Proteome and Secretome Characterization of Glioblastoma-Derived Neural Stem Cells

Abstract

Glioblastoma multiforme (GBM) (grade IV astrocytoma) is the most common and aggressive primary brain tumor. GBM consists of heterogeneous cell types including a subset of stem cell-like cells thought to sustain tumor growth. These tumor-initiating glioblastoma multiforme-derived neural stem (GNS) cells as well as their genetically normal neural stem (NS) counterparts can be propagated in culture as relatively pure populations. Here, we perform quantitative proteomics to globally characterize and compare total proteome plus the secreted proteome (secretome) between GNS cells and NS cells. Proteins and pathways that distinguish malignant cancer (GNS) stem cells from their genetically normal counterparts (NS cells) might have value as new biomarkers or therapeutic targets. Our analysis identified and quantified ∼7,500 proteins in the proteome and ∼2,000 in the secretome, 447 and 138 of which were differentially expressed, respectively. Notable tumor-associated processes identified using gene set enrichment analysis included: extracellular matrix interactions, focal adhesion, cell motility, and cell signaling. We focused on differentially expressed surface proteins, and identified 26 that participate in ligand-receptor pairs that play a prominent role in tumorigenesis. Immunocytochemistry and immunoblotting confirmed that CD9, a recently identified marker of adult subventricular zone NS cells, was consistently enriched across a larger set of primary GNS cell lines. CD9 may, therefore, have value as a GNS-specific surface marker and a candidate therapeutic target. Altogether, these findings support the notion that increased cell-matrix and cell-cell adhesion molecules play a crucial role in promoting the tumor initiating and infiltrative properties of GNS cells. Stem Cells 2017;35:967-980.

Glioblastoma hijacks microglial gene expression to support tumor growth

“…However, in the in vivo tumor model described here, all tumor lipid bilayers are GFP-positive and thus it is not clear whether all GFP pos microglia have taken up EVs per se or may possibly have taken up tumor cell membrane debris. Other intercellular communication modes such as secreted molecules [69], exchange of molecules through gap junctions between cells [70], and cell connecting nano/microtubes may contribute to the observed effects as well. Glioma secreted cytokines (e.g., CSF-1, MCP-3, CX3CL1, SDF-1, and GM-CSF) that are especially known to be involved in the recruitment of microglial cells and could be responsible (in part) for the observed changes in gene expression, with EV-GFP uptake being a mere side-effect [3] Glioblastomas are heterogeneous tumors at the interand intratumor level and they express gene patterns associated with mesenchymal, proneural, and classical subtypes [71].…”

Q-Cell Glioblastoma Resource: Proteomics Analysis Reveals Unique Cell-States Are Maintained in 3D Culture

“…In our analysis, we observed a number of key GBM-associated genes that were not detected at the protein level and may reflect either a lack of translation or limitations of the MS-based approach used. MS-based proteomics has been used effectively by others to measure the proteome, secretome, and glycoproteins in immortalised GBM cell lines [37,38].…”

In vitro effects of platelet-derived factors of brain glioma patients on C6 glioma cells

“…The formation of spheroidal derivations in the growth dynamics in culture is believed to be the fundamental property of brain tumour stem cells (BTSC), which determines the initiation and proliferation of tumours in brain tissue (Laks et al, 2009) and is similar to the NSC/NPCs property to form the "neurospheres". It should be noted that the similarity of characteristics between the glioma cells and NSCs: a similar phenotype, proteome, secretome, comparable profile of receptor expression, adhesion molecules and identical targets of migration (Nakano, 2015;Yamamuro et al, 2015;Song et al, 2016;Amodeo et al, 2017;Garcia et al, 2017;Mehta & Lo Cascio, 2017;Qin et al, 2017) -is assumed as phylogenetic and it is suggested that brain tumours are derived from NSC/NPCs undergoing aberrant changes, -BTSCs (Kusne & Sanai, 2015;Stangeland et al, 2015;Zong et al, 2015;Ledur et al, 2016;Okawa et al, 2017). The content of BTSCs in glioma tissue enlarges proportionally with an increase in their malignancy, which is accompanied by raised expression levels of immunocytochemical markers of their stem phenotype (Bao et al, 2014;Wang et al, 2014).…”