Fig. 3.

ZIC5 positively regulates the phosphorylation of STAT3, although ZIC5 knockdown attenuates survival of PDAC and CCA cells despite interleukin (IL) -6-mediated activation of STAT3. (A) The levels of phosphorylated STAT3 (Tyr705) (pSTAT3) as well as of total STAT3 and GAPDH were determined in PANC-1 and RBE cells transfected with a negative control (siNeg) or ZIC5 (siZIC5) siRNA. Quantification of phosphorylated STAT3 levels normalized to total STAT3 are shown as mean ± SD (n = 3) in the bar graphs. Statistical analysis was performed using the two-tailed non-paired Student's t-test (**P < 0.01, *P < 0.05). (B) PANC-1 and RBE cells were transfected with siNeg or siZIC5. At 2 days after transfection, the cells were treated with 1% FBS with or without IL-6 (20 ng/mL) or IL-22 (50 ng/mL). After 24 h, the cells were harvested to assess the phosphorylation of STAT3. (C) The relative cell number was determined after 6 days of IL-6 treatment (20 ng/mL) with or without gemcitabine (gem) (0.1 μM) from three independent experiments. Statistical analysis was performed using the two-tailed Tukey's multiple comparison test (***P < 0.001, **P < 0.01, *P < 0.05).