ROS1 amplification mediates resistance to gefitinib in glioblastoma cells

Area of Science:

• Oncology
• Neuro-oncology
• Molecular Biology

Background:

• Glioblastoma (GBM) is an aggressive brain tumor with poor prognosis.
• EGFR mutations are common in GBM, making EGFR tyrosine kinase inhibitors (TKIs) a therapeutic target.
• Tumor recurrence due to drug resistance necessitates identification of alternative signaling pathways.

Purpose of the Study:

• To investigate mechanisms of resistance to EGFR tyrosine kinase inhibitors (TKIs) in glioblastoma.
• To identify novel therapeutic targets for overcoming TKI resistance in GBM.
• To explore combination therapies for enhanced glioblastoma treatment.

Main Methods:

• Glioblastoma cells overexpressing EGFR were treated with gefitinib to isolate resistant clones.
• RNA sequencing (RNAseq) was performed on resistant clones to identify upregulated genes.
• Western blot analysis confirmed protein level upregulation of ROS1 and DDR1.
• ROS1 inhibitor was used in combination with gefitinib to assess drug synergy and cell death.

Main Results:

• Resistant GBM clones exhibited upregulation of alternative tyrosine kinase receptors, including ROS1, DDR1, and PDGFRA.
• Upregulation of ROS1 and DDR1 was confirmed at the protein level.
• Inhibition of ROS1 sensitized resistant cells to gefitinib, leading to massive apoptosis.
• Combined gefitinib and ROS1 inhibition induced prolonged S phase cell cycle arrest.

Conclusions:

• Glioblastoma cells evade EGFR TKI therapy through alternative signaling pathways, notably ROS1 activation.
• ROS1 represents a promising therapeutic target to overcome gefitinib resistance in GBM.
• Combination therapy targeting both EGFR and ROS1 may improve treatment efficacy and prevent glioblastoma recurrence.