PMID: 11316567Apr 24, 2001

Cell cycle and growth response of CHO cells to X-irradiation: threshold-free repair at low doses

International Journal of Radiation Oncology, Biology, Physics
D BartkowiakE M Röttinger


To test the hypothesis of a threshold for induced repair of DNA damage (IR) and, secondarily, of hyperradiosensitivity (HRS) to low-dose X-irradiation. Exponentially growing Chinese hamster ovary cells (CHO) were X-irradiated with doses from 0.2 to 8 Gy. Survival data were established by conventional colony-forming assay and flow-cytometric population counting. The early cell cycle response to radiation was studied based on DNA-profiles and bromodeoxyuridine pulse-labeling experiments. Colony-forming data were consistent with HRS. However, these data were of low statistic significance. Population counting provided highly reproducible survival curves that were in perfect accord with the linear-quadratic (LQ) model. The dominant cell cycle reaction was a dose-dependent delay of G2 M and late S-phase. There was no evidence for a threshold of IR and for low-dose HRS in X-irradiated CHO cells. It is suggested that DNA damage repair activity is constitutively expressed during S-phase and is additionally induced in a dose-dependent and threshold-free manner in late S-phase and G2. The resulting survival is precisely described by the LQ model.


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Jun 28, 2003·International Journal of Radiation Oncology, Biology, Physics·Jack F FowlerDavid J Brenner
Jul 2, 2014·Cancer Letters·Lynn M MartinLaure Marignol
Apr 18, 2002·International Journal of Radiation Oncology, Biology, Physics·Nicole Boehringer-WyssAbdelkarim S Allal
May 23, 2013·Cancer Letters·Lynn M MartinLaure Marignol
Jun 16, 2010·International Journal of Radiation Biology·Shumei MaXiaodong Liu
Apr 4, 2008·International Journal of Radiation Biology·Sarah KoenigHans Christiansen
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Jul 6, 2004·International Journal of Radiation Oncology, Biology, Physics·Timothy M Pawlik, Khandan Keyomarsi
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May 26, 2006·Physics in Medicine and Biology·L M GarciaG P Raaphorst

Related Concepts

Cell Cycle
Cell Division Phases
Cell Survival
Colony-Forming Units Assay
DNA, Double-Stranded
Genotoxic Stress
Base Excision Repair
Dose-Response Relationship, Radiation
Radiation Tolerance

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