Epstein-Barr virus growth/latency III program alters cellular microRNA expression

The Epstein-Barr virus (EBV) is associated with lymphoid and epithelial cancers. Initial EBV infection alters lymphocyte gene expression, inducing cellular proliferation and differentiation as the virus transitions through consecutive latency transcription programs. Cellular microRNAs (miRNAs) are important regulators of signaling pathways and are implicated in carcinogenesis. The extent to which EBV exploits cellular miRNAs is unknown. Using micro-array analysis and quantitative PCR, we demonstrate differential expression of cellular miRNAs in type III versus type I EBV latency including elevated expression of miR-21, miR-23a, miR-24, miR-27a, miR-34a, miR-146a and b, and miR-155. In contrast, miR-28 expression was found to be lower in type III latency. The EBV-mediated regulation of cellular miRNAs may contribute to EBV signaling and associated cancers. There were two major objectives for this study. The first objective was to determine whether EBV infected cells exhibiting type I latency influence cellular microRNA expression. For this study, four EBV negative derivatives of the type I latency cell line, Mutu I, were derived by retroviral infection with a dominant negative from of the EBV episomal replication factor, EBNA1. RNA from these four clones were compared to parental EBV positive Mutu I cells. Four dual labeling experiments were carried out for this comparison with dye reversal for every second pair of RNAs. The second objective was to determine whether EBV type III latency cells exhibit altered cellular microRNA gene expression compared to type I latency cells or EBV negative B cells. Four dual labeling experiments were carried out for this analysis with dye reversal for every second pair of RNAs.