Evaluation of radiation-induced DNA damage and DNA repair in human lung cancer cell lines with different radiosensitivity using alkaline and neutral single cell gel electrophoresis

Using the comet assay, radiation-induced DNA strand breaks were evaluated in human lung cancer cell lines with different radiosensitivity (U-1285, U-1906E, U-1752 and U-1810). Single strand breaks were more sensitive indicators of the radiation-induced damage than double strand breaks. However, there was no consistent pattern in the way the various cell lines responded to 1–5 Gy of γ-irradiation and all cell lines showed a remarkably efficient DNA repair after 1 h. In a separate study of the repair kinetics of DNA double strand breaks, the radioresistant cell line U-1810 showed a more efficient initial strand rejoining than the radiosensitive cell line U-1285 after irradiation at 2 Gy. The latter finding suggests that the detection of early DNA repair may be useful when monitoring the intrinsic radiosensitivity of human lung cancer cells.