RESUMEN
Non-coding regions amplified beyond oncogene borders have largely been ignored. Using a computational approach, we find signatures of significant co-amplification of non-coding DNA beyond the boundaries of amplified oncogenes across five cancer types. In glioblastoma, EGFR is preferentially co-amplified with its two endogenous enhancer elements active in the cell type of origin. These regulatory elements, their contacts, and their contribution to cell fitness are preserved on high-level circular extrachromosomal DNA amplifications. Interrogating the locus with a CRISPR interference screening approach reveals a diversity of additional elements that impact cell fitness. The pattern of fitness dependencies mirrors the rearrangement of regulatory elements and accompanying rewiring of the chromatin topology on the extrachromosomal amplicon. Our studies indicate that oncogene amplifications are shaped by regulatory dependencies in the non-coding genome.
Asunto(s)
Cromosomas Humanos/genética , Elementos de Facilitación Genéticos , Amplificación de Genes , Oncogenes , Acetilación , Sistemas CRISPR-Cas/genética , Línea Celular Tumoral , Supervivencia Celular/genética , Cromatina/metabolismo , ADN de Neoplasias/genética , Receptores ErbB/genética , Receptores ErbB/metabolismo , Genes Relacionados con las Neoplasias , Sitios Genéticos , Glioblastoma/genética , Glioblastoma/patología , Histonas/metabolismo , Humanos , Neuroglía/metabolismoRESUMEN
Genetic drivers of cancer can be dysregulated through epigenetic modifications of DNA. Although the critical role of DNA 5-methylcytosine (5mC) in the regulation of transcription is recognized, the functions of other non-canonical DNA modifications remain obscure. Here, we report the identification of novel N6-methyladenine (N6-mA) DNA modifications in human tissues and implicate this epigenetic mark in human disease, specifically the highly malignant brain cancer glioblastoma. Glioblastoma markedly upregulated N6-mA levels, which co-localized with heterochromatic histone modifications, predominantly H3K9me3. N6-mA levels were dynamically regulated by the DNA demethylase ALKBH1, depletion of which led to transcriptional silencing of oncogenic pathways through decreasing chromatin accessibility. Targeting the N6-mA regulator ALKBH1 in patient-derived human glioblastoma models inhibited tumor cell proliferation and extended the survival of tumor-bearing mice, supporting this novel DNA modification as a potential therapeutic target for glioblastoma. Collectively, our results uncover a novel epigenetic node in cancer through the DNA modification N6-mA.
Asunto(s)
Adenina/análogos & derivados , Neoplasias Encefálicas/patología , Metilación de ADN , Glioblastoma/patología , Adenina/análisis , Adenina/química , Adulto , Anciano , Histona H2a Dioxigenasa, Homólogo 1 de AlkB/antagonistas & inhibidores , Histona H2a Dioxigenasa, Homólogo 1 de AlkB/genética , Histona H2a Dioxigenasa, Homólogo 1 de AlkB/metabolismo , Animales , Astrocitos/citología , Astrocitos/metabolismo , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/mortalidad , Hipoxia de la Célula , Niño , Epigenómica , Femenino , Glioblastoma/metabolismo , Glioblastoma/mortalidad , Heterocromatina/metabolismo , Histonas/metabolismo , Humanos , Estimación de Kaplan-Meier , Masculino , Ratones , Persona de Mediana Edad , Células Madre Neoplásicas/citología , Células Madre Neoplásicas/metabolismo , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Bidirectional communication between tumours and neurons has emerged as a key facet of the tumour microenvironment that drives malignancy1,2. Another hallmark feature of cancer is epigenomic dysregulation, in which alterations in gene expression influence cell states and interactions with the tumour microenvironment3. Ependymoma (EPN) is a paediatric brain tumour that relies on epigenomic remodelling to engender malignancy4,5; however, how these epigenetic mechanisms intersect with extrinsic neuronal signalling during EPN tumour progression is unknown. Here we show that the activity of serotonergic neurons regulates EPN tumorigenesis, and that serotonin itself also serves as an activating modification on histones. We found that inhibiting histone serotonylation blocks EPN tumorigenesis and regulates the expression of a core set of developmental transcription factors. High-throughput, in vivo screening of these transcription factors revealed that ETV5 promotes EPN tumorigenesis and functions by enhancing repressive chromatin states. Neuropeptide Y (NPY) is one of the genes repressed by ETV5, and its overexpression suppresses EPN tumour progression and tumour-associated network hyperactivity through synaptic remodelling. Collectively, this study identifies histone serotonylation as a key driver of EPN tumorigenesis, and also reveals how neuronal signalling, neuro-epigenomics and developmental programs are intertwined to drive malignancy in brain cancer.
