Predictive effect of γH2AX expression on the radiosensitivity of glioma

Objective To observe the expression changes of γH2AX in high-grade glioma cell lines (U87, U251 and LN229) and to investigate the relationship between the expression of γ H2AX and the radiosensitivity of high-grade glioma cells in vitro. Methods The radiosensitivity of glioma U251, U87 and LN229 cell lines were measured by clone forming assay. Afte X-ray irradiation of different doses (0, 2, 4, 6, 8 and 10 Gy), the clone forming rates of 3 cell lines were measured, and cell survival curves were drawn. The DNA double-strand break (DSB) damage of 3 cell lines were determined by Western blotting assay. Results For glioma U251, U87 and LN229 cell lines, the survival fraction and clone forming rate were gradually decreased with the increase of Χ-ray radiation dose, and the radiotherapy sensitization enhancement ratio (SER) of U87 cells was slightly higher compared with LN229, U251 cells (P = 0.000, for all). In the Western blotting assay, the kinetics of the expression of γH2AX protein after irradiation was featured by increase and decay. The γH2AX expression of U87, LN229 and U251 cells after irradiation reached the peak value at 2 h, 1 h and 1 h respectively (P = 0.000, 0.000, 0.015). There was positive correlation between SER and γH2AX attenuation speed (r = 0.733, P = 0.025), as well as between SER and degree of increasing (r = 0.672, P = 0.047). Conclusions The phosphorylated histone γH2AX is expected to become a powerful tool to monitor DNA DSB and to predict the radiosensitivity in high-grade glioma nradiotherapy.