Figure 4.

The role of STAT3 in SP4–mediated VEGF induction by the IL-6 + sIL-6R complex. (A and B) Kinetics of STAT3 and SP4 mRNA induction in HPMCs treated with IL-6 + sIL-6R (both at 100 ng/ml). *P<0.05 versus control cells at each time point (n=4). (C–F) Effect of STAT3 silencing on STAT3, SP4, and VEGF expression. Cells were transiently transfected with either STAT3 siRNA or scrambled (scramb.) siRNA and then, stimulated with IL-6 + sIL-6R (both at 100 ng/ml) for 9 hours. Cells were assessed for (C) STAT3 protein expression by Western blotting and mRNA expression by quantitative PCR for (D) STAT3, (E) SP4, and (F) VEGF. In C, a representative immunoblot is presented together with quantified data from four independent experiments. STAT3 protein expression was normalized per that of glyceraldehyde 3-phosphate dehydrogenase (GAPDH). *P<0.05 versus cells stimulated with IL-6 + sIL-6R in the absence of siRNA (n=4).