RESUMO
Cancer cells are highly heterogeneous at the transcriptional level and epigenetic state. Methods to study epigenetic heterogeneity are limited in throughput and information obtained per cell. Here, we adapted cytometry by time-of-flight (CyTOF) to analyze a wide panel of histone modifications in primary tumor-derived lines of diffused intrinsic pontine glioma (DIPG). DIPG is a lethal glioma, driven by a histone H3 lysine 27 mutation (H3-K27M). We identified two epigenetically distinct subpopulations in DIPG, reflecting inherent heterogeneity in expression of the mutant histone. These two subpopulations are robust across tumor lines derived from different patients and show differential proliferation capacity and expression of stem cell and differentiation markers. Moreover, we demonstrate the use of these high-dimensional data to elucidate potential interactions between histone modifications and epigenetic alterations during the cell cycle. Our work establishes new concepts for the analysis of epigenetic heterogeneity in cancer that could be applied to diverse biological systems.
Assuntos
Neoplasias do Tronco Encefálico , Glioma , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/metabolismo , Neoplasias do Tronco Encefálico/patologia , Cromatina/genética , Epigênese Genética , Glioma/metabolismo , Histonas/genética , Histonas/metabolismo , Humanos , MutaçãoRESUMO
Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMGs) are universally lethal paediatric tumours of the central nervous system1. We have previously shown that the disialoganglioside GD2 is highly expressed on H3K27M-mutated glioma cells and have demonstrated promising preclinical efficacy of GD2-directed chimeric antigen receptor (CAR) T cells2, providing the rationale for a first-in-human phase I clinical trial (NCT04196413). Because CAR T cell-induced brainstem inflammation can result in obstructive hydrocephalus, increased intracranial pressure and dangerous tissue shifts, neurocritical care precautions were incorporated. Here we present the clinical experience from the first four patients with H3K27M-mutated DIPG or spinal cord DMG treated with GD2-CAR T cells at dose level 1 (1 × 106 GD2-CAR T cells per kg administered intravenously). Patients who exhibited clinical benefit were eligible for subsequent GD2-CAR T cell infusions administered intracerebroventricularly3. Toxicity was largely related to the location of the tumour and was reversible with intensive supportive care. On-target, off-tumour toxicity was not observed. Three of four patients exhibited clinical and radiographic improvement. Pro-inflammatory cytokine levels were increased in the plasma and cerebrospinal fluid. Transcriptomic analyses of 65,598 single cells from CAR T cell products and cerebrospinal fluid elucidate heterogeneity in response between participants and administration routes. These early results underscore the promise of this therapeutic approach for patients with H3K27M-mutated DIPG or spinal cord DMG.
Assuntos
Astrocitoma , Neoplasias do Tronco Encefálico , Gangliosídeos , Glioma , Histonas , Imunoterapia Adotiva , Mutação , Receptores de Antígenos Quiméricos , Astrocitoma/genética , Astrocitoma/imunologia , Astrocitoma/patologia , Astrocitoma/terapia , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/imunologia , Neoplasias do Tronco Encefálico/patologia , Neoplasias do Tronco Encefálico/terapia , Criança , Gangliosídeos/imunologia , Perfilação da Expressão Gênica , Glioma/genética , Glioma/imunologia , Glioma/patologia , Glioma/terapia , Histonas/genética , Humanos , Imunoterapia Adotiva/métodos , Receptores de Antígenos Quiméricos/imunologia , Neoplasias da Medula Espinal/genética , Neoplasias da Medula Espinal/imunologia , Neoplasias da Medula Espinal/patologia , Neoplasias da Medula Espinal/terapiaRESUMO
The embryonal central nervous system (CNS) tumor with PLAGL1 (pleomorphic adenoma gene-like) amplification is a novel type of pediatric neoplasm with a distinct methylation profile, described for the first time in 2022. It may be located anywhere in the neuroaxis and, as its name implies, it is driven by the amplification and overexpression of one of the PLAG family genes. Although the associated clinical, immunohistopathological, and molecular characteristics are well characterized in the seminal report of this entity, data on the radiological features is still lacking. Here, we present a case report of a 4-year-old girl with a biopsy-proven PLAGL1-amplified brainstem tumor and provide a detailed description of the corresponding conventional neuroimaging characteristics, aiming to better delineate this entity and to increase the awareness of this pathology in the radiological community.
