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  • GROWTH  (7)
  • DIFFERENTIATION  (4)
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  • 1
    Keywords: APOPTOSIS ; CANCER ; CANCER CELLS ; CELLS ; EXPRESSION ; GROWTH ; IN-VITRO ; INHIBITOR ; proliferation ; tumor ; CELL ; CELL-PROLIFERATION ; Germany ; DRUG ; DIFFERENTIATION ; INDUCTION ; ACID ; NERVOUS-SYSTEM ; ASSAY ; CANCER-CELLS ; HISTONE DEACETYLASE ; histone deacetylase inhibitor ; p21(waf1) ; neuroblastoma ; INVITRO ; LEUKEMIA-CELLS ; ONCOLOGY ; CHILDHOOD ; RE ; medulloblastoma ; cell proliferation ; ASSAYS ; pharmacology ; USA ; anticancer drug ; childhood cancer ; HELMINTHOSPORIUM-CARBONUM (HC)-TOXIN ; HKI46F08
    Abstract: Embryonic childhood cancer such as neuroblastoma and medulloblastoma are still a therapeutic challenge requiring novel treatment approaches. Here, we investigated the antitumoral effects of HKI 46F08, a novel trifluoromethyl ketone histone deacetylase (HDAC) inhibitor with a nonhydroxamic acid type structure. HKI 46F08 inhibits in-vitro HDAC activity in cell-free assays with a half maximal inhibitory concentration of 0.6 mu mol/l and intracellular HDAC activity with a half maximal inhibitory concentration of 1.8 mu mol/l. The compound reduces viability of both cultured neuroblastoma and medulloblastoma cells with an EC50 of 0.1-4 mu mol/l. HKI 461708 efficiently arrests tumor cell proliferation, represses clonogenic growth and induces differentiation and apoptosis in both MYCN-amplified and nonamplified neuroblastoma cells. In summary, we identified HKI 48F08 as a structural novel, potent HDAC inhibitor with strong antitumoral activity against embryonic childhood cancer cells in the low micromolar range
    Type of Publication: Journal article published
    PubMed ID: 18765999
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  • 2
    Keywords: APOPTOSIS ; CANCER ; CELLS ; GROWTH ; INHIBITOR ; tumor ; CELL ; Germany ; IN-VIVO ; INHIBITION ; MODEL ; PATHWAY ; THERAPY ; DISEASE ; GENE ; GENES ; PROTEIN ; PROTEINS ; DRUG ; DIFFERENTIATION ; TUMORS ; NEUROBLASTOMA-CELLS ; ACTIVATION ; MECHANISM ; FAMILY ; prognosis ; mechanisms ; cell cycle ; CELL-CYCLE ; CYCLE ; MEMBERS ; SUSCEPTIBILITY ; ANTITUMOR-ACTIVITY ; MOUSE ; TRIAL ; TRIALS ; CELL-DEATH ; CLINICAL-TRIALS ; chemotherapy ; MOUSE MODEL ; TARGETS ; CHILDREN ; HDAC inhibitors ; HISTONE DEACETYLASE ; INTERFERON-ALPHA ; REPRESSION ; TRAIL-INDUCED APOPTOSIS ; neuroblastoma ; HDAC ; INHIBITORS ; ADULT ; review ; FAMILIES ; THERAPIES ; tumor suppressor gene ; EPIGENETICS ; CANCERS ; valproic acid ; Phase I ; SODIUM VALPROATE ; MALIGNANT PHENOTYPE ; NUCLEAR EXPORT ; drug targets ; DRUG-TARGET ; HDAC inhibitor
    Abstract: Histone deacetylases (HDACs) are an emerging class of novel anti-cancer drug targets. Recently, studies in adult cancers and in neuroblastoma have shown that individual HDAC family members are aberrantly expressed in tumors and correlate with disease stage and prognosis. In neuroblastoma, knockdown of individual HDAC family members causes distinct phenotypes ranging from differentiation to apoptosis. HDACs are involved in controlling MYCN function and are upregulated in chemotherapy-resistant neuroblastoma cells. Treatment with unselective pan-HDAC inhibitors causes cell cycle arrest, differentiation, apoptosis, and inhibition of clonogenic growth of neuroblastoma cells, and restores susceptibility to chemotherapy