RESUMEN
Mutation is a fundamental process in tumorigenesis. However, the degree to which the rate of somatic mutation varies across the human genome and the mechanistic basis underlying this variation remain to be fully elucidated. Here, we performed a cross-cancer comparison of 402 whole genomes comprising a diverse set of childhood and adult tumors, including both solid and hematopoietic malignancies. Surprisingly, we found that the inactive X chromosome of many female cancer genomes accumulates on average twice and up to four times as many somatic mutations per megabase, as compared to the individual autosomes. Whole-genome sequencing of clonally expanded hematopoietic stem/progenitor cells (HSPCs) from healthy individuals and a premalignant myelodysplastic syndrome (MDS) sample revealed no X chromosome hypermutation. Our data suggest that hypermutation of the inactive X chromosome is an early and frequent feature of tumorigenesis resulting from DNA replication stress in aberrantly proliferating cells.
Asunto(s)
Cromosomas Humanos X , Mutación , Neoplasias/genética , Inactivación del Cromosoma X , Adulto , Anciano , Replicación del ADN , Femenino , Humanos , Masculino , Meduloblastoma/genética , Meduloblastoma/patología , Síndromes Mielodisplásicos/genética , Síndromes Mielodisplásicos/patología , Polimorfismo de Nucleótido Simple , Fase SRESUMEN
Study of the origin and development of cerebellar tumours has been hampered by the complexity and heterogeneity of cerebellar cells that change over the course of development. Here we use single-cell transcriptomics to study more than 60,000 cells from the developing mouse cerebellum and show that different molecular subgroups of childhood cerebellar tumours mirror the transcription of cells from distinct, temporally restricted cerebellar lineages. The Sonic Hedgehog medulloblastoma subgroup transcriptionally mirrors the granule cell hierarchy as expected, while group 3 medulloblastoma resembles Nestin+ stem cells, group 4 medulloblastoma resembles unipolar brush cells, and PFA/PFB ependymoma and cerebellar pilocytic astrocytoma resemble the prenatal gliogenic progenitor cells. Furthermore, single-cell transcriptomics of human childhood cerebellar tumours demonstrates that many bulk tumours contain a mixed population of cells with divergent differentiation. Our data highlight cerebellar tumours as a disorder of early brain development and provide a proximate explanation for the peak incidence of cerebellar tumours in early childhood.
Asunto(s)
Neoplasias Cerebelosas/genética , Neoplasias Cerebelosas/patología , Evolución Molecular , Feto/metabolismo , Regulación del Desarrollo de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Transcripción Genética , Animales , Neoplasias Cerebelosas/clasificación , Cerebelo/citología , Cerebelo/embriología , Cerebelo/metabolismo , Niño , Femenino , Feto/citología , Glioma/clasificación , Glioma/genética , Glioma/patología , Humanos , Meduloblastoma/clasificación , Meduloblastoma/genética , Meduloblastoma/patología , Ratones , Análisis de Secuencia de ARN , Análisis de la Célula Individual , Factores de Tiempo , Transcriptoma/genéticaRESUMEN
Epigenetic dysregulation is a universal feature of cancer that results in altered patterns of gene expression that drive malignancy. Brain tumors exhibit subtype-specific epigenetic alterations; however, the molecular mechanisms responsible for these diverse epigenetic states remain unclear. Here, we show that the developmental transcription factor Sox9 differentially regulates epigenomic states in high-grade glioma (HGG) and ependymoma (EPN). Using our autochthonous mouse models, we found that Sox9 suppresses HGG growth and expands associated H3K27ac states, while promoting ZFTA-RELA (ZRFUS) EPN growth and diminishing H3K27ac states. These contrasting roles for Sox9 correspond with protein interactions with histone deacetylating complexes in HGG and an association with the ZRFUS oncofusion in EPN. Mechanistic studies revealed extensive Sox9 and ZRFUS promoter co-occupancy, indicating functional synergy in promoting EPN tumorigenesis. Together, our studies demonstrate how epigenomic states are differentially regulated in distinct subtypes of brain tumors, while revealing divergent roles for Sox9 in HGG and EPN tumorigenesis.
