[Cisplatin promotes PD-L1 expression in A549 human lung adenocarcinoma cells via activating the ERK pathway]

Objective To investigate the effect of cisplatin (DDP) on the expression of programmed death 1 ligand 1 (PD-L1) in human lung adenocarcinoma A549 cells and its possible mechanism. Methods Human lung adenocarcinoma A549 cells were cultured in vitro and treated with (0, 0.5, 1, 2, 4, 8) mg/L of DDP for 24, 36, 48 hours. CCK-8 assay was used to detect the cell proliferation inhibition rate and the half maximal inhibitory concentration (IC₅₀) was calculated. The optimal inhibition time of 48 hours and its IC₅₀ were selected for subsequent experiments. A549 cells were then randomized into four groups: blank control group, group with DDP (IC₅₀), group with 20 μmol/L of mitogen-activated protein kinase kinase inhibitor PD98059, and group with DDP (IC₅₀) combined with 20 μmol/L of PD98059. The cells were cultured for 48 hours. The expression of ERK and p-ERK were detected by Western blotting, and PD-L1 expression was detected by flow cytometry. Results Compared with that in the control group, the expression of PD-L1 in A549 cells treated with DDP was up-regulated in a dose-dependent manner. The optimal time was 48 hours and the IC₅₀ was 3.586 mg/L. Also compared with that in the control group, the expression of p-ERK and PD-L1 in the DDP treatment group increased, and the expression of p-ERK in the group with PD98059 decreased. The expressions of p-ERK and PD-L1 in the group with DDP combined with PD98059 were lower than those in the group with DDP, but higher than those in the group with PD98059. Conclusion DDP up-regulates the expression of PD-L1 in A549 cells by activating the ERK signaling pathway.