Effects of circulating IL-6 on tumor aggressiveness. a. The levels of IL-6 in cell supernatant and serum of mice bearing tumors with or without IL-6 silencing vectors were examined by ELISA. Columns, means of 3 separate experiments; bars, SD. *, P < 0.05. b. Serum IL-6 levels of patients were examined by ELISA analysis. Columns are the means of specimen; Bars, SD; *, P < 0.05. (LR = Local-regional Recurrence /persistent; DM = distant metastasis). c. IHC using MMP-9, E-cadherin, CD31, and VEGF staining in tumors 20 days after implantation. IL-6 silencing vectors were significantly reduced by the angiogenesis and EMT-related changes as compared with control-GFP vector. 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).