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  • 1
    Keywords: GENE-EXPRESSION ; DIFFERENTIATION ; TUMORS ; BIOLOGY ; PROGRESSION ; PHENOTYPE ; P-TEFB ; RISK STRATIFICATION ; SUBGROUPS ; MIRNA EXPRESSION
    Abstract: Neuroblastoma, a childhood cancer that originates from neural crest-derived cells, is the most common deadly solid tumor of infancy. Amplification of the MYCN oncogene, which occurs in approximately 20-25% of human neuroblastomas, is the most prominent genetic marker of high-stage disease. The availability of valid preclinical in vivo models is a prerequisite to develop novel targeted therapies. We here report on the generation of transgenic mice with Cre-conditional induction of MYCN in dopamine beta-hydroxylase-expressing cells, termed LSL-MYCN;Dbh-iCre. These mice develop neuroblastic tumors with an incidence of 〉75%, regardless of strain background. Molecular profiling of tumors revealed upregulation of the MYCN-dependent miR-17-92 cluster as well as expression of neuroblastoma marker genes, including tyrosine hydroxylase and the neural cell adhesion molecule 1. Gene set enrichment analyses demonstrated significant correlation with MYC-associated expression patterns. Array comparative genome hybridization showed that chromosomal aberrations in LSL-MYCN;Dbh-iCre tumors were syntenic to those observed in human neuroblastomas. Treatment of a cell line established from a tumor derived from a LSL-MYCN;Dbh-iCre mouse with JQ1 or MLN8237 reduced cell viability and demonstrated oncogene addiction to MYCN. Here we report establishment of the first Cre-conditional human MYCN-driven mouse model for neuroblastoma that closely recapitulates the human disease with respect to tumor localization, histology, marker expression and genomic make up. This mouse model is a valuable tool for further functional studies and to assess the effect of targeted therapies.Oncogene advance online publication, 1 September 2014; doi:10.1038/onc.2014.269.
    Type of Publication: Journal article published
    PubMed ID: 25174395
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  • 2
    Keywords: EXPRESSION ; GENE ; CELL-CYCLE ; DOWN-REGULATION ; TARGET ; PROSTATE-CANCER ; beta-catenin ; N-MYC ; RNA INTERFERENCE ; REIC/DKK-3
    Abstract: Neuroblastoma (NB) is a paediatric tumour with a remarkable diverse clinical behaviour. Approximately half of the high stage aggressive tumours are characterized by MYCN gene amplification but our understanding of the role of MYCN in NB oncogenesis is incomplete. Previous studies have shown that MYCN expression is inversely correlated with expression of Dickkopf-3 (DKK3), a gene encoding an extracellular protein with presumed tumour suppressor activity, but direct MYCN regulation of DKK3 was excluded leaving the mechanism of regulation unexplained. Given the recently established role of MYCN-regulated miRNAs in downregulation of protein-coding genes and predicted seeds for miR-17-92 cluster members within the DKK3 3'UTR, we hypothesized that this mechanism would act in MYCN regulation of DKK3. To investigate this, we used a validated miR-17-92-inducible cellular system and could demonstrate robust downregulation of DKK3 mRNA and protein levels upon miR-17-92 overexpression. Next, two of the three predicted miRNAs, miR-19b and miR-92a, were shown to lower DKK3 protein levels, in addition to measurable DKK3 mRNA knock-down by miR-92a. Direct interaction between miR-19b or miR-92a and the 3'UTR of DKK3 was validated using luciferase reporter assays. In conclusion, this study demonstrates that the MYCN-induced downregulation of DKK3 results from direct upregulation of miR-17-92 components effecting both DKK3 mRNA stability and translation which further contributes to the pleiotropic oncogenic effect of elevated MYCN levels. The strict MYCN-mediated regulation of DKK3 is suggestive for an important downstream function of the MYCN protein and thus warrants further investigations to unravel the role of DKK3 in NB.
