Fig. 3

Inhibitory efficacy of CPA-7 on STAT3 activity. a, functional depletion of activated STAT3 in RM-9 cells. RM-9 cells were incubated for 24 h with CPA-7 at the indicated doses or vehicle containing 1 % DMSO, respectively. Total protein was isolated and thereafter western blot was performed against STAT3, pSTAT3, and Bcl-xL. Immunobloting against β-tubulin was included as control. b, transcriptive activity of STAT3 determined by luciferase reporter assay. HEK-293 T cells were maintained and transfected with vectors as indicated in the Materials and Methods. After CPA-7 or vehicle treatment, total protein was extracted and STAT3 specific firefly luciferase activity was determined, with normalization to renilla luciferase activity. c, d and e, in vivo level of pSTAT3 after CPA-7 treatment. pSTAT3 positive cells were calculated by individually counting three different random microscope fields in the central regions of the tumor tissues (d) or in the infiltrating areas (e). Percentage of positive rate in the central region of the tumor tissues was obtained by dividing each number with the total number of cells in the corresponding field (c). *, P < 0.05, **, P < 0.01, ***, P < 0.001 when compared with the vehicle group