Investigation of Genomic Instability in Clonal Descendants after X-ray Irradiation

Introduction Exposure of normal human fibroblasts to ionizing radiation may cause a delayed instability of the genome in the descendants of the initially irradiated cells [1, 2]. This genomic instability appears as a de novo formation of structural chromosomal aberrations and is considered as a step towards malignant transformation and induced carcinogenesis [3]. The relevance of effects, related to genomic instability, observed in different experimental setups, cell strains and the dependence on radiation quality are still under debate [4]. In recent (or previous) experiments we have shown the occurrence of genomic instability in the progeny of mixed cell populations of fibroblasts initially irradiated with high doses of X-rays [2]. To circumvent a selective pressure and population dynamics on the yield and types of chromosomal aberrations in bulk cultures and to investigate the fate of single cells, colonies formed by single cells after irradiation with X-rays were isolated and analysed for cytogenetic changes in the present study.