MicroRNA-155 is a potential molecular marker of natural killer/T-cell lymphoma.

Natural killer/T-cell lymphoma (NKTCL) is characterized by its highly aggressive nature and rapid progression. MicroRNAs (miRNAs) play key roles in the development of NKTCL. We utilized next-generation Solexa high-throughput sequencing to compare miRNA expression in the SNK-6 and YTS NKTCL cell lines with expression in normal NK cells. We found that 195 miRNAs were upregulated in the SNK-6 cells and 286 miRNAs were upregulated in the YTS cells. Based on those results, we selected six miRNAs, including miRNA-155, and confirmed their expression using real-time polymerase chain reaction. Expression of miRNA-155 was higher in SNK-6 and YKS cells than in normal NK cells. We next determined the levels of miRNA-155 in the serum of healthy individuals and NKTCL patients, and correlated its expression with clinical parameters and inflammatory factors detected using enzyme-linked immunoabsorbent assays. Levels of miRNA-155 were higher in NKTCL patients' serum than in serum from healthy individuals. miRNA-155 expression was higher in patients with stable or progressive disease (SD+PD) than in those with partial or complete remission (PR+CR). While further studies are needed to clarify the underlying molecular mechanisms, it appears miRNA-155 may be a molecular marker of NKTCL.

miRNA-155 modulates the malignant biological characteristics of NK/T-cell lymphoma cells by targeting FOXO3a gene.

This study investigated the effects of miRNA-155 on malignant biological characteristics of NK/T-cell lymphoma cell lines and the possible mechanism. The expression of miRNA-155 was detected in lymphoma cell lines from different sources (SNK-6, YTS, Jurkat and DOHH2) by real-time PCR. Lentiviral vectors (pLL3.7) that could overexpress or downexpress miRNA-155 were constructed. Recombinant lentiviral particles were prepared and purified, and their titers determined. The expression of miRNA-155 in the infected SNK-6 cells and the cell proliferation were detected by PCR and CCK-8, respectively. Flow cytometry was used to determine the apoptosis of infected SNK-6 cells. The target of miRNA155 was predicted from Targetscan website. The effect of miRNA155 on FOXO3a expression was examined by Western blotting. The results showed that among the human NK/T-cell lymphoma cell lines SNK-6, YTS, Jurkat and DOHH2, the expression of miRNA-155 was highest in SNK-6. The infection efficiency of the recombinant lentivirus in SNK-6 was more than 70% at multiplicity of infection (MOI) of 100. The expression of miRNA-155 was significantly increased in SNK-6 cells infected by lentivirus vectors with high expression of miRNA-155 (4 times higher than the control group), and profoundly decreased in those infected with lentiviruses with low expression of miRNA-155. The proliferation of letivirus-infected SNK-6 cells was decreased as the expression of miRNA-155 reduced. The apoptosis rate was increased with the reduction in the expression of miRNA-155. FOXO3a was found to be a possible target of miRNA155, as suggested by Targetscan website. Western blotting showed that the expression of FOXO3a was significantly elevated in SNK-6 cells with miRNA-155 inhibition. It was concluded that reduction in miRNA-155 expression can inhibit the proliferation of SNK-6 lymphoma cells and promote their apoptosis, which may be associated with regulation of FOXO3a gene.