treatment. The molecular mechanisms mediating the anti-cancer effects of HDAC inhibitors on neuroblastoma cells are incompletely understood and involve targeting of aberrant epigenetic repression of tumor suppressor genes, activation of developmental differentiation pathways, as well as changing the acetylation level and function of non-histone proteins. In neuroblastoma mouse models, unselective HDAC inhibitors demonstrate antitumoral effects. First phase I clinical trials in children with refractory cancers using HDAC inhibitors depsipeptide and the recently approved vorinostat are underway. This review summarizes our current knowledge about classical HDAC family members as novel drug targets for neuroblastoma therapy and discusses the potential role of next generation, selective HDAC inhibitors
    Type of Publication: Journal article published
    PubMed ID: 19199971
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  • 3
    Keywords: GROWTH ; IRRADIATION ; THERAPY ; MDM2 ; ANTAGONIST ; HYPOXIA ; MACULAR DEGENERATION ; CHOROIDAL NEOVASCULARIZATION ; PERIOCULAR TRIAMCINOLONE ; RANIBIZUMAB
    Abstract: Neovascular age-related macular degeneration is a leading cause of irreversible vision loss in the Western world. Cytokine-targeted therapies (such as anti-vascular endothelial growth factor) are effective in treating pathologic ocular angiogenesis, but have not led to a durable effect and often require indefinite treatment. Here, we show that Nutlin-3, a small molecule antagonist of the E3 ubiquitin protein ligase MDM2, inhibited angiogenesis in several model systems. We found that a functional p53 pathway was essential for Nutlin-3-mediated retinal antiangiogenesis and disruption of the p53 transcriptional network abolished the antiangiogenic activity of Nutlin-3. Nutlin-3 did not inhibit established, mature blood vessels in the adult mouse retina, suggesting that only proliferating retinal vessels are sensitive to Nutlin-3. Furthermore, Nutlin-3 inhibited angiogenesis in nonretinal models such as the hind limb ischemia model. Our work demonstrates that Nutlin-3 functions through an antiproliferative pathway with conceivable advantages over existing cytokine-targeted antiangiogenesis therapies.
    Type of Publication: Journal article published
    PubMed ID: 24018558
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  • 4
    Keywords: CANCER ; GROWTH ; TUMORS ; NERVOUS-SYSTEM ; ADULT ; MOUSE MODELS ; PEDIATRIC MEDULLOBLASTOMA ; HEDGEHOG PATHWAY INHIBITOR ; TERT PROMOTER MUTATIONS ; ITRACONAZOLE
    Abstract: Smoothened (SMO) inhibitors recently entered clinical trials for sonic-hedgehog-driven medulloblastoma (SHH-MB). Clinical response is highly variable. To understand the mechanism(s) of primary resistance and identify pathways cooperating with aberrant SHH signaling, we sequenced and profiled a large cohort of SHH-MBs (n = 133). SHH pathway mutations involved PTCH1 (across all age groups), SUFU (infants, including germline), and SMO (adults). Children 〉3 years old harbored an excess of downstream MYCN and GLI2 amplifications and frequent TP53 mutations, often in the germline, all of which were rare in infants and adults. Functional assays in different SHH-MB xenograft models demonstrated that SHH-MBs harboring a PTCH1 mutation were responsive to SMO inhibition, whereas tumors harboring an SUFU mutation or MYCN amplification were primarily resistant.
