title: Mitotic DNA damages induced by carbon-ion radiation incur additional chromosomal breaks in polyploidy.
abstract: Compared with low linear energy transfer (LET) radiation, carbon-ion radiation has been proved to induce high frequency of more complex DNA damages, including DNA double strands (DSBs) and non-DSB clustered DNA lesions. Chemotherapeutic drug doxorubicin has been reported to elicit additional H2AX phosphorylation in polyploidy. Here, we investigated whether mitotic DNA damage induced by high-LET carbon-ion radiation could play the same role. We demonstrate that impairment of post-mitotic G1 and S arrest and abrogation of post-mitotic G2-M checkpoint failed to prevent mis-replication of damaged DNA and mis-separation of chromosomes. Meanwhile, mitotic slippage only nocodazole-related, cytokinesis failure and cell fusion collectively contributed to the formation of binucleated cells. Chk1 and Cdh1 activation was inhibited when polyploidy emerged in force, both of which are critical components for mitotic exit and cytokinesis. Carbon-ion radiation irrelevant of nocodazole incurred additional DNA breaks in polyploidy, manifesting as structural and numerical karyotype changes. The proliferation of cells given pre-synchronization and radiation was completely inhibited and cells were intensely apoptotic. Since increased chromosomal damage resulted in extensive H2AX phosphorylation during polyploidy, we propose that the additional γ-H2AX during polyploidy incurred by carbon-ion radiation provides a final opportunity for these dangerous and chromosomally unstable cells to be eliminated.
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China.
authors.forename: Libin
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China.
authors.forename: Xiongxiong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Jin
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Ye
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China.
authors.forename: Xinguo
authors.initials: X
authors.lastname: Liu
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Hirayama
authors.affiliation: Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China. Electronic address: liqiang@impcas.ac.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
mesh_terms: D015703:Antigens, CD; D017209:Apoptosis / Q000528:radiation effects; D015820:Cadherins / Q000378:metabolism; D049109:Cell Proliferation / Q000528:radiation effects; D000071877:Checkpoint Kinase 1; D019457:Chromosome Breakage; D004249:DNA Damage; D005260:Female; D059585:G1 Phase Cell Cycle Checkpoints / Q000528:radiation effects; D059565:G2 Phase Cell Cycle Checkpoints / Q000528:radiation effects; D006367:HeLa Cells; D063193:Heavy Ion Radiotherapy; D006657:Histones / Q000378:metabolism; D006801:Humans; D008938:Mitosis / Q000528:radiation effects*; D010766:Phosphorylation; D011123:Polyploidy; D011494:Protein Kinases / Q000378:metabolism; D011836:Radiation Tolerance; D013997:Time Factors; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; C468783:H2AX protein, human; D006657:Histones; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1
keywords: Carbon–ion radiation; Checkpoint; Chromosome instability; H2AX phosphorylation; Polyploidy