MicroRNA-4458 Regulates PD-L1 Expression to Enhance Anti-tumor Immunity in NSCLC via Targeting STAT3.

MicroRNA-4458 (miR-4458) has been reported to be associated with several cancers including non-small-cell lung cancer (NSCLC), while its role in tumor immunity remains unclear. The purpose of the current research was to explore the anti-tumor immunity of miR-4458 in NSCLC. The results showed that the expression level of miR-4458 decreased and STAT3 increased in NSCLC tissues and cells. For in vitro experiments, miR-4458 mimics suppressed cell proliferation and decreased the expression level of PD-L1. Moreover, STAT3 was confirmed as a target gene of miR-4458. Upregulation of STAT3 level ameliorated the inhibitive effects of miR-4458 on cells proliferation and PD-L1 expression in cells. For in vivo studies, overexpression of miR-4458 hindered tumor growth, decreased the proportion of PD-1+ T cells, the expression of PD-L1 and IL-10, upregulated the proportion of CD4+ T, CD8+ T cells as well as the expression of IFN-γ and IL-2, which were all reversed by overexpression of STAT3, and the effects of STAT3 were counteracted after knockdown of PD-L1. MiR-4458 overexpression enhanced anti-tumor immunity via targeting STAT3 to block the PD-L1/PD-1 pathway.