Body fluids are a rich source of extracellular vesicles (EVs), which carry cargo derived from the secreting cells. So far, biomarkers for pathological conditions have been mainly searched from their protein, (mi)RNA, DNA and lipid cargo. Here, we explored the small molecule metabolites from urinary and platelet EVs relative to their matched source samples. As a proof-of-concept study of intra-EV metabolites, we compared alternative normalization methods to profile urinary EVs from prostate cancer patients before and after prostatectomy and from healthy controls.We employed targeted ultra-performance liquid chromatography-tandem mass spectrometry to profile over 100 metabolites in the isolated EVs, original urine samples and platelets. We determined the enrichment of the metabolites in the EVs and analyzed their subcellular origin, pathways and relevant enzymes or transporters through data base searches. EV- and urine-derived factors and ratios between metabolites were tested for normalization of the metabolomics data.Approximately 1 x 1010 EVs were sufficient for detection of metabolite profiles from EVs. The profiles of the urinary and platelet EVs overlapped with each other and with those of the source materials, but they also contained unique metabolites. The EVs enriched a selection of cytosolic metabolites including members from the nucleotide and spermidine pathways, which linked to a number of EV-resident enzymes or transporters. Analysis of the urinary EVs from the patients indicated that the levels of glucuronate, D-ribose 5-phosphate and isobutyryl-L-carnitine were 2-26-fold lower in all pre-prostatectomy samples compared to the healthy control and post-prostatectomy samples (p < 0.05). These changes were only detected from EVs by normalization to EV-derived factors or with metabolite ratios, and not from the original urine samples.Our results suggest that metabolite analysis of EVs from different samples is feasible using a high-throughput platform and relatively small amount of sample material. With the knowledge about the specific enrichment of metabolites and normalization methods, EV metabolomics could be used to gain novel biomarker data not revealed by the analysis of the original EV source materials.
Abstract Background Beyond their conventional roles in hemostasis and wound healing, platelets have been shown to facilitate hematogenous metastasis by interacting with cancer cells. Depending on the activation route, platelets also generate different platelet-derived extracellular vesicles (PEVs) that may educate cancer cells in the circulation or within the tumor microenvironment. We engaged different platelet-activating receptors, including glycoprotein VI and C-type lectin-like receptor 2, to generate a spectrum of PEV types. This allowed us to investigate the differential capacity of PEVs to alter cancer hallmark functions such as proliferation, invasion, and pro-angiogenic potential using melanoma as a model. Additionally, we analyzed changes in the cell transcriptomes and cancer EV profiles. Methods Two human melanoma cell lines (MV3 and A2058) with differential metastatic potential were studied in the 3D spheroid cultures. Human platelets were activated with collagen related peptide (CRP), fucoidan from Fucus vesiculosus (FFV), thrombin & collagen co-stimulus and Ca 2+ ionophore, and PEVs were isolated by size-exclusion chromatography followed by ultrafiltration. Spheroids or cells were treated with PEVs and used in functional assays of proliferation, invasion, and endothelial tube formation as well as for the analysis of cancer EV production and their tetraspanin profiles. Differentially expressed genes and enriched signaling pathways in the PEV-treated spheroids were analyzed at 6 h and 24 h by RNA sequencing. Results Among the studied PEVs, those generated by CRP and FFV exhibited the most pronounced effects on altering cancer hallmark functions. Specifically, CRP and FFV PEVs increased proliferation in both MV3 and A2058 spheroids. Distinct tetraspanin signatures of melanoma EVs were induced by all PEV types. While the PI3K-Akt and MAPK signaling pathways were activated by both CRP and FFV PEVs, they differently upregulated the immunomodulatory TGF-β and type-I interferon signaling pathways, respectively. Conclusions Our study revealed both shared and distinct, cancer-promoting functions of PEVs, which contributed to the transcriptome and metastatic capabilities of the melanoma spheroids. Inhibiting the platelet receptors that modulate the PEVs’ cancer-promoting properties may open up new strategies for identifying promising treatment targets for cancer therapy.
Extracellular vesicles (EVs) have been showcased as auspicious candidates for delivering therapeutic cargo, including oncolytic viruses for cancer treatment. Delivery of oncolytic viruses in EVs could provide considerable advantages, hiding the viruses from the immune system and providing alternative entry pathways into cancer cells. Here we describe the formation and viral cargo of EVs secreted by cancer cells infected with an oncolytic adenovirus (IEVs, infected cell-derived EVs) as a function of time after infection. IEVs were secreted already before the lytic release of virions and their structure resembled normally secreted EVs, suggesting that they were not just apoptotic fragments of infected cells. IEVs were able to carry the viral genome and induce infection in other cancer cells. As such, the role of EVs in the life cycle of adenoviruses may be an important part of a successful infection and may also be harnessed for cancer- and gene therapy.
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