Fig. 3

Effect of STAT3 inhibition on PD-L1 and EGFR expression in HCT116-MR colon cancer cells. a. The mRNA expression levels of STAT3, PD-L1 and EGFR 24 h, 48 h, and 72 h after transfection with a specific siRNA targeting STAT3 in HCT116-MR cells. One way anova test: *p < 0.05, ***p < 0.001 compared with the control. b. Western blot analysis of cell signalling proteins in HCT116-MR cells transfected with a specific siRNA targeting STAT3 or with a scrambled, control siRNA for 24, 48 and 72 h. Total cell protein extracts were subjected to immune-blotting with the indicated antibodies, as described in Materials and Methods. c. HCT116-MR cells were transfected with siRNA targeting STAT3. 72 h after transfection, cells were treated with increasing concentrations of MEKi (BAY86–9766, range 0–15 μM). Cells were evaluated for proliferation after 48 h by MTT staining. The results are average ± SD of three independent experiments each done in duplicate. d. The mRNA expression levels of STAT3, PD-L1 and EGFR with a specific siRNA targeting STAT3 or with a scrambled, control siRNA for 72 h and subsequently treated with the indicated dose of MEKi (BAY86–9766) treatment for 24 h. One way anova test: *p < 0.05, ***p < 0.001 compared with the control