Lightning Talk & Poster Australasian Extracellular Vesicles Conference 2018

Extracellular vesicles from glioblastoma cells stimulate normal astrocytes to acquire an invasive phenotype via p53 inhibition and induction of MYC (#51)

Susannah Hallal 1 , Duthika M. Mallawaaratchy 2 , Saeideh Ebrahimkhani 1 , Brett W Stringer 3 , Andrew W Boyd 3 , Bryan W Day 3 , Gilles J Guillemin 4 , Michael E Buckland 1 5 , Kimberley L Kaufman 2 5
  1. Discipline of Pathology, Brain and Mind Centre, The University of Sydney, Camperdown, NSW, Australia
  2. School of Life and Environmental Science, Brain and Mind Centre, The University of Sydney, Camperdown, NSW, Australia
  3. Brain Cancer Research Unit,, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
  4. Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia
  5. Department of Neuropathology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia

The role of reactive astrocytes is becoming increasingly important to understanding how glioblastoma (GBM) tumour cells diffusely invade the brain. Yet, little is known of the contribution of extracellular vesicle (EV) signalling in GBM/astrocyte interactions. We modelled GBM-EV signalling to normal astrocytes in vitro to assess whether this mode of intercellular communication could support GBM progression. EVs were isolated and characterized from three patient-derived GBM ‘stem’ cells (NES+/CD133+) and their differentiated (diff) progeny cells (NES-/CD133-). Uptake of GBM-EVs by normal primary astrocytes was confirmed by fluorescence microscopy and changes in astrocyte podosome formation and gelatin degradation were measured. Quantitative mass spectrometry-based proteomics was performed on GBM-EV stimulated astrocytes. Interaction network maps were then generated from common, differentially abundant proteins using Ingenuity Pathway Analysis (Qiagen Bioinformatics) and predicted upstream regulators were tested by qPCR assays. We observed significant increases in podosome formation and Cy3-gelatin degradation by astrocytes following 24 h exposure to GBM-stem and –diff EVs, with EVs released by GBM-stem cells eliciting a greater effect on the astrocytes. More than 1,700 proteins were quantified, and bioinformatics predicted activations of MYC, NFE2L2, FN1, TGFB1 and inhibition of TP53 in GBM-EV stimulated astrocytes that were then confirmed by qPCR. Structural and functional differences in EVs derived from stem versus diff cell lines were also observed. Inhibition of TP53 and activation of MYC signaling pathways in normal astrocytes exposed to GBM-EVs may be a mechanism by which GBM cells manipulate normal astrocytes to acquire a cancerous phenotype and support tumour expansion.