Abstract
BACKGROUND AND OBJECTIVE: It has been proven that the development and biological behavior of lung carcinoma is affected by a number of signaling pathway elements. The expression levels of Krüppel-like factor 4 (KLF4) and secreted protein acidic and rich in cysteine (SPARC) were correlated with tumorigenesis and prognosis. This study aims to investigate KLF4 and SPARC expression and their correlation with the clinical characteristics of non-small cell lung cancer (NSCLC). METHODS: KLF4 and SPARC expression was examined immunohistochemically in NSCLC and normal lung tissues from 89 patients. RESULTS: SPARC expression was increased in the tumor specimens compared with the control tissue (70.8% vs 7.9%, P<0.05), whereas KLF4 protein was reduced compared with that in the control tissue (42.7% vs 88.8%, P<0.05). KLF4 expression was significantly correlated with lymph node metastasis and clinical stage (P<0.05). KLF4 expression in NSCLC decreased with the increasing clinical stage. The positive rate of SPARC expression in NSCLC with lymph node metastasis was significantly higher than that without lymph node metastasis (81.3% vs 58.5%, P<0.05). Lung carcinomas in stages I and II disease had significantly lower rates of positive SPARC expression than that in stages III and IV diseases (P<0.05). Both were not related to age, sex, and tumor size (P>0.05). KLF4 expression was negatively correlated with SPARC expression in NSCLC (r=-0.245, P<0.05). CONCLUSIONS: The SPARC overexpression may play an important role in the initiation and development of NSCLC, whereas KLF4 inhibits this process. These proteins may be used as marker for evaluating the biological characteristics and clinical stages of NSCLC.