RAS–Mitogen-Activated Protein Kinase Signal Is Required for Enhanced PD-L1 Expression in Human Lung Cancers (original) (raw)
Fig 5
STAT3 signal, but not PI3K signal, partially contributes to ectopic PD-L1 expression in human lung cancer cell lines.
A, STAT3 RNAi reduced PD-L1 expression at both protein (upper) and mRNA (lower) levels in NCI-H1373 and NCI-H441 cells but not in NCI-H358 cells. The experimental conditions were similar to those in Fig 3B. Data are the mean of three independent experiments. B, Immunoblot (upper) and qRT-PCR (lower) of STAT3 showed the decreases in STAT3 protein and mRNA levels, respectively. One representative immunoblot and the mean of three independent qRT-PCR experiments are shown. C, LY294002, a PI3K inhibitor, did not suppress PD-L1 protein expression. Three _KRAS_-mutant lung adenocarcinoma cell lines were treated with DMSO or LY294002 (40 μM) for 24 h. PD-L1 protein levels did not show any significant changes with LY294002 with regard to both the surface (upper) and total protein (lower) levels. Data are the mean of three independent experiments.