Asunto(s)
Neoplasias Encefálicas , Ependimoma , Epigénesis Genética , Factor de Transcripción SOX9 , Animales , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patología , Carcinogénesis/genética , Ependimoma/genética , Ependimoma/patología , Ratones , Neoplasias Experimentales/genética , Neoplasias Experimentales/patología , Factor de Transcripción SOX9/genética , Factor de Transcripción SOX9/fisiologíaRESUMEN
Genomic sequencing has driven precision-based oncology therapy; however, the genetic drivers of many malignancies remain unknown or non-targetable, so alternative approaches to the identification of therapeutic leads are necessary. Ependymomas are chemotherapy-resistant brain tumours, which, despite genomic sequencing, lack effective molecular targets. Intracranial ependymomas are segregated on the basis of anatomical location (supratentorial region or posterior fossa) and further divided into distinct molecular subgroups that reflect differences in the age of onset, gender predominance and response to therapy. The most common and aggressive subgroup, posterior fossa ependymoma group A (PF-EPN-A), occurs in young children and appears to lack recurrent somatic mutations. Conversely, posterior fossa ependymoma group B (PF-EPN-B) tumours display frequent large-scale copy number gains and losses but have favourable clinical outcomes. More than 70% of supratentorial ependymomas are defined by highly recurrent gene fusions in the NF-κB subunit gene RELA (ST-EPN-RELA), and a smaller number involve fusion of the gene encoding the transcriptional activator YAP1 (ST-EPN-YAP1). Subependymomas, a distinct histologic variant, can also be found within the supratetorial and posterior fossa compartments, and account for the majority of tumours in the molecular subgroups ST-EPN-SE and PF-EPN-SE. Here we describe mapping of active chromatin landscapes in 42 primary ependymomas in two non-overlapping primary ependymoma cohorts, with the goal of identifying essential super-enhancer-associated genes on which tumour cells depend. Enhancer regions revealed putative oncogenes, molecular targets and pathways; inhibition of these targets with small molecule inhibitors or short hairpin RNA diminished the proliferation of patient-derived neurospheres and increased survival in mouse models of ependymomas. Through profiling of transcriptional enhancers, our study provides a framework for target and drug discovery in other cancers that lack known genetic drivers and are therefore difficult to treat.
Asunto(s)
Elementos de Facilitación Genéticos/genética , Ependimoma/tratamiento farmacológico , Ependimoma/genética , Regulación Neoplásica de la Expresión Génica , Redes Reguladoras de Genes/genética , Terapia Molecular Dirigida , Oncogenes/genética , Factores de Transcripción/metabolismo , Animales , Secuencia de Bases , Ependimoma/clasificación , Ependimoma/patología , Femenino , Humanos , Ratones , Medicina de Precisión , Interferencia de ARN , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Glioblastoma is a universally lethal cancer with a median survival time of approximately 15 months. Despite substantial efforts to define druggable targets, there are no therapeutic options that notably extend the lifespan of patients with glioblastoma. While previous work has largely focused on in vitro cellular models, here we demonstrate a more physiologically relevant approach to target discovery in glioblastoma. We adapted pooled RNA interference (RNAi) screening technology for use in orthotopic patient-derived xenograft models, creating a high-throughput negative-selection screening platform in a functional in vivo tumour microenvironment. Using this approach, we performed parallel in vivo and in vitro screens and discovered that the chromatin and transcriptional regulators needed for cell survival in vivo are non-overlapping with those required in vitro. We identified transcription pause-release and elongation factors as one set of in vivo-specific cancer dependencies, and determined that these factors are necessary for enhancer-mediated transcriptional adaptations that enable cells to survive the tumour microenvironment. Our lead hit, JMJD6, mediates the upregulation of in vivo stress and stimulus response pathways through enhancer-mediated transcriptional pause-release, promoting cell survival specifically in vivo. Targeting JMJD6 or other identified elongation factors extends survival in orthotopic xenograft mouse models, suggesting that targeting transcription elongation machinery may be an effective therapeutic strategy for glioblastoma. More broadly, this study demonstrates the power of in vivo phenotypic screening to identify new classes of 'cancer dependencies' not identified by previous in vitro approaches, and could supply new opportunities for therapeutic intervention.
