Single-cell sequencing-guided design of synergistic chemo-immunotherapy nanodrugs for cGAS-STING activation in prostate cancer therapy

Characterizing the tumor immune microenvironment (TIME) to explore potential therapeutic targets is fundamental to advancing precision tumor immunotherapy. However, the immunosuppressive nature of "cold" tumors, notably prostate cancer, poses a significant barrier to immunotherapy, demanding new approaches to simultaneously reinvigorate anti-tumor immunity and modulate the molecular drivers of immune evasion. Here, we identified VSIG4 as a key regulator of prostate tumor-resident macrophage fate through single-cell sequencing analysis. Meanwhile, a shikonin (Shik)-mediated downregulation of VSIG4 in macrophages is verified, potentially attenuating its immunosuppressive effects. Building on these findings, cytosine guanine dinucleotide (CpG) oligodeoxynucleotide (ODN)-modified manganese (Mn)-Shik metal-polyphenol network nanodrugs (Mn/Shik@CpG NDs) are designed to reverse the "cold" immune environment of prostate tumor. In this scenario, Mn/Shik@CpG NDs release monomeric components under the stimulation of acidic and glutathione-rich tumor microenvironment (TME), thus exerting their immunomodulatory effects synergistically. Since the released Shik can induce DNA damage by necroptosis promoting reactive oxygen species production, cGAS-STING signaling pathway is initiated, which further activates interferon production in the TME. In addition, the necroptosis of Shik initiates immunogenic cell death, further activating innate immunity and promoting adaptive immune responses. Mn²⁺ is a cGAS-STING sensitizer, which amplifies the intratumoral interferon response. As an immune adjuvant, CpG ODN effectively promotes the maturation of dendritic cells, as well as the helper T cell differentiation and pro-inflammatory cytokine secretion, thus activating both innate and adaptive immunity. In vivo studies suggest that Shik-mediated VSIG4 downregulation, combined with innate and adaptive immune activation, remodels the TIME to evoke a significant anti-tumor response. Furthermore, transcriptomic analysis of rechallenged tumors indicated this durable protection was driven by a genuine immune memory response, revealing a gene signature of T cell activation and immune reprogramming. Collectively, beyond presenting a novel therapeutic candidate for converting immunologically "cold" tumors into "hot" ones, our work validates a data-guided design pipeline, offering a conceptual blueprint to inform the precise engineering of future nanodrugs.