Figure 8: Constitutive EGFR signalling activates the interferon pathway.

(a) EGFR overexpression leads to increased mRNA for IFN-β compared with vector-transfected cells. Addition of EGF or Erlotinib leads to a loss of this increase in IFN-β in EGFR-overexpressing cells. (b) EGFR overexpression leads to increased mRNA for IFN-α compared with vector-transfected cells. Addition of EGF or Erlotinib leads to decreased IFN-α in EGFR-overexpressing cells. (c) An ELISA done on supernatants from U251EGFR or vector-transfected cells shows that EGFR overexpression leads to increased IFN-β at a protein level. (d) STAT1 is phosphorylated in U251EGFR cells. This phosphorylation is lost when EGF (15 min) is added to cells. (e,f) U251EGFR cells were incubated with Ruxolinitib (1 μM) overnight followed by extraction of RNA and quantitative PCR (qPCR) for IFIT1 or IFI27. (g) U251EGFR cells were incubated with Tofacitinib (300 nM) overnight followed by extraction of RNA and qPCR. Cells were serum starved and cultured in serum-free DMEM overnight for all experiments. The EGF concentration used was 50 ng ml⁻¹. Error bars represent the means±standard deviations of three independent experiments. Data were analysed by one-way ANOVA followed by Tukey’s multiple comparison test. *P≤0.05,**P≤0.01, ***P≤0.001.