TEL-AML1 regulation of survivin and apoptosis via miRNA-494 and miRNA-320a

Laboratory for Molecular Epidemiology, University of California, San Francisco, San Francisco, CA, USA.
Blood (Impact Factor: 10.45). 12/2010; 116(23):4885-93. DOI: 10.1182/blood-2009-02-206706
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There is increasing evidence that miRNA and transcription factors interact in an instructive fashion in normal and malignant hematopoiesis. We explored the impact of TEL-AML1 (ETV6-RUNX1), the most common fusion protein in childhood leukemia, on miRNA expression and the leukemic phenotype. Using RNA interference, miRNA expression arrays, and quantitative polymerase chain reaction, we identified miRNA-494 and miRNA-320a to be up-regulated upon TEL-AML1 silencing independently of TEL expression. Chromatin immunoprecipitation analysis identified miRNA-494 as a direct miRNA target of the fusion protein TEL-AML1. Using bioinformatic analysis as well as functional luciferase experiments, we demonstrate that survivin is a target of the 2 miRNAs. miRNA-494 and miRNA-320a were introduced to the cells by transfection and survivin expression determined by Western blot analysis. These miRNAs blocked survivin expression and resulted in apoptosis in a similar manner as TEL-AML1 silencing by itself; this silencing was also shown to be Dicer-dependent. miRNAs-494 and -320a are expressed at lower levels in TEL-AML1+ leukemias compared with immunophenotype-matched nonTEL-AML1 acute lymphoblastic leukemia subtypes, and within TEL-AML1+ leukemias their expression is correlated to survivin levels. In summary our data suggest that TEL-AML1 might exert its antiapoptotic action at least in part by suppressing miRNA-494 and miRNA-320a, lowering their expression causing enhanced survivin expression.

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Available from: Renate Panzer-Grümayer, Sep 15, 2015
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    • "Underexpression of miR-494 was also reported in prostate cancer [10,11], lung cancer [12], gastrointestinal stromal tumors [13], and cholangiocarcinoma [14]. In contrast, overexpression of miR-494 was reported in acute myeloblastic leukemia [15], bronchial carcinogenesis [16], and retinoblastoma [17]. Since nothing is known about potential targets of miR-494 in human OSCC, examining the role of miR-494 in OSCC is the main objective in current report. "
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    ABSTRACT: miR-494 was identified as a candidate of the most significantly underexpressed microRNAs (miRNAs) in our oral cancer screen. The aim of this study was to validate whether miR-494 has a functional role in oral cancer. Quantitative miRNA analyses were performed on oral tumor RNA and oral cancer cell lines. HOXA10 was selected for further analysis based on bioinformatics analysis of miR-494 targets and a previous report of overexpression of HOXA10 in oral cancer. Transient transfection of miRNA-mimic and inhibitor were performed in SCC-25 (tongue), CAL 27 (tongue), and FaDu (pharynx) cancer cells and regulation of HOXA10 by miR-494 was investigated. Dual luciferase assay was used to verify the interaction between miR-494 and HOXA10 in reporter cells. The effect of miR-494 on cell proliferation was examined. Our data showed that miR-494 was underexpressed whereas HOXA10 was overexpressed in oral cancer compared to normal tissues. An inverse correlation between miR-494 and HOXA10 was observed in the human tissues (p<0.05). Transient transfection of miR-494 in all cancer cell lines significantly reduced the expression of HOXA10 mRNA. The luciferase reporter that contains the 3'UTR of HOXA10 showed a significantly reduced luciferase activity by miR-494 indicating a direct interaction between HOXA10 and miR-494. Significant reduction in cell proliferation was demonstrated in tongue cancer cells transfected with miR-494. miR-494 repressed the expression of HOXA10 and also reduced the proliferation of oral cancer cells. These data give more evidence of the role of miR-494 as a tumor suppressor miRNA in oral cancer. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Oral Oncology 12/2014; 51(2). DOI:10.1016/j.oraloncology.2014.11.019 · 3.61 Impact Factor
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    • "BUB3 and BUB1b; CDCA2, CDCA4 and CDCA7; RFC2 and RFC3). We excluded BIRC5 (survivin) from further investigation, as it was already validated by others [31]. "
