Publications by authors named "Daniel Picard"

47 Publications

The long non-coding RNA HOTAIRM1 promotes tumor aggressiveness and radiotherapy resistance in glioblastoma.

Cell Death Dis 2021 Sep 28;12(10):885. Epub 2021 Sep 28.

Institute for Experimental Cancer Research in Pediatrics, Goethe University Frankfurt, Frankfurt, Germany.

Glioblastoma is the most common malignant primary brain tumor. To date, clinically relevant biomarkers are restricted to isocitrate dehydrogenase (IDH) gene 1 or 2 mutations and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation. Long non-coding RNAs (lncRNAs) have been shown to contribute to glioblastoma pathogenesis and could potentially serve as novel biomarkers. The clinical significance of HOXA Transcript Antisense RNA, Myeloid-Specific 1 (HOTAIRM1) was determined by analyzing HOTAIRM1 in multiple glioblastoma gene expression data sets for associations with prognosis, as well as, IDH mutation and MGMT promoter methylation status. Finally, the role of HOTAIRM1 in glioblastoma biology and radiotherapy resistance was characterized in vitro and in vivo. We identified HOTAIRM1 as a candidate lncRNA whose up-regulation is significantly associated with shorter survival of glioblastoma patients, independent from IDH mutation and MGMT promoter methylation. Glioblastoma cell line models uniformly showed reduced cell viability, decreased invasive growth and diminished colony formation capacity upon HOTAIRM1 down-regulation. Integrated proteogenomic analyses revealed impaired mitochondrial function and determination of reactive oxygen species (ROS) levels confirmed increased ROS levels upon HOTAIRM1 knock-down. HOTAIRM1 knock-down decreased expression of transglutaminase 2 (TGM2), a candidate protein implicated in mitochondrial function, and knock-down of TGM2 mimicked the phenotype of HOTAIRM1 down-regulation in glioblastoma cells. Moreover, HOTAIRM1 modulates radiosensitivity of glioblastoma cells both in vitro and in vivo. Our data support a role for HOTAIRM1 as a driver of biological aggressiveness, radioresistance and poor outcome in glioblastoma. Targeting HOTAIRM1 may be a promising new therapeutic approach.
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http://dx.doi.org/10.1038/s41419-021-04146-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8478910PMC
September 2021

Identification and Functional Characterization of Novel MYC-Regulated Long Noncoding RNAs in Group 3 Medulloblastoma.

Cancers (Basel) 2021 Jul 30;13(15). Epub 2021 Jul 30.

Institute of Molecular Biology and Pathology, CNR, 00185 Rome, Italy.

The impact of protein-coding genes on cancer onset and progression is a well-established paradigm in molecular oncology. Nevertheless, unveiling the contribution of the noncoding genes-including long noncoding RNAs (lncRNAs)-to tumorigenesis represents a great challenge for personalized medicine, since they (i) constitute the majority of the human genome, (ii) are essential and flexible regulators of gene expression and (iii) present all types of genomic alterations described for protein-coding genes. LncRNAs have been increasingly associated with cancer, their highly tissue- and cancer type-specific expression making them attractive candidates as both biomarkers and therapeutic targets. Medulloblastoma is one of the most common malignant pediatric brain tumors. Group 3 is the most aggressive subgroup, showing the highest rate of metastasis at diagnosis. Transcriptomics and reverse genetics approaches were combined to identify lncRNAs implicated in Group 3 Medulloblastoma biology. Here we present the first collection of lncRNAs dependent on the activity of the MYC oncogene, the major driver gene of Group 3 Medulloblastoma. We assessed the expression profile of selected lncRNAs in Group 3 primary tumors and functionally characterized these species. Overall, our data demonstrate the direct involvement of three lncRNAs in Medulloblastoma cancer cell phenotypes.
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http://dx.doi.org/10.3390/cancers13153853DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8345409PMC
July 2021

Expression of cell type incongruent alpha-cardiac actin 1 subunit in medulloblastoma reveals a novel mechanism for cancer cell survival and control of migration.

Neurooncol Adv 2021 Jan-Dec;3(1):vdab064. Epub 2021 Apr 23.

Montreal Neurological Institute, McGill University, Montreal, Québec, Canada.

Background: Alterations in actin subunit expression have been reported in multiple cancers, but have not been investigated previously in medulloblastoma.

Methods: Bioinformatic analysis of multiple medulloblastoma tumor databases was performed to profile mRNA levels. Western blot was used to verify protein expression in established medulloblastoma cell lines. Immunofluorescence microscopy was performed to assess ACTC1 localization. Stable cell lines with ACTC1 overexpression were generated and shRNA knockdown of ACTC1 was accomplished. We used PARP1 cleavage by Western blot as a marker of apoptosis and cell survival was determined by FACS viability assay and colony formation. Cell migration with overexpression or knockdown of ACTC1 was determined by the scratch assay. Stress fiber length distribution was assessed by fluorescence microscopy.

Results: mRNA expression is highest in SHH and WNT medulloblastoma among all subgroups. ACTC1 protein was confirmed by Western blot in SHH subgroup and Group 3 subgroup cell lines with the lowest expression in Group 3 cells. Microscopy demonstrated ACTC1 co-localization with F-actin. Overexpression of ACTC1 in Group 3 cells abolished the apoptotic response to Aurora kinase B inhibition. Knockdown of ACTC1 in SHH cells and in Myc overexpressing SHH cells induced apoptosis, impaired colony formation, and inhibited migration. Changes in stress fiber length distribution in medulloblastoma cells are induced by alterations in ACTC1 abundance.

Conclusions: Alpha-cardiac actin (ACTC1) is expressed in SHH medulloblastoma. Expression of this protein in medulloblastoma modifies stress fiber composition and functions in promoting resistance to apoptosis induced by mitotic inhibition, enhancing cell survival, and controlling migration.
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http://dx.doi.org/10.1093/noajnl/vdab064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8320690PMC
April 2021

The Second Oncogenic Hit Determines the Cell Fate of Positive Leukemia.

Front Cell Dev Biol 2021 15;9:704591. Epub 2021 Jul 15.

