The biogenesis of the extracellular vesicles-associated DNA:RNA hybrids

Extracellular vesicles (EVs) cargo is set-up by a wealth of molecules that incite a variety of phenotypes in recipient cells. At present, the mechanisms underlying the packaging of DNA into EVs
and the biologic significance of this phenomenon are under analysis.
Our work identifies DNA:RNA hybrids as part of the EV-DNA payload and that their transfer into recipient cancer cells can be tracked by integrate viral sequences. In particular, we demonstrate that, following intermittent hypoxia large amounts of DNA:RNA hybrids build in the cytoplasm and into EVs compartment of cancer cells. By deep sequencing we report that EV-DNA:RNA hybrids content is enriched in mitochondrial, centromeric, pericentromeric, ribosomal and circular DNA sequences. Moreover, we demonstrate the transfer of EV associated DNA:RNA hybrids into recipient cells. In these latter, a Stat1-dependent up-regulation of the interferon response pathway occurs which is abolished by DNAseIII/TREX1 activation.
Overall, our findings show the horizontal transfer of the EV-DNA:RNA hybrids cargo to recipient cancer- and cancer stromal cells inducing the activation of interferon response in the tumor microenvironment.

Collaborators: Dr. Massimiliano Bonafè (University of Bologna)
Dr. Gianluca Storci (University of Bologna)
Dr. Pasquale Sansone (Memorial Sloan Kettering Cancer Center, New York)

Super-resolution (3D-SIM) images of normoxic (left) and intermittent hypoxia-derived (right) HeLa cells showing nuclear (white) and cytoplasmic (red) localization of DNA:RNA hybrids (DAPI in blue).