Integrated analysis of the differential cellular and EBV miRNA expression profiles in microdissected nasopharyngeal carcinoma and non-cancerous nasopharyngeal tissues.

Nasopharyngeal carcinoma (NPC) is commonly diagnosed in southern Asia. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression post-transcriptionally. Increasing evidence suggests that the dysregulation of miRNAs promotes NPC tumorigenesis. Epstein-Barr virus (EBV) infection and EBV-encoded miRNAs are also associated with the development of NPC. However, it is unclear how cellular and EBV miRNAs jointly regulate target genes and signaling pathways in NPC. In the present study, we analyzed the differential cellular and EBV miRNA expression profiles in 20 pooled NPC tissues using microarrays. We found that 19 cellular miRNAs and 9 EBV miRNAs were upregulated and 31 cellular miRNAs were downregulated in NPC tissues. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the 19 upregulated miRNAs target mainly the p53 signaling pathway in cancer, whereas the downregulated miRNAs regulate pathways related to cancer, focal adhesion and Erb, and MAPK signaling. In contrast, the upregulated EBV miRNAs target primarily the TGF-β and Wnt signaling pathways. Data also suggested that cellular miR-34b, miR-34c, miR-18a, miR‑200a/b, miR-449a, miR-31 and let-7 may be dysregulated in NPCs, and that the aberrant activation of their target genes in the p53 pathway and cell cycle enhance NPC cell survival and proliferation. In addition, EBV-miRNAs such as BART3 and BART5 target genes in the p53, TGF-β and Wnt signaling pathways to modulate NPC apoptosis and transformation. To better elucidate the interaction between miRNAs and target genes, we constructed an anti-correlated cellular and EBV miRNA/target gene regulatory network. The current findings may help dissect the roles played by cellular and EBV miRNAs during NPC tumorigenesis, and also provide useful biomarkers for the diagnosis and treatment of NPCs.