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EBV is a casual agent of NPC and products of EBV genome are believed to be involved in the pathogenesis of NPC. EBV is the first human virus found to express microRNAs (miRNAs). EBV has been found encoded more than forty miRNAs, the functions of which remain largely unknown. In this study, We discovered that BART9 was expressed at high levels in NPC tissues examined. In addition, the level of BART9 was higher than the best documented human oncogenic miR-21. Next, we investigated the role and mechanism of BART9 in NPC cells, and found that exogenous expression of BART9 enhanced the migration and invasion but not proliferation of EBV negative-NPC cells in vitro. Further, depletion of endogenous BART9 suppressed migration and invasion of EBV-positive NPC cells. We further demonstrated that BART9 directly targeted CDH1-3’-UTR and repressed the expression of CDH1, a metastasis suppressor. In addition, restoring of BART9-resistant CDH1 expression in BART9 over-expression cells recovered the migratory and invasive ability of BART9. More importantly, ectopic expression of BART9 triggered spontaneous metastasis of NPC cells in vivo. Finally, in situ hybridization for BART9 showed strong positive staining in paraffin-embedded nasopharyngeal carcinoma tissues and the CDH1 protein levels have an inverse correlation with BART9 expression. Collectively, our findings indicate that BART9 promoted migration, invasion and metastasis in NPC. It is the first case reported that EBV encodes an BART miRNA has effect on motility of infected cells, suggesting a novel mechanism by which Epstein-Barr virus induces the metastasis and recurrence of NPC. Citation Format: Hsu Chung Yuan. BART9, an EBV encoded miRNA, regulates E-cadherin and metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2711. doi:10.1158/1538-7445.AM2013-2711