Thyroid transcription factor-1 expression is significantly associated with mutations in exon 21 of the epidermal growth factor receptor gene in Chinese patients with lung adenocarcinoma

Abstract

Qingchun Zhao,1,* Song Xu,1,2,* Jinghao Liu,1 Ying Li,2 Yaguang Fan,2 Tao Shi,3 Sen Wei,1 Shou-Ching Tang,4,5 Hongyu Liu,2 Jun Chen1,2 1Department of Lung Cancer Surgery, 2Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, 3Department of Pathology, Tianjin Medical University General Hospital, Tianjin, People’s Republic of China; 4Division of Hematology and Oncology, Georgia Regents University Cancer Center, Augusta, GA, USA; 5Department of Surgery, Tianjin Tumor Hospital and Research Institute, Tianjin Medical University Cancer Institute and Hospital, Tianjin, People’s Republic of China *These authors contributed equally to this work Objective: The aim of this retrospective study was to investigate the relationship between thyroid transcription factor-1 (TTF-1) expression and epidermal growth factor receptor (EGFR) gene mutations in lung adenocarcinomas of Chinese patients. Methods: There were 200 lung adenocarcinoma patients who were enrolled in this study. Tumor specimens of these patients were investigated for TTF-1 expression and mutations in EGFR using immunohistochemistry and a liquid chip platform for DNA analysis of slides with sections of formalin-fixed, paraffin-embedded specimens. Results: The rates of TTF-1 expression and EGFR mutations were 81.5% and 45.5%, respectively, in the lung adenocarcinoma specimens of the recruited patients. Among female nonsmokers (n=72), 93.1% of specimens were positive for TTF-1 expression, and 63.9% had EGFR mutations. Of 89 patients with EGFR mutations, 83 (50.9%) specimens were simultaneously positive for TTF-1 expression. Kaplan–Meier analysis of all patient specimens found that postoperative survival time was not significantly associated with TTF-1 expression and the presence of EGFR mutations. However, patients with disease stages III–IV whose tumors were positive for TTF-1 expression and EGFR mutations had better postoperative survival than similar patients whose tumors were negative for TTF-1 expression and EGFR mutations. Conclusion: Our study showed a significant association between TTF-1 positivity and the presence of EGFR mutations (exon 21) in the Chinese lung adenocarcinoma patients. We further identify that patients with disease stages III–IV who were positive for TTF-1 expression and EGFR mutations had a better postoperative survival than those patients who were negative for TTF-1 expression and EGFR mutations. Therefore, TTF-1 might be a potential prognostic biomarker for stages III–IV lung adenocarcinoma patients. In clinical practice, TTF-1 expression may be a marker for planning therapy for certain patients with lung adenocarcinoma, especially for selection of EGFR tyrosine kinase inhibitors. Keywords: EGFR, lung adenocarcinoma, survival, TTF-1