Chronic exposure to low-dose of X-rays induces DNA double-strand breaks in mammalian cells

GRILLO, C.A. AND GUERCI, AM

International Journal of Low Radiation

Inderscience

Año: 2011 vol. 8 p. 198 - 213

1477-6545

The purpose of present study is to evaluate the induction ofclastogenic effect after chronic exposure to low dose of ionising radiation inboth CHO-K1 cells and in their DNA Double-Strand Breaks (DSBs)-repairdeficient mutant xrs-5. Cells were cultured for 14 dilution cycles and grown toconfluency. Radiation treatment was performed once per cycle with 10 mGyX-rays to carry out the structural chromosome aberration test. The resultsshowed a significant increase in the frequency of achromatic lesions(p < 0.001) in CHO-K1 cells. In addition, xrs-5 cells showed an increase ofchromatid and chromosome-type aberrations (p < 0.001). Sequential exposureproduced a level of DNA damage that is amplified through successive cyclestriggering the efficient repair of DSBs. The increased damage in xrs-5 cellsprovides evidence that the non-homologous end-joining repair of DNA DSBsis involved after low dose X-ray exposure.