Figure 3.

D816V-KIT oncogenic activity drives ligand-independent IL-6 induction. (A) IL-6 released to the extracellular media was measured in LAD2, HMC-1.1 and HMC-1.2 cells incubated for 48 hours (h) (37C, 5%CO₂) in serum-free medium in the presence or absence of 100 ng/mL stem cell factor (SCF). (B) IL-6 mRNA levels were measured in HMC-1.2 after 2 h incubation in serum-free medium in the presence or absence of the KIT inhibitors, dasatinib and imatinib, or the EGFR inhibitor gefitinib at the indicated concentrations. Relative expression of IL-6 mRNA was obtained by normalizing to the expression of GAPDH using the DCt method and the results are expressed as fold change compared to untreated cells. The effect of the KIT inhibitor dasatinib (0.5 mM) on the secretion of IL-6 by HMC-1.2 (C) or by P815 mast cells (D) was determined after 6 h incubation in serum free medium. All data are the mean±Standard Error of Mean of three independent experiments done in triplicates. SCF: stem cell factor. *P=0.01, **P<0.01 and ****P<0.0001.