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Updated: May 25, 2026
Coculture Assays to Study Macrophage and Microglia Stimulation of Glioblastoma Invasion
Published on: October 20, 2016
Microglial stimulation of glioblastoma invasion involves epidermal growth factor receptor (EGFR) and colony
Salvatore J Coniglio1, Eliseo Eugenin, Kostantin Dobrenis
1Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA. salvatore.coniglio@einstein.yu.edu
Abstract:
Glioblastoma multiforme is a deadly cancer for which current treatment options are limited. The ability of glioblastoma tumor cells to infiltrate the surrounding brain parenchyma critically limits the effectiveness of current treatments. We investigated how microglia, the resident macrophages of the brain, stimulate glioblastoma cell invasion. We first examined the ability of normal microglia from C57Bl/6J mice to stimulate GL261 glioblastoma cell invasion in vitro. We found that microglia stimulate the invasion of GL261 glioblastoma cells by approximately eightfold in an in vitro invasion assay. Pharmacological inhibition of epidermal growth factor receptor (EGFR) strongly inhibited microglia-stimulated invasion. Furthermore, blockade of colony stimulating factor 1 receptor (CSF-1R) signaling using ribonucleic acid (RNA) interference or pharmacological inhibitors completely inhibited microglial enhancement of glioblastoma invasion. GL261 cells were found to constitutively secrete CSF-1, the levels of which were unaffected by epidermal growth factor (EGF) stimulation, EGFR inhibition or coculture with microglia. CSF-1 only stimulated microglia invasion, whereas EGF only stimulated glioblastoma cell migration, demonstrating a synergistic interaction between these two cell types. Finally, using PLX3397 (a CSF-1R inhibitor that can cross the blood-brain barrier) in live animals, we discovered that blockade of CSF-1R signaling in vivo reduced the number of tumor-associated microglia and glioblastoma invasion. These data indicate that glioblastoma and microglia interactions mediated by EGF and CSF-1 can enhance glioblastoma invasion and demonstrate the possibility of inhibiting glioblastoma invasion by targeting glioblastoma-associated microglia via inhibition of the CSF-1R.
Insights
Microglia enhance glioblastoma invasion through epidermal growth factor (EGF) and colony-stimulating factor 1 (CSF-1) signaling. Targeting colony-stimulating factor 1 receptor (CSF-1R) in microglia reduces tumor invasion, offering a potential therapeutic strategy.
Area of Science:
- Neuro-oncology
- Immunology
- Cell Biology
Background:
- Glioblastoma multiforme (GBM) is an aggressive brain tumor with limited treatment options.
- Tumor cell infiltration into brain parenchyma hinders treatment efficacy.
- Microglia, the brain's resident immune cells, play a role in GBM progression.
Purpose of the Study:
- To investigate the mechanisms by which microglia stimulate glioblastoma cell invasion.
- To evaluate the therapeutic potential of targeting microglia-mediated signaling pathways.
Main Methods:
- In vitro co-culture invasion assays using GL261 glioblastoma cells and primary microglia.
- Pharmacological inhibition of epidermal growth factor receptor (EGFR) and colony-stimulating factor 1 receptor (CSF-1R).
- In vivo studies using the CSF-1R inhibitor PLX3397 in a mouse model.
Main Results:
- Microglia significantly enhanced GL261 glioblastoma cell invasion in vitro.
- EGFR inhibition partially reduced microglia-stimulated invasion, while CSF-1R blockade completely abolished it.
- GL261 cells secrete CSF-1, and EGF promotes glioblastoma cell migration, indicating synergistic interaction.
- In vivo CSF-1R inhibition reduced tumor-associated microglia and glioblastoma invasion.
Conclusions:
- Microglia-glioblastoma interactions, mediated by EGF and CSF-1, promote tumor invasion.
- Targeting CSF-1R signaling in tumor-associated microglia is a promising strategy to inhibit glioblastoma invasion.
