Krüppel-like factor 4: A new potential biomarker of lung cancer

Lung cancer is most prevalent human cancer worldwide. However, no molecular markers are currently available for predicting lung cancer prognosis. Therefore, identifying novel biomarkers may be useful for improving clinical diagnosis and patient stratification. Krüppel-like factor 4 (KLF4) is a transcription factor with opposing roles in different human cancers. Its overexpression in several cancers is correlated with a poor prognosis. However, the expression and role of KLF4 in lung cancer remains to be elucidated. The aim of this study was to determine the profile of KLF4 expression in different types of lung cancer. The KLF4 protein expression level was tested and evaluated by immunohistochemical analysis in 47 lung tumors and normal tissues, and then correlated with clinical characteristics. A differential expression of KLF4 was observed between normal tissue and each of the lung cancer types. A significant decrease in KLF4 expression was observed in non-small-cell lung cancer (NSCLC) compared with that in normal tissue, while significant overexpression was detected in small-cell lung cancer. Furthermore, a higher rate of expression was observed in stage II, III and IV disease compared with stage I disease in NSCLC tissues. KLF4 expression was not found to be associated with age or gender. Our results suggested that the KLF4 protein level may be a potential biomarker in patients with advanced lung cancer.