Correlation between cell reproductive death and chromosome aberrations assessed by FISH for low and high doses of radiation and sensitization by iodo-deoxyuridine in human SW-1573 cells

Abstract

Purpose : To study the relationship between cell reproductive death and exchange frequency in SW-1573 human lung tumour cells with and without incorporated iodo-deoxyuridine (IdUrd) following irradiation of plateau-phase cultures with gamma -rays. Method : Linear-quadratic (LQ) analysis was performed for the data on clonogenicsurvival and on the frequency of chromosomal exchanges studied with fluorescence in situ hybridization in chromosomes X and 2. Results : Differences in the LQ parameters alpha and beta of both nonsensitized and sensitized chromosomes were found. In both chromosomes an increase in the number of chromosomal exchanges in IdUrd-radiosensitized cells compared with nonsensitized cells was observed. The alpha -enhancement factors of 1.7 and 1.9 for the X-chromosome and for chromosome 2, respectively, are similar. For the X-chromosome, the beta coefficient increased by a factor of 3.9 and for chromosome 2 by a factor of 1.4. After correction to a full genome equivalence, no significant difference in alpha was found between chromosomes X and 2 for both control and sensitized cells. In contrast, an almost 2.8 times higher beta was found for the sensitized X-chromosome compared to this value for chromosome 2. Conclusions : It can be concluded that the linear-quadratic analysis of dose-response relationships offers insights into the correlation between cell survival and induction of exchanges in nonsensitized and radiosensitized cells.