Introduction: Like all nucleated cells, glioblastoma (GBM) cells shed small membrane-encapsulated particles called extracellular vesicles (EVs). EVs can transfer oncogenic components and promote tumor growth by transferring short non-coding RNAs, altering target cell gene expression. Furthermore, GBM-derived EVs can be detected in blood and have potential to serve as liquid biopsies.
Methods: EVs were harvested from culture supernatants from human GBM cell lines, purified via sequential centrifugation, and quantified by nanoparticle tracking. RNA was isolated and short non-coding RNA was sequenced. Data was analyzed via the OASIS-2.0 platform using HG38. MirTarBase and MirDB interrogated validated/predicted miRNA-gene interactions respectively.
Results: Many short non-coding RNA's were identified within GBM EV's. In keeping with earlier reports utilizing GBM EV micro-RNA (miRNA) arrays, these included abundant micro-RNA's including miR-21. However, RNA sequencing revealed a total of 712 non-coding RNA sequences most of which have not been associated with GBM EV's previously. These included many RNA species (piRNA, snoRNA, snRNA, rRNA and yRNAs) in addition to miRNA's. miR-21-5p, let-7b-5p, miR-3182, miR-4448, let-7i-5p constituted highest overall expression. Top genes targeted by non-coding RNA's were highly conserved and specific for cell cycle, PI3K/Akt signaling, p53 and Glioma curated KEGG pathways.
Conclusions: Next generation short non-coding RNA sequencing on GBM EV's validates findings from earlier studies using miRNA arrays but also demonstrates expression of many additional non-coding RNA sequences and classes previously unassociated with GBM. This may yield important insights into pathophysiology, point to new therapeutic targets, and help develop new biomarkers for disease burden and treatment response.
Keywords: Exosomes; Extracellular vesicles; Glioblastoma; Short non-coding RNA; microRNA.