Institute for Biomedical Research of Salamanca, Salamanca, Spain.

ETV6-RUNX1 is almost exclusively associated with childhood B-cell acute lymphoblastic leukemia (B-ALL), but the consequences of ETV6-RUNX1 expression on cell lineage decisions during B-cell leukemogenesis are completely unknown. Clinically silent ETV6-RUNX1 preleukemic clones are frequently found in neonatal cord blood, but few carriers develop B-ALL as a result of secondary genetic alterations. The understanding of the mechanisms underlying the first transforming steps could greatly advance the development of non-toxic prophylactic interventions. Using genetic lineage tracing, we examined the capacity of ETV6-RUNX1 to instruct a malignant phenotype in the hematopoietic lineage by cell-specific Cre-mediated activation of ETV6-RUNX1 from the endogenous gene locus. Here we show that, while ETV6-RUNX1 has the propensity to trigger both T- and B-lymphoid malignancies, it is the second hit that determines tumor cell identity. To instigate leukemia, both oncogenic hits must place early in the development of hematopoietic/precursor cells, not in already committed B-cells. Depending on the nature of the second hit, the resulting B-ALLs presented distinct entities that were clearly separable based on their gene expression profiles. Our findings give a novel mechanistic insight into the early steps of ETV6-RUNX1+ B-ALL development and might have major implications for the potential development of ETV6-RUNX1+ B-ALL prevention strategies.
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http://dx.doi.org/10.3389/fcell.2021.704591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8320889PMC
July 2021

Allosteric Antagonist Modulation of TRPV2 by Piperlongumine Impairs Glioblastoma Progression.

ACS Cent Sci 2021 May 14;7(5):868-881. Epub 2021 Apr 14.

Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal.

The use of computational tools to identify biological targets of natural products with anticancer properties and unknown modes of action is gaining momentum. We employed self-organizing maps to deconvolute the phenotypic effects of piperlongumine (PL) and establish a link to modulation of the human transient receptor potential vanilloid 2 (hTRPV2) channel. The structure of the PL-bound full-length rat TRPV2 channel was determined by cryo-EM. PL binds to a transient allosteric pocket responsible for a new mode of anticancer activity against glioblastoma (GBM) in which hTRPV2 is overexpressed. Calcium imaging experiments revealed the importance of Arg539 and Thr522 residues on the antagonistic effect of PL and calcium influx modulation of the TRPV2 channel. Downregulation of hTRPV2 reduces sensitivity to PL and decreases ROS production. Analysis of GBM patient samples associates hTRPV2 overexpression with tumor grade, disease progression, and poor prognosis. Extensive tumor abrogation and long term survival was achieved in two murine models of orthotopic GBM by formulating PL in an implantable scaffold/hydrogel for sustained local therapy. Furthermore, in primary tumor samples derived from GBM patients, we observed a selective reduction of malignant cells in response to PL . Our results establish a broadly applicable strategy, leveraging data-motivated research hypotheses for the discovery of novel means tackling cancer.
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http://dx.doi.org/10.1021/acscentsci.1c00070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8161495PMC
May 2021

Thrombospondin-1 mimetics are promising novel therapeutics for MYC-associated medulloblastoma.

Neurooncol Adv 2021 Jan-Dec;3(1):vdab002. Epub 2021 Feb 18.

Department of Pediatrics, Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.

Background: Medulloblastoma (MB) comprises four subtypes of which group 3 MB are the most aggressive. Although overall survival for MB has improved, the outcome of group 3 MB remains dismal. C- amplification or MYC overexpression which characterizes group 3 MB is a strong negative prognostic factor and is frequently associated with metastases and relapses. We previously reported that MYC expression alone promotes highly aggressive MB phenotypes, in part via repression of thrombospondin-1 (TSP-1), a potent tumor suppressor.

Methods: In this study, we examined the potential role of TSP-1 and TSP-1 peptidomimetic ABT-898 in amplified human MB cell lines and two distinct murine models of MYC-driven group 3 MBs.

Results: We found that TSP-1 reconstitution diminished metastases and prolonged survival in orthotopic xenografts and promoted chemo- and radio-sensitivity via AKT signaling. Furthermore, we demonstrate that ABT-898 can recapitulate the effects of TSP-1 expression in MB cells in vitro and specifically induced apoptosis in murine group 3 MB tumor cells.

Conclusion: Our data underscore the importance of TSP-1 as a critical tumor suppressor in MB and highlight TSP-1 peptidomimetics as promising novel therapeutics for the most lethal subtype of MB.
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http://dx.doi.org/10.1093/noajnl/vdab002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7890793PMC
February 2021

Classical and Variant Merkel Cell Carcinoma Cell Lines Display Different Degrees of Neuroendocrine Differentiation and Epithelial-Mesenchymal Transition.

J Invest Dermatol 2021 Jul 16;141(7):1675-1686.e4. Epub 2021 Feb 16.

Group of Translational Skin Cancer Research (TSCR), University Duisburg-Essen, Essen, Germany; German Cancer Consortium (DKTK) & German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Dermatology, University Hospital Essen, Essen, Germany. Electronic address:

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer characterized by high invasiveness, early metastases, and high mortality. Because of the lack of suitable animal models, most functional studies are performed using cell lines, some of which lack classical neuroendocrine growth characteristics. Here, we scrutinized the molecular characteristics of classical MCC and variant MCC cell lines by differential gene expression and the respective epigenetic regulation by microRNAs and DNA methylation. Cutaneous squamous cell carcinoma cell lines were used for comparison. The most striking observation was a lower expression of epithelial-mesenchymal transition-related genes in classical MCCs, which was accompanied by higher expression of the epithelial-mesenchymal transition-regulating microRNA clusters miR-200c-141 and miR-183-96-182 and hypomethylation of the respective microRNA loci. Experimental expression of the MCC lineage factor ATOH1 in variant MCCs resulted in an increased expression of miR-200c-141 paralleled by a reduction of genes associated with epithelial-mesenchymal transition, thus demonstrating a connection between neuroendocrine characteristics and the lack of epithelial-mesenchymal transition. Together, our observations not only reinforce concerns about the use of variant MCCs as proper MCC representatives, but also suggest variant MCCs as cells locked in an intermediate state between neuroendocrine and epithelial differentiation.
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http://dx.doi.org/10.1016/j.jid.2021.01.012DOI Listing
July 2021

Involvement of CXCL1/CXCR2 During Microglia Activation Following Inflammation-Sensitized Hypoxic-Ischemic Brain Injury in Neonatal Rats.

