Epstein–Barr virus-encoded microRNA BART22 serves as novel biomarkers and drives malignant transformation of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy ubiquitously associated with Epstein–Barr virus (EBV). EBV generates various viral microRNAs (miRNAs) by processing the BHRF1 and BamHI A rightward (BART) transcripts. These BART miRNAs are abundantly expressed in NPC, but their functions and molecular mechanisms remain largely unknown. Our study found that the EBV-encoded microRNA BART-22 was significantly upregulated in NPC tissues and positively correlated with tumor progression. Furthermore, we found that EBV-miR-BART-22 was a significant predictor of poor prognosis in NPC. A reliable nomogram model to predict the preoperative overall survival (OS) of NPC patients was established. The area under the receiver operating characteristic (ROC) curve value for 5-year survival was 0.91. Elevated levels of EBV-miR-BART-22 significantly promoted the epithelial-mesenchymal transition (EMT) and metastasis of NPC cells in vivo and in vitro. We found that EBV-miR-BART-22 directly targets the 3′-UTR of MOSPD2 mRNA to promote the EMT and metastasis of NPC cells by activating the Wnt/β-catenin signaling pathway. Our findings provide a potential prognostic biomarker and new insight into the molecular mechanisms of NPC metastasis.