Figure 3. Signal transduction alterations involved in STAT3 after treatment with sorafenib and sunitinib and effects of STAT3C on cytotoxicity of sorafenib and sunitinib.

(A) HaCaT, Caki-1, and HepG2 cells were incubated with a medium that included sorafenib or sunitinib at the indicated concentrations for 2 h. Thereafter, Western blot analysis was performed using total cell lysates. (B) Immunostaining images. HaCaT cells were treated with sorafenib (10 µM), sunitinib (10 µM), or DMSO (Control; cont) for 2 h and were fixed and incubated with an anti-STAT3 antibody, followed by incubation with FITC-conjugated anti-rabbit IgG (green), and then visualized with the IN Cell Analyzer 2000. Nuclear translocation of STAT3 was determined with cell population analysis by determining the nucleus/cytoplasm intensity ratio of green fluorescence. Bar shows 50 µm. (C) Effects of STAT3C transfection on sorafenib- and sunitinib-induced cell growth inhibition. HaCaT cells transiently transfected with STAT3C or an empty vector were preincubated for 24 h, followed by incubation in medium containing sorafenib or sunitinib at the indicated concentrations for 48 h. Cell viability was determined by WST-8 colorimetric assay. *p<0.01 (Student’s t-test) as compared with control (DMSO). Each bar represents mean ± SD (n = 4).