Characterization of human thyroid cells exposed to heavy ions

Chromosomal aberrations (CAs) are useful biomarkers for radiation exposure, as their frequencies are related to absorbed dose and they are related to an increased risk of cancer induction [1]. Epidemiological studies of the population exposed during Chernobyl accident demonstrate that thyroid cancer is a typical radiation induced tumour. These data provide risk estimates of thyroid cancer induction for low LET radiation exposure. No data are available for heavy ions irradiation. Gene analysis of papillary thyroid carcinomas in children of the Chernobyl area [2] show in more than 87% a characteristic family of CAs, the RET/PTC family, involving the RET gene mapped on chromosome 10 and other gene located mostly on the same chromosome (intrachanges, CAs produced from DNA breaks on the same chromosome). The aim of our project is to examine aberrations in chromosome 10 after high and low LET irradiation to obtain a biological estimate for the different efficiency in intrachange induction (RBE). Characterization of the cell line selected for this study (H-Tori 3 cells) is necessary. Here we present the data concerning the delayed reproductive death, an index of radiation-induced genomic instability [3]. H-Tori 3 cells have been exposed to different doses of Fe ions and subcultivated for a long time in order to measure their clonogenic capability many generations after exposure. We also present early data from cytogenetic analysis on unirradiated sample.