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The Six1 oncoprotein represses translation of p53 via concomitant regulation of RPL26 and microRNA-27a

ABSTRACT: TP53 is mutated in 50% of all cancers, and is often functionally compromised in cancers where it is not mutated. We demonstrate that the pro-tumorigenic/metastatic Six1 homeoprotein decreases p53 levels through a mechanism that does not involve the negative regulator of p53, MDM2. Instead, Six1 regulates p53 via a dual mechanism involving upregulation of microRNA-27a and downregulation of the ribosomal protein L26 (RPL26), a positive regulator of p53 translation. Mutation analysis confirms that RPL26, whose expression inversely correlates with Six1 expression in numerous tumor types, inhibits miR-27a binding to the p53 3’UTR and prevents microRNA-mediated translational inhibition of p53. Thus, through simultaneous downregulation of RPL26 and upregulation of miR-27a, Six1 efficiently lowers p53 levels despite regulation of p53 at the level of the proteasome. Consequently, Six1 overexpression, which is observed in numerous tumor types, leads to dramatic resistance to nutlins, as well as other therapies targeting the p53-MDM2 interaction.

ORGANISM(S): Mus musculus

PROVIDER: GSE65677 | GEO | 2016/03/21

SECONDARY ACCESSION(S): PRJNA274770

REPOSITORIES: GEO

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The Six1 oncoprotein represses translation of p53 via concomitant regulation of RPL26 and microRNA-27a

Project description:TP53 is mutated in 50% of all cancers, and is often functionally compromised in cancers where it is not mutated. We demonstrate that the pro-tumorigenic/metastatic Six1 homeoprotein decreases p53 levels through a mechanism that does not involve the negative regulator of p53, MDM2. Instead, Six1 regulates p53 via a dual mechanism involving upregulation of microRNA-27a and downregulation of the ribosomal protein L26 (RPL26), a positive regulator of p53 translation. Mutation analysis confirms that RPL26, whose expression inversely correlates with Six1 expression in numerous tumor types, inhibits miR-27a binding to the p53 3’UTR and prevents microRNA-mediated translational inhibition of p53. Thus, through simultaneous downregulation of RPL26 and upregulation of miR-27a, Six1 efficiently lowers p53 levels despite regulation of p53 at the level of the proteasome. Consequently, Six1 overexpression, which is observed in numerous tumor types, leads to dramatic resistance to nutlins, as well as other therapies targeting the p53-MDM2 interaction.

2016-01-15 | GSE65200 | GEO

Escherichia coli 27A

Project description:Escherichia coli 27A Genome sequencing and assembly

| PRJNA224233 | ENA

MiR-27a-3p in peripheral blood mononuclear cells as a potential marker for pancreatic cancer screening

Project description:Background & Aims: MicroRNAs have been shown to offer great potential in the diagnosis of cancer. We aimed to identify microRNAs in peripheral blood mononuclear cells (PBMCs) for diagnosing pancreatic cancer (PC). Methods: PBMCs microRNA expression was investigated in three independent cohorts including 352 participants (healthy, benign pancreatic/peripancreatic diseases (BPD), and PC). First, we used sequencing technology to identify differentially expressed microRNAs in 60 PBMCs samples for diagnosing PC. Quantitative reverse-transcriptase polymerase chain reaction assay was then applied to evaluate the expression of selected microRNAs. A logistic regression model was constructed using an independent cohort. Area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic accuracy. Results: We found that PBMCs miR-27a-3p could efficiently discriminate PC from BPD (AUC=0.840; 95% CI, 0.787 to 0.885; sensitivity=82.2%, specificity=76.7%). A panel composed of PBMCs miR-27a-3p and serum CA19-9 provided a high diagnostic accuracy in differentiating PC from BPD in the clinical setting (AUC=0.886; 95% CI, 0.837 to 0.923; sensitivity=85.3%, specificity=81.6%). The satisfactory diagnostic performance of the panel persisted regardless of disease status (AUCs for tumour-node-metastasis stages?,?, and ? were 0.881, 0.884, and 0.893, respectively). Conclusion: PBMCs miR-27a-3p could be a potential marker for PC screening. A panel composed of PBMCs miR-27a-3p and serum CA19-9 has considerable clinical value in diagnosing early-stage PC. Therefore, patients who would have otherwise missed the curative treatment window can benefit from optimal therapy. Examination of different MicroRNA profiles in 3 types of PBMCs samples

