Large extracellular vesicles—a new frontier of liquid biopsy in oncology

Extracellular Vesicles (EVs) are emerging as pivotal elements in cancer. Many studies have focused on the role of Small- (S)-EVs but in recent years Large-(L)-EVs have progressively gained increasing interest due to their peculiar content and functions. Tumor-derived L-EVs carry a lot of oncogenic proteins, nucleic acids and lipids to recipient cells and are involved in the reshaping of the tumor microenvironment as well as in the metabolic rewiring and the promotion of the pro-metastatic attitude of cancer cells. Several techniques have been developed for the isolation of L-EVs and commercial kits are also available for efficient and easy recovery of these vesicles. Also, the improvement in DNA sequencing and “omics sciences” profoundly changed the way to analyze and explore the molecular content of L-EVs, thus providing novel and potentially useful cancer biomarkers. Researchers from the University of Bari ‘Aldo Moro’ discuss the most recent findings concerning the role of L-EVs in cancer and discuss their possible use in oncology as “liquid biopsy” tools as compared to the other classes of EVs.

Principal mechanisms involved in the biogenesis of large extracellular vesicles (L-EVs)

Many pathways are involved in L-EVs’ generation. (A) The Arrestin Domain-Containing Protein-1 (ARRDC1) induces the relocalization of TSG101 from the endosomal compartment to the plasma membrane, thus provoking shape changes in the cell membrane curvature that initiate the microvesicle gemmation. (B) Similar membrane plasticity modifications depend on the translocation of phosphatidylserine on the outer membrane layer or by the acid sphingomyelinase-mediated formation of ceramide. (C) The ADP-ribosylation factor 6 (ARF6) can influence the incorporation of integrins and the Major Histocompatibility Complexes type I (MHC-I) into the microvesicles. It also recruits the myosin light-chain kinase (MLCK) via ERK, thus initiating the outward budding of the plasma membrane. (D) Parallel, the generation of membrane blebs of 1–10 μm in diameter is mediated by the Diaphanous-related formin-3 (DIAPH3) inactivation, namely a cytoskeletal regulating protein often down-regulated in cancer.