Background: ANXA2 (Annexin A2) is a pleiotropic calcium-dependent phospholipid binding protein that is abnormally expressed in various cancers. We previously found that ANXA2 is upregulated in esophageal squamous cell carcinoma (ESCC). This study was designed to investigate the functional significance of ANXA2 dysregulation and underlying mechanism in ESCC.
Methods: Proliferation, migration, invasion and metastasis assay were performed to examine the functional roles of ANXA2 in ESCC cells in vitro and in vivo. Real-time RT-PCR, immunoblotting, ChIP, reporter assay, confocal-immunofluorescence staining, co-immunoprecipitation and ubiquitination assay were used to explore the molecular mechanism underlying the actions of deregulated ANXA2 in ESCC cells.
Results: Overexpression of ANXA2 promoted ESCC cells migration and invasion in vitro and metastasis in vivo through activation of the MYC-HIF1A-VEGF cascade. Notably, ANXA2 phosphorylation at Tyr23 by SRC led to its translocation into the nucleus and enhanced the metastatic potential of ESCC cells. Phosphorylated ANXA2 (Tyr23) interacted with MYC and inhibited ubiquitin-dependent proteasomal degradation of MYC protein. Accumulated MYC directly potentiated HIF1A transcription and then activated VEGF expression. Correlation between these molecules were also found in ESCC tissues. Moreover, dasatinib in combination with bevacizumab or ANXA2-siRNA produced potent inhibitory effects on the growth of ESCC xenograft tumors in vivo.
Conclusions: This study provides evidence that highly expressed p-ANXA2 (Tyr23) contributes to ESCC progression by promoting migration, invasion and metastasis, and suggests that targeting the SRC-ANXA2-MYC-HIF1A-MYC axis may be an efficient strategy for ESCC treatment.
Keywords: Annexin A2; Esophageal squamous cell carcinoma; Invasion; Metastasis; VEGF.