EGFRvIII mutation in lung cancer correlates with increased EGFR copy number

Abstract

Overexpression of the epidermal growth factor receptor (EGFR) is caused by EGFR gene amplification and is sometimes associated with expression of a variant EGFR (deletion exon 2-7 or EGFRvIII ). EGFRvIII mutation has oncogenic potential and is investigated as a potential therapeutic target. We genotyped the EGFRvIII mutation status in 252 surgically treated lung cancer cases. The presence or absence of EGFRvIII mutation was analyzed by real-time quantitative polymerase chain reaction (PCR) with mutation specific sensor and anchor probes. EGFR copy number was evaluated with PCR-based assay. EGFR mutation status at kinase domain has been examined and reported. EGFRvIII mutation was found on 8 of 252 patients. All patients were male, smokers, and 7 had squamous cell carcinoma. The mutation status was significantly correlated with pathological subtypes (squamous cell carcinoma vs. adenocarcinoma, p=0.0114). Sixty EGFR mutations at kinase domain exclusively existed with EGFRvIII mutations. EGFR gene copy number was significantly higher in EGFRvIII mutant (4.711±4.968) than in non- EGFRvIII mutant (2.284±1.224) (p=0.0001). EGFRvIII gene mutation might be one of the mechanisms of increased EGFR copy number. Further studies are needed to confirm the mechanisms of EGFRvIII mutations for possible anti-EGFR therapy for lung cancer.