Non-keratinizing nasopharyngeal carcinoma, the major subtype of nasopharyngeal carcinoma, is characterized by low differentiation and a close relation to Epstein-Barr virus infection, which indicates a link between Epstein-Barr virus oncogenesis and loss of differentiation, and raises our interest in investigating the involvement of Epstein-Barr virus in nasopharyngeal carcinoma dedifferentiation. Our previous study showed abundant expression of an Epstein-Barr virus-encoded microRNA, BART10-3p, in nasopharyngeal carcinoma tissues, but the association between BART10-3p and nasopharyngeal carcinoma differentiation remains unknown. Here, we examined the expression and prognostic value of BART10-3p, and undertook bioinformatics analysis and functional assays to investigate the influence of BART10-3p on nasopharyngeal carcinoma differentiation and proliferation and the underpinning mechanism. Microarray analysis identified BART10-3p as the most significantly upregulated Epstein-Barr virus-encoded microRNA in nasopharyngeal carcinoma tissues and the upregulation was confirmed in two public datasets. The expression of BART10-3p was an independent unfavorable prognosticator in nasopharyngeal carcinoma and its integration with the clinical stage showed improved prognosis predictive performance. Bioinformatics analysis suggested a potential role of BART10-3p in tumor differentiation and progression. Functional assays demonstrated that BART10-3p could promote nasopharyngeal carcinoma cell dedifferentiation, epithelial-mesenchymal transition, and proliferation in vitro, and tumorigenicity in vivo. Mechanistically, BART10-3p directly targeted the 3'UTR of ALK7 and suppressed its expression. Reconstitution of ALK7 rescued BART10-3p-induced malignant phenotypes. Overall, our study demonstrates that BART10-3p promotes dedifferentiation and proliferation of nasopharyngeal carcinoma by targeting ALK7, suggesting a promising therapeutic opportunity to reverse the malignant phenotypes of nasopharyngeal carcinoma.
Keywords: ALK7; BART10-3p; Epstein-Barr virus; Nasopharyngeal carcinoma; dedifferentiation; proliferation.