    Type of Publication: Journal article published
    PubMed ID: 21796614
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  • 3
    Keywords: EXPRESSION ; CELL LUNG-CANCER ; GENE ; IDENTIFICATION ; N-MYC ; SOLID TUMORS ; ONCOGENIC MUTATIONS ; HIGH-RISK NEUROBLASTOMA ; ANAPLASTIC LYMPHOMA KINASE ; ACTIVATING MUTATIONS
    Abstract: Treatment for neuroblastoma, the most common extracranial childhood tumor, spans a broad range of aggressiveness that mirrors the risk profiles of disease subtypes, with high-risk neuroblastoma still presenting a clinical challenge. Currently, most patients with relapsed neuro-blastoma die of disease and present a major challenge for treatment. New therapeutic options are urgently needed to improve patient survival. Activating mutations in the gene encoding the anaplastic lymphoma kinase (ALK) remain the most frequent druggable mutations identified in neuroblastomas to date. Preclinical data support an oncogene addiction of neuroblastoma cells to mutated ALK and demonstrate that ALK inhibitory therapy strongly combats tumor models. Most recently, pediatric phase I testing has been completed for the first approved ALK inhibitor, Crizotinib, showing very encouraging antitumoral results in neuroblastoma patients. Subsequently, an international phase I study with the second generation ALK inhibitor, LDK-378, will be launched that makes ALK inhibitory therapy also available to pediatric patients in Germany.
    Type of Publication: Journal article published
    PubMed ID: 24166094
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  • 4
    Abstract: MYCN is a master regulator controlling many processes necessary for tumor cell survival. Here, we unravel a microRNA network that causes tumor suppressive effects in MYCN-amplified neuroblastoma cells. In profiling studies, histone deacetylase (HDAC) inhibitor treatment most strongly induced miR-183. Enforced miR-183 expression triggered apoptosis, and inhibited anchorage-independent colony formation in vitro and xenograft growth in mice. Furthermore, the mechanism of miR-183 induction was found to contribute to the cell death phenotype induced by HDAC inhibitors. Experiments to identify the HDAC(s) involved in miR-183 transcriptional regulation showed that HDAC2 depletion induced miR-183. HDAC2 overexpression reduced miR-183 levels and counteracted the induction caused by HDAC2 depletion or HDAC inhibitor treatment. MYCN was found to recruit HDAC2 in the same complexes to the miR-183 promoter, and HDAC2 depletion enhanced promoter-associated histone H4 pan-acetylation, suggesting epigenetic changes preceded transcriptional activation. These data reveal miR-183 tumor suppressive properties in neuroblastoma that are jointly repressed by MYCN and HDAC2, and suggest a novel way to bypass MYCN function.
    Type of Publication: Journal article published
    PubMed ID: 23625969
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  • 5
    Keywords: CANCER ; EXPRESSION ; tumor ; ACTIVATION ; RESPONSES ; C-MYC ; neuroblastoma ; CHROMOSOMES ; SUBGROUPS ; BRD4
    Abstract: Medulloblastoma is the most common malignant brain tumor of childhood, and represents a significant clinical challenge in pediatric oncology, since overall survival currently remains under 70%. Patients with tumors overexpressing MYC or harboring a MYC oncogene amplification have an extremely poor prognosis. Pharmacologically inhibiting MYC expression may, thus, have clinical utility given its pathogenetic role in medulloblastoma. Recent studies using the selective small molecule BET inhibitor, JQ1, have identified BET bromodomain proteins, especially BRD4, as epigenetic regulatory factors for MYC and its targets. Targeting MYC expression by BET inhibition resulted in antitumoral effects in various cancers. Our aim here was to evaluate the efficacy of JQ1 against preclinical models for high-risk MYC-driven medulloblastoma. Treatment of medulloblastoma cell lines with JQ1 significantly reduced cell proliferation and preferentially induced apoptosis in cells expressing high levels of MYC. JQ1 treatment of medulloblastoma cell lines downregulated MYC expression and resulted in a transcriptional deregulation of MYC targets, and also significantly altered expression of genes involved in cell cycle progression and p53 signalling. JQ1 treatment prolonged the survival of mice harboring medulloblastoma xenografts and reduced the tumor burden in these mice. Our preclinical data provide evidence to pursue testing BET inhibitors, such as JQ1, as molecular targeted therapeutic options for patients with high-risk medulloblastomas overexpressing MYC or harboring MYC amplifications.