Asunto(s)
Evaluación Preclínica de Medicamentos/métodos , Glioblastoma/tratamiento farmacológico , Glioblastoma/genética , Terapia Molecular Dirigida/tendencias , Factores de Elongación Transcripcional/antagonistas & inhibidores , Factores de Elongación Transcripcional/metabolismo , Animales , Línea Celular Tumoral , Supervivencia Celular , Cromatina/metabolismo , Elementos de Facilitación Genéticos/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Glioblastoma/patología , Humanos , Histona Demetilasas con Dominio de Jumonji/antagonistas & inhibidores , Histona Demetilasas con Dominio de Jumonji/metabolismo , Masculino , Ratones , Interferencia de ARN , Transcripción Genética , Microambiente Tumoral , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Tissues with defined cellular hierarchies in development and homeostasis give rise to tumors with cellular hierarchies, suggesting that tumors recapitulate specific tissues and mimic their origins. Glioblastoma (GBM) is the most prevalent and malignant primary brain tumor and contains self-renewing, tumorigenic cancer stem cells (CSCs) that contribute to tumor initiation and therapeutic resistance. As normal stem and progenitor cells participate in tissue development and repair, these developmental programs re-emerge in CSCs to support the development and progressive growth of tumors. Elucidation of the molecular mechanisms that govern CSCs has informed the development of novel targeted therapeutics for GBM and other brain cancers. CSCs are not self-autonomous units; rather, they function within an ecological system, both actively remodeling the microenvironment and receiving critical maintenance cues from their niches. To fulfill the future goal of developing novel therapies to collapse CSC dynamics, drawing parallels to other normal and pathological states that are highly interactive with their microenvironments and that use developmental signaling pathways will be beneficial.
Asunto(s)
Neoplasias Encefálicas/patología , Glioblastoma/patología , Células Madre Neoplásicas/patología , Animales , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/inmunología , Neoplasias Encefálicas/terapia , Regulación Neoplásica de la Expresión Génica , Glioblastoma/genética , Glioblastoma/inmunología , Glioblastoma/terapia , Humanos , Células Madre Neoplásicas/citología , Células Madre Neoplásicas/metabolismoRESUMEN
The development of targeted anti-cancer therapies through the study of cancer genomes is intended to increase survival rates and decrease treatment-related toxicity. We treated a transposon-driven, functional genomic mouse model of medulloblastoma with 'humanized' in vivo therapy (microneurosurgical tumour resection followed by multi-fractionated, image-guided radiotherapy). Genetic events in recurrent murine medulloblastoma exhibit a very poor overlap with those in matched murine diagnostic samples (<5%). Whole-genome sequencing of 33 pairs of human diagnostic and post-therapy medulloblastomas demonstrated substantial genetic divergence of the dominant clone after therapy (<12% diagnostic events were retained at recurrence). In both mice and humans, the dominant clone at recurrence arose through clonal selection of a pre-existing minor clone present at diagnosis. Targeted therapy is unlikely to be effective in the absence of the target, therefore our results offer a simple, proximal, and remediable explanation for the failure of prior clinical trials of targeted therapy.
