Expression of seven stem-cell-associated markers in human airway biopsy specimens obtained via fiberoptic bronchoscopy

BACKGROUND Previous reports have suggested that malignant transformations originate from adult stem cells, and may thus express the stem-cell-associated markers. The purpose of this study is to investigate the differential expression and clinical significance of seven stem-cell-associated markers (Bmi1, CD133, CD44, Sox2, Nanog, OCT4 and Msi2) in lung cancer, providing new targets for the diagnosis and treatment of lung cancer. METHODS In this study, we evaluated the differential expression of mRNA levels seven stem-cell-associated markers by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) from 112 human lung cancer and 18 non-cancer tissues obtained by bronchoscopy. We further verified the differential expression of these markers by immunohistochemistry in 50 lung cancer specimens, 30 benign inflammatory lesion tissues and 20 non-tumor adjacent lung tissues. RESULTS With the exception of OCT4, other markers Bmi1, CD133, CD44, Sox2, Nanog and Msi2 mRNA and protein were abundantly expressed in lung cancer. Additionally, Nanog expression was highly upregulated in lung cancer tissues and rarely presented in non-cancerous lung tissues, the sensitivity and specificity of Nanog mRNA reached 63.4% and 66.7%, respectively. Nanog therefore possessed high diagnostic value, however, CD44, Bmi1 and CD133 showed poor diagnostic value in lung cancer. CONCLUSION Nanog may serve as a promising diagnostic marker of lung cancer and potential therapeutic target in lung cancer.