Identification of annexin A1 as a proinvasive and prognostic factor for lung adenocarcinoma

Metastasis is the most common cause of death in lung cancer patients and is a major obstacle to the successful treatment. To discover novel metastasis-related proteins in lung adenorcinoma (AdC), quantitative proteomic analysis was performed between primary lung AdC tissues with (LNM AdC) and without lymph node metastasis (non-LNM AdC). In this study, annexin A1 was identified to be significantly up-regulated in LNM AdC compared with non-LNM AdC. Immunohistochemistry showed that annexin A1 over-expression was frequently observed in LNM AdCs and matched lymph node metastases compared with non-LNM AdCs. Annexin A1 over-expression was significantly associated with advanced clinical stage (P < 0.05) and lymph node metastasis (P < 0.05) and increased relapse rate (P < 0.05) and decreased overall survival (P < 0.05) in lung AdCs. Cox regression analysis indicated annexin A1 over-expression was an independent prognostic factor. Furthermore, suppression of annexin A1 expression by siRNA interference significantly inhibited the invasion ability of lung adenocarcinoma cell A549 in vitro. In conclusion, annexin A1 expression correlated with tumor stage, lymph node metastasis, relapse, and patient survival. Annexin A1 is proposed to function importantly in the progression of lung AdC.