Cancer exosomes dynamics in vitro and in vivo

Exosomes are involved in many intercellular communication processes but also cancer progression. Deciphering exosome-release mechanics and dynamics is essential to understand the physiology of exosomes. However, tools to study this process directly have been lacking. We describe a novel imaging approach that can visualize multivesicular body (MVB) fusion with the plasma membrane (PM) directly, an essential step for exosome release. We used our technique to follow MVB-PM fusion dynamics in living tumor cell lines and provide evidence that SNARE molecules and G-protein-coupled receptor signaling control the functional release of exosomes, affecting invasive behavior. Apart from these findings our approach will be imperative for monitoring the dynamics of exosome release and their post-fusion fate, but will also allow researchers to uncover further new insights into the endosomal-exosomal pathway, including their biogenesis, maturation and function.