MicroRNA-129-3p suppresses tumor growth by targeting E2F5 in glioblastoma.

OBJECTIVE: Neuroma is the most common intracranial tumor. The mechanism of miRNA in glioma has gradually been understood. The purpose of this study was to investigate the role of MicroRNA-129-3p (miR-129-3p) in the pathogenesis of glioblastoma (GBM). PATIENTS AND METHODS: Differential expression of miR-129-3p in samples was analyzed by bioinformatics. PCR was used to detect the expression of miR-129-3p in samples. CCK8 assay was used to detect the cell viability. Transfection of mimic and inhibitor altered the expression of miR-129-3p, and the biological function of miRNA was explored. Luciferase reporter gene was used to detect target genes of miRNA. E2F5 expression was inhibited by transfection of small interfering RNAs. Western blotting was used to detect protein expressions of cells. RESULTS: miR-129-3p was low-expressed in the tissue samples. By transfecting mimic and the inhibitor, we found that increasing the expression of miR-129-3p can inhibit the cell viability. In contrast, inhibition of miR-129-3p promoted cell growth. Luciferase reporter gene and Western blot results suggested that E2F5 can be used as the target gene of miR-129-3p. Knockdown the target gene of the miR-129-3p, E2F5, also inhibited proliferation of glioblastoma. CONCLUSIONS: miR-129-3p can inhibit the growth of glioblastoma by down-regulating the expression of E2F5. miR-129-3p can be a new target for the treatment of glioblastoma. Our research provides new ideas for the target therapy of glioma.

MiR-613 suppresses retinoblastoma cell proliferation, invasion, and tumor formation by targeting E2F5.

Retinoblastoma is a common intraocular malignancy that occurs during childhood. MicroRNAs play critical roles in the regulation of retinoblastoma initiation and progression, and aberrant expression of miR-613 had been reported in various types of cancer. However, the role and mechanism of its function in retinoblastoma are still unclear. In this study, we found that miR-613 was downregulated in retinoblastoma tissues and cell lines. Overexpression of miR-613 suppressed retinoblastoma cell proliferation, migration, and invasion and induced cell cycle arrest in vitro. Additionally, overexpressed miR-613 also inhibited tumor formation of retinoblastoma cells in vivo. We further identified E2F5 as a direct target of miR-613. Reintroduction of E2F5 without 3'-untranslated region reversed the inhibitory effects of miR-613 on cell proliferation and invasion. Our data collectively indicate that miR-613 functions as a tumor suppressor in retinoblastoma through downregulating E2F5, supporting the targeting of the novel miR-613/E2F5 axis as a potentially effective therapeutic approach for retinoblastoma.

Up-regulated MicroRNA-181a induces carcinogenesis in hepatitis B virus-related hepatocellular carcinoma by targeting E2F5.

BACKGROUND: Accumulating evidence showed that microRNAs are involved in development and progression of multiple tumors. Recent studies have found that miR-181a were dysregulated in several types of cancers, however, the function of miR-181a in hepatocellular carcinoma (HCC) remains unclear. In this study we assessed the potential association between miR-181a, HBV and HCC. METHODS: The expression of miR-181a in HBV-expressing cells was determined by using qRT-PCR. Dual-Luciferase reporter Assay, qRT-PCR and western blot were performed to investigate the target genes of miR-181a. The effects of miR-181a on HCC proliferation were analyzed by MTS and colony formation assay. Tumor growth assay was used to analyze the effect of miR-181a on tumor formation. RESULTS: HBV up-regulated miR-181a expression by enhancing its promoter activity. Overexpression of miR-181a in hepatoma cells promoted cell growth in vitro and tumor formation in vivo. Conversely, inhibition of miR-181a suppressed the proliferation of HBV-expressing cells. Mechanism investigation revealed that miR-181a inhibited the expression of transcription factor E2F5 by specifically targeting its mRNA 3'UTR. Moreover, E2F5 inhibition induced cell growth and rescued the suppressive effect of miR-181a inhibitor on the proliferation of SMMC-7721 cells. Interestingly, we also discovered that HBV could down-regulate E2F5 expression. CONCLUSIONS: Those results strongly suggested that HBV down-regulated E2F5 expression, in part, by up-regulating the expression of miR-181a. Up-regulation of miR-181a by HBV in hepatoma cells may contribute to the progression of HCC possibly by targeting E2F5, suggesting miR-181a plays important role in HCC development.

Effects of microRNA-106 on proliferation of gastric cancer cell through regulating p21 and E2F5.

OBJECTIVE: To investigate the effects of miR-106b on malignant characteristics of gastric cancer cells, and explore possible mechanisms. METHODS: Expression of miR-106b, p21 and E2F was determined by real-time PCR. Transfection with miR-106b mimics was conducted, and gastric cancer cells with miR-106b overexpression were obtained. Cells transfected with mimic mutants and those without transfection served as negative and blank controls, respectively. Flow cytometry and transwell assays were adopted to detect the effects of miR-106b overexpression on cell cycle, migration and invasion of gastric cancer cells. RESULTS: . The expression of miR- 106b in gastric cancer cells was significantly higher than that in normal gastric mucosa cells. Furthermore, the expression level of miR-106b rose according to the degree of malignacy among the three GC cell strains (MKN- 45 > SGC-7901 > MKN-28). Overexpression of miR-106b shortened the G0/G1 phase and accelerated cell cycle progression, while reducing p21 and E2F5, without any significant effects on the capacity for migration and invasion of gastric cancer cells. CONCLUSIONS: miR-106b may promote cell cycling of gastric cancer cells through regulation of p21 and E2F5 target gene expression.

Wild-type p53 and p73 negatively regulate expression of proliferation related genes.

When normal cells come under stress, the wild-type (WT) p53 level increases resulting in the regulation of gene expression responsible for growth arrest or apoptosis. Here we show that elevated levels of WT p53 or its homologue, p73, inhibit expression of a number of cell cycle regulatory and growth promoting genes. Our analysis also identified a group of genes whose expression is differentially regulated by WT p53 and p73. We have infected p53-null H1299 human lung carcinoma cells with recombinant adenoviruses expressing WT p53, p73 or beta-galactosidase, and have undertaken microarray hybridization analyses to identify genes whose expression profile is altered by p53 or p73. Quantitative real-time PCR verified the repression of E2F-5, centromere protein A and E, minichromosome maintenance proteins (MCM)-2, -3, -5, -6 and -7 and human CDC25B after p53 expression. 5-Fluorouracil treatment of colon carcinoma HCT116 cells expressing WT p53 results in a reduction of the cyclin B2 protein level suggesting that DNA damage may indeed cause repression of these genes. Transient transcriptional assays verified that WT p53 repressed promoters of a number of these genes. Interestingly, a gain-of-function p53 mutant instead upregulated a number of these promoters in transient transfection. Using promoter deletion mutants of MCM-7 we have found that WT p53-mediated repression needs a minimal promoter that contains a single E2F site and surrounding sequences. However, a single E2F site cannot be significantly repressed by WT p53. Many of the genes identified are also repressed by p21. Thus, our work shows that WT p53 and p73 repress a number of growth-related genes and that in many instances this repression may be through the induction of p21.