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Updated: Apr 27, 2026
A Rapid Screening Workflow to Identify Potential Combination Therapy for GBM using Patient-Derived Glioma Stem Cells
Published on: March 28, 2021
Metformin plus sorafenib highly impacts temozolomide resistant glioblastoma stem-like cells
Mihaela D Aldea1, Bobe Petrushev, Olga Soritau
1Research Center for Functional Genomics, Biomedicine and Translational Medicine, University of Medicine and Pharmacy Iuliu Hatieganu and Department of Functional Genomics, the Oncology Institute Prof. Dr. Ion Chiricuta, Cluj Napoca, Romania.
Purpose:
Glioblastoma stem cells (GSCs), responsible for the dismal disease prognosis after conventional treatments, are driven by overactive signaling pathways, such as PI3K/ AKT/mTOR and RAS/RAF/MAPK. The objective of our study was to target in vitro-GSCs by combining metformin (Met) as a mTOR inhibitor, with sorafenib (Soraf) as a RAF inhibitor.
Methods:
GSCs cultured under basal conditions were treated with Met, temozolomide (TMZ), Soraf, Met+TMZ and Met+Soraf; as untreated arm served as control. At 4 hrs of drug exposure, we measured the level of reactive oxygen species (ROS) by 2',7'-dichlorofluorescein diacetate (DCFDA) assay, apoptosis by prodium iodide (PI)-V Annexin staining and efflux pump activity by using the fluorescent dye rhodamine 123. At 24 hrs, we measured cell proliferation by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay, apoptosis and malondialdehyde (MDA) levels. MTT results were compared with corresponding measurements on cultures of non-stem glioblastoma cells and osteoblasts.
Results:
Met+Soraf exerted the highest antiproliferative effects in GSCs and non-stem glioblastoma cells (p<0.001). Both Met and Soraf monotherapy exhibited a selective cytotoxic effect on GSCs (p<0.001), while no effect was detected on non-stem glioblastoma cells (p>0.05). Soraf, but not Met, impacted the proliferation of normal cells. Soraf displayed synergism with Met in producing high levels of ROS, decreasing efflux pump activity and generating the highest apoptotic rates when compared to either drug alone (p<0.001).
Conclusion:
GSCs were highly sensitive to the combination of Met and Soraf which reduced cell proliferation, increased oxidative stress, inhibited efflux pump activity and ultimately killed GSCs. We strongly believe that these results warrant further in vivo exploration.
Insights
Metformin and sorafenib combination effectively targets glioblastoma stem cells (GSCs) by reducing proliferation, increasing oxidative stress, and inducing apoptosis. This combination therapy shows promise for treating GSCs, warranting further in vivo investigation.
Area of Science:
- Oncology
- Cancer Stem Cell Biology
- Pharmacology
Background:
- Glioblastoma stem cells (GSCs) drive treatment resistance and poor prognosis.
- Overactive PI3K/AKT/mTOR and RAS/RAF/MAPK pathways fuel GSC survival.
- Targeting these pathways is crucial for effective glioblastoma therapy.
Purpose of the Study:
- To investigate the in vitro efficacy of combining metformin (mTOR inhibitor) with sorafenib (RAF inhibitor) against glioblastoma stem cells.
- To evaluate the synergistic effects of metformin and sorafenib on GSC proliferation, apoptosis, reactive oxygen species (ROS) production, and efflux pump activity.
Main Methods:
- Glioblastoma stem cells were treated with metformin, sorafenib, or their combination.
- Assays included reactive oxygen species (DCFDA), apoptosis (Annexin V/PI), efflux pump activity (rhodamine 123), and cell proliferation (MTT).
- Comparisons were made with non-stem glioblastoma cells and osteoblasts.
Main Results:
- The metformin-sorafenib combination demonstrated significant antiproliferative effects on GSCs and non-stem glioblastoma cells.
- Metformin and sorafenib monotherapy selectively reduced GSC viability.
- The combination synergistically increased ROS, decreased efflux pump activity, and elevated apoptosis in GSCs.
Conclusions:
- Metformin and sorafenib combination therapy is highly effective against glioblastoma stem cells in vitro.
- This combination reduces proliferation, enhances oxidative stress, inhibits efflux pumps, and induces GSC apoptosis.
- Further in vivo studies are warranted to explore the therapeutic potential of this combination.
