Figure 4

VPA attenuates radiation-induced DNA damage repair in Hep3B cells. (a) DNA damage repair after photon or proton irradiation was assessed by γ-H2AX immunostaining. γ-H2AX foci (green) in nuclei (blue) were visualized at 2 h and 24 h after irradiations. Scale bar, 20 µm. (b) Quantification of the number of γ-H2AX foci per cell. Data are mean values ± SD of twelve cells. n.s., not significant; *p < 0.05; **p < 0.01. (c) Western blot analysis reveals combined treatment with proton and VPA led to delayed abrogation of γ-H2AX. (d) Combined treatment with proton and VPA led to persistent activation of ATM and ATR. The samples were harvested 72 h after 6 Gy irradiation. β-actin is used as a loading control. The cropped blots are presented and their full-length blots are included in the Supplementary Fig. S1.