Differential response of two cell lines sequentially irradiated with low X-ray doses

A.M. GÜERCI, F.N. DULOUT, C.A. GRILLO AND A.I. SEOANE

INTERNATIONAL JOURNAL OF RADIATION BIOLOGY

Taylor and Francis Group

Año: 2005 vol. 81 p. 367 - 372

1362-3095

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mso-level-tab-stop:324.0pt; mso-level-number-position:right; text-indent:-9.0pt;} ol {margin-bottom:0cm;} ul {margin-bottom:0cm;} --> An experiment was designed ir order to compare the effect of repeated low doses of X-rays in two different cell lines: one transformed, epithelial like and aneuploid (CHO-K1) and the other originated from a primary culture, fibroblasts, diploid and non transformed (MRC-5). Materials and methods: CHO and MRC-5 cells were cultured for 14 or 8 passages respectively. Irradiation treatment was performed once per passage, and three irradiation doses were employed: 2.5, 5.0 and 10.0 mSv. Results:  Ionizing radiation did not induce apoptosis nor necrosis in the exposed CHO cell population. Significant increases of low level damage cells were found for the 14 expositions when compared with controls, except for the first irradiation. No significant increase of the frequency of cells with severe damage was observed. The frequency of MRC-5 cells with low damage increase significantly when compare to controls for expositions 7 and 8. Significant increaments of apoptosis, necrosis and severe damage was found only for the highest dose. Conclusions: Transformed and non-transformed phenotype could be related with the occurence of direct and indirect damage by this kind of exposure. Even more investigation is needed to understand the mechanisms of radiation effects in chronic low dose exposed cell populations, cellular type should be taken into account in order to design in vitro experiments for understanding low dose irradiation effects.