Quantitative proteome analysis reveals annexin A3 as a novel biomarker in lung adenocarcinoma.

Metastasis is a common phenomenon and the major lethal cause of lung adenocarcinoma (AdC). To discover novel potential biomarkers associated with lymph node metastasis and prognosis in lung AdC, we assessed differences in protein expression between primary lung AdC with (LNM AdC) and without lymph node metastasis (non-LNM AdC) using a quantitative proteomic approach. Laser capture microdissection was performed to purify the cancer cells from primary lung AdC tissues. The differential proteins between the pooled microdissected non-LNM AdC and LNM AdC tissues were identified by two-dimensional difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry (MS). In this study, twenty proteins were found to be differentially expressed in two types of lung AdC. ANXA3, significantly up-regulated in LNM AdC compared with non-LNM AdC, was validated by western blotting. Immunohistochemistry showed that ANXA3 over-expression was frequently observed in LNM AdCs and matched lymph node metastases compared with non-LNM AdCs. ANXA3 over-expression was significantly associated with advanced clinical stage (p < 0.001) and lymph node metastasis (p < 0.001) and increased relapse rate (p < 0.001) and decreased overall survival (p < 0.001) in lung AdCs. Cox regression analysis indicated ANXA3 over-expression was an independent prognostic factor. Our results indicate that ANXA3 might serve as a novel biomarker for lymph node metastasis and prognosis in lung AdC, and play an important role in lung AdC progression.