Figure 2

IL-17 activates AKT and IL-6/STAT3, and up-regulates proinvasive factors production in SMMC7721 cells. (A) Western blotting showed that phosphorylation of JAK2, STAT3 and AKT were obviously increased as early as 3 h after IL-17 treatment and lasted for 24 h after IL-17 stimulation. SMMC7721 cells were incubated with IL-17 at the indicated concentrations for 24 h or at 50 ng/ml for the indicated time. (B and C) Cells were cultured for 24 h with IL-17 (50 ng/ml). In siRNA-STAT3-SMMC7721 cells, IL-17-induced AKT and JAK2 phosphorylation were not affected, while in siRNA-AKT-SMMC7721, IL-17-induced JAK2/STAT3 phosphorylation was significantly reduced. (D) IL-17-induced AKT phosphorylation was obviously increased as early as 5 minutes after IL-17 treatment, while phosphorylation of JAK2 and STAT3 were not affected during the 60 minutes treatment. (E) HCC cells were cultured for 24 h with IL-17 (50 ng/ml) and/or IL-6 mAb (10 ng/ml), and concentrations of the proinvasive factors in culture supernatants were measured by ELISA. IL-17 selectively up-regulated the production of IL-6, IL-8, MMP2 and VEGF by tumor cells. Both IL-6 mAb and siRNA-STAT3 significantly downregulated the expression of IL-8, MMP2 and VEGF, while IL-17-induced IL-6 upregulation was not altered. (F) IL-6 mAb reduced STAT3 activation, whereas AKT activation by IL-17 was not affected. Data are expressed as mean ± SD; Student's t test; # p > 0.05; *p < 0.05, **p < 0.01, and ***p < 0.001.