Fig. 5

STAT3 mediates the function of FZKA on enhancing Gefitinib-induced cell apoptosis. a, b The expression of STAT3 was obviously inhibited in the combined group when treated with FZKA and Gefitinib at both mRNA and protein levels. qRT-PCR and western blot were done to test the expression of STAT3 at mRNA and protein levels in lung cancer cells (A549 and PC9) treated with FKZA, Gefitinib, or FZKA combined with Gefitinib for 24 h, respectively. *p < 0.05; one-way ANOVA. The qRT-PCR data were analyzed with 2^−ΔΔCt for relative changed in gene expression. GAPDH was used as an internal control. Densitometric analysis was performed using ImageJ. c STAT3 was silenced in A549 cells transfected with siSTAT3 (#1, 2 and 3). Western blot was performed to verity the protein expression of STAT3 after transfecting with siSTAT3 (left panel). qRT-PCR was performed to verify the STAT3 expression at mRNA level by transfecting with siSTAT3 (right panel). ***p < 0.0001; Student’s t-test; siSTAT#1, 2 and 3 was compared to NC, respectively. The qRT-PCR data were analyzed with 2^−ΔΔCt for relative changed in gene expression. GAPDH was used as an internal control. Densitometric analysis was performed using ImageJ. d Cell apoptosis was greatly induced in the siSTAT3 group when treated with the combination of FZKA with Gefitinib. Flow cytometry of cell apoptosis was performed in A549 cells when treated with FZKA combined with Gefitinib as well as transfecting with siGAP, or NC, or siSTAT3. ***p < 0.0001; one-way ANOVA. Data represent mean ± SD of three independent experiments