Overexpression of PD-L1 is associated with higher expression of EGFR and immune-related genes, and sensitivity to EGFR inhibitors.

<p>(A) Lung cancer cell lines (N186) from Cancer Cell Line Encyclopedia (CCLE) database were divided into two groups according to median expression of PD-L1 at Log₂ Robust Multi-array Average (RMA), 5.087. Mean Log₂ RMAs of PD-L1 expression of PD-L1^high and PD-L1^low groups were 7.171 ±1.508 and 4.578 ± 0.2630, respectively. (B) EGFR expression of PD-L1^high and PD-L1^low lung cancer cell lines, and correlation between EGFR and PD-L1 expression (C) The half maximum inhibitory concentration (IC₅₀) of Erlotinib for PD-L1^high lung cancer cell lines (N51) and PD-L1^low lung cancer cell lines (N40). (D) Expression of MHC-I and genes associated with MHC-I antigen presentation from PD-L1^high and PD-L1^low lung cancer cell lines. (E) Expression of MHC-II and genes associated with MHC-II antigen presentation from PD-L1^high and PD-L1^low lung cancer cell lines. (F) Expression of genes associated with inflammation from PD-L1^high and PD-L1^low lung cancer cell lines. PD-L1^high lung cancer cell lines are associated with higher expression of EGFR and sensitivity to erlotinib (B and C). In addition, PD-L1^high lung cancer cell lines express genes associated with MHC-I and II antigen presenting pathways higher than PD-L1^low lung cancer cell lines (D and E). Significantly higher expression of IL-6 and positive regulators for IFNγ signaling pathway such as STAT1, STAT3, and IRF9 were associated with PD-L1^high lung cancer cell lines, while the expression of negative regulators for IFNγ signaling pathway such as IRF2BP2 and SIN3A were significantly lower in PD-L1^high lung cancer cell lines (F). P values were calculated by Wilcoxon-Man-Whitney test and summarized as follows, ****: <i>p</i> < 0.0001, ***: <i>p</i> = 0.0001 to 0.001, **: <i>p</i> = 0.001 to 0.01, *: <i>p</i> = 0.01 to 0.05, ns: <i>p</i> > 0.05.