Assessment of human fibroblast radiosensitivity by the micronucleus and colony-forming assay
摘要
The relationship between radiosensitivity of normal human skin fibroblasts determined by the micronucleus (Mn) assay and the colony-forming assay was investigated. Prediction of radiation-induced normal-tissue response in individuals necessitates a rapid and reproducible in vitro assay that correlates well with cell survival after irradiation. The Mn-assay is a quick test that was applied to primary skin biopsies from 10 unselected breast cancer patients in whom a significant correlation previously was found between the expression of subcutaneous fibrosis after radiotherapy and the cell surviving fraction at SF3.5 (Spearman's rho = −0.81,P < 0.01). Early generations of fibroblasts in exponential growth were irradiated with 250 kV X-rays at room temperature. The micronucleus frequency in Cytochalasin B-induced binucleated cells (Mn/BNC) was scored after doses of 0, 1, 2, and 3.5 Gy, and Mn/BNC after irradiation with 3.5 Gy was estimated (range 1.11-1.77). Mn/BNC at 3.5 Gy showed no correlation with SF3.5 as determined by the colony-forming assay. A possible reason for lack of correlation include variable numbers of scorable binucleated cells after irradiation with 3.5 Gy (4%-21%).