The epithelial-mesenchymal transition (EMT) is crucial to cancer progression and metastasis. Although multiple cellular miRNAs have been identified to regulate the EMT and metastasis in cancers, the role of viral miRNAs in cancer progression remains largely unknown. Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated malignancy typically characterized by its early metastasis. In the present study, we have discovered the involvement of a viral miRNA, EBV-miR-BART7-3p, in the EMT and metastasis of NPC cells. Initially, we observed that EBV-miR-BART7-3p was highly expressed in NPC and positively correlated with lymph node metastasis and clinical stage of NPC. Subsequently, we demonstrated that EBV-miR-BART7-3p enhanced cell migration/invasion in vitro, cancer metastasis in vivo, and particularly the EMT characterized by loss of epithelial markers and gain of mesenchymal features in NPC cells. Furthermore, mechanistic studies disclosed that EBV-miR-BART7-3p targeted a major human tumor suppressor PTEN, modulating PI3K/Akt/GSK-3β signaling and eventually leading to the high expression and nuclear accumulation of Snail and β-catenin, which favor EMT. Knockdown of PTEN could phenocopy the effect of EBV-miR-BART7-3p, whereas re-expression of PTEN resulted in a phenotypic reversion. Moreover, these findings were supported by an observation of an EBV-positive cell model in which silencing of endogenous EBV-miR-BART7-3p partially attenuated cell migration/invasion and altered EMT protein expression pattern via reverting PI3K/Akt, Snail and β-catenin expression. Thus, this study suggests a novel mechanism by which EBV-miR-BART7-3p modulates the EMT and metastasis of NPC cells, and a clinical implication of EBV-miR-BART7-3p as a potential biomarker or therapeutic target.

The molecular mechanisms underlying the increase of natural killer (NK) cell anticancer activity mediated by interleukin (IL)-10 have not been elucidated. The aim of this study was to identify potential molecular mediators of IL-10 stimulatory effects by exploring the NK cell gene display induced by this cytokine. Gene profile was determined by high-throughput cDNA microarray and quantitative real-time PCR. In vitro, NK cells resting or conditioned with IL-10 were tested for cytotoxicity, migration and proliferation. IL-10 enhanced mRNA levels of cell activation/cytotoxicity-related genes (eg secretogranin, TIA-1, HMG-1, interferon-inducible genes) not upregulated by IL-2. In line with these findings, IL-10 increased NK cell in vitro cytotoxicity against Daudi cells. Unlike IL-2, IL-10 did not show any significant effect on NK cell in vitro proliferation and migration. However, gene profile analysis showed that IL-10 increased the expression of cell migration-related genes (eg L-selectin, vascular endothelium growth factor receptor-1, plasminogen activator, tissue; formyl peptide receptor, lipoxin A4 receptor), which might support a stimulatory effect not evident with the in vitro functional assay. Overall, gene profiling allowed us to formulate new hypotheses regarding the molecular pathways underlying the stimulatory effects of IL-10 on NK cells, supporting further investigation aimed at defining its role in cancer immune rejection.

Background:Several lines of evidence suggest a dichotomy between immune active and quiescent cancers, with the former associated with a good prognostic phenotype and better responsiveness to immunotherapy. Central to such dichotomy is the master regulator of the acute inflammatory process interferon regulatory factor (IRF)-1. However, it remains unknown whether the responsiveness of IRF-1 to cytokines is able to differentiate cancer immune phenotypes.Methods:IRF-1 activation was measured in 15 melanoma cell lines at basal level and after treatment with IFN-γ, TNF-α and a combination of both. Microarray analysis was used to compare transcriptional patterns between cell lines characterised by high or low IRF-1 activation.Results:We observed a strong positive correlation between IRF-1 activation at basal level and after IFN-γ and TNF-α treatment. Microarray demonstrated that three cell lines with low and three with high IRF-1 inducible translocation scores differed in the expression of 597 transcripts. Functional interpretation analysis showed mTOR and Wnt/β-cathenin as the top downregulated pathways in the cell lines with low inducible IRF-1 activation, suggesting that a low IRF-1 inducibility recapitulates a cancer phenotype already described in literature characterised by poor prognosis.Conclusion:Our findings support the central role of IRF-1 in influencing different tumour phenotypes.