    Type of Publication: Journal article published
    PubMed ID: 24651015
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  • 5
    Keywords: GROWTH ; CELL LUNG-CANCER ; PHASE-I ; ASSAY ; MONONUCLEAR-CELLS ; HUMAN SERUM ; SUBEROYLANILIDE HYDROXAMIC ACID ; HDAC inhibitor ; SAHA ; RITONAVIR
    Abstract: Vorinostat (suberoylanilide hydroxamic acid) is the first approved histone deacetylase (HDAC) inhibitor for the treatment of cutaneous T-cell lymphoma after progressive disease following two systemic therapies. Intracellular access of vorinostat is essential to exert its epigenetic effects. Therefore, we studied the relationship between vorinostat extracellular (plasma) and intracellular (peripheral blood mononuclear cells, PBMCs) concentration and assessed its concentration-effect relationship by HDAC activity testing. Assays were developed and validated for the low nanomolar quantification of vorinostat and two inactive metabolites in human plasma and PBMCs. For the vorinostat extraction from plasma and PBMCs solid-phase extraction and liquid-liquid extraction methods were applied. Extraction recoveries ranged from 88.6% to 114.4% for all analytes and extraction methods. Extracts were chromatographed on a Phenomenex Luna column isocratically (plasma) or by gradient (PBMCs) consisting of acidic ammonium acetate, acetonitrile, and methanol. The analytes were quantified using deuterated internal standards and positive electrospray tandem mass spectrometry (multiple reaction monitoring) with lower limits of quantification of 11.0 ng/mL (plasma) and 0.1 ng/3 x 10(6) cells (PBMCs). The calibrated ranges were linear for vorinostat in plasma 11.0-1100 (11,000) ng/mL (metabolites) and PBMCs 0.1-10.0 ng/3 x 10(6) cells with correlation coefficients 〉0.99, an overall accuracy varying between -6.7% and +3.8% in plasma, -8.1% and -1.5% in PBMCs, and an overall precision ranging from 3.2% to 6.1% in plasma and 0.8% to 4.0% in PBMCs (SD batch-to-batch). The application to blood samples from healthy volunteers incubated with vorinostat revealed accumulation of vorinostat in PBMCs, effective intracellular HDAC inhibition at therapeutic vorinostat concentrations and a direct vorinostat concentration dependency to HDAC inhibition.
    Type of Publication: Journal article published
    PubMed ID: 24636840
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  • 6
    Keywords: DIFFERENTIATION ; PROGNOSTIC-SIGNIFICANCE ; CENTRAL-NERVOUS-SYSTEM ; EMBRYONIC STEM-CELLS ; BRAIN-TUMORS ; intermediate filament protein ; CHILDHOOD EPENDYMOMAS ; PEDIATRIC INTRACRANIAL EPENDYMOMAS ; DIFFERENT TUMORS ; MARKER NESTIN
    Abstract: Ependymomas are primary brain tumors found throughout the central nervous system (CNS) in children and adults. Currently, many treatment protocols stratify grade I and II ependymomas as low-risk tumors, whereas grade III anaplastic ependymomas are considered high-risk tumors. The prognostic significance of World Health Organization (WHO) grade II or III, however, remains debated, and it is furthermore increasingly recognized that the pathologic differentiation between grades II and III is arbitrary in daily practice, thus resulting in imprecise risk stratification. Therefore, prognostic markers enabling more precise stratification to guide treatment decisions are urgently needed. An analysis of n = 379 tumor samples revealed that protein expression of nestin, a marker for neural stem and progenitor cells established as a routine staining in most neuropathology centers, is associated with poor outcome in intracranial ependymomas. Most importantly, nestin-positive grade II ependymomas have the same prognosis as grade III ependymomas. Multivariable analysis demonstrates that nestin positivity is an independent marker for poor progression-free survival (PFS) and overall survival (OS). Gene expression analysis for transcriptionally co-regulated genes revealed a strong association of developmental and epigenetic processes with nestin. In summary, our data implicate nestin as a useful novel marker for intracranial ependymoma risk stratification easily implementable in routine diagnostics.