2012-05-03 | E-GEOD-37710 | biostudies-arrayexpress

Expression data from Control and Six1 expressing MCF7 cells

Project description:Inappropriate activation of developmental pathways is a well-recognized tumor-promoting mechanism. Here we show that overexpression of the homeoprotein Six1, normally a developmentally restricted transcriptional regulator, increases Transforming Growth Factor-beta (TGF-beta) signaling in mammary carcinoma cells and induces an epithelial to mesenchymal transition (EMT) that is in part dependent on its ability to increase TGF-beta signaling. TGF-beta signaling and EMT have been implicated in metastatic dissemination of carcinoma. Using spontaneous and experimental metastasis mouse models, we demonstrate that Six1 overexpression promotes breast cancer metastasis. In addition, we show that, like its induction of EMT, Six1-induced experimental metastasis is dependent on its ability to activate TGF-beta signaling. Importantly, in human breast cancers Six1 significantly correlates with nuclear Smad3, and thus increased TGF-beta signaling. Further, breast cancer patients whose tumors overexpress Six1 have a shortened time to relapse and metastasis, and an overall decrease in survival. Finally, we show that the effects of Six1 on tumor progression likely extend beyond breast cancer, since its overexpression correlates with adverse outcomes in numerous other cancers, including brain, cervical, prostate, colon, kidney, and liver, amongst others. Our findings argue that Six1, acting through TGF-beta signaling and EMT, is a powerful and global promoter of cancer metastasis.

2010-08-21 | GSE23655 | GEO

MicroRNA-27a regulates lipid metabolism and inhibits hepatitis C virus replication in human hepatoma cells

Project description:Gene expression profiling was carried out in Huh-7.5 cells in which miR-27a was over- or under-expressed. Transfection of cells with pre-miR-27a and pre-miR-control, or anti-miR-27a and anti-miR-control enabled down- and up-regulated genes to be determined, respectively. Replication and infectivity of the lipotrophic hepatitis C virus (HCV) is regulated by cellular lipid status. Among differentially expressed micro (mi)RNAs, we found that miR-27a was preferentially expressed in HCV-infected compared with hepatitis B virus (HBV)-infected liver. Gene expression profiling of Huh-7.5 cells showed that miR-27a regulates lipid metabolism by targeting the lipid synthetic transcriptional factor, RXRα, and the lipid transporter, ABCA1 Carrying out a Target Scan (Release 5.2) of miR-27a predicted 921 candidate target genes, and functional gene ontology enrichment analysis of these genes by MetaCore (Thomson Reuters, NY) showed that miR-27a could target the signaling pathways of cytoskeleton remodeling and lipid metabolism . To examine whether these signaling pathways were regulated by miR-27a, gene expression profiling was carried out in Huh-7.5 cells in which miR-27a was over- or under-expressed. Transfection of cells with pre-miR-27a and pre-miR-control, or anti-miR-27a and anti-miR-control enabled down- and up-regulated genes to be determined, respectively. Huh-7.5 cells with miR-27a over- or under-expressed

2013-06-05 | E-GEOD-41737 | biostudies-arrayexpress

Mouse gene expression profile after transfected with miR-27a mimics and mimic NC in Raw

Project description:Microarry analysis of mouse gene expression profile after transfected with miR-27a mimics (27a-7) and mimic NC (NC-9) Goal was to determine the effects of miR-27a transfection on global gene expression. Two-condition experiment, 27a-7 vs.NC-9.

