DNA damage in Chinese hamster cells repeatedly exposed to low doses of X-rays

2- GÜERCI, ALBA M; DULOUT, FERNANDO N. AND SEOANE ANALÍA

CYTOGENETIC AND GENOME RESEARCH

Editada por: Klinger, H.P. Schmid, M.

Lugar: Suiza; Año: 2004 vol. 104 p. 173 - 177

1424-8581

In a recent paper we reported the results of an experiment carried out by analysing chromosomal damage in Chinese hamster (CHO) cells exposed to low doses of X-rays. The present investigation was undertaken in order to validate those results using a different approach, the single cell gel electrophoresis assay (comet assay) immediately after irradiation. Cells were cultured  during 14 cycles, irradiation treatment was performed once per cycle when the cells are at 90-95 % of confluence. Doses of 2.5, 5.0 and 10.0 mSv were employed. Sequential irradiation of CHO cells induced a decrease of cells without migration and an increase of cells showing DNA damage with the three doses employed. Significant increases of low level damaged cells    (p < 0.001) were found for the 14 exposures when compared to controls except for the first irradiations with 2.5 and 10 mSv respectively. No significant increase of the frequency of cells with severe damage was observed in any case. These findings could be explained assuming a complex interactive process of cell recovering, DNA damage and repair together with the induction of genomic instability, the incidence of bystander effects as well as some kind of radioadaptative response of the cell line. If these phenomena are limited to the cell line employed deserves further investigation.