    Type of Publication: Journal article published
    PubMed ID: 22568867
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  • 7
    Keywords: GROWTH ; IN-VITRO ; tumor ; MODEL ; IDENTIFICATION ; STEM-CELLS ; ABNORMALITIES ; SUPRATENTORIAL ; CHILDHOOD EPENDYMOMAS ; PEDIATRIC INTRACRANIAL EPENDYMOMAS
    Abstract: PURPOSE OF REVIEW: Effective treatment options for ependymoma apart from radical surgery and radiotherapy remain scarce, and the understanding of the molecular basis of ependymoma biology is crucial to the development of novel therapies. Comprehensive work revealing molecular pathomechanisms of ependymoma has been done; however, the elucidation of the processes underlying the origins of various clearly distinguishable ependymoma subgroups has proved to be difficult. The future challenges will be to reach consensus about molecular subgroups, to translate these into a clinical setting, and to use available models for drug screening and preclinical testing. RECENT FINDINGS: Ependymoma subgroups with clearly distinct biology have been delineated and novel mouse models generated, and the first high-throughput drug screens were successfully conducted leading to the identification of subgroup-specific active regimens. SUMMARY: Coordinated efforts to advance novel therapies into the clinic have led to breakthrough insights into the molecular biology of ependymoma. The next step will be the translation of preclinical findings into the clinical setting, and international study groups are starting to implement the most recent advances into clinical trials.
    Type of Publication: Journal article published
    PubMed ID: 23007011
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  • 8
    Keywords: EXPRESSION ; GENE ; DIFFERENTIATION ; IDENTIFICATION ; EMBRYONIC STEM-CELLS ; HYPERMETHYLATION ; SUPPRESSOR ; methylome ; CANCER GENOME ; CPG ISLAND SHORES
    Abstract: Epigenetic alterations, that is, disruption of DNA methylation and chromatin architecture, are now acknowledged as a universal feature of tumorigenesis. Medulloblastoma, a clinically challenging, malignant childhood brain tumour, is no exception. Despite much progress from recent genomics studies, with recurrent changes identified in each of the four distinct tumour subgroups (WNT-pathway-activated, SHH-pathway-activated, and the less-well-characterized Group 3 and Group 4), many cases still lack an obvious genetic driver. Here we present whole-genome bisulphite-sequencing data from thirty-four human and five murine tumours plus eight human and three murine normal controls, augmented with matched whole-genome, RNA and chromatin immunoprecipitation sequencing data. This comprehensive data set allowed us to decipher several features underlying the interplay between the genome, epigenome and transcriptome, and its effects on medulloblastoma pathophysiology. Most notable were highly prevalent regions of hypomethylation correlating with increased gene expression, extending tens of kilobases downstream of transcription start sites. Focal regions of low methylation linked to transcription-factor-binding sites shed light on differential transcriptional networks between subgroups, whereas increased methylation due to re-normalization of repressed chromatin in DNA methylation valleys was positively correlated with gene expression. Large, partially methylated domains affecting up to one-third of the genome showed increased mutation rates and gene silencing in a subgroup-specific fashion. Epigenetic alterations also affected novel medulloblastoma candidate genes (for example, LIN28B), resulting in alternative promoter usage and/or differential messenger RNA/microRNA expression. Analysis of mouse medulloblastoma and precursor-cell methylation demonstrated a somatic origin for many alterations. Our data provide insights into the epigenetic regulation of transcription and genome organization in medulloblastoma pathogenesis, which are probably also of importance in a wider developmental and disease context.
    Type of Publication: Journal article published
    PubMed ID: 24847876
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  • 9
    Keywords: RISK STRATIFICATION ; HISTONE DEACETYLASES ; medulloblastoma ; RISK-STRATIFICATION ; STRATIFICATION ; journals ; Jun ; MARKERS ; ONCOLOGY ; CELL-GROWTH ; CELL ; GROWTH ; MARKER ; RISK
    Type of Publication: Meeting abstract published
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