Front Neurol 2020 6;11:540878. Epub 2020 Oct 6.

Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany.

Microglia are key mediators of inflammation during perinatal brain injury. As shown experimentally after inflammation-sensitized hypoxic ischemic (HI) brain injury, microglia are activated into a pro-inflammatory status 24 h after HI involving the NLRP3 inflammasome pathway. The chemokine (C-X-C motif) ligand 1 (CXCL1), and its cognate receptor, CXCR2, have been shown to be involved in NLRP3 activation, although their specific role during perinatal brain injury remains unclear. In this study we investigated the involvement of CXCL1/CXCR2 in brain tissue and microglia and brain tissue after inflammation-sensitized HI brain injury of newborn rats. Seven-day old Wistar rat pups were either injected with vehicle (NaCl 0.9%) or lipopolysaccharide (LPS), followed by left carotid ligation combined with global hypoxia (8% O for 50 min). Pups were randomized into four different treatment groups: (1) Sham group ( = 21), (2) LPS only group ( = 20), (3) Veh/HI group ( = 39), and (4) LPS/HI group ( = 42). Twenty-four hours post hypoxia transcriptome and gene expression analysis were performed on isolated microglia cells in our model. Additionally protein expression was analyzed in different brain regions at the same time point. Transcriptome analyses showed a significant microglial upregulation of the chemokine CXCL1 and its receptor CXCR2 in the LPS/HI group compared with the other groups. Gene expression analysis showed a significant upregulation of CXCL1 and NLRP3 in microglia cells after inflammation-sensitized hypoxic-ischemic brain injury. Additionally, protein expression of CXCL1 was significantly upregulated in cortex of male pups from the LPS/HI group. These results indicate that the CXCL1/CXCR2 pathway may be involved during pro-inflammatory microglia activation following inflammation-sensitized hypoxic-ischemic brain injury in neonatal rats. This may lead to new treatment options altering CXCR2 activation early after HI brain injury.
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http://dx.doi.org/10.3389/fneur.2020.540878DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573390PMC
October 2020

Interferon-β exposure induces a fragile glioblastoma stem cell phenotype with a transcriptional profile of reduced migratory and MAPK pathway activity.

Neurooncol Adv 2020 Jan-Dec;2(1):vdaa043. Epub 2020 Mar 28.

Laboratory of Molecular Neuro-Oncology, Department of Neurology, University Hospital and University of Zurich, Zurich, Switzerland.

Background: Type I interferons (IFN-α/β) are cytokines that are typically expressed in response to double-stranded RNA associated with viral infections. Glioblastomas are the most common malignant primary brain tumors, characterized by an infiltrative growth pattern and prominent angiogenic activity, and thought to be maintained by a subpopulation of glioma-initiating (stem-like) cells (GICs). The growth of human GIC lines is highly sensitive to IFN-β.

Methods: Repetitive pulse stimulation with IFN-β1a (IS) was used to generate IS sublines that had acquired resistance to IFN-β-induced suppression of sphere formation. These cell lines were characterized by analyses of type 1 IFN signaling, growth patterns, and transcriptomic profiles.

Results: Here we report that repetitive IFN-β1a stimulation (IS) induces a stable phenotype (referred to as IS) at the level of maintaining sphere formation, although classical IFN signaling defined by the expression of both IFN receptors, myxovirus resistance protein A (MxA) accumulation, and STAT1 induction is unaffected. Furthermore, this stably altered IS phenotype is characterized by constitutively decreased sphere formation capacity and morphological features of senescence and autophagy. Transcriptional profiling reveals increased type I IFN signaling in these IS cells, but decreased expression of genes involved in receptor signaling and cell migration.

Conclusions: Altogether, these data suggest a role for promoting IFN-β signaling in glioblastoma and might provide clues to design future therapeutic approaches.
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http://dx.doi.org/10.1093/noajnl/vdaa043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7212887PMC
March 2020

YBX1 Indirectly Targets Heterochromatin-Repressed Inflammatory Response-Related Apoptosis Genes through Regulating CBX5 mRNA.

Int J Mol Sci 2020 Jun 23;21(12). Epub 2020 Jun 23.

Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany.

Medulloblastomas arise from undifferentiated precursor cells in the cerebellum and account for about 20% of all solid brain tumors during childhood; standard therapies include radiation and chemotherapy, which oftentimes come with severe impairment of the cognitive development of the young patients. Here, we show that the posttranscriptional regulator Y-box binding protein 1 (YBX1), a DNA- and RNA-binding protein, acts as an oncogene in medulloblastomas by regulating cellular survival and apoptosis. We observed different cellular responses upon YBX1 knockdown in several medulloblastoma cell lines, with significantly altered transcription and subsequent apoptosis rates. Mechanistically, PAR-CLIP for YBX1 and integration with RNA-Seq data uncovered direct posttranscriptional control of the heterochromatin-associated gene ; upon YBX1 knockdown and subsequent CBX5 mRNA instability, heterochromatin-regulated genes involved in inflammatory response, apoptosis and death receptor signaling were de-repressed. Thus, YBX1 acts as an oncogene in medulloblastoma through indirect transcriptional regulation of inflammatory genes regulating apoptosis and represents a promising novel therapeutic target in this tumor entity.
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http://dx.doi.org/10.3390/ijms21124453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7352269PMC
June 2020

A Sexually Dimorphic Role for STAT3 in Sonic Hedgehog Medulloblastoma.

Cancers (Basel) 2019 Nov 1;11(11). Epub 2019 Nov 1.

Centre for Cancer Research, Hudson Institute of Medical Research, 27-31 Wright St, Clayton, Victoria 3168, Australia.

