Aspirin‐targeted PD‐L1 in lung cancer growth inhibition

BACKGROUND: Aspirin is a classic anti‐inflammatory drug and its anticancer effect has been previously explored in many types of cancer including colorectal cancer therapy. Programmed cell death‐ligand 1 (PD‐L1) is widely expressed in tumor cells and displays an inhibitory role in antitumor immunity. This study aimed to clarify the role of PD‐L1 in aspirin‐suppressed lung cancer. METHODS: The inhibitory effect of aspirin on lung cancer cell proliferation was assessed using an MTT cell viability assay. The role of aspirin in the modulation of PD‐L1 expression was analyzed by western blot or RT‐PCR assays. In lung cancer cells, the influence of aspirin on PD‐L1 promoter activity was detected using a luciferase reporter assay. The interaction of TAZ with PD‐L1 promoter in the cells, with or without aspirin administration, was tested via chromatin immunoprecipitation (ChIP) analysis. The function of PD‐L1 in aspirin‐mediated growth inhibition of lung cancer was examined using a cell viability assay. RESULTS: Following treatment with aspirin, lung cancer cell growth was markedly suppressed. Aspirin was able to markedly decrease the expression of PD‐L1 at the mRNA and protein levels in lung cancer cells. For the mechanism study, we found that the promoter of PD‐L1 was inactivated by aspirin via TAZ transcriptional coactivator in the cells. With regard to the functional investigation, aspirin was capable of resisting cell proliferation and PD‐L1 overexpression abolished aspirin‐depressed cell proliferation in lung cancer. CONCLUSIONS: Aspirin suppressed the growth of lung cancer cells via targeting the TAZ/PD‐L1 axis.