Assuntos
Fatores de Transcrição , Humanos , Feminino , Pré-Escolar , Fatores de Transcrição/genética , Proteínas Supressoras de Tumor/genética , Neoplasias Embrionárias de Células Germinativas/diagnóstico por imagem , Neoplasias Embrionárias de Células Germinativas/genética , Neoplasias Embrionárias de Células Germinativas/patologia , Imageamento por Ressonância Magnética , Amplificação de Genes , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/patologia , Proteínas de Ciclo CelularRESUMO
BACKGROUND: With the recent advent of genetic testing, IDH-mutant glioma has been found among adult brainstem gliomas. However, the clinical outcome and prognosis of IDH-mutant brainstem gliomas in adults have not been elucidated. This study aimed to investigate the clinical outcome, radiological findings, and genetic features of adult patients with IDH-mutant diffuse brainstem gliomas. METHODS: Data from adult patients with brainstem glioma at Hokkaido University Hospital between 2006 and 2022 were retrospectively analyzed. Patient characteristics, treatment methods, genetic features, and prognosis were evaluated. RESULTS: Of 12 patients with brainstem glioma with proven histopathology, 4 were identified with IDH mutation. All patients underwent local radiotherapy with 54 Gray in 27 fractions combined with chemotherapy with temozolomide. Three patients had IDH1 R132H mutation and one had IDH2 R172G mutation. The median progression-free survival and overall survival were 68.4 months and 85.2 months, respectively, longer than that for IDH-wildtype gliomas (5.6 months and 12.0 months, respectively). At the time of initial onset, contrast-enhanced lesions were observed in two of the four cases in magnetic resonance imaging. CONCLUSION: As some adult brainstem gliomas have IDH mutations, and a clearly different prognosis from those with IDH-wildtype, biopsies are proactively considered to confirm the genotype.
Assuntos
Neoplasias do Tronco Encefálico , Glioma , Isocitrato Desidrogenase , Mutação , Humanos , Isocitrato Desidrogenase/genética , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/patologia , Neoplasias do Tronco Encefálico/terapia , Masculino , Glioma/genética , Glioma/diagnóstico por imagem , Glioma/patologia , Glioma/terapia , Feminino , Pessoa de Meia-Idade , Adulto , Estudos Retrospectivos , Idoso , Resultado do Tratamento , Prognóstico , Imageamento por Ressonância Magnética , Adulto JovemRESUMO
Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive pediatric brain tumor with limited therapeutic options. Here, we investigated the potential of dimethyl alpha-ketoglutarate (DMKG) as an anti-proliferative agent against DIPG and unraveled its underlying molecular mechanisms. DMKG exhibited robust inhibition of DIPG cell proliferation, colony formation, and neurosphere growth. Transcriptomic analysis revealed substantial alterations in gene expression, with upregulated genes enriched in hypoxia-related pathways and downregulated genes associated with cell division and the mitotic cell cycle. Notably, DMKG induced G1/S phase cell cycle arrest and downregulated histone H3 lysine 27 acetylation (H3K27ac) without affecting H3 methylation levels. The inhibition of AKT and ERK signaling pathways by DMKG coincided with decreased expression of the CBP/p300 coactivator. Importantly, we identified the c-MYC-p300/ATF1-p300 axis as a key mediator of DMKG's effects, demonstrating reduced binding to target gene promoters and decreased H3K27ac levels. Depletion of c-MYC or ATF1 effectively inhibited DIPG cell growth. These findings highlight the potent anti-proliferative properties of DMKG, its impact on epigenetic modifications, and the involvement of the c-MYC-p300/ATF1-p300 axis in DIPG, shedding light on potential therapeutic strategies for this devastating disease.
