Identification of Active Compounds of Centipeda minima for Potentiating Tumor Immunotherapy in Non-Small Cell Lung...

Activation of cGAS/STING/IFN-I signaling pathway serves as a potential therapeutic strategy to enhance CD8⁺ T cells infiltration and augment antitumor immunotherapy. The medicinal herb Centipeda minima has been traditionally employed to treat respiratory diseases and cancer; however, whether C. minima and its bioactive constituents can activate CD8⁺ T cell-mediated antitumor immunity in non-small cell lung cancer (NSCLC) remains elusive. In this study, the ethanol extract of C. minima (ECM) significantly enhanced the cytotoxic activity of human peripheral blood mononuclear cell-derived activated T cells and murine primary CD8⁺ T cells against NSCLC cells, and promoted CD8⁺ T cell infiltration in the LLC syngeneic tumor model. RNA-seq profiling indicated that ECM potentially triggers type-I interferon (IFN-I)-mediated innate immunity in NSCLC. Mechanistically, ECM treatment activated the cGAS/STING pathway in NSCLC cells, as evidenced by increased phosphorylation of TBK1 and IRF3, elevated IFN-I gene expression, and enhanced CD8⁺ T cells activity. Notably, ECM markedly downregulated both mitochondrial and nuclear FANCD2 protein levels, which may facilitate cytosolic release of mitochondrial and nuclear DNA, thereby stimulating the cGAS/STING/IFN-I signaling axis. ECM-induced FANCD2 downregulation was markedly reversed by the proteasome inhibitor MG-132. Combination treatment with ECM and anti-PD-1 antibody synergistically suppressed tumor growth in the LLC syngeneic model, accompanied by elevated IFN-I expression and pronounced recruitment of activated CD8⁺ T cells. Moreover, 3-O-methylquercetin and several sesquiterpene lactones abundant in ECM were identified to downregulate FANCD2, activate TBK1/IRF3 pathway, and enhance IFN-I expression in NSCLC cells. Among these active compounds, arnicolide D promoted FANCD2 degradation in a proteasome-dependent manner, whereas 3-O-methylquercetin predominantly suppressed FANCD2 gene expression. Collectively, our findings suggest that FANCD2 may serve as a novel therapeutic target for enhancing antitumor innate immunity, and that C. minima along with its active compounds can potentiate antitumor immunotherapy by activating the FANCD2-cGAS/STING/IFN-I signaling axis.