Quantum dots immunofluorescence histochemical detection of EGFR gene mutations in the non-small cell lung cancers using mutation-specific antibodies

Yan-Gang Qu,1 Qian Zhang,2 Qi Pan,3 Xian-Da Zhao,4 Yan-Hua Huang,2 Fu-Chun Chen,3 Hong-Lei Chen41Department of Pathology, The Central Hospital of Enshi Autonomous Prefecture, Enshi, 2Department of Molecular Pathology, Wuhan Nano Tumor Diagnosis Engineering Research Center, Wuhan, Hubei, People’s Republic of China; 3Department of Thoracosurgery, Traditional Chinese Medical Hospital of Wenling, Wenling, Zhejiang, People’s Republic of China; 4Department of Pathology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei, People’s Republic of ChinaBackground: Epidermal growth factor receptor (EGFR) mutation status plays an important role in therapeutic decision making for non-small cell lung cancer (NSCLC) patients. Since EGFR mutation-specific antibodies (E746-A750del and L858R) have been developed, EGFR mutation detection by immunohistochemistry (IHC) is a suitable screening test. On this basis, we want to establish a new screening test, quantum dots immunofluorescence histochemistry (QDs-IHC), to assess EGFR gene mutation in NSCLC tissues, and we compared it to traditional IHC and amplification refractory mutation system (ARMS).Materials and methods: EGFR gene mutations were detected by QDs-IHC, IHC, and ADx-ARMS in 65 cases of NSCLC composed of 55 formalin-fixed, paraffin-embedded specimens and ten pleural effusion cell blocks, including 13 squamous cell carcinomas, two adenosquamous carcinomas, and 50 adenocarcinomas.Results: Positive rates of EGFR gene mutations detected by QDs-IHC, IHC, and ADx-ARMS were 40.0%, 36.9%, and 46.2%, respectively, in 65 cases of NSCLC patients. The sensitivity of QDs-IHC when detecting EGFR mutations, as compared to ADx-ARMS, was 86.7% (26/30); the specificity for both antibodies was 100.0% (26/26). IHC sensitivity was 80.0% (24/30) and the specificity was 92.31% (24/26). When detecting EGFR mutations, QDs-IHC and ADx-ARMS had perfect consistency κ=0.882; P<0.01. Excellent agreement was observed between IHC and ADx-ARMS when detecting EGFR mutations κ=0.826; P<0.01.Conclusion: QDs-IHC is a simple and standardized method to detect EGFR mutations with its high sensitivity and specificity, as compared with real-time polymerase chain reaction. In addition, the development of specific antibodies against EGFR mutation proteins might be useful for the diagnosis and treatment of lung cancer.Keywords: quantum dots, lung cancer, EGFR, gene mutation, real-time PCR, immuno­histochemistry