2013-01-31 | E-GEOD-43910 | biostudies-arrayexpress

Expression data from Control and Six1 expressing MCF7 derived xenograft tumors

Project description:Although an important association between lymph node metastasis and poor prognosis in breast cancer was observed decades ago, an active role for the lymphatic system in metastatic dissemination has only recently been examined. We demonstrate that the Six1 homeoprotein promotes peri- and intra-tumoral lymphangiogenesis, lymphatic invasion, and distant metastasis of breast cancer cells. We identify the pro-lymphangiogenic factor, VEGF-C, as required for this process, and demonstrate transcriptional induction as the mechanism of regulation of VEGF-C expression by Six1. Using a different, but complementary animal model, we show that while required, VEGF-C is not sufficient for the pro-metastatic effects of Six1. Verifying the clinical significance of this pro-metastatic Six1-VEGF-C axis, we demonstrate co-expression of Six1 and VEGF-C in human breast cancer. Two Control and two Six1 expressing MCF7 clones were orthotopically injected into NOD/Scid mice forming a total of 3 Control and 3 Six1 tumors that were allowed to grow to 2 cm^3 . The tumors were dissected and total RNA was isolated from each tumor and hybridized to Affymetrix arrays

2012-03-31 | E-GEOD-35314 | biostudies-arrayexpress

Genome-wide transcriptome analyses of transgenic mice, that express Cre recombinase flanked by mutated estrogen receptors (MerCreMer; mcm), and carry loxP-flanked sequences of p53 and Mdm2 was performed in the presence and absence of Tamoxifen

Project description:Genome-wide transcriptome analyses of transgenic mice, that express Cre recombinase flanked by mutated estrogen receptors (MerCreMer; mcm), and carry loxP-flanked sequences of p53 and Mdm2 was performed in the presence and absence of Tamoxifen.<br>The molecular mechanisms underlying heart failure remain poorly understood. As such, identifying the factors which effectively maintain cardiac tissue homeostasis is of great scientific and clinical importances. The tumor suppressor Trp53 (p53) inhibits cell growth after acute stress by regulating gene transcription. The mammalian genome contains hundreds of p53 binding sites. However, whether p53 participates in the regulation of cardiac tissue homeostasis under normal conditions is not known. To examine the physiologic consequences of p53 and Mdm2 ablation in adult cardiomyocytes in vivo, cardiac morphology and function were assessed in conditional mutant mice.

2017-02-23 | E-MTAB-5441 | biostudies-arrayexpress

CDK4 inhibition diminishes p53 activation by Mdm2-antagonists

Project description:CDK4 inhibitors have reached clinical approval for cancer therapy. In parallel, the p53 antagonist Mdm2 remains an attractive target for anti-cancer therapy, including numerous clinical studies. The genes encoding Mdm2 and CDK4 are frequently co-amplified in human malignancies, most notably in liposarcomas, suggesting their combined targeting for therapy. Here we show, however, that small compounds that inhibit Mdm2 and CDK4 antagonize each other rather than synergize in their cytotoxicity towards sarcoma cells. CDK4 inhibition attenuates the induction of p53-responsive genes upon Mdm2 inhibition, and similar results were obtained when depleting Mdm2 and/or CDK4 with siRNA. CDK4 inhibitors also interfered with p53 activity in response to DNA damage. CDK4 inhibition did not reduce p53 binding or histone acetylation to promoters, but rather attenuated the subsequent recruitment of RNA polymerase II. The complexes of p53 and Mdm2, as well as CDK4 and Cyclin D1, physically associated with each other. Upon combined inhibition of Mdm2 and CDK4/6, the interaction of this complex was impaired. Thus, the CDK4-Cyclin D1 complex plays a key role in enabling the transcription of p53 target genes. Taken together, our results raise caution regarding the combination of CDK4 inhibitors with Mdm2 antagonists or conventional DNA-damaging chemotherapeutics in the clinics. Moreover, they suggest a hitherto unknown role for CDK4-cyclin D1 complex in sustaining p53 activity, possibly focusing p53-mediated transcription on actively proliferating cells.

2018-09-20 | GSE113369 | GEO

Mouse gene expression profile after transfected with miR-27a mimics and mimic NC in Raw

2013-01-31 | GSE43910 | GEO

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