EV-DNA primes the anti-tumor immunity to prevent metastatic progression

To successfully establish metastasis, the tumor must establish the pre metastatic niche (PMN), a set of changes in the organ that set ideal conditions for circulating tumor cells to seed. Among all tumor secreting factors, Extracellular vesicles (EVs) play a crucial role in PMN establishment. EVs carry a wide range of complex biomolecules that mediate their function, one of those biomolecules is DNA. The DNA is presented on the surface of EVs, however little is known about the biogenesis and function of EV-DNA DNA in tumor progression. Given that extranuclear DNA is extremely immunogenic, we hypothesize that EV-DNA can stimulate the pro-inflammatory system, thus cancer cells that secrete reduced levels of EV-DNA can evade the immune response, therefore have an enhanced metastatic capacity. Indeed, we found that EV-DNA amount is inversely correlated to metastatic potential in both human cancer cell lines and patient samples. In this work we show that EV-DNA DNA has unique structural characteristics, which are dramatically different than genomic DNA, and may contribute to its presentation to the immune system. Moreover, we performed a whole genome CRISPR KO screen that identified genes and pathways that regulate EV- DNA packaging. We utilize those genes to establish novel tools to genetically modulate EV-DNA packaging without affecting general EVs biogenesis. A profound understanding of EV-DNA biogenesis, structure and function will open new avenues to utilize EV-DNA as both diagnostic and therapeutic tool for metastatic disease.