Serum-Induced Differentiation of Glioblastoma Neurospheres Leads to Enhanced Migration/Invasion Capacity That Is Associated with Increased MMP9

Abstract

Glioblastoma (GBM) is a highly infiltrative brain tumor in which cells with properties of stem cells, called glioblastoma stem cells (GSCs), have been identified. In general, the dominant view is that GSCs are responsible for the initiation, progression, invasion and recurrence of this tumor. In this study, we addressed the question whether the differentiation status of GBM cells is associated with their invasive capacity. For this, several primary GBM cell lines were used, cultured either as neurospheres known to enrich for GSCs or in medium supplemented with 10% FCS that promotes differentiation. The differentiation state of the cells was confirmed by determining the expression of stem cell and differentiation markers. The migration/invasion potential of these cells was tested using in vitro assays and intracranial mouse models. Interestingly, we found that serum-induced differentiation enhanced the invasive potential of GBM cells, which was associated with enhanced MMP9 expression. Chemical inhibition of MMP9 significantly reduced the invasive potential of differentiated cells in vitro. Furthermore, the serum-differentiated cells could revert back to an undifferentiated/stem cell state that were able to form neurospheres, although with a reduced efficiency as compared to non-differentiated counterparts. We propose a model in which activation of the differentiation program in GBM cells enhances their infiltrative potential and that depending on microenvironmental cues a significant portion of these cells are able to revert back to an undifferentiated state with enhanced tumorigenic potential. Thus, effective therapy should target both GSCs and differentiated offspring and targeting of differentiation-associated pathways may offer therapeutic opportunities to reduce invasive growth of GBM.

EGF stimulates glioblastoma metastasis by induction of matrix metalloproteinase-9 in an EGFR-dependent mechanism

“…MMP-9 upregulation has been detected in GBMs, [ 16 ] and MMP-9 is involved in GBM metastasis [ 19 ]. To extend these findings, we dissected the signaling pathways responsible for MMP-9 regulation in EGF-stimulated A172 cells.…”

“…Low expression of MMP-9 is correlated with better survival outcomes, [ 16 ] and MMP-9 is upregulated in human GBM [ 17 ]. MMP-9 is a candidate biomarker for high-grade glioma [ 18 ] that directs the migration and invasion of serum-stimulated GBM [ 19 ]. In GBM cells treated with micro (mi) RNA-181c, EGFR activates MMP-9 by inducing the phosphorylation of AKT [ 20 ].…”

Glutamate controls vessel-associated migration of GABA interneurons from the pial migratory route via NMDA receptors and endothelial protease activation

“…1f). Although MMP-9 is well known to contribute to the pathophysiology of several diseases involving dysfunction of the neurovascular unit during stroke [34] or dysregulation of cell migration with cancers [35], the contribution of MMP-9 to the control of vasculo-associated neuronal migration has never been investigated. Immunohistochemistry showed strong MMP-9 labeling at the level of the pial migratory route ( Fig.…”

Three‐Dimensional Models of the Human Brain Development and Diseases

“…[140,141] For example, Joseph J. V. et al showed that glioblastoma stem cells have similar characteristic of stem cells in terms of proliferation and migration. [140] They cultured floating neurospheroids in a serum-free medium with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF), allowing the neurospheroids to differentiate into different cell lineages and invasive into the brain parenchyma similar to stem cells.…”

“…The authors found that differentiated cancer neurospheroids increase their migration and invasion properties compared to the non-differentiated ones. [141] …”