Saratov JOURNAL of Medical and Scientific Research

Characteristics of changes in the number of yH2AX and Rad51 protein foci in human skin fibroblasts after prolonged exposure to low-dose rate X-ray radiation

Year: 2014, volume 10 Issue: №4 Pages: 739-743
Heading: Genetics Article type: Original article
Authors: Ozerov I.V., Eremin P.S., Osipov A.N., Eremin I.I., Tsvetkova A.D., Guseva S.S., Ivanova K.Yu., Gavrilenko 0.I., Pustovalova M.V., Smetanina N.M., Grekhova A.K., Lazareva N.L., Pullin A.A., Maksimova О.A., Gordeev A.V., Bushmanov A.Yu., Kotenko K.V.
Organization: Lomonosov Moscow State University, State Scientific Research Center n.a. A.I. Burnasyan — Federal Medical Biophysical Center of Federal Medical Biological Agency

Aim: to compare the repair process of DNA double-strand breaks in mammalian cells after acute versus prolonged exposure to X-ray irradiation with different dose rates. Material and methods. Studies were performed on primary human fibroblasts isolated from skin biopsies of healthy volunteers (women, 29 and 30 years). Cells were irradiated using an X-ray machine RUB RUST-M1 (JSC "Ruselectronics", Moscow, Russia) at 37°C temperature with a dose rate of 400 mGy/min (200 kV, 2*2.4 mA, a filter of 1.5mm AI) or 4 mGy/min (50 kV, 2*0.4 mA, a filter of 1.5 mm AI). Immuno-cytochemical protein staining was utilized for yH2AX and Rad51 foci analysis. Results. Phosphorylated histone H2AX (yH2AX) and the key protein of homologous recombination Rad51 foci formation and disappearance kinetics were investigated simultaneously in primary human dermal fibroblasts after acute and prolonged exposure to X-ray radiation at a same dose. It was shown that the relative yield of yH2AX foci per dose reduces with decrease in dose rate, while the relative yield of Rad51 foci conversely increases. Conclusion. Our findings suggest the fundamental differences in the ratio of non-homologous end joining and homologous recombination DNA repair in acute versus prolonged irradiated cells.

1. Vignard J, Mirey G, Salles B. lonizing-radiation induced DNA double-strand breaks: a direct and indirect lighting up. Ra-diother Oncol 2013; 108 (3): 362-369
2. Rodriguez-Rocha H, Garcia-Garcia A, Panayiotidis M, Franco R. DNA damage and autophagy. Mutat Res 2011; 711 (1-2): 158-166
3. Osipov AN, Buleeva G, Arkhangelskaya E, Klokov D. In vivo y-irradiation low dose threshold for suppression of DNA double strand breaks below the spontaneous level in mouse blood and spleen cells. Mutat Res 2013; 756 (1 -2): 141 -145
4. Ozerov IV, Bushmanov AYu, Anchishkina NA, et al. Induction and reparation of double-strand DNA breaks in V79 cells continuously exposed to low dose-rate y-radiation. Saratov J Med Sci Res 2013; 9 (4): 787-791
5. Kotenko KV, Bushmanov AY, Ozerov IV, et al. Changes in the number of double-strand DNA breaks in Chinese hamster V79 cells exposed to y-radiation with different dose rates. Int J Mol Sci 2013; 14 (7): 13719-13726
6. Kakarougkas A, Jeggo PA. DNA DSB repair pathway choice: an orchestrated handover mechanism. Br J Radiol 2014; 87 (1035): 20130685
7. Lim YC, Roberts TL, Day BW, et al. Increased sensitivity to ionizing radiation by targeting the homologous recombination pathway in glioma initiating cells. Mol Oncol 2014; 8 (8): 1603-1615
8. Bitomsky N, Hofmann TG. Apoptosis and autophagy: Regulation of apoptosis by DNA damage signalling — roles of p53, p73 and HIPK2. FEBS J 2009; 276 (21): 6074-6083
9. Alessio N, Del Gaudio S, Capasso S, et al. Low dose radiation induced senescence of human mesenchymal stromal cells and impaired the autophagy process. Oncotarget 2014 Dec 11. [Epub ahead of print]
10. Kuwahara Y, Oikawa T, Ochiai Y, et al. Enhancement of autophagy is a potential modality for tumors refractory to radiotherapy. Cell Death Dis 2011; 2: 177.

No votes yet