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Neoplasias Cerebelosas/terapia , Células Clonales/efectos de los fármacos , Células Clonales/metabolismo , Meduloblastoma/terapia , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/patología , Selección Genética/efectos de los fármacos , Animales , Neoplasias Cerebelosas/genética , Neoplasias Cerebelosas/patología , Neoplasias Cerebelosas/radioterapia , Neoplasias Cerebelosas/cirugía , Células Clonales/patología , Irradiación Craneoespinal , Análisis Mutacional de ADN , Modelos Animales de Enfermedad , Drosophila melanogaster/citología , Drosophila melanogaster/genética , Femenino , Genoma Humano/genética , Humanos , Masculino , Meduloblastoma/genética , Meduloblastoma/patología , Meduloblastoma/radioterapia , Meduloblastoma/cirugía , Ratones , Terapia Molecular Dirigida/métodos , Recurrencia Local de Neoplasia/terapia , Radioterapia Guiada por Imagen , Transducción de Señal , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Of nine ependymoma molecular groups detected by DNA methylation profiling, the posterior fossa type A (PFA) is most prevalent. We used DNA methylation profiling to look for further molecular heterogeneity among 675 PFA ependymomas. Two major subgroups, PFA-1 and PFA-2, and nine minor subtypes were discovered. Transcriptome profiling suggested a distinct histogenesis for PFA-1 and PFA-2, but their clinical parameters were similar. In contrast, PFA subtypes differed with respect to age at diagnosis, gender ratio, outcome, and frequencies of genetic alterations. One subtype, PFA-1c, was enriched for 1q gain and had a relatively poor outcome, while patients with PFA-2c ependymomas showed an overall survival at 5 years of > 90%. Unlike other ependymomas, PFA-2c tumors express high levels of OTX2, a potential biomarker for this ependymoma subtype with a good prognosis. We also discovered recurrent mutations among PFA ependymomas. H3 K27M mutations were present in 4.2%, occurring only in PFA-1 tumors, and missense mutations in an uncharacterized gene, CXorf67, were found in 9.4% of PFA ependymomas, but not in other groups. We detected high levels of wildtype or mutant CXorf67 expression in all PFA subtypes except PFA-1f, which is enriched for H3 K27M mutations. PFA ependymomas are characterized by lack of H3 K27 trimethylation (H3 K27-me3), and we tested the hypothesis that CXorf67 binds to PRC2 and can modulate levels of H3 K27-me3. Immunoprecipitation/mass spectrometry detected EZH2, SUZ12, and EED, core components of the PRC2 complex, bound to CXorf67 in the Daoy cell line, which shows high levels of CXorf67 and no expression of H3 K27-me3. Enforced reduction of CXorf67 in Daoy cells restored H3 K27-me3 levels, while enforced expression of CXorf67 in HEK293T and neural stem cells reduced H3 K27-me3 levels. Our data suggest that heterogeneity among PFA ependymomas could have clinicopathologic utility and that CXorf67 may have a functional role in these tumors.
Asunto(s)
Ependimoma/genética , Regulación Neoplásica de la Expresión Génica/genética , Neoplasias Infratentoriales/genética , Mutación/genética , Proteínas Oncogénicas/genética , Metilación de ADN , Ependimoma/clasificación , Ependimoma/patología , Femenino , Perfilación de la Expresión Génica , Células HEK293 , Histonas/genética , Humanos , Neoplasias Infratentoriales/clasificación , Neoplasias Infratentoriales/patología , Masculino , TransfecciónRESUMEN
Posterior fossa ependymoma comprise three distinct molecular variants, termed PF-EPN-A (PFA), PF-EPN-B (PFB), and PF-EPN-SE (subependymoma). Clinically, they are very disparate and PFB tumors are currently being considered for a trial of radiation avoidance. However, to move forward, unraveling the heterogeneity within PFB would be highly desirable. To discern the molecular heterogeneity within PFB, we performed an integrated analysis consisting of DNA methylation profiling, copy-number profiling, gene expression profiling, and clinical correlation across a cohort of 212 primary posterior fossa PFB tumors. Unsupervised spectral clustering and t-SNE analysis of genome-wide methylation data revealed five distinct subtypes of PFB tumors, termed PFB1-5, with distinct demographics, copy-number alterations, and gene expression profiles. All PFB subtypes were distinct from PFA and posterior fossa subependymomas. Of the five subtypes, PFB4 and PFB5 are more discrete, consisting of younger and older patients, respectively, with a strong female-gender enrichment in PFB5 (age: p = 0.011, gender: p = 0.04). Broad copy-number aberrations were common; however, many events such as chromosome 2 loss, 5 gain, and 17 loss were enriched in specific subtypes and 1q gain was enriched in PFB1. Late relapses were common across all five subtypes, but deaths were uncommon and present in only two subtypes (PFB1 and PFB3). Unlike the case in PFA ependymoma, 1q gain was not a robust marker of poor progression-free survival; however, chromosome 13q loss may represent a novel marker for risk stratification across the spectrum of PFB subtypes. Similar to PFA ependymoma, there exists a significant intertumoral heterogeneity within PFB, with distinct molecular subtypes identified. Even when accounting for this heterogeneity, extent of resection remains the strongest predictor of poor outcome. However, this biological heterogeneity must be accounted for in future preclinical modeling and personalized therapies.
