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Dynamic recognition and repair of DNA complex damage |
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| Authors: | Junfang Yan Yi Xie Qianjing Zhang Lu Gan Fang Wang Hongyan Li Jing Si Hong Zhang |
| Affiliation: | 1. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, Gansu, China Graduate School of University of Chinese Academy of Sciences, Beijing, China Yan and Xie have contributed equally to this work.;2. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China;3. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, Gansu, China Graduate School of University of Chinese Academy of Sciences, Beijing, China;4. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, Gansu, China |
| Abstract: | Irradiation (IR) can be used to treat cancer by inducing complex and irreparable DNA damage in the cancer cells, which may lead to their apoptotic death. However, little is known about the molecular mechanism of this DNA damage. Here, the non-small-cell lung cancer cell line A549 was treated with either X-ray or carbon ion combined with bleomycin (BLM). The cell survival rate, frequency of double-strand breaks (DSBs), dynamic changes in γH2AX, and p53 binding protein 1 (53BP1), and protein expression of Ku70, Rad51, and XRCC1 were determined by the clone formation assay, agarose gel electrophoresis, immunofluorescence, and western blot analysis. The results showed that the most obvious complex DSBs occurred in the carbon IR + BLM group. The number of γH2AX and 53BP1 foci in the 0.5 hr X-ray IR + BLM group was the highest (p < 0.001) among all the groups. γH2AX foci were detected in the nucleus at 0.5, 1, 2, and 4 hr, but were distributed throughout the cell at 6 hr after IR in the carbon ion IR + BLM group. The expression of Ku70 increased and XRCC1 decreased at 2 and 6 hr after IR. Our data indicate that a DNA damage frequency of 13.4/Mbp is caused by clustered DNA damage and further show a correlation between γH2AX, 53BP1, and XRCC1 levels and the extent of DNA damage. The results of this study provide insights into DNA damage recognition and a rationale for the clinical use of radiotherapy. |
| Keywords: | bleomycin carbon ion irradiation DNA damage |