Figure 7

γH2AX expression in MRT xenografts treated with ionizing radiation (XRT) or suberoylanilide hydroxamic acid (SAHA) and XRT. The mice were treated with either vehicle control, SAHA 100 mg/kg for two consecutive days, XRT (10 Gy) or SAHA (100 mg/kg) on two consecutive days with XRT (10 Gy) on the second day of SAHA treatment. After 30 min, tumors of mice treated with XRT and SAHA showed a significantly higher induction of γH2AX expression compared to tumors treated with XRT alone. γH2AX expression decreased successively from 2 h to 6 h and 24 h after XRT. 24 h after XRT, γH2AX expression of irradiated tumors reached the level of the untreated controls whereas the tumors of the combination group showed still an elevated expression level.