EGFR soluble isoforms and their transcripts are expressed in meningiomas

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Epidermal growth factor receptor (EGFR) plays a role in oncogenesis.
• Tumor cells express full-length EGFR (isoform a) and soluble isoforms (sEGFR) lacking intracellular domains.
• sEGFR isoforms b, c, and d are encoded by EGFR variants 2, 3, and 4 mRNA.

Purpose of the Study:

• Investigate the expression of sEGFR and EGFRvIII mutant in meningiomas.
• Analyze the correlation between EGFR expression and clinical data, including tumor grade and patient outcome.
• Determine if EGFR oncogenetic mechanisms in meningiomas differ from other tumor types.

Main Methods:

• Immunohistochemistry using extracellular domain (ECD-Ab) and intracellular domain (ICD-Ab) targeted antibodies on 69 meningiomas.
• RT-PCR to quantify EGFRv1-v4 and EGFRvIII mRNAs.
• MLPA for EGFR amplification analysis.
• Correlation analysis with clinical data (Simpson grade, histology, tumor grade, Ki67 index).

Main Results:

• Immunohistochemical staining was stronger with ECD-Ab than ICD-Ab.
• Meningiomas expressed EGFRv1-v4 mRNAs but not EGFRvIII mutant.
• Higher ECD-Ab staining and EGFRv1-v4 mRNA levels were associated with better progression-free survival (PFS).
• Improved PFS observed in women, with Simpson grades 1 or 2 resection, grade I tumors, and lower Ki67 index (<10%).

Conclusions:

• EGFR protein isoforms without intracellular domains and their corresponding mRNA variants are expressed in meningiomas.
• EGFRvIII mutant was not detected in the studied meningiomas.
• High expression levels of sEGFR and its mRNA variants appear linked to a better prognosis in meningiomas.
• The EGFR pathway's oncogenetic role in meningiomas may differ from other cancers.