Cyogenetics effects in AG01522 human primary fibroblasts exposed to low doses of radiations with different quality

Abstract

Purpose: Biological effects produced by low doses of ionizing radiations, though relevant for the risk assessment, have not been fully elucidated. The aim of the present work was to evaluate cytogenetic endpoints, as telomere dysfunctions and chromosome instability in the low-dose range as a function of radiation quality. In particular, we analyzed whether the telomere length was modulated, as well as the involvement of telomeres in chromosomal alterations at anaphase, and the yield of stable simple and complex chromosome aberrations.

Materials and methods: AG01522 human primary fibroblasts were irradiated with 0.1–1 Gy of X-rays, protons (28.5 keV/μm), and 4He²⁺ ions (62 keV/μm). Frequency of chromosome bridges carrying or not telomeric signals and telomere length were measured in irradiated samples up to 72 h. Moreover, chromosome instability was measured using multicolor fluorescence in situ hybridization (mFISH).

Results: The results evidenced a linear energy transfer (LET)- and dose-dependent response in the frequency of anaphase bridges induction and in their persistence as a function of time. However, neither variation in telomere length and telomere loss, nor in the proportion of bridges bearing telomeric signals, was detected, thus indicating a minor role of telomeres in the generation of the radiation-induced chromosome bridges. Chromosome instability followed a linear-dependence with dose and LET, showing a far higher extent of complex translocations in helium-ion-irradiated cells than in proton- or X-ray-irradiated samples.

Conclusions: Altogether, the results indicated the lack of telomere involvement in cytogenetic effects induced by low-dose ionizing radiation. On the contrary, chromosome aberration yield and spectrum were LET- and dose-dependent.

Keywords::

• Human primary fibroblasts
• ionizing radiations
• low-energy protons
• helium-4 ions
• telomere
• chromosome bridges
• chromosome aberrations
• mFISH
• complex translocations

Acknowledgements

The authors are grateful to Mr L. Maran and Mr L. Pranovi for their technical assistance during the 7MV CN accelerator operations. An acknowledgement is given to Dako as the supplier of the chromosome 2 centromeric PNA probe. We would also like to thank Luisella Mattace for editorial assistance.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Supported by INFN CSN5 (Experiment EXCALIBUR). D.N. is a PhD fellow at the Department of Sciences, Roma Tre University.