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Updated: Jun 24, 2026
Coculture Assays to Study Macrophage and Microglia Stimulation of Glioblastoma Invasion
Published on: October 20, 2016
Stat3 inhibition activates tumor macrophages and abrogates glioma growth in mice
Leying Zhang1, Darya Alizadeh, Michelle Van Handel
1Division of Neurosurgery, Beckman Research Institute, City of Hope Medical Center, Duarte, California, USA.
Abstract:
As the main effector-cell population of the central nervous system, microglia (MG) are considered to play an important immunoregulatory function in a number of pathological conditions such as inflammation, trauma, degenerative disease, and brain tumors. Recent studies, however, have suggested that the anti-neoplastic function of MG may be suppressed in malignant brain tumors. Considering the proposed suppressive role of signal transducers and activators of transcription 3 (Stat3) in antitumor immunity, we evaluated the role of Stat3 inhibition on MG and macrophage (MP) activation and tumor growth in a murine glioma model. N9 MG cells were exposed to GL261 glioma conditioned medium (GL261-CM) and evaluated for Stat3 activity and cytokine expression. Furthermore, the role of Stat3 inhibition on MG and MP activation was studied both in vitro and in vivo. Finally, the effect of Stat3 inhibition on tumor growth was assessed in intracranial GL261 gliomas. GL261-CM increased Stat3 activity in N9 cells in vitro and resulted in overexpression of IL-10 and IL-6, and downregulation of IL1-beta, a pro-inflammatory cytokine. Inhibition of Stat3 by CPA-7 or siRNA reversed glioma-induced cytokine expression profile in N9 cells. Furthermore, inactivation of Stat3 in intracranial GL261 tumors by siRNA resulted in MG/MP activation and tumor growth inhibition. Glioma-induced MG and MP suppression may be mediated thorough Stat3. Inhibition of Stat3 function in tumor MG/MP may result in their activation and can potentially be used as an adjunct immunotherapy approach for gliomas.
Insights
Signal transducers and activators of transcription 3 (Stat3) suppress microglia (MG) and macrophage (MP) anti-tumor function in gliomas. Inhibiting Stat3 activates these immune cells, potentially enhancing glioma immunotherapy.
Area of Science:
- Neuroimmunology
- Cancer Immunology
- Molecular Biology
Background:
- Microglia (MG) are key immune cells in the central nervous system, crucial for regulating pathological conditions.
- Malignant brain tumors, like gliomas, may suppress the anti-neoplastic functions of microglia and macrophages (MP).
- Signal transducer and activator of transcription 3 (Stat3) is implicated in suppressing anti-tumor immunity.
Purpose of the Study:
- To investigate the role of Stat3 inhibition in activating microglia and macrophages within a murine glioma model.
- To determine the impact of Stat3 inhibition on glioma growth and immune cell activation.
Main Methods:
- Cultured N9 microglia cells were exposed to GL261 glioma conditioned medium (GL261-CM) to assess Stat3 activity and cytokine profiles.
- Stat3 inhibition was achieved using CPA-7 or siRNA in vitro and in vivo.
- Tumor growth and immune cell activation were evaluated in an intracranial GL261 glioma model.
Main Results:
- GL261-CM increased Stat3 activity in microglia, leading to elevated IL-10 and IL-6, and reduced IL1-beta expression.
- Stat3 inhibition reversed the glioma-induced cytokine profile in microglia.
- In vivo Stat3 inactivation in gliomas activated microglia/macrophages and inhibited tumor growth.
Conclusions:
- Glioma-induced suppression of microglia and macrophages appears to be mediated by Stat3.
- Inhibiting Stat3 in tumor-associated microglia/macrophages can restore their anti-tumor function.
- Stat3 inhibition represents a potential adjunctive immunotherapy strategy for gliomas.