Asunto(s)
Variaciones en el Número de Copia de ADN/genética , Ependimoma/clasificación , Ependimoma/genética , Neoplasias Infratentoriales/clasificación , Neoplasias Infratentoriales/genética , Adolescente , Adulto , Factores de Edad , Niño , Estudios de Cohortes , Metilación de ADN/genética , Ependimoma/patología , Ependimoma/cirugía , Femenino , Perfilación de la Expresión Génica , Humanos , Neoplasias Infratentoriales/patología , Neoplasias Infratentoriales/cirugía , Estimación de Kaplan-Meier , Masculino , Análisis por Micromatrices , Persona de Mediana Edad , Adulto JovenRESUMEN
Advances in genomic, transcriptomic and epigenomic profiling now identifies pediatric ependymoma as a defined biological entity. Molecular interrogation has segregated these tumors into distinct biological subtypes based on anatomical location, age and clinical outcome, which now defines the need to tailor therapy even for histologically similar tumors. These findings now provide reasons for a paradigm shift in therapy, which should profile future clinical trials focused on targeted therapeutic strategies and risk-based treatment. The need to diagnose and differentiate the aggressive variants, which include the posterior fossa group A and the supratentorial RELA fusion subtypes, is imperative to escalate therapy and improve survival.
Asunto(s)
Ependimoma/terapia , Animales , Ensayos Clínicos como Asunto , Terapia Combinada , Manejo de la Enfermedad , Ependimoma/diagnóstico , Ependimoma/etiología , Ependimoma/mortalidad , Humanos , Resultado del TratamientoRESUMEN
PURPOSE OF REVIEW: To synthesize, integrate, and comment on recent research developments to our understanding of the molecular basis of ependymoma (EPN), and to place this in context with current treatment and research efforts. RECENT FINDINGS: Our recent understanding of the histologically defined molecular entity EPN has rapidly advanced through genomic, transcriptomic, and epigenomic profiling studies. SUMMARY: These advancements lay the groundwork for development of future EPN biomarkers, models, and therapeutics. Our review discusses these discoveries and their impact on our clinical understanding of this disease. Lastly, we offer insight into clinical and research areas requiring further validation, and open questions remaining in the field.
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Neoplasias del Sistema Nervioso Central/diagnóstico , Neoplasias del Sistema Nervioso Central/terapia , Ependimoma/diagnóstico , Ependimoma/terapia , Animales , Neoplasias del Sistema Nervioso Central/genética , Neoplasias del Sistema Nervioso Central/patología , Ependimoma/genética , Ependimoma/patología , HumanosRESUMEN
Multiple independent genomic profiling efforts have recently identified clinically and molecularly distinct subgroups of ependymoma arising from all three anatomic compartments of the central nervous system (supratentorial brain, posterior fossa, and spinal cord). These advances motivated a consensus meeting to discuss: (1) the utility of current histologic grading criteria, (2) the integration of molecular-based stratification schemes in future clinical trials for patients with ependymoma and (3) current therapy in the context of molecular subgroups. Discussion at the meeting generated a series of consensus statements and recommendations from the attendees, which comment on the prognostic evaluation and treatment decisions of patients with intracranial ependymoma (WHO Grade II/III) based on the knowledge of its molecular subgroups. The major consensus among attendees was reached that treatment decisions for ependymoma (outside of clinical trials) should not be based on grading (II vs III). Supratentorial and posterior fossa ependymomas are distinct diseases, although the impact on therapy is still evolving. Molecular subgrouping should be part of all clinical trials henceforth.
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Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/terapia , Ependimoma/metabolismo , Ependimoma/terapia , Animales , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patología , Consenso , Manejo de la Enfermedad , Ependimoma/genética , Ependimoma/patología , Humanos , Estadificación de NeoplasiasRESUMEN
BACKGROUND: Mutations in the tail of histone H3 (K27M) are frequently found in pediatric midline high-grade glioma's but have rarely been reported in other malignancies. Recently, recurrent somatic nucleotide variants in histone H3 (H3 K27M) have been reported in group A posterior fossa ependymoma (EPN_PFA), an entity previously described to have no recurrent mutations. However, the true incidence of H3 K27M mutations in EPN_PFA is unknown. METHODS: In order to discern the frequency of K27M mutations in histone H3 in EPN_PFA, we analyzed 151 EPN_PFA previously profiled with genome-wide methylation arrays using a validated droplet digital PCR assay. RESULTS: We identified only 1 case out of 151 EPN_PFA harboring the K27M mutation indicating that histone mutations are extremely rare in EPN_PFA. Morphologically, this single mutated case is clearly consistent with an ependymoma, and the presence of the K27M mutation was confirmed using immunohistochemistry. DISCUSSION: K27M mutations are extremely rare in EPN_PFA. Routine evaluation of K27M mutations in EPN_PFA is of limited utility, and is unlikely to have any bearing on prognosis and/or future risk stratification.