Medulloblastoma is the most common malignant brain tumor in children and represents 20% of all pediatric central nervous system neoplasms. While advances in surgery, radiation and chemotherapy have improved overall survival, the lifelong sequelae of these treatments represent a major health care burden and have led to ongoing efforts to find effective targeted treatments. There is a well-recognized male bias in medulloblastoma diagnosis, although the mechanism remains unknown. Herein, we identify a sex-specific role for the transcription factor Signal Transducer and Activator of Transcription 3 (STAT3) in the Sonic Hedgehog (SHH) medulloblastoma subgroup. Specific deletion of from granule cell precursors in a spontaneous mouse model of SHH medulloblastoma completely protects male, but not female mice from tumor initiation. Segregation of SHH medulloblastoma patients into high and low STAT3 expressing cohorts shows that low STAT3 expression correlates with improved overall survival in male patients. We observe sex specific changes in and expression and show that IL-6 stimulation enhances SHH-mediated gene transcription in a STAT3-dependent manner. Together these data identify STAT3 as a key molecule underpinning the sexual dimorphism in medulloblastoma.
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http://dx.doi.org/10.3390/cancers11111702DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6895805PMC
November 2019

ABC Transporter Inhibition Plus Dexamethasone Enhances the Efficacy of Convection Enhanced Delivery in H3.3K27M Mutant Diffuse Intrinsic Pontine Glioma.

Neurosurgery 2020 05;86(5):742-751

Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina.

Background: An impermeable blood-brain barrier and drug efflux via ATP-binding cassette (ABC) transporters such as p-glycoprotein may contribute to underwhelming efficacy of peripherally delivered agents to treat diffuse intrinsic pontine glioma (DIPG).

Objective: To explore the pharmacological augmentation of convection-enhanced delivery (CED) infusate for DIPG.

Methods: The efficacy of CED dasatinib, a tyrosine kinase inhibitor, in a transgenic H3.3K27M mutant murine model was assessed. mRNA expression of ABCB1 (p-glycoprotein) was analyzed in 14 tumor types in 274 children. In Vitro viability studies of dasatinib, the p-glycoprotein inhibitor, tariquidar, and dexamethasone were performed in 2 H3.3K27M mutant cell lines. Magnetic resonance imaging (MRI) was used to evaluate CED infusate (gadolinium/dasatinib) distribution in animals pretreated with tariquidar and dexamethasone. Histological assessment of apoptosis was performed.

Results: Continuous delivery CED dasatinib improved median overall survival (OS) of animals harboring DIPG in comparison to vehicle (39.5 and 28.5 d, respectively; P = .0139). Mean ABCB1 expression was highest in K27M gliomas. In Vitro, the addition of tariquidar and dexamethasone further enhanced the efficacy of dasatinib (P < .001). In Vivo, MRI demonstrated no difference in infusion dispersion between animals pretreated with dexamethasone plus tariquidar prior to CED dasatinib compared to the CED dasatinib. However, tumor apoptosis was the highest in the pretreatment group (P < .001). Correspondingly, median OS was longer in the pretreatment group (49 d) than the dasatinib alone group (39 d) and no treatment controls (31.5 d, P = .0305).

Conclusion: ABC transporter inhibition plus dexamethasone enhances the efficacy of CED dasatinib, resulting in enhanced tumor cellular apoptosis and improved survival in H3.3K27M mutant DIPG.
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http://dx.doi.org/10.1093/neuros/nyz212DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7443593PMC
May 2020

The long noncoding RNA TP73-AS1 promotes tumorigenicity of medulloblastoma cells.

Int J Cancer 2019 12 12;145(12):3402-3413. Epub 2019 Jun 12.

Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.

Medulloblastoma is the most common malignant brain cancer in children. Since previous studies have mainly focused on alterations in the coding genome, our understanding of the contribution of long noncoding RNAs (lncRNAs) to medulloblastoma biology is just emerging. Using patient-derived data, we show that the promoter of lncRNA TP73-AS1 is hypomethylated and that the transcript is highly expressed in the SHH subgroup. Furthermore, high expression of TP73-AS1 is correlated with poor outcome in patients with TP53 wild-type SHH tumors. Silencing TP73-AS1 in medulloblastoma tumor cells induced apoptosis, while proliferation and migration were inhibited in culture. In vivo, silencing TP73-AS1 in medulloblastoma tumor cells resulted in reduced tumor growth, reduced proliferation of tumor cells, increased apoptosis and led to prolonged survival of tumor-bearing mice. Together, our study suggests that the lncRNA TP73-AS1 is a prognostic marker and therapeutic target in medulloblastoma tumors and serves as a proof of concept that lncRNAs are important factors in the disease.
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http://dx.doi.org/10.1002/ijc.32400DOI Listing
December 2019

The lncRNA TP73-AS1 is linked to aggressiveness in glioblastoma and promotes temozolomide resistance in glioblastoma cancer stem cells.

Cell Death Dis 2019 03 13;10(3):246. Epub 2019 Mar 13.

Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

Glioblastoma multiform (GBM) is the most common brain tumor characterized by a dismal prognosis. GBM cancer stem cells (gCSC) or tumor-initiating cells are the cell population within the tumor-driving therapy resistance and recurrence. While temozolomide (TMZ), an alkylating agent, constitutes the first-line chemotherapeutic significantly improving survival in GBM patients, resistance against this compound commonly leads to GBM recurrence and treatment failure. Although the roles of protein-coding transcripts, proteins and microRNA in gCSC, and therapy resistance have been comprehensively investigated, very little is known about the role of long noncoding RNAs (lncRNAs) in this context. Using nonoverlapping, independent RNA sequencing and gene expression profiling datasets, we reveal that TP73-AS1 constitutes a clinically relevant lncRNA in GBM. Specifically, we demonstrate significant overexpression of TP73-AS1 in primary GBM samples, which is particularly increased in the gCSC. More importantly, we demonstrate that TP73-AS1 comprises a prognostic biomarker in glioma and in GBM with high expression identifying patients with particularly poor prognosis. Using CRISPRi to downregulate our candidate lncRNA in gCSC, we demonstrate that TP73-AS1 promotes TMZ resistance in gCSC and is linked to regulation of the expression of metabolism- related genes and ALDH1A1, a protein known to be expressed in cancer stem cell markers and protects gCSC from TMZ treatment. Taken together, our results reveal that high TP73-AS1 predicts poor prognosis in primary GBM cohorts and that this lncRNA promotes tumor aggressiveness and TMZ resistance in gCSC.
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http://dx.doi.org/10.1038/s41419-019-1477-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416247PMC
March 2019

Insertional Mutagenesis Reveals Important Genetic Drivers of Central Nervous System Embryonal Tumors.

