Figure 6.

EGF induces PD-L1 expression through EGFR and downstream pathway.

(A) SACC-83 cells were treated with EGF for 24 and 48 hours and the expression of PD-L1 were examined by western blotting and RT-PCR.(B) SACC-83 cells were pre-treated with either erlotinib, or gefitinib or AG1478 for 1 h before stimulation with EGF for 48 h. Or after 24-h pre-transfection with si-EGFR or si-NC siRNAs, cells were further treated with EGF for an additional 48 h. The expression of PD-L1 and the activation of EGFR were examined by western blotting.(C) Western blot analysis of PD-L1, p-EGFR, EGFR, p-AKT, AKT, p-ERK, ERK, p-STAT3, STAT3 from SACC-83 cells pretreated with various inhibitors for 1 hr followed by stimulation with EGF for 48 hr.