Unique structural configuration of EV-DNA primes Kupffer cell-mediated antitumor immunity to prevent metastatic progression

Extracellular vesicles (EVs) transport biomolecules that mediate intercellular communication. We previously showed that EVs contain DNA (EV-DNA) representing the entire genome. However, the mechanism of genomic EV-DNA packaging and its role in cancer remain elusive. We now demonstrate that EV-DNA is predominantly localized on the vesicle surface and associated with uniquely modified and cleaved histones. Moreover, a genome-wide clustered regularly interspaced short palindromic repeats knockout screen revealed that immune developmental pathways and genes, including apoptotic peptidase activating factor 1 (APAF1) and neutrophil cytosolic factor 1 (NCF1), regulate EV-DNA packaging. Furthermore, in colorectal cancer models, uptake of EV-DNA by pre-metastatic liver Kupffer cells (KCs) activated DNA damage responses. This activation rewired KC cytokine production and promoted the formation of tertiary lymphoid structures, thereby suppressing liver metastasis. Conversely, loss of APAF1 decreased EV-DNA packaging and promoted liver metastasis. Importantly, colorectal cancer biopsy EV-DNA secretion could serve as a predictive biomarker for postoperative metastasis. Taken together, our findings indicate that uniquely chromatinized EV-DNA induces antitumor immunity. Lyden and colleagues find that immune developmental genes, such as apoptotic peptidase activating factor 1 (APAF1), support DNA packaging on the surface of tumor-derived extracellular vesicles that are taken up by resident liver macrophages, thereby suppressing metastasis.