Effects of IL-6 on radiation responses. a. Cells were irradiated with 0, 2, 4, 6, and 8 Gy, and survival curves were constructed using colony-forming assay data. Data represent the means of three experiments. *, p < 0.05. IL-6 silencing vectors significantly sensitized tumor cells to irradiation. b. Effects of IL-6 on in vivo radiosensitivity, as assessed by evaluation of tumor growth following irradiation (15 Gy). The y-axis shows the tumor volume ratio at each time point, divided by the tumor volume at irradiation. (C-V, cells transfected with the control vector; IL-6 SV, cells transfected with the IL-6 silencing vector). c. The in vitro effects of IL-6 inhibition on p-STAT3 and p-H2AX levels and cell death, as evaluated by IHC staining and Annexin V-PI staining in irradiated cells. d. An IL-6-silencing vector decreased angiogenesis in tumors, as evaluated by immunoblotting and IHC analysis of tumor specimens 14 days after local irradiation. Representative slides are shown. The Y axis represents the ratio normalized by the value of target protein in tumor transfected with control vectors. Columns, means of 3 separate experiments; bars, SD. *, P < 0.05. (C-V, cells transfected with the control vector; IL-6 SV, cells transfected with the IL-6 silencing vector).