Combined Inactivation of MEK and mTOR Can Lead to Synergistic Cell Death in Glioblastoma Models and Associates with...

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Glioblastoma (GB) is an aggressive brain tumor characterized by genetic alterations in kinase signaling pathways like Pi3K/mTOR and RAS/MAPK.
• Understanding co-vulnerabilities within these pathways is crucial for identifying effective therapeutic targets in GB.

Purpose of the Study:

• To investigate drug sensitivity to monotherapy and dual combination therapy targeting the Pi3K/mTOR and RAS/MAPK pathways in glioblastoma.
• To correlate drug sensitivities with genetic alterations (NF1) and transcriptomic subtypes of glioblastoma.
• To evaluate the efficacy of MEK and mTOR inhibitors in combination, including sequential and simultaneous administration.

Main Methods:

• Assessed drug sensitivity of glioblastoma cell line models to monotherapy and dual combination therapies.
• Correlated synergy levels with phosphoproteomic data and genetic tumor-driving lesions (NF1 alterations, GB subtypes).
• Conducted longitudinal experiments with serial or simultaneous MEK and mTOR inhibitor administration.

Main Results:

• Dual inhibition of MEK and mTOR demonstrated synergistic effects in glioblastoma models.
• Synergistic effects were strongly associated with NF1-deficiency and the mesenchymal glioblastoma subtype.
• Dual MEK and mTOR inhibition led to prolonged growth inhibition in glioblastoma spheroids, with sequential and simultaneous treatments showing similar efficacy.

Conclusions:

• Dual inhibition of MEK and mTOR presents a promising therapeutic strategy for glioblastoma.
• This approach is particularly effective in NF1-deficient and mesenchymal glioblastoma, the most lethal subtypes.
• Findings support the development of combination kinase inhibitor therapies for glioblastoma treatment.