Tumor exosome-initiated neutrophil IRG1/itaconate axis awakens dormant tumor cells and promotes lung metastasis

Purpose/Objective(s): Tumor cell dormancy and metabolic reprogramming are critical events in metastatic relapse. However, the mechanisms, particularly how the lung pre-metastatic niche and its associated metabolic alterations awaken dormant disseminated tumor cells (DTCs), remain elusive. This study aims to decipher the cascade from primary tumor-derived exosomes to DTC reactivation in the pre-metastatic lung, specifically identifying the key metabolite-mediated pathway driving this process. Materials/Methods: We employed multiple mouse models of spontaneous lung metastasis (e.g., B16-F10, Lewis). To comprehensively profile the pre-metastatic niche, we performed untargeted metabolomics on lung tissues to identify differentially enriched metabolites, and single-cell RNA sequencing (scRNA-seq) to delineate the cellular source of Irg1 . Other key techniques included: in vivo imaging and H&E staining for metastasis tracking; generation of Irg1 flox/flox mice with Mrp8-Cre for neutrophil-specific Irg1 deletion; RNA-seq of sorted alveolar macrophages; co-immunoprecipitation and Western blotting for itaconate-mediated LATS2 alkylation validation; chromatin immunoprecipitation (ChIP) for YAP1 nuclear translocation. Results: We delineated a sequential pathway driving metastatic reactivation in the lung. Initially, primary tumor-derived exosomes educated SPP1 + alveolar macrophages to bolster the production of CXCL2 and ensue neutrophil recruitment. Subsequently, these lung-infiltrating neutrophils specifically expressed Irg1 , resulting in a marked accumulation of the metabolite itaconate within the pre-metastatic niche. Mechanistically, itaconate directly alkylated dormant DTCs at the C910 and C911 site of the key upstream kinase LATS2 in the Hippo pathway. This modification inhibited the LATS2's capacity to phosphorylate YAP1, thereby promoting the nuclear translocation of unphosphorylated YAP1 to activate a pro-proliferative transcriptional program, forcing DTCs to exit dormancy. Crucially, this entire axis was disrupted by either neutrophil-specific genetic ablation of Irg1 or pharmacological inhibition of CXCR2, both of which significantly reduced tumor lung metastasis. Conclusions: Our work unveils a novel paradigm in which the tumor exosome-neutrophil axis drives metastatic reactivation via metabolite-mediated protein alkylation. We pinpoint the neutrophil-IRG1-itaconate axis as a pivotal signaling cascade in this process, and our findings demonstrate that therapeutic targeting of this axis, either upstream at CXCR2 or at the metabolite itaconate, represents a viable strategy to prevent tumor lung metastasis.