Studies on the influence of DNA repair on radiosensitivity in prostate cell lines
The relationship between radiosensitivity and DNA repair was investigated in six human prostate cell lines, 1542-NPTX, BPH-1, 1542-CP3TX, 1532-CP2TX, 1535-CP1TX and LNCaP. Except for LNCaP, these cell lines are new and were derived from primary prostate tumours and normal non-tumourigenic prostate tissue. Cell survival was assessed by clonogenic assay. DNA damage was determined in non-synchronised cells by constant-field gel electrophoresis, and expressed as the fraction of DNA released. For initial damage, cells were embedded in agarose and irradiated on ice with 0-100 Gy 60Co γ-irradiation. Residual DNA damage was measured after 2 h and 20 h of repair. Radiosensitivity, given as the mean inactivation dose, was found to vary between 1.62 and 2.77 Gy. We found that radiosensitivity significantly correlates with the 2 h DNA repair component, giving a correlation coefficient of 0.92 (P=0.009). In the cell lines examined here the 2 h repair component emerges as an indicator of radiosensitivity.