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Mol Cell Proteomics. 2018 Oct;17(10):1948-1964. doi: 10.1074/mcp.RA118.000644. Epub 2018 Jul 13.

The Impact of Oncogenic EGFRvIII on the Proteome of Extracellular Vesicles Released from Glioblastoma Cells.

Author information

1
From the ‡Research Institute of the McGill University Health Centre, Glen Site, McGill University, Montreal, Quebec, H4A 3J1, Canada.
2
§Donnelly Centre and Departments of Molecular Genetics and Computer Science, University of Toronto, Toronto, Ontario, M5S 3E1, Canada.
3
¶Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada.
4
‖Canadian Institute for Advanced Research, Toronto, Ontario, M5G 1M1, Canada.
5
From the ‡Research Institute of the McGill University Health Centre, Glen Site, McGill University, Montreal, Quebec, H4A 3J1, Canada; janusz.rak@mcgill.ca.

Abstract

Glioblastoma multiforme (GBM) is a highly aggressive and heterogeneous form of primary brain tumors, driven by a complex repertoire of oncogenic alterations, including the constitutively active epidermal growth factor receptor (EGFRvIII). EGFRvIII impacts both cell-intrinsic and non-cell autonomous aspects of GBM progression, including cell invasion, angiogenesis and modulation of the tumor microenvironment. This is, at least in part, attributable to the release and intercellular trafficking of extracellular vesicles (EVs), heterogeneous membrane structures containing multiple bioactive macromolecules. Here we analyzed the impact of EGFRvIII on the profile of glioma EVs using isogenic tumor cell lines, in which this oncogene exhibits a strong transforming activity. We observed that EGFRvIII expression alters the expression of EV-regulating genes (vesiculome) and EV properties, including their protein composition. Using mass spectrometry, quantitative proteomic analysis and Gene Ontology terms filters, we observed that EVs released by EGFRvIII-transformed cells were enriched for extracellular exosome and focal adhesion related proteins. Among them, we validated the association of pro-invasive proteins (CD44, BSG, CD151) with EVs of EGFRvIII expressing glioma cells, and downregulation of exosomal markers (CD81 and CD82) relative to EVs of EGFRvIII-negative cells. Nano-flow cytometry revealed that the EV output from individual glioma cell lines was highly heterogeneous, such that only a fraction of vesicles contained specific proteins (including EGFRvIII). Notably, cells expressing EGFRvIII released EVs double positive for CD44/BSG, and these proteins also colocalized in cellular filopodia. We also detected the expression of homophilic adhesion molecules and increased homologous EV uptake by EGFRvIII-positive glioma cells. These results suggest that oncogenic EGFRvIII reprograms the proteome and uptake of GBM-related EVs, a notion with considerable implications for their biological activity and properties relevant for the development of EV-based cancer biomarkers.

KEYWORDS:

Cancer Biology; EGFRvIII; Exosomes; Glioblastoma; Oncogenes; Secretome; extracellular vesicles; heterogeneity; invasion; nano-flow cytometry

PMID:
30006486
PMCID:
PMC6166673
[Available on 2019-10-01]
DOI:
10.1074/mcp.RA118.000644

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