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Neoplasias Encefálicas/genética , Ependimoma/genética , Histonas/genética , Mutación/genética , Neoplasias Encefálicas/diagnóstico por imagen , Niño , Ependimoma/diagnóstico por imagen , Histonas/metabolismo , Humanos , Lisina/genética , Imagen por Resonancia Magnética , Masculino , Metionina/genéticaRESUMEN
Pediatric ependymomas are highly recurrent tumors resistant to conventional chemotherapy. Telomerase, a ribonucleoprotein critical in permitting limitless replication, has been found to be critically important for the maintenance of tumor-initiating cells (TICs). These TICs are chemoresistant, repopulate the tumor from which they are identified, and are drivers of recurrence in numerous cancers. In this study, telomerase enzymatic activity was directly measured and inhibited to assess the therapeutic potential of targeting telomerase. Telomerase repeat amplification protocol (TRAP) (n = 36) and C-circle assay/telomere FISH/ATRX staining (n = 76) were performed on primary ependymomas to determine the prevalence and prognostic potential of telomerase activity or alternative lengthening of telomeres (ALT) as telomere maintenance mechanisms, respectively. Imetelstat, a phase 2 telomerase inhibitor, was used to elucidate the effect of telomerase inhibition on proliferation and tumorigenicity in established cell lines (BXD-1425EPN, R254), a primary TIC line (E520) and xenograft models of pediatric ependymoma. Over 60 % of pediatric ependymomas were found to rely on telomerase activity to maintain telomeres, while no ependymomas showed evidence of ALT. Children with telomerase-active tumors had reduced 5-year progression-free survival (29 ± 11 vs 64 ± 18 %; p = 0.03) and overall survival (58 ± 12 vs 83 ± 15 %; p = 0.05) rates compared to those with tumors lacking telomerase activity. Imetelstat inhibited proliferation and self-renewal by shortening telomeres and inducing senescence in vitro. In vivo, Imetelstat significantly reduced subcutaneous xenograft growth by 40 % (p = 0.03) and completely abolished the tumorigenicity of pediatric ependymoma TICs in an orthotopic xenograft model. Telomerase inhibition represents a promising therapeutic approach for telomerase-active pediatric ependymomas found to characterize high-risk ependymomas.
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Neoplasias Encefálicas/tratamiento farmacológico , Inhibidores Enzimáticos/farmacología , Ependimoma/tratamiento farmacológico , Indoles/farmacología , Células Madre Neoplásicas/efectos de los fármacos , Niacinamida/análogos & derivados , Telomerasa/antagonistas & inhibidores , Animales , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/enzimología , Carcinogénesis/efectos de los fármacos , Carcinogénesis/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Proliferación Celular/fisiología , Preescolar , Estudios de Cohortes , Supervivencia sin Enfermedad , Ependimoma/diagnóstico , Ependimoma/enzimología , Femenino , Humanos , Ratones , Recurrencia Local de Neoplasia/diagnóstico , Recurrencia Local de Neoplasia/enzimología , Trasplante de Neoplasias , Células Madre Neoplásicas/enzimología , Niacinamida/farmacología , Oligonucleótidos , Telomerasa/metabolismo , Telómero/efectos de los fármacos , Telómero/metabolismoRESUMEN
Brain tumors represent the leading cause of childhood cancer mortality, of which medulloblastoma (MB) is the most frequent malignant tumor. Recent studies have demonstrated the presence of several MB molecular subgroups, each distinct in terms of prognosis and predicted therapeutic response. Groups 1 and 2 are characterized by relatively good clinical outcomes and activation of the Wnt and Shh pathways, respectively. In contrast, groups 3 and 4 ("non-Shh/Wnt MBs") are distinguished by metastatic disease, poor patient outcome, and lack a molecular pathway phenotype. Current gene expression platforms have not detected brain tumor-initiating cell (BTIC) self-renewal genes in groups 3 and 4 MBs as BTICs typically comprise a minority of tumor cells and may therefore go undetected on bulk tumor analyses. Since increasing BTIC frequency has been associated with increasing tumor aggressiveness and poor patient outcome, we investigated the subgroup-specific gene expression profile of candidate stem cell genes within 251 primary human MBs from four nonoverlapping MB transcriptional databases (Amsterdam, Memphis, Toronto, Boston) and 74 NanoString-subgrouped MBs (Vancouver). We assessed the functional relevance of two genes, FoxG1 and Bmi1, which were significantly enriched in non-Shh/Wnt MBs and showed these genes to mediate MB stem cell self-renewal and tumor initiation in mice. We also identified their transcriptional regulation through reciprocal promoter occupancy in CD15+ MB stem cells. Our work demonstrates the application of stem cell data gathered from genomic platforms to guide functional BTIC assays, which may then be used to develop novel BTIC self-renewal mechanisms amenable to therapeutic targeting.
