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.