Under-expression of annexin A2 is associated with Kazakh's esophageal squamous cell carcinoma.

The aim of the study was to identify candidate biomarkers for esophageal squamous cell carcinoma (ESCC) in Kazakh ethnic in Xinjiang as well as to reveal the potential role of Annexin A2 in ESCC carcinogenesis and progression. Five paired of Kazakh's ESCC tissues (T) and matched adjacent morphologically normal tissues (N) were separated by two-dimensional electrophoresis (2-DE) and differential proteins were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Annexin A2 was identified as a down-regulated protein in Kazakh's ESCC and further validated by immunohistochemistry (IHC) in 77 Kazakh's ESCC formalin-fixed paraffin-embeded (FFPE) samples. The expression level of Annexin A2 protein significantly correlated with the degree of ESCC differentiation and depth of invasion. For clarification of the role of Annexin A2 in regulating cell phenotype, in vitro eukaryotic expression vectors harboring full length Annexin A2 (pCMV-XL5-Annexin A2) was tranfected into Eca109 cells, and transfection effects were evaluated by RT-PCR and Western blotting analysis, respectively. Functionally, there was a significant decrease in cell proliferation, migration, and invasion capability in Eca109 with transfected pCMV-XL5-Annexin A2 compared to the controls. Furthermore, up-regulating Annexin A2 can significantly cause cell cycle arrest at the G2 phase, but no apoptosis was induced. Together, our findings suggested that Annexin A2 was involved in malignant phenotype and was a potential biomark for molecular classification in ESCC.