Fig. 3

Curcumin inhibited STAT3 activation in ESCC cells. a TE13 cells were transfected with vector or STAT3-luc by Lipofectamine^® 2000 for 24 h. Cells were then treated with 0, 8 or 16 μM curcumin for 12 h. Luciferase activity was measured followed by stimulation with IL-6 or vehicle control for 20 min. b EC9706 and TE13 cells were treated with different concentrations of curcumin for 24 h. Then, cells were prepared for immunoblotting against p-STAT3, STAT3 and GAPDH. c EC9706 and TE13 cells were treated with 16 μM curcumin for indicated time, followed by immunoblotting against p-STAT3, STAT3 and β-actin. d Following starved overnight in serum-free medium, EC9706 and TE13 cells were incubated with 0, 4, 8 or 16 μM curcumin for 4 h, then stimulated with IL-6 (50 ng/ml) for 20 min. The cells were lysed and analyzed by immunoblotting against p-STAT3, STAT3 and GAPDH. e mRNA levels of Cyclin D1, MCL1 and IL-6 were measured by qRT-PCR in TE13 cells treated with 0, 4, 8 or 16 μM curcumin overnight. *p < 0.05, **p < 0.01