Fig. 4

Exosomes, cancer stem cells and EMT. Exosomes induce a cancer stem cell (CSC)-like phenotype in tumor cells through epithelial to mesenchymal transition (EMT). CSC are considered therapy resistant by increased drug efflux capacities and increased DNA repair. A key feature of CSC is their ability to become dormant and thus evade therapy, which is manly effective against proliferating cells. Cellular dormancy means that cells are recruited in to the G0-phase of the cell cycle but remain capable of cell division in response to mitotic stimulation. After therapy CSC can cause repopulation of the tumor mass under the influence of exosomes by undergoing mesenchymal to epithelial transition (MET)