Tumor-derived exosomes modulate PD-L1 expression in monocytes

Cancer cell-derived vesicles, so-called exosomes, are important means in cell-cell communication between tumor cells and the tissue microenvironment. Amongst others, exosomes harbor functional RNAs, which are transferred to recipient cells and alter the cellular phenotype of respective cells. Aim of the current study was a detailed characterization of the RNA composition of cancer-cell derived exosomes in CLL. Due to prior results showing an enrichment of small RNAs in exosomes, this was focused on profiling of small RNAs. Further, the impact of high abundant exosomal RNAs in phenotypic alterations of cells in the tumor microenvironment upon exosome uptake was studied. Overall design: Small RNA sequencing of exosomes (n=5) and respective parental cells (n=3) was conducted. Exosomes were isolated from the CLL cell line MEC-1 and for 3 out of 5 samples, paired cellular samples were harvested.