Negative regulators antagonizing antitumor innate immune pathways in lung cancer immune evasion

The innate immune sensing system serves as a critical line of defense for recognizing tumor-associated abnormal nucleic acids and initiating antitumor immune responses, and it plays an essential role in lung cancer development, progression, and therapeutic response. Recent studies have shown that, under conditions such as genomic instability, mitochondrial damage, epigenetic dysregulation, and therapy-induced stress, lung cancer cells can release a variety of abnormal DNA, RNA, and damage-associated molecular patterns (DAMPs), thereby activating key innate immune pathways, including cGAS-STING, Toll-like receptor (TLR), and RIG-I-like receptor (RLR) signaling. These pathways regulate the recruitment, activation, and functional differentiation of multiple immune cell populations, including dendritic cells, natural killer cells, neutrophils, macrophages, and T cells, through the induction of type I interferons, inflammatory cytokines, and chemokines, thereby shaping an antitumor immune network in lung cancer. However, during long-term evolution, lung cancer develops multilayered immunosuppressive mechanisms that inhibit innate immune signaling through genetic alterations, epigenetic modifications, ubiquitin-mediated protein degradation, metabolic reprogramming, and non-coding RNA regulation. These processes impair antigen presentation, restrict effector lymphocyte infiltration, and promote the accumulation of immunosuppressive cell populations such as tumor-associated macrophages, myeloid-derived suppressor cells, and regulatory T cells, ultimately leading to immune evasion. This review comprehensively discusses the activation mechanisms of three major innate immune pathways in lung cancer-cGAS-STING, TLR, and RLR signaling-the tumor-mediated negative regulatory mechanisms that suppress them, and their impact on the tumor immune microenvironment. Furthermore, it discusses the potential clinical value of targeting these pathways in immunotherapy, with the aim of providing a theoretical basis for optimizing lung cancer immunotherapeutic strategies and designing combination interventions.