    Type of Publication: Journal article published
    PubMed ID: 24231268
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  • 6
    Abstract: Identifying relevant signatures for clinical patient outcome is a fundamental task in high-throughput studies. Signatures, composed of features such as mRNAs, miRNAs, SNPs or other molecular variables, are often non-overlapping, even though they have been identified from similar experiments considering samples with the same type of disease. The lack of a consensus is mostly due to the fact that sample sizes are far smaller than the numbers of candidate features to be considered, and therefore signature selection suffers from large variation. We propose a robust signature selection method that enhances the selection stability of penalized regression algorithms for predicting survival risk. Our method is based on an aggregation of multiple, possibly unstable, signatures obtained with the preconditioned lasso algorithm applied to random (internal) subsamples of a given cohort data, where the aggregated signature is shrunken by a simple thresholding strategy. The resulting method, RS-PL, is conceptually simple and easy to apply, relying on parameters automatically tuned by cross validation. Robust signature selection using RS-PL operates within an (external) subsampling framework to estimate the selection probabilities of features in multiple trials of RS-PL. These probabilities are used for identifying reliable features to be included in a signature. Our method was evaluated on microarray data sets from neuroblastoma, lung adenocarcinoma, and breast cancer patients, extracting robust and relevant signatures for predicting survival risk. Signatures obtained by our method achieved high prediction performance and robustness, consistently over the three data sets. Genes with high selection probability in our robust signatures have been reported as cancer-relevant. The ordering of predictor coefficients associated with signatures was well-preserved across multiple trials of RS-PL, demonstrating the capability of our method for identifying a transferable consensus signature. The software is available as an R package rsig at CRAN (http://cran.r-project.org).
    Type of Publication: Journal article published
    PubMed ID: 25295525
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  • 7
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    Science Signaling 7 (349), Art. Nr.: pe27- 
    Keywords: TUMORS ; LYMPHOMA ; CRIZOTINIB
    Abstract: The gene expressing the receptor tyrosine kinase anaplastic lymphoma kinase (ALK) is mutated and aberrantly expressed in several cancers. The clinical efficacy of the ALK inhibitor, crizotinib, lags behind expectations for treating MYCN-amplified, ALK-mutant neuroblastoma, a deadly childhood cancer. In this issue of Science Signaling, Umapathy et al. identify the kinase extracellular signal-regulated kinase 5 (ERK5) as a central mediator that enables ALK to boost MYCN expression, and they show that inhibiting ERK5 in concert with ALK reduced neuroblastoma cell viability in vitro and in xenograft tumor models. This report has important clinical implications for the treatment of patients with neuroblastoma or other tumors that overexpress MYC(N) and harbor ALK mutations, such as non-small-cell lung cancer.
    Type of Publication: Journal article published
    PubMed ID: 25351246
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  • 8
    Keywords: APOPTOSIS ; CANCER ; GROWTH ; GENE-EXPRESSION ; STEM-CELLS ; CENTRAL-NERVOUS-SYSTEM ; neuroblastoma ; N-MYC ; BRAIN-TUMORS ; TUMOR-SUPPRESSOR
    Abstract: Previous studies have evaluated the role of miRNAs in cancer initiation and progression. MiR-34a was found to be downregulated in several tumors, including medulloblastomas. Here we employed targeted transgenesis to analyze the function of miR-34a in vivo. We generated mice with a constitutive deletion of the miR-34a gene. These mice were devoid of mir-34a expression in all analyzed tissues, but were viable and fertile. A comprehensive standardized phenotypic analysis including more than 300 single parameters revealed no apparent phenotype. Analysis of miR-34a expression in human medulloblastomas and medulloblastoma cell lines revealed significantly lower levels than in normal human cerebellum. Re-expression of miR-34a in human medulloblastoma cells reduced cell viability and proliferation, induced apoptosis and downregulated the miR-34a target genes, MYCN and SIRT1. Activation of the Shh pathway by targeting SmoA1 transgene overexpression causes medulloblastoma in mice, which is dependent on the presence and upregulation of Mycn. Analysis of miR-34a in medulloblastomas derived from ND2:SmoA1(tg) mice revealed significant suppression of miR-34a compared to normal cerebellum. Tumor incidence was significantly increased and tumor formation was significantly accelerated in mice transgenic for SmoA1 and lacking miR-34a. Interestingly, Mycn and Sirt1 were strongly expressed in medulloblastomas derived from these mice. We here demonstrate that miR-34a is dispensable for normal development, but that its loss accelerates medulloblastomagenesis. Strategies aiming to re-express miR-34a in tumors could, therefore, represent an efficient therapeutic option. (c) 2014 Wiley Periodicals, Inc.