Cancer Res 2019 03 23;79(5):905-917. Epub 2019 Jan 23.

Division of Hematology, The Hospital for Sick Children, Toronto, Ontario, Canada.

Medulloblastoma and central nervous system primitive neuroectodermal tumors (CNS-PNET) are aggressive, poorly differentiated brain tumors with limited effective therapies. Using () transposon mutagenesis, we identified novel genetic drivers of medulloblastoma and CNS-PNET. Cross-species gene expression analyses classified -driven tumors into distinct medulloblastoma and CNS-PNET subgroups, indicating they resemble human Sonic hedgehog and group 3 and 4 medulloblastoma and CNS neuroblastoma with activation. This represents the first genetically induced mouse model of CNS-PNET and a rare model of group 3 and 4 medulloblastoma. We identified several putative proto-oncogenes including , and . Genetic manipulation of these genes demonstrated a robust impact on tumorigenesis and . We also determined that FOXR2 interacts with N-MYC, increases C-MYC protein stability, and activates FAK/SRC signaling. Altogether, our study identified several promising therapeutic targets in medulloblastoma and CNS-PNET. SIGNIFICANCE: A transposon-induced mouse model identifies several novel genetic drivers and potential therapeutic targets in medulloblastoma and CNS-PNET.
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http://dx.doi.org/10.1158/0008-5472.CAN-18-1261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6397665PMC
March 2019

The Senescence-associated Secretory Phenotype Mediates Oncogene-induced Senescence in Pediatric Pilocytic Astrocytoma.

Clin Cancer Res 2019 03 7;25(6):1851-1866. Epub 2018 Dec 7.

Hopp Children's Cancer Center Heidelberg (KiTZ), Heidelberg, Germany.

Purpose: Pilocytic astrocytoma is the most common childhood brain tumor, characterized by constitutive MAPK activation. MAPK signaling induces oncogene-induced senescence (OIS), which may cause unpredictable growth behavior of pilocytic astrocytomas. The senescence-associated secretory phenotype (SASP) has been shown to regulate OIS, but its role in pilocytic astrocytoma remains unknown. The patient-derived pilocytic astrocytoma cell culture model, DKFZ-BT66, was used to demonstrate presence of the SASP and analyze its impact on OIS in pilocytic astrocytoma. The model allows for doxycycline-inducible switching between proliferation and OIS. Both states were studied using gene expression profiling (GEP), Western blot, ELISA, and cell viability testing. Primary pilocytic astrocytoma tumors were analyzed by GEP and multiplex assay.

Results: SASP factors were upregulated in primary human and murine pilocytic astrocytoma and during OIS in DKFZ-BT66 cells. Conditioned medium induced growth arrest of proliferating pilocytic astrocytoma cells. The SASP factors IL1B and IL6 were upregulated in primary pilocytic astrocytoma, and both pathways were regulated during OIS in DKFZ-BT66. Stimulation with rIL1B but not rIL6 reduced growth of DKFZ-BT66 cells and induced the SASP. Anti-inflammatory treatment with dexamethasone induced regrowth of senescent cells and inhibited the SASP. Senescent DKFZ-BT66 cells responded to senolytic BCL2 inhibitors. High and SASP expression in pilocytic astrocytoma tumors was associated with favorable progression-free survival.

Conclusions: We provide evidence for the SASP regulating OIS in pediatric pilocytic astrocytoma, with IL1B as a relevant mediator. SASP expression could enable prediction of progression in patients with pilocytic astrocytoma. Further investigation of the SASP driving the unpredictable growth of pilocytic astrocytomas, and its possible therapeutic application, is warranted.
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http://dx.doi.org/10.1158/1078-0432.CCR-18-1965DOI Listing
March 2019

Characterization of a Clival Chordoma Xenograft Model Reveals Tumor Genomic Instability.

Am J Pathol 2018 12 22;188(12):2902-2911. Epub 2018 Sep 22.

Division of Neurosurgery, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.

Patient-derived xenografts retain the genotype of the parent tumors more readily than tumor cells maintained in culture. The two previously reported clival chordoma xenografts were derived from recurrent tumors after radiation. To study the genetics of clival chordoma in the absence of prior radiation exposure we established a patient-derived xenograft at primary resection of a clival chordoma. Epicranial grafting of clival chordoma collected during surgery was performed. Tumor growth was established in a nonobese diabetic/severe combined immunodeficiency mouse and tumors have been passaged serially for seven generations. Physaliferous cell architecture was shown in the regenerated tumors, which stained positive for Brachyury, cytokeratin, and S100 protein. The tumors showed bone invasion. Single-nucleotide polymorphism analysis of the tumor xenograft was compared with the parental tumor. Copy number gain of the T gene (brachyury) and heterozygous loss of cyclin dependent kinase inhibitor 2A (CDKN2A) was observed. Heterozygous loss of the tumor-suppressor fragile histidine triad (FHIT) gene also was observed, although protein expression was preserved. Accumulation of copy number losses and gains as well as increased growth rate was observed over three generations. The patient-derived xenograft reproduces the phenotype of clival chordoma. This model can be used in the future to study chordoma biology and to assess novel treatments.
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http://dx.doi.org/10.1016/j.ajpath.2018.08.004DOI Listing
December 2018

Aberrant ERBB4-SRC Signaling as a Hallmark of Group 4 Medulloblastoma Revealed by Integrative Phosphoproteomic Profiling.

Cancer Cell 2018 09;34(3):379-395.e7

Hopp Children's Cancer Center at the NCT Heidelberg (KiTZ), Heidelberg, Germany; Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), and German Cancer Consortium (DKTK), Heidelberg, Germany.