Assuntos
Neoplasias do Tronco Encefálico , Glioma Pontino Intrínseco Difuso , Glioma , Criança , Humanos , Histonas/metabolismo , Glioma Pontino Intrínseco Difuso/genética , Glioma Pontino Intrínseco Difuso/metabolismo , Glioma Pontino Intrínseco Difuso/patologia , Neoplasias do Tronco Encefálico/tratamento farmacológico , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/patologia , Glioma/patologia , Redes Reguladoras de Genes , Epigênese Genética , Proliferação de Células/genéticaRESUMO
We present 4 children (diagnosed between 1 and 8 y, 3 females and 1 male) with molecularly distinct tectal gliomas (2 KRAS mutant, 1 EGFR mutant, 1 SRGAP3-RAF-1 fusion) that contributes to the growing literature of this uncommonly biopsied tumor. The patient with EGFR R222C mutation had a more severe course, earlier diagnosis, subsequent leptomeningeal metastatic disease, required more aggressive therapies, and died 9 years after diagnosis. Patients with KRAS mutations and SRGAP3-RAF-1 fusion had a more indolent course. Our series expands the molecular phenotype of tectal glioma with the potential for leptomeningeal dissemination. Future studies on establishing genotypic/phenotypic correlation from those who undergo biopsy are needed.
Assuntos
Neoplasias Encefálicas , Neoplasias do Tronco Encefálico , Glioma , Feminino , Masculino , Humanos , Glioma/genética , Glioma/patologia , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/diagnóstico , Neoplasias do Tronco Encefálico/patologia , Proteínas Proto-Oncogênicas p21(ras)/genética , Receptores ErbB/genética , Mutação , Neoplasias Encefálicas/genéticaRESUMO
Pontine gliomas represent difficult to treat entity due to the location and heterogeneous biology varying from indolent low-grade gliomas to aggressive diffuse intrinsic pontine glioma (DIPG). Making the correct tumor diagnosis in the pontine location is thus critical. Here, we report a case study of a 14-month-old patient initially diagnosed as histone H3 wild-type DIPG. Due to the low age of the patient, the MRI appearance of DIPG, and anaplastic astrocytoma histology, intensive chemotherapy based on the HIT-SKK protocol with vinblastine maintenance chemotherapy was administered. Rapid clinical improvement and radiological regression of the tumor were observed with nearly complete remission with durable effect and excellent clinical condition more than 6.5 years after diagnosis. Based on this unexpected therapeutic outcome, genome-wide DNA methylation array was employed and the sample was classified into the methylation class "Low-grade glioma, MYB(L1) altered." Additionally, RT-PCR revealed the presence of MYB::QKI fusion. Taken together, the histopathological classification, molecular-genetic and epigenetic features, clinical behavior, and pontine location have led us to reclassify the tumor as a pontine MYB-altered glioma. Our case demonstrates that more intensive chemotherapy can achieve long-term clinical effect in the treatment of MYB-altered pontine gliomas compared to previously used LGG-based regimens or radiotherapy. It also emphasizes the importance of a biopsy and a thorough molecular investigation of pontine lesions.
Assuntos
Astrocitoma , Neoplasias do Tronco Encefálico , Glioma , Humanos , Lactente , Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/tratamento farmacológico , Neoplasias do Tronco Encefálico/genética , Astrocitoma/diagnóstico por imagem , Astrocitoma/tratamento farmacológico , Astrocitoma/genética , Glioma/diagnóstico por imagem , Glioma/tratamento farmacológico , Glioma/genética , Histonas/genética , Ponte/patologiaRESUMO
BACKGROUND: Diffuse intrinsic pontine gliomas (DIPGs) are high-grade gliomas (HGGs) that occur primarily in children, and represent a leading cause of death in pediatric patients with brain tumors with a median overall survival of only 8-11 months. SUMMARY: While these lesions were previously thought to behave similarly to adult HGG, emerging data have demonstrated that DIPG is a biologically distinct entity from adult HGG frequently driven by mutations in the histone genes H3.3 and H3.1 not found in adult glioma. While biopsy of DIPG was historically felt to confer unacceptable risk of morbidity and mortality, multiple studies have demonstrated that stereotactic biopsy of DIPG is safe, allowing not only for improved understanding of DIPG but also forming the basis for protocols for personalized medicine in DIPG. However, current options for personalized medicine in DIPG are limited by the lack of efficacious targeted therapies for the mutations commonly found in DIPG. Multiple treatment modalities including targeted therapies, immunotherapy, convection-enhanced delivery, and focused ultrasound are in various stages of investigation. KEY MESSAGE: Increasing frequency of biopsy for DIPG has identified distinct driving mutations that may serve as therapeutic targets. Novel treatment modalities are under investigation.
Assuntos
Neoplasias do Tronco Encefálico , Glioma Pontino Intrínