Background/Aims: Although numerous studies have explored the mechanisms regulating the enzyme activity of NADPH oxidase in diabetic nephropathy (DN), little information is available for the contribution of microRNAs (miRNAs) to the regulation of NADPH oxidase expression. Therefore, the present study was to test whether miRNAs importantly contribute to the regulation of NOX4 expression, a major catalytic subunit of NADPH oxidase under hyperglycemia. Methods: Diabetic rats were induced by streptozotocin. miRNA microarray, Western blot, real-time RT-PCR and luciferase reporter assays were employed in this study. Results: Among 5 miRNAs, which are predicted to have a binding capacity to rat NOX4, the miRNA-25 level was significantly reduced both in the kidney from diabetic rats and in high glucose-treated mesangial cells, accompanied by the increases in NOX4 expression levels. In an in vitrostudy, we found that NADPH activity was increased by 226.2% in miRNA-25 inhibitor transfected cells and decreased by 51.0% in miRNA-25 precursor transfected cells. miR-25 inhibitor dramatically increased both NOX4 mRNA and protein levels. We then showed that miR-25 negatively regulated NOX4 expression by directly targeting the 3′-UTR by luciferase reporter assays. It was found that transfection of miR-25 precursor significantly decreased the luciferase activity of NOX4 3′-UTR by 39.5%, whereas the mutant sequence restored levels to 79.4%. Finally, our results indicated that the miR-25-mediated NOX4 mRNA level may result from the regulation of mRNA stability. Conclusions: These findings for the first time indicate that miRNA-25 may serve as an endogenous gene silencing factor and contributes to the regulation of NOX4 expression and function in DN.

Abstract. The aim of this study was to investigate the role of microRNA-21 (miR-21) in the regulation of phosphatase and tensin homolog deleted from chromosome-10 (PTEN) expression and proliferation of endometrioid endometrial cancer (EEC) cells. We performed a qRT-PCR assay with miR-21 and PTEN in 16 paired EEC tumor tissues and adjacent non-tumor endometrium. To investigate the regulation of PTEN by miR-21, we designed gain-and loss-of-function of miR-21 experiments in the KLE cell line by transfection with a synthetic miR-21 mimic and inhibitor. To validate the putative binding site of miR-21 in the 3' untranslated region (3'-UTR) of PTEN messenger RNA (mRNA), a dual-luciferase reporter assay was carried out. To evaluate the potential effect of miR-21 on EEC proliferation, we performed both overexpression experiments, using an miR-21 mimic, and inhibition assays, using an miR-21 inhibitor. miR-21 was overexpressed in EEC and was inversely correlated with PTEN protein expression (P<0.001). miR-21 regulated PTEN protein expression and cell proliferation in the KLE cell line and the direct binding of miR-21 to the PTEN 3'-UTR was confirmed using a dual-luciferase reporter assay. The upregulation of miR-21 led to a significant decrease in the PTEN protein expression level (P=0.007). The downregulation of miR-21 led to a significant increase in PTEN protein (P=0.002). The expression of luciferase in the wt-PTEN-3'-UTR-pGL3 group was downregulated in the presence of the miR-21 mimic (P=0.001). miR-21 was overexpressed in EEC. In conclusion, we demonstrated that the expression of PTEN protein, but not mRNA, was negatively directly regulated by miR-21 in the KLE cell line. The overexpression of miR-21 modulated EEC cell proliferation through the downregulation of PTEN.

Cancer cells prefer glycolysis for energy metabolism, even when there is sufficient oxygen to make it unnecessary. This is called the Warburg effect, and it promotes tumorigenesis and malignant progression. In this study, we demonstrated that EZH2, a multifaceted oncogenic protein involved in tumor proliferation, invasion and metastasis, promotes glioblastoma tumorigenesis and malignant progression through activation of the Warburg effect. We observed that HIF1α is a target of EZH2 whose activation is necessary for EZH2-mediated metabolic adaption, and that HIF1α is activated upon EZH2 overexpression. EZH2 suppressed expression of EAF2, which in turn upregulated HIF1α levels. We conclude from these results that EZH2 promotes tumorigenesis and malignant progression in part by activating glycolysis through an EAF2-HIF1α signaling axis.