| Summary: | 碩士 === 長庚大學 === 生物醫學研究所 === 97 === Latent Epstein-Barr virus infection is associated with several cancers, including nasopharyngeal carcinoma (NPC) that is especially common in Southern China. Recently, some of the EBV-encode miRNAs have been found to play important roles in regulating EBV gene expression or host immune responses and survival. But the functions of most EBV miRNAs remain largely unknown. Using stem-loop RT-PCR to detect the expression level of EBV miRNAs in NPC tissues, we found that the expression level of ebv-miR-BART18-5p was higher than other EBV miRNAs. We using computational prediction, microarray and systems biology approaches to investigate the functional pathways that are regulated by BART18-5p.
We compared the mRNA levels in control with BART18-5p over-expressing stable cell lines by microarray, and generated a differentially expressed gene list with 1018 genes (p-value < 0.05, fold change > 1.1). By analyzing the differentially expressed genes in MetaCore 5.1, we found that the expression level of MMP9 in ECM remodeling pathway is significantly elevated. Using Q-PCR and western blot, we demonstrated that BART18-5p could induce MMP9 gene expression in mRNA and protein levels. We further analyzed the activities of transcription activator of MMP9 by promoter reporter assay. The results showed that the activities of NF-kB and AP-1 were up-regulated by BART18-5p. Furthermore, by using pMIR-luciferase reporter assay, we demonstrated that the inhibitors of NF-kB and AP-1, such as RBPJ and PIAS1, could be inhibited by BART18-5p. Collectively, our findings suggest that BRAT18-5p could inhibit RBPJ and PIAS1 to activate NF-kB and AP-1, and sequentially up-regulate MMP9 expression. These events may lead to regulate host cell proliferation, survival, invasion and immune response in NPC.
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