Fibulin-1 functions as a prognostic factor in lung adenocarcinoma

Fibulin-1 is a member of the fibulin gene family, characterized by tandem arrays of epidermal growth factor-like domains and a C-terminal fibulin-type module. Fibulin-1 plays important roles in a range of cellular functions including morphology, growth, adhesion and mobility. It acts as a tumor suppressor gene in cutaneous melanoma, prostate cancer and gastric cancer. However, whether fibulin-1 also acts as a tumor suppressor gene in lung adenocarcinoma remains unknown. We also determined the association of fibulin-1 expression with various clinical and pathological parameters, which would show its potential role in clinical prognosis. We investigated and followed up 140 lung adenocarcinoma patients who underwent lung resection without pre- and post-operative systemic chemotherapy at the Affiliated Hospital of Nantong University from 2009 to 2013. Western blot assay and immunohistochemistry were used to evaluate the expression of fibulin-1 in lung adenocarcinoma tissues. We then analyzed the correlations between fibulin-1 expression and clinicopathological variables as well as the patients' overall survival rate. Both western blot assay and immunohistochemistry demonstrated that the level of fibulin-1 was downregulated in human lung adenocarcinoma tissues compared with that of normal lung tissues. Fibulin-1 expression significantly correlated with histological differentiation (P = 0.046), clinical stage (P < 0.01), lymph node status (P = 0.038) and expression of Ki-67 (P = 0.013). More importantly, multivariate analysis revealed that fibulin-1 was an independent prognostic marker for lung adenocarcinoma, and high expression of fibulin-1 was significantly associated with better prognosis of lung adenocarcinoma patients. The results supported our hypothesis that fibulin-1 can act as a prognostic factor in lung adenocarcinoma progression.