The current consensus recognizes four main medulloblastoma subgroups (wingless, Sonic hedgehog, group 3 and group 4). While medulloblastoma subgroups have been characterized extensively at the (epi-)genomic and transcriptomic levels, the proteome and phosphoproteome landscape remain to be comprehensively elucidated. Using quantitative (phospho)-proteomics in primary human medulloblastomas, we unravel distinct posttranscriptional regulation leading to highly divergent oncogenic signaling and kinase activity profiles in groups 3 and 4 medulloblastomas. Specifically, proteomic and phosphoproteomic analyses identify aberrant ERBB4-SRC signaling in group 4. Hence, enforced expression of an activated SRC combined with p53 inactivation induces murine tumors that resemble group 4 medulloblastoma. Therefore, our integrative proteogenomics approach unveils an oncogenic pathway and potential therapeutic vulnerability in the most common medulloblastoma subgroup.
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http://dx.doi.org/10.1016/j.ccell.2018.08.002DOI Listing
September 2018

The homeobox transcription factor HB9 induces senescence and blocks differentiation in hematopoietic stem and progenitor cells.

Haematologica 2019 01 9;104(1):35-46. Epub 2018 Aug 9.

Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty of Heinrich-Heine-University, Düsseldorf

The homeobox gene encodes for the transcription factor HB9, which is essential for pancreatic as well as motor neuronal development. Beside its physiological expression pattern, aberrant HB9 expression has been observed in several neoplasias. Especially in infant translocation t(7;12) acute myeloid leukemia, aberrant HB9 expression is the only known molecular hallmark and is assumed to be a key factor in leukemic transformation. However, so far, only poor functional data exist addressing the oncogenic potential of HB9 or its influence on hematopoiesis. We investigated the influence of HB9 on cell proliferation and cell cycle , as well as on hematopoietic stem cell differentiation using murine and human model systems. , HB9 expression led to premature senescence in human HT1080 and murine NIH3T3 cells, providing for the first time evidence for an oncogenic potential of HB9. Onset of senescence was characterized by induction of the p53-p21 tumor suppressor network, resulting in growth arrest, accompanied by morphological transformation and expression of senescence-associated β-galactosidase. , HB9-transduced primary murine hematopoietic stem and progenitor cells underwent a profound differentiation arrest and accumulated at the megakaryocyte/erythrocyte progenitor stage. In line, gene expression analyses revealed expression of erythropoiesis-related genes in human CD34hematopoietic stem and progenitor cells upon HB9 expression. In summary, the novel findings of HB9-dependent premature senescence and myeloid-biased perturbed hematopoietic differentiation, for the first time shed light on the oncogenic properties of HB9 in translocation t(7;12) acute myeloid leukemia.
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http://dx.doi.org/10.3324/haematol.2018.189407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6312034PMC
January 2019

Metastatic group 3 medulloblastoma is driven by PRUNE1 targeting NME1-TGF-β-OTX2-SNAIL via PTEN inhibition.

Brain 2018 05;141(5):1300-1319

German Cancer Consortium (DKTK), Department of Paediatric Oncology, Haematology, and Clinical Immunology, University Hospital Düsseldorf, Düsseldorf, Germany.

Genetic modifications during development of paediatric groups 3 and 4 medulloblastoma are responsible for their highly metastatic properties and poor patient survival rates. PRUNE1 is highly expressed in metastatic medulloblastoma group 3, which is characterized by TGF-β signalling activation, c-MYC amplification, and OTX2 expression. We describe the process of activation of the PRUNE1 signalling pathway that includes its binding to NME1, TGF-β activation, OTX2 upregulation, SNAIL (SNAI1) upregulation, and PTEN inhibition. The newly identified small molecule pyrimido-pyrimidine derivative AA7.1 enhances PRUNE1 degradation, inhibits this activation network, and augments PTEN expression. Both AA7.1 and a competitive permeable peptide that impairs PRUNE1/NME1 complex formation, impair tumour growth and metastatic dissemination in orthotopic xenograft models with a metastatic medulloblastoma group 3 cell line (D425-Med cells). Using whole exome sequencing technology in metastatic medulloblastoma primary tumour cells, we also define 23 common 'non-synonymous homozygous' deleterious gene variants as part of the protein molecular network of relevance for metastatic processes. This PRUNE1/TGF-β/OTX2/PTEN axis, together with the medulloblastoma-driver mutations, is of relevance for future rational and targeted therapies for metastatic medulloblastoma group 3.10.1093/brain/awy039_video1awy039media15742053534001.
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http://dx.doi.org/10.1093/brain/awy039DOI Listing
May 2018

TAp73 is a marker of glutamine addiction in medulloblastoma.

Genes Dev 2017 09 26;31(17):1738-1753. Epub 2017 Sep 26.

Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, United Kingdom.

Medulloblastoma is the most common solid primary brain tumor in children. Remarkable advancements in the understanding of the genetic and epigenetic basis of these tumors have informed their recent molecular classification. However, the genotype/phenotype correlation of the subgroups remains largely uncharacterized. In particular, the metabolic phenotype is of great interest because of its druggability, which could lead to the development of novel and more tailored therapies for a subset of medulloblastoma. p73 plays a critical role in a range of cellular metabolic processes. We show overexpression of p73 in a proportion of non-WNT medulloblastoma. In these tumors, p73 sustains cell growth and proliferation via regulation of glutamine metabolism. We validated our results in a xenograft model in which we observed an increase in survival time in mice on a glutamine restriction diet. Notably, glutamine starvation has a synergistic effect with cisplatin, a component of the current medulloblastoma chemotherapy. These findings raise the possibility that glutamine depletion can be used as an adjuvant treatment for p73-expressing medulloblastoma.
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http://dx.doi.org/10.1101/gad.302349.117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5666673PMC
September 2017

Tropomyosin receptor kinase C (TrkC) expression in medulloblastoma: relation to the molecular subgroups and impact on treatment response.

Childs Nerv Syst 2017 Sep 10;33(9):1463-1471. Epub 2017 Jul 10.

Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

Purpose: High messenger RNA (mRNA) expression of the tropomyosin receptor kinase C gene (TrkC) has been associated with favorable survival in medulloblastoma patients. Untested is whether it plays a role through modulating the response to therapy or whether it might be a surrogate marker for a favorable molecular subgroup.

