endpoint cannot be single-value dependent on LET alone, but also on particle species, due to the different dose deposition profiles on microscopic scale. Hence LET is not sufficient as a predictor of RBE, and this is one of the motivations for development of radiobiological models which explicitly depend on the detailed particle energy spectrum of the applied radiation field. The aim of the present study is to summarize the available data in the literature regarding the dependency of RBE on LET for different particles. METHOD As RBE is highly dependent on cell type and endpoint, we discriminated the RBE-LET relationship for the three investigated cell lines and at the same endpoint (10% survival in colony formation). Data points were collected from 20, four and four publications for V79, CHO and T1, respectively, in total covering 228 RBE values from a broad range of particle species. RESULTS AND DISCUSSION All RBE-LET data points demonstrate surprising agreement within the general error band formed by the numerous data points, and display the expected RBE peak at around 100-200 keV/μm. For all three cell lines, the influence of varying the particle type on the RBE was far from obvious, compared to the general experimental noise. Therefore, a dependence of particle type cannot be concluded, and LET alone in fact does seem to be an adequate parameter for describing RBE at 10% survival.
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Affiliation(s)
- Brita Singers Sørensen
- Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark.
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Comparison of the micronucleus and chromosome aberration techniques for the documentation of cytogenetic damage in radiochemotherapy-treated patients with rectal cancer. Strahlenther Onkol 2010; 187:52-8. [PMID: 21234528 DOI: 10.1007/s00066-010-2163-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Accepted: 09/16/2010] [Indexed: 01/08/2023]
Abstract
PURPOSE The goal of the interdisciplinary Clinical Research Unit KFO179 (Biological Basis of Individual Tumor Response in Patients with Rectal Cancer) is to develop an individual Response and Toxicity Score for patients with locally advanced rectal cancer treated with neoadjuvant radiochemotherapy. The aim of the present study was to find a reliable and sensitive method with easy scoring criteria and high numbers of cell counts in a short period of time in order to analyze DNA damage in peripheral blood lymphocytes. Thus, the cytokinesis-block micronucleus (CBMN) assay and the chromosome aberration technique (CAT) were tested. MATERIALS AND METHODS Peripheral blood lymphocytes obtained from 22 patients with rectal cancer before (0 Gy), during (21.6 Gy), and after (50.4 Gy) radiochemotherapy were stimulated in vitro by phytohemagglutinin (PHA); the cultures were then processed for the CBMN assay and the CAT to compare the two methods. RESULTS A significant increase of chromosomal damage was observed in the course of radiochemotherapy parallel to increasing radiation doses, but independent of the chemotherapy applied. The equivalence of both methods was shown by Westlake's equivalence test. CONCLUSION The results show that the CBMN assay and the CAT are equivalent. For further investigations, we prefer the CBMN assay, because it is simpler through easy scoring criteria, allows high numbers of cell counts in less time, is reliable, sensitive, and has higher statistical power. In the future, we plan to integrate cytogenetic damage during radiochemotherapy into the planned Response and Toxicity Score within our interdisciplinary Clinical Research Unit.
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The influence of reduced glutathione on chromosome damage induced by X-rays or heavy ion beams of different LETs and on the interaction of DNA lesions induced by radiations and bleomycin. Mutat Res 2010; 696:154-9. [PMID: 20100593 DOI: 10.1016/j.mrgentox.2010.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 01/13/2010] [Accepted: 01/17/2010] [Indexed: 11/20/2022]
Abstract
It is thought that high linear energy transfer (LET) radiation induces more complex DNA damage than low-LET particles, specifically clustered DNA damage that causes cells to repair DNA double strand breaks (DSB) more slowly and leads to severe biological consequences. The present study aimed to investigate the role of exogenously added glutathione (GSH) on (12)C-beam (287keV/mum) and (7)Li-beam (60keV/mum) induced chromosome aberration (CA) formation, particularly on exchange aberration formation. In order to characterize the role of GSH in the joining of DNA DSBs, we induced DNA lesions with bleomycin (Blem) in conjunction with either high- or low-LET radiation (X-rays) since the chemistry of the free DNA ends created by Blem and X-rays is similar. CHO cells were exposed to reduced GSH at a concentration of 2mM for 3h before radiation. Treatment with Blem (20mug/ml) was carried out for 2h before the cells were exposed to radiation. Our results show that the frequency of chromosomal aberration increases with increased LET. Heavy ion exposed cells show a higher frequency of CA over time than do X-irradiated cells. An analysis of the first post-irradiation mitosis of exposed CHO cells shows that high-LET radiation induces more breaks than exchange-type aberrations and exogenous GSH has no influence on high-LET radiation-induced DNA damage. The DNA lesions induced by low-LET radiation interact relatively strongly with Blem-induced lesions whereas interaction between Blem and high-LET radiations was poor. This could be attributed to differences in repair kinetics and qualitative differences in the DNA lesions induced by Blem and high-LET radiation.
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Pathak R, Dey SK, Sarma A, Khuda-Bukhsh AR. Cell killing, nuclear damage and apoptosis in Chinese hamster V79 cells after irradiation with heavy-ion beams of (16)O, (12)C and (7)Li. Mutat Res 2007; 632:58-68. [PMID: 17532254 DOI: 10.1016/j.mrgentox.2007.04.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 04/07/2007] [Accepted: 04/14/2007] [Indexed: 01/09/2023]
Abstract
Chinese hamster V79 cells were exposed to high LET (linear energy transfer) (16)O-beam (625keV/mum) radiation in the dose range of 0-9.83Gy. Cell survival, micronuclei (MN), chromosomal aberrations (CA) and induction of apoptosis were studied as a follow up of our earlier study on high LET radiations ((7)Li-beam of 60keV/mum and (12)C-beam of 295keV/mum) as well as (60)Co gamma-rays. Dose dependent decline in surviving fraction was noticed along with the increase of MN frequency, CA frequency as well as percentage of apoptosis as detected by nuclear fragmentation assay. The relative intensity of DNA ladder, which is a useful marker for the determination of the extent of apoptosis induction, was also increased in a dose dependent manner. Additionally, expression of tyrosine kinase lck-1 gene, which plays an important role in response to ionizing radiation induced apoptosis, was increased with the increase of radiation doses and also with incubation time. The present study showed that all the high LET radiations were generally more effective in cell killing and inflicting other cytogenetic damages than that of low LET gamma-rays. The dose response curves revealed that (7)Li-beam was most effective in cell killing as well as inducing other nuclear damages followed by (12)C, (16)O and (60)Co gamma-rays, in that order. The result of this study may have some application in biological dosimetry for assessment of genotoxicity in heavy ion exposed subjects and in determining suitable doses for radiotherapy in cancer patients where various species of heavy ions are now being generally used.
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Affiliation(s)
- Rupak Pathak
- Department of Biotechnology, West Bengal University of Technology, Salt Lake Sector-I, Kolkata 700064, India
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