Figure 4

Nuclear PKM2-induced gefitinib resistance is mediated by STAT3.

(A) STAT3 was knocked down in HT29/PKM2-NLS cells by siRNA (50 nM final concentration for both STAT3-specific and negative control siRNA). (B) STAT3 siRNA reinstated gefitinib sensitivity of HT29/PKM2-NLS cells. The indicated cells lines were treated with gefitinib for three days, which was followed by an MTS assay, at two days after transfection. (C) Cleaved PARP and caspase-3 were detected with Western blotting in HT29/PKM2-NLS cells, which were transfected with STAT3 siRNA. (D) Flow cytometry was used to analyze the annexin V-positive population of HT29/PKM2-NLS cells. The final concentration of gefitinib was 10 μM. (E) Western blot analysis was employed to detect the expression level of cyclin D1 and p27kip1 in HT29/PKM2-NLS cells, which were transfected with STAT3 siRNA. (F) The proportions of cells in the different phases were quantified using flow cytometry. The final concentration of gefitinib was 10 μM.