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Daudee R, Gonen R, German U, Orion I, Alfassi ZB, Priel E. DNA Topoisomerase IB as a Potential Ionizing Radiation Exposure and Dose Biomarker. Radiat Res 2018; 189:652-660. [PMID: 29633912 DOI: 10.1667/rr14859.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In radiation exposure scenarios where physical dosimetry is absent or inefficient, dose estimation must rely on biological markers. A reliable biomarker is of utmost importance in correlating biological system changes with radiation exposure. Human DNA topoisomerase ІB (topo І) is a ubiquitous nuclear enzyme, which is involved in essential cellular processes, including transcription, DNA replication and DNA repair, and is the target of anti-cancer drugs. It has been shown that the cellular activity of this enzyme is significantly sensitive to various DNA lesions, including radiation-induced DNA damages. Therefore, we investigated the potential of topo I as a biomarker of radiation exposure and dose. We examined the effect of exposure of different human cells to beta, X-ray and gamma radiation on the cellular catalytic activity of topo I. The results demonstrate a significant reduction in the DNA relaxation activity of topo I after irradiation and the level of the reduction was correlated with radiation dose. In normal human peripheral blood lymphocytes, exposure for 3 h to an integral dose of 0.065 mGy from tritium reduced the enzyme activity to less than 25%. In MG-63 osteoblast-like cells and in human pulmonary fibroblast (HPF) cells exposed to gamma radiation from a 60Co source (up to 2 Gy) or to X rays (up to 2.8 Gy), a significant decrease in topo I catalytic activity was also observed. We observed that the enzyme-protein level was not altered but was partially posttranslational modified by ADP-ribosylation of the enzyme protein that is known to reduce topo I activity. The results of this study suggest that the decrease in the cellular topo I catalytic activity after low-dose exposure to different radiation types may be considered as a novel biomarker of ionizing radiation exposure and dose. For this purpose, a suitable ELISA-based method for large-scale analysis of radiation-induced topo I modification is under development.
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Affiliation(s)
- Rotem Daudee
- a The Shraga Segal Department of Immunology, Microbiology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.,c Nuclear Research Center, Negev, Beer Sheva, Israel
| | - Rafi Gonen
- a The Shraga Segal Department of Immunology, Microbiology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.,c Nuclear Research Center, Negev, Beer Sheva, Israel
| | - Uzi German
- c Nuclear Research Center, Negev, Beer Sheva, Israel
| | - Itzhak Orion
- b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Zeev B Alfassi
- b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Esther Priel
- a The Shraga Segal Department of Immunology, Microbiology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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