Icariside I enhances the effects of immunotherapy in gastrointestinal cancer via targeting TRPV4 and upregulating the cGAS-STING-IFN-I pathway

Gastrointestinal cancer is among the most common cancers worldwide. Immune checkpoint inhibitor-based cancer immunotherapy has become an innovative approach in cancer treatment; however, its efficacy in gastrointestinal cancer is limited by the absence of infiltration of immune cells within the tumor microenvironment. Therefore, it is therefore urgent to develop a novel therapeutic drug to enhance immunotherapy. In this study, we describe a previously unreported potentiating effect of Icariside I (ICA I, GH01), the main bioactive compound isolated from the Epimedium species, on anti-tumor immune responses. Mechanistically, molecular docking and SPR assay result show that ICA I binding with TRPV4. ICA I induced intracellular Ca 2+ increasing and mitochondrial DNA release by targeting TRPV4, which triggered cytosolic ox-mitoDNA release. Importantly, these intracellular ox-mitoDNA fragments were taken up by immune cells in the tumor microenvironment, which amplified the immune response. Moreover, our study shows the remarkable efficacy of sequential administration of ICA I and anti-α-PD-1 mAb in advanced tumors and provides a strong scientific rationale for recommending such a combination therapy for clinical trials. ICA I enhanced the anti-tumor effects with PD-1 inhibitors by regulating the TRPV4/Ca 2+ /Ox-mitoDNA/cGAS/STING axis. We expect that these findings will be translated into clinical therapies, which will benefit more patients with cancer in the near future. Mechanism of IFN-I release stimulated by ICA-I, which includes induction of dendritic cell (DC) maturation and M1-polarization of tumor-associated macrophages (TAMs) triggered by the activation of the TRPV4/Ca 2+ /mtDNA/cGAS/STING axis pathway. • ICA I was efficiently extracted by computer-aided protein design strategy. • ICA I induces mitochondrial dysfunction by binding to TRPV4 channel and increasing intracellular Ca 2+ concentration • ICA I enhanced anti-tumor effects of PD-1 inhibitors by modulating the TRPV4/Ca 2+ /Ox-mitoDNA/cGAS/STING axis