Rapid Detection of the Epidermal Growth Factor Receptor Mutation in Non-Small-Cell Lung Cancer for Analysis of Acquired Resistance Using Molecular Beacons

A secondary mutation (T790M) in epidermal growth factor receptor (EGFR) is a hallmark of acquired resistance to EGFR inhibitors used to treat non-small-cell lung cancer (NSCLC). Therefore, identifying the T790M mutation is crucial to guide treatment decisions. Given that DNA sequencing methods are time-consuming and insensitive, we developed and investigated the feasibility of using molecular beacons for the detection of the T790M mutation in EGFR. A molecular beacon complementary to the region of the secondary EGFR mutation (T790M) was designed and used in NSCLC samples bearing drug-sensitive and -resistant EGFR mutations. For a rapid and simple assay, we attempted to use the molecular beacon with real-time PCR and in situ fluorescence imaging. The ability of the designed molecular beacon to specifically detect the T790M mutation of EGFR was tested for samples from two patients with drug resistance and compared with conventional DNA sequencing methods. The molecular beacon successfully detected the T790M mutation in patient samples with drug resistance. The sensitivity of the molecular beacon, which detected as little as 2% of genomic DNA from the drug-resistant cells (H1975), was much higher than direct sequencing. Furthermore, in situ fluorescence imaging with the molecular beacon gave rise to a distinguishable signal for the T790M mutation in drug-resistant cells. The molecular beacon-based approach enabled rapid and sensitive detection of the EGFR mutation (T790M) in NSCLC with in situ fluorescence imaging, which can be directed to determine various treatment options in patients with cancer. (J Mol Diagn 2010, 12:644-652; DOI: 10.2353/jmoldx.2010.090208)