Methods: The medulloblastoma-derived cell line DAOY was stably transfected to overexpress TrkC (clone DAOY-TrkC) and compared to a control (clone DAOY-EV, empty vector transfected). Cell viability (MTS assay) was tested after irradiation or incubation with chemotherapeutic drugs. Neuroradiologic response to postoperative chemotherapy or craniospinal irradiation (CSI) of medulloblastoma patients aged 3-21 years with postoperative residual disease treated within the consecutive trials HIT'91/HIT2000 was compared to TrkC mRNA expression in their tumor samples. Five well-characterized independent expression-profiling studies covering together 686 medulloblastoma patients were analyzed for TrkC levels according to the molecular subgroups.

Results: Cell viability of DAOY-TrkC compared to DAOY-EV was not different after exposure to increasing doses of irradiation, cisplatin, etoposide, or vincristine. While TrkC mRNA expression tended to be higher in non-responders (n = 5/19) to postoperative CSI (p = 0.03, ratio 15.5, 95% CI 9-267), this was the case in responders (n = 23/43) to chemotherapy (p = 0.04, ratio 6.1, 95% CI 1.1-35), both analyzed with Mann-Whitney U test (not significant after Bonferroni adjustment). The highest TrkC mRNA levels were found in the SHH subgroup across all expression-profiling studies.

Conclusions: High TrkC mRNA expression appears to be frequent in the SHH subgroup and seems not to have a major effect on therapy responsiveness in medulloblastoma patients.
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http://dx.doi.org/10.1007/s00381-017-3506-yDOI Listing
September 2017

Spatial heterogeneity in medulloblastoma.

Nat Genet 2017 May 10;49(5):780-788. Epub 2017 Apr 10.

Developmental &Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.

Spatial heterogeneity of transcriptional and genetic markers between physically isolated biopsies of a single tumor poses major barriers to the identification of biomarkers and the development of targeted therapies that will be effective against the entire tumor. We analyzed the spatial heterogeneity of multiregional biopsies from 35 patients, using a combination of transcriptomic and genomic profiles. Medulloblastomas (MBs), but not high-grade gliomas (HGGs), demonstrated spatially homogeneous transcriptomes, which allowed for accurate subgrouping of tumors from a single biopsy. Conversely, somatic mutations that affect genes suitable for targeted therapeutics demonstrated high levels of spatial heterogeneity in MB, malignant glioma, and renal cell carcinoma (RCC). Actionable targets found in a single MB biopsy were seldom clonal across the entire tumor, which brings the efficacy of monotherapies against a single target into question. Clinical trials of targeted therapies for MB should first ensure the spatially ubiquitous nature of the target mutation.
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http://dx.doi.org/10.1038/ng.3838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5553617PMC
May 2017

The role of angiogenesis in Group 3 medulloblastoma pathogenesis and survival.

Neuro Oncol 2017 Sep;19(9):1217-1227

Department of Neurosurgery, Duke University, Durham, North Carolina; Preston Robert Tisch Brain Tumor Center, Duke University, Durham, North Carolina; Brain Imaging and Analysis Center, Duke University, Durham, North Carolina; Department of Radiology, Duke University, Durham, North Carolina; Department of Radiology, Stanford University, Palo Alto, California; Department of Medicine, Duke University, Durham, North Carolina; Department of Pediatric Oncology, Hematology, and Clinical Immunology, Medical Faculty, University Hospital Düsseldorf, Düsseldorf, Germany; and Department of Pediatric Neuro-Oncogenomics, German Cancer Consortium and German Cancer Research Center, Heidelberg, Germany; Department of Pathology, Duke University, Durham, North Carolina; Division of Haematology/Oncology, the Arthur and Sonia Labatt Brain Tumour Research Centre, Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Division of Neurosurgery, the Arthur and Sonia Labatt Brain Tumour Research Centre, Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.

Background: Of the 4 medulloblastoma subgroups, Group 3 is the most aggressive but the importance of angiogenesis is unknown. This study sought to determine the role of angiogenesis and identify clinically relevant biomarkers of tumor vascularity and survival in Group 3 medulloblastoma.

Methods: VEGFA mRNA expression and survival from several patient cohorts were analyzed. Group 3 xenografts were implanted intracranially in nude rats. Dynamic susceptibility weighted (DSC) MRI and susceptibility weighted imaging (SWI) were obtained. DSC MRI was used to calculate relative cerebral blood volume (rCBV) and flow (rCBF). Tumor vessel density and rat vascular endothelial growth factor alpha (VEGFA) expression were determined.

Results: Patient VEGFA mRNA levels were significantly elevated in Group 3 compared with the other subgroups (P < 0.001) and associated with survival. Xenografts D283, D341, and D425 were identified as Group 3 by RNA hierarchical clustering and MYC amplification. The D283 group had the lowest rCBV and rCBF, followed by D341 and D425 (P < 0.05). These values corresponded to histological vessel density (P < 0.05), rat VEGFA expression (P < 0.05), and survival (P = 0.002). Gene set enrichment analysis identified 5 putative genes with expression profiles corresponding with these findings: RNH1, SCG2, VEGFA, AGGF1, and PROK2. SWI identified 3 xenograft-independent categories of intratumoral vascular architecture with distinct survival (P = 0.004): organized, diffuse microvascular, and heterogeneous.

Conclusions: Angiogenesis plays an important role in Group 3 medulloblastoma pathogenesis and survival. DSC MRI and SWI are clinically relevant biomarkers for tumor vascularity and overall survival and can be used to direct the use of antivascular therapies for patients with Group 3 medulloblastoma.
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http://dx.doi.org/10.1093/neuonc/nox033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5570262PMC
September 2017

Integrated (epi)-Genomic Analyses Identify Subgroup-Specific Therapeutic Targets in CNS Rhabdoid Tumors.

Cancer Cell 2016 Dec;30(6):891-908

Division of Hematology/Oncology, Hospital for Sick Children, Toronto, ON M5G1X8, Canada; Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, ON M5G1X8, Canada.