Asunto(s)
Neoplasias Cerebelosas/metabolismo , Factores de Transcripción Forkhead/metabolismo , Meduloblastoma/metabolismo , Células Madre Neoplásicas/fisiología , Proteínas del Tejido Nervioso/metabolismo , Complejo Represivo Polycomb 1/metabolismo , Animales , Procesos de Crecimiento Celular/fisiología , Línea Celular Tumoral , Neoplasias Cerebelosas/genética , Neoplasias Cerebelosas/patología , Factores de Transcripción Forkhead/genética , Humanos , Meduloblastoma/genética , Meduloblastoma/patología , Ratones , Ratones Endogámicos NOD , Ratones SCID , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Proteínas del Tejido Nervioso/genética , Complejo Represivo Polycomb 1/genética , Pronóstico , Regiones Promotoras Genéticas , Transducción de Señal , TranscriptomaRESUMEN
Glioblastoma (GBM) is the most aggressive malignant primary brain tumor characterized by a highly heterogeneous and immunosuppressive tumor microenvironment (TME). The symbiotic interactions between glioblastoma stem cells (GSCs) and tumor-associated macrophages (TAM) in the TME are critical for tumor progression. Here, we identified that IFI35, a transcriptional regulatory factor, plays both cell-intrinsic and cell-extrinsic roles in maintaining GSCs and the immunosuppressive TME. IFI35 induced non-canonical NF-kB signaling through proteasomal processing of p105 to the DNA-binding transcription factor p50, which heterodimerizes with RELB (RELB/p50), and activated cell chemotaxis in a cell-autonomous manner. Further, IFI35 induced recruitment and maintenance of M2-like TAMs in TME in a paracrine manner. Targeting IFI35 effectively suppressed in vivo tumor growth and prolonged survival of orthotopic xenograft-bearing mice. Collectively, these findings reveal the tumor-promoting functions of IFI35 and suggest that targeting IFI35 or its downstream effectors may provide effective approaches to improve GBM treatment.
Asunto(s)
Glioblastoma , FN-kappa B , Células Madre Neoplásicas , Transducción de Señal , Macrófagos Asociados a Tumores , Glioblastoma/metabolismo , Glioblastoma/patología , Glioblastoma/genética , Humanos , Animales , Ratones , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Macrófagos Asociados a Tumores/metabolismo , Macrófagos Asociados a Tumores/patología , FN-kappa B/metabolismo , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/genética , Línea Celular Tumoral , Microambiente TumoralRESUMEN
Metabolic reprogramming in pediatric diffuse midline glioma is driven by gene expression changes induced by the hallmark histone mutation H3K27M, which results in aberrantly permissive activation of oncogenic signaling pathways. Previous studies of diffuse midline glioma with altered H3K27 (DMG-H3K27a) have shown that the RAS pathway, specifically through its downstream kinase, extracellular-signal-related kinase 5 (ERK5), is critical for tumor growth. Further downstream effectors of ERK5 and their role in DMG-H3K27a metabolic reprogramming have not been explored. We establish that ERK5 is a critical regulator of cell proliferation and glycolysis in DMG-H3K27a. We demonstrate that ERK5 mediates glycolysis through activation of transcription factor MEF2A, which subsequently modulates expression of glycolytic enzyme PFKFB3. We show that in vitro and mouse models of DMG-H3K27a are sensitive to the loss of PFKFB3. Multi-targeted drug therapy against the ERK5-PFKFB3 axis, such as with small-molecule inhibitors, may represent a promising therapeutic approach in patients with pediatric diffuse midline glioma.