    Type of Publication: Journal article published
    PubMed ID: 25348795
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  • 9
    Keywords: APOPTOSIS ; CANCER ; CELLS ; EXPRESSION ; ONCOGENE ; MYCN ; CHROMOSOME 1P ; MicroRNAs ; AURORA-B ; YM155
    Abstract: MicroRNAs (miRNAs) are deregulated in a variety of human cancers, including neuroblastoma, the most common extracranial tumor of childhood. We previously reported a signature of 42 miRNAs to be highly predictive of neuroblastoma outcome. One miRNA in this signature, miR-542, was downregulated in tumors from patients with adverse outcome. Reanalysis of quantitative PCR and next-generation sequencing transcript data revealed that miR-542-5p as well as miR-542-3p expression is inversely correlated with poor prognosis in neuroblastoma patients. We, therefore, analyzed the function of miR-542 in neuroblastoma tumor biology. Ectopic expression of miR-542-3p in neuroblastoma cell lines reduced cell viability and proliferation, induced apoptosis and downregulated Survivin. Survivin expression was also inversely correlated with miR-542-3p expression in primary neuroblastomas. Reporter assays confirmed that miR-542-3p directly targeted Survivin. Downregulating Survivin using siRNA copied the phenotype of miR-542-3p expression in neuroblastoma cell lines, while cDNA-mediated ectopic expression of Survivin partially rescued the phenotype induced by miR-542-3p expression. Treating nude mice bearing neuroblastoma xenografts with miR-542-3p-loaded nanoparticles repressed Survivin expression, decreased cell proliferation and induced apoptosis in the respective xenograft tumors. We conclude that miR-542-3p exerts its tumor suppressive function in neuroblastoma, at least in part, by targeting Survivin. Expression of miR-542-3p could be a promising therapeutic strategy for treating aggressive neuroblastoma.
    Type of Publication: Journal article published
    PubMed ID: 25046253
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  • 10
    Keywords: CANCER ; INVASION ; chemotherapy ; FEATURES ; STAGING SYSTEM ; CHILDREN RECEIVING CARBOPLATIN ; UNILATERAL RETINOBLASTOMA ; ORBITAL RETINOBLASTOMA ; OTOTOXICITY
    Abstract: BACKGROUND: Retinoblastoma can extend beyond the structures of the eye, where cells can enter the bloodstream and cause metastases. Various types of protocols for adjuvant treatment risk-adapted according to histopathological risk factors are used worldwide. METHODS: Between 1997 and 2009, 420 children were diagnosed with retinoblastoma at the German Retinoblastoma Referral Centre and risk factors were assessed. Patients with post-laminar optic nerve infiltration or choroid or minor scleral invasion received six courses of adjuvant chemotherapy using vincristine, etoposide, carboplatin and cyclophosphamide (group 1). Patients with microscopic extension beyond the sclera to the resection margin of the optic nerve or potential spread due to vitrectomy received chemotherapy plus orbital radiotherapy (group 2). Neoadjuvant chemotherapy was performed in patients with local extraocular invasion detected on MRI. RESULTS: Following this protocol, 42 of the 420 patients and 21 referred from other centres showed high-risk histopathological factors qualifying for adjuvant therapy (57 in group 1 and 6 in group 2). Seven of the 63 patients received neoadjuvant and adjuvant treatment. During a mean follow-up of 5.8 (range 0.4-15.4) years, one of six patients in group 2 developed metastases and died. No patients died from toxicity. The 5-year overall survival was 100% for group 1 and 80% for group 2. CONCLUSIONS: This retrospective single-site study reveals a 10% incidence of high-risk features in children with retinoblastoma diagnosed at the German Retinoblastoma Referral Centre. Overall survival rates of 98.3% underline the safety of this adjuvant chemotherapy protocol and its efficiency in preventing metastasis.
    Type of Publication: Journal article published
    PubMed ID: 25583279
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