Deep sequencing of circulating exosomal microRNA allows non-invasive glioblastoma diagnosis

Abstract

Exosomes are nano-sized extracellular vesicles released by many cells that contain molecules characteristic of their cell of origin, including microRNA. Exosomes released by glioblastoma cross the blood–brain barrier into the peripheral circulation and carry molecular cargo distinct to that of “free-circulating” miRNA. In this pilot study, serum exosomal microRNAs were isolated from glioblastoma (n = 12) patients and analyzed using unbiased deep sequencing. Results were compared to sera from age- and gender-matched healthy controls and to grade II–III (n = 10) glioma patients. Significant differentially expressed microRNAs were identified, and the predictive power of individual and subsets of microRNAs were tested using univariate and multivariate analyses. Additional sera from glioblastoma patients (n = 4) and independent sets of healthy (n = 9) and non-glioma (n = 10) controls were used to further test the specificity and predictive power of this unique exosomal microRNA signature. Twenty-six microRNAs were differentially expressed in serum exosomes from glioblastoma patients relative to healthy controls. Random forest modeling and data partitioning selected seven miRNAs (miR-182-5p, miR-328-3p, miR-339-5p, miR-340-5p, miR-485-3p, miR-486-5p, and miR-543) as the most stable for classifying glioblastoma. Strikingly, within this model, six iterations of these miRNA classifiers could distinguish glioblastoma patients from controls with perfect accuracy. The seven miRNA panel was able to correctly classify all specimens in validation cohorts (n = 23). Also identified were 23 dysregulated miRNAs in IDHMUT gliomas, a partially overlapping yet distinct signature of lower-grade glioma. Serum exosomal miRNA signatures can accurately diagnose glioblastoma preoperatively. miRNA signatures identified are distinct from previously reported “free-circulating” miRNA studies in GBM patients and appear to be superior.

Analysis and Simulation of Glioblastoma Cell Lines-Derived Extracellular Vesicles Metabolome

“…Accumulating evidence has shown that cancers, including GBMs, release large amounts of EVs, including exosomes, into the bloodstream, offering a new opportunity for non-invasive biomarker discovery. Circulating EVs from glioblastomas have been shown to contain microRNA [9,10] and DNA [11]. Several laboratories have published the proteomic profiles of GBM-derived EVs and identified specific proteins highly enriched in EVs [12][13][14][15].…”

A comprehensive proteomic SWATH-MS workflow for profiling blood extracellular vesicles: a new avenue for glioma tumour surveillance

“…Circulating-EVs hold real promise as robust and readily accessible pools of glioma biomarkers. While high-throughput nextgeneration-sequencing technologies have allowed thorough characterisation of nucleic acids in blood-derived EVs [30,57], the proteome of circulating-EVs remains largely unexplored. Shot-gun proteomic methods have been primarily used to investigate glioma-EV proteomes [58,59].…”

“…We have shown that glioma-EVs can be sampled directly from the glioma microenvironment and are capable of stratifying patients [24,25]. EV secretion is increased in neoplasia [26,27] and glioma-derived EVs cross the blood-brainbarrier (BBB) into the circulation [28,29], allowing peripheral sampling of glioma molecular information [30]. Capturing glioma-EVs from body fluids and screening their molecular contents may therefore serve as a complementary approach to assess the heterogeneic molecular landscape of gliomas in real-time as tumours evolve [21].…”

Nanomedicine and Immunotherapy: A Step Further towards Precision Medicine for Glioblastoma

“…The mutant transcript of IDH1 can be detected in EV isolated from CSF, and the quantity of mutant IDH1 transcripts is directly correlated with the tumor volume [63]. The miRNA signatures for IDH-wt glioblastoma and IDH-mutant grades II and III gliomas have been described in serum exosomes and could distinguish preoperative glioblastoma patients from healthy controls with high accuracy [64]. The protein miR-21 is a miRNA that is highly overexpressed in glioblastoma tissue cells [65]; miR-21 levels in exosomes isolated from the CSF of glioblastoma patients were 10-fold higher than those from controls.…”