FURTHER-STUDIES ON THE POSSIBLE RELATIONSHIP BETWEEN RADIATION-INDUCED RECIPROCAL TRANSLOCATIONS AND INTRINSIC RADIOSENSITIVITY OF HUMAN TUMOR-CELLS

Background and purpose. The aim of the present study was to estimate y ields of radiation-induced translocations in surviving cells of severa l human tumor cell lines and in normal diploid human fibroblasts, and to compare these yields with corresponding intrinsic radiosensitivitie s determined by standard colony-formation assay. Material and methods. The yields of radiation-induced reciprocal translocations were invest igated by fluorescence in situ hybridization. Chromosomes no. 1 and no . 4 were 'painted' with fluorescent hybridization probes for whole chr omosomes. Translocation yields and cell survival were determined for d ifferent doses. up to 6 Gy of 200 kV X-rays. Results. We observed a hi gher frequency of reciprocal translocations in the radiosensitive cell s MCF-7 and MDA-MB-436 than in the radioresistant cells CaSki, WiDr, A 549 and normal skin fibroblasts. For primary squamous cell carcinoma c ells, ZMK-1, an intermediate radiosensitivity and an intermediate tran slocation yield were observed. The dose-dependence of translocation yi elds involving chromosomes no. 1 or no. 4 varied in different cell lin es: it was linear or linear with a plateau at higher doses. Conclusion s. A comparison of the data obtained with chromosomes no. 1 and no. 4 in the investigated cell types, indicates that intrinsic radiosensitiv ity of different tumor cells observed at the survival level, is correl ated with different translocation yields, respectively. This correlati on was observed for all cell types investigated, independent of the nu mber of copies of the painted chromosome per cell or the radiation dos e. However, for low doses (under 1 Gy), the yields of translocations d etermined for the individual chromosomes seem to be too low for a disc rimination between radioresistant or radiosensitive cells.