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    ABSTRACT: In the last decades, cellular senescence is viewed as a complex mechanism involved in different processes, ranging from tumor suppression to induction of age-related degenerative alterations. Senescence-inducing stimuli are myriad and, recently, we and others have demonstrated the role exerted by microRNAs in the induction and maintenance of senescence, by the identification of a subset of Senescence-Associated microRNAs (SAmiRs) up-regulated during replicative or stress-induced senescence and able to induce a premature senescent phenotype when over-expressed in human primary cells. With the intent to find novel direct targets of two specific SAmiRs, SAmiR-494 and -486-5p, and cellular pathways which they are involved in, we performed a comparative analysis of gene expression profiles available in literature to select genes down-regulated upon replicative senescence of human primary fibroblasts. Among them, we searched for SAmiR's candidate targets by analyzing with different target prediction algorithms their 3'UTR for the presence of SAmiR-binding sites. The expression profiles of selected candidates have been validated on replicative and stress-induced senescence and the targeting of the 3'UTRs was assessed by luciferase assay. Results allowed us to identify Cell Division Cycle Associated 2 (CDCA2) and Inhibitor of DNA binding/differentiation type 4 (ID4) as novel targets of SAmiR-494 and SAmiR-486-5p, respectively. Furthermore, we demonstrated that the over-expression of CDCA2 in human primary fibroblasts was able to partially counteract etoposide-induced senescence by mitigating the activation of DNA Damage Response.
    PLoS ONE 06/2014; 9(6):e98669. DOI:10.1371/journal.pone.0098669 · 3.23 Impact Factor
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    • "Serum miR-320a levels were lower in female GC patients than in controls, and this difference was especially marked in older women, aged over 60, suggesting that miR-320a may be a new clinical biomarker for GC diagnosis with population specificity. Studies of miR-320a to date have been limited to its roles in regulating the physiological functions of the blood–brain barrier [33], and in intrahepatic cholangiocarcinoma [34,35], colon cancer [36] and childhood leukaemia [37]. To the best of our knowledge, the current study is the first to report that miR-320a could act as a serum biomarker of GC, especially in older women. "
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    ABSTRACT: Background The identification of serial miRNAs targeting the same functional gastric protein could provide new and effective serological biomarkers for the diagnosis of gastric cancer (GC). The aim of this study was to evaluate the potential of miR-20a-5p, let-7a and miR-320a in the diagnosis of AG or GC and the correlation of the three miRNAs with their predicted target molecules PGA, PGC and PGA/PGC ratio. Methods The total of 291 patients included 103 controls (CON), 94 with atrophic gastritis (AG) and 94 with GC. The levels of serum miRNAs were detected by quantitative reverse transcription-polymerase chain reaction and serum pepsinogen A (PGA) and C (PGC) were determined by enzyme-linked immunosorbent assays. Results Serum miR-320a level decreased through the controls, AG and GC groups which were the cascades of GC development, while there were no significant differences in levels of miR-20a-5p and let-7a among the controls, AG and GC groups. When stratified by gender and age, serum miR-320a expression was lower in female GC patients than in controls (p = 0.035), especially in female GC patients older than 60 years (p = 0.008). For distinguishing female GC patients aged over 60, the area under the receiver operating characteristic curve for miR-320a was 0.699, and the best cut-off point was 4.76 with a sensitivity of 65.2% and specificity of 68.2%. Concerning the correlations between the selected miR-20a-5p, let-7a, miR-320a and PGs, we found that there were positive correlations between all the three and the ratio of PGA/PGC (r = 0.408, 0.255, 0.324; p = <0.001, 0.009, 0.001, respectively), but there was no relationship between the expression of serum miR-20a-5p and its predicted target PGA, or between let-7a and miR-320a and their predicted target PGC. Serum miR-320a was decreased and PGC was increased in the GC group compared with the control group. Conclusions Levels of serum miR-320a were lower in female GC patients older than 60 than in controls, which may provide a potential valuable marker for diagnosing older women with GC. The levels of serum miR-20a-5p, let-7a and miR-320a were positively correlated with PGA/PGC, which may indirectly reflect the functional status of the gastric mucosa.
    BMC Clinical Pathology 03/2013; 13(1):11. DOI:10.1186/1472-6890-13-11
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