Figure 3

Effects of IL-6 on the radiosensitivity of prostate cancer. The IL-6–silencing vector significantly decreased IL-6 expression in tumor cells after irradiation, as demonstrated by Western blotting in vitro, IHC in vivo (a). The effects of IL-6 on in vitro radiosensitivity were evaluated using irradiated prostate cancer cells treated with vectors or IL-6–silencing vectors; (b) FACS with PI and Annexin V staining 24 h after 9-Gy irradiation and clonogenic assays; (c) Intracellular ROS levels as measured by the fluorescent dye DCFH-DA in prostate cancer cells, and immunofluorescence staining of oxidative DNA damage (DAPI, blue; 8-oxoG, red), 30 min after irradiation. Columns show the mean of three independent experiments; bars, SD. *, P < 0.05. (d) Effects of IL-6 on in vivo radiosensitivity were evaluated by means of the growth delay of ectopic prostate tumors following 15-Gy irradiation. Y-axis shows the tumor volume ratio at each time point, divided by that at the time of irradiation. (CV = cells transfected with control vectors; IL-6 SV = cells transfected with IL-6 silencing vectors). The effects of IL-6 on the expressions of activated STAT3, p53 and AR (e) and the sensitivity of radiation (f) were assessed using cells pre-incubated in the presence or absence of 5 ug/ml IL-6 neutralizing antibody for 24 h.