Double-strand breaks on F98 glioma rat cells induced by minibeam and broad-beam synchrotron radiation therapy

Purpose To assess the DNA damage induced by MBRT and BB radiations on glioma cells. Methods The analysis of fluorescent intensity emitted per nucleus was plotted versus DNA content 2 and 17 h after irradiations. At around cell-doubling time (17 h) after exposures, the remaining DNA radiation damage could be correlated with cellular death. Results A higher γH2AX IF intensity per cell could be detected 2 and 17 h after MBRT when compared with BB. 17 h after MBRT, misrepaired damaged cells remained arrested in both G 1 and G 2 phases. Conclusions A pronounced G 2 phase arrest was detected at 17 h after MBRT and BB. However, only after MBRT, a dose-dependent increasing number of damaged cells appeared arrested also in the G 1 phase, and a higher amount of cells more prone to undergo apoptosis were detected. The threshold dose required to enhance the effectiveness of both synchrotron radiation techniques was 12 Gy.