We recently reported that atypical teratoid rhabdoid tumors (ATRTs) comprise at least two transcriptional subtypes with different clinical outcomes; however, the mechanisms underlying therapeutic heterogeneity remained unclear. In this study, we analyzed 191 primary ATRTs and 10 ATRT cell lines to define the genomic and epigenomic landscape of ATRTs and identify subgroup-specific therapeutic targets. We found ATRTs segregated into three epigenetic subgroups with distinct genomic profiles, SMARCB1 genotypes, and chromatin landscape that correlated with differential cellular responses to a panel of signaling and epigenetic inhibitors. Significantly, we discovered that differential methylation of a PDGFRB-associated enhancer confers specific sensitivity of group 2 ATRT cells to dasatinib and nilotinib, and suggest that these are promising therapies for this highly lethal ATRT subtype.
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http://dx.doi.org/10.1016/j.ccell.2016.11.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500911PMC
December 2016

MEK Inhibitors Reverse Growth of Embryonal Brain Tumors Derived from Oligoneural Precursor Cells.

Cell Rep 2016 10;17(5):1255-1264

Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA. Electronic address:

Malignant brain tumors are the leading cause of cancer-related deaths in children. Primitive neuroectodermal tumors of the CNS (CNS-PNETs) are particularly aggressive embryonal tumors of unknown cellular origin. Recent genomic studies have classified CNS-PNETs into molecularly distinct subgroups that promise to improve diagnosis and treatment; however, the lack of cell- or animal-based models for these subgroups prevents testing of rationally designed therapies. Here, we show that a subset of CNS-PNETs co-express oligoneural precursor cell (OPC) markers OLIG2 and SOX10 with coincident activation of the RAS/MAPK (mitogen-activated protein kinase) pathway. Modeling NRAS activation in embryonic OPCs generated malignant brain tumors in zebrafish that closely mimic the human oligoneural/NB-FOXR2 CNS-PNET subgroup by histology and comparative oncogenomics. The zebrafish CNS-PNET model was used to show that MEK inhibitors selectively eliminate Olig2/Sox10 CNS-PNET tumors in vivo without impacting normal brain development. Thus, MEK inhibitors represent a promising rationally designed therapy for children afflicted with oligoneural/NB-FOXR2 CNS-PNETs.
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http://dx.doi.org/10.1016/j.celrep.2016.09.081DOI Listing
October 2016

MB3W1 is an orthotopic xenograft model for anaplastic medulloblastoma displaying cancer stem cell- and Group 3-properties.

BMC Cancer 2016 Feb 17;16:115. Epub 2016 Feb 17.

University Children's Hospital, Pediatric Oncology, Hematology and Stem Cell Transplantation, University of Würzburg, Würzburg, Germany.

Background: Medulloblastoma is the most common malignant brain tumor in children and can be divided in different molecular subgroups. Patients whose tumor is classified as a Group 3 tumor have a dismal prognosis. However only very few tumor models are available for this subgroup.

Methods: We established a robust orthotopic xenograft model with a cell line derived from the malignant pleural effusions of a child suffering from a Group 3 medulloblastoma.

Results: Besides classical characteristics of this tumor subgroup, the cells display cancer stem cell characteristics including neurosphere formation, multilineage differentiation, CD133/CD15 expression, high ALDH-activity and high tumorigenicity in immunocompromised mice with xenografts exactly recapitulating the original tumor architecture.

Conclusions: This model using unmanipulated, human medulloblastoma cells will enable translational research, specifically focused on Group 3 medulloblastoma.
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http://dx.doi.org/10.1186/s12885-016-2170-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756501PMC
February 2016

Molecular subgroups of atypical teratoid rhabdoid tumours in children: an integrated genomic and clinicopathological analysis.

Lancet Oncol 2015 May 14;16(5):569-82. Epub 2015 Apr 14.

Department of Neurosurgery, University of Debrecen, Debrecen, Hungary.

Background: Rhabdoid brain tumours, also called atypical teratoid rhabdoid tumours, are lethal childhood cancers with characteristic genetic alterations of SMARCB1/hSNF5. Lack of biological understanding of the substantial clinical heterogeneity of these tumours restricts therapeutic advances. We integrated genomic and clinicopathological analyses of a cohort of patients with atypical teratoid rhabdoid tumours to find out the molecular basis for clinical heterogeneity in these tumours.

Methods: We obtained 259 rhabdoid tumours from 37 international institutions and assessed transcriptional profiles in 43 primary tumours and copy number profiles in 38 primary tumours to discover molecular subgroups of atypical teratoid rhabdoid tumours. We used gene and pathway enrichment analyses to discover group-specific molecular markers and did immunohistochemical analyses on 125 primary tumours to evaluate clinicopathological significance of molecular subgroup and ASCL1-NOTCH signalling.

Findings: Transcriptional analyses identified two atypical teratoid rhabdoid tumour subgroups with differential enrichment of genetic pathways, and distinct clinicopathological and survival features. Expression of ASCL1, a regulator of NOTCH signalling, correlated with supratentorial location (p=0·004) and superior 5-year overall survival (35%, 95% CI 13-57, and 20%, 6-34, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·033) in 70 patients who received multimodal treatment. ASCL1 expression also correlated with superior 5-year overall survival (34%, 7-61, and 9%, 0-21, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·001) in 39 patients who received only chemotherapy without radiation. Cox hazard ratios for overall survival in patients with differential ASCL1 enrichment treated with chemotherapy with or without radiation were 2·02 (95% CI 1·04-3·85; p=0·038) and 3·98 (1·71-9·26; p=0·001). Integrated analyses of molecular subgroupings with clinical prognostic factors showed three distinct clinical risk groups of tumours with different therapeutic outcomes.

Interpretation: An integration of clinical risk factors and tumour molecular groups can be used to identify patients who are likely to have improved long-term radiation-free survival and might help therapeutic stratification of patients with atypical teratoid rhabdoid tumours.

Funding: C17 Research Network, Genome Canada, b.r.a.i.n.child, Mitchell Duckman, Tal Doron and Suri Boon foundations.
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http://dx.doi.org/10.1016/S1470-2045(15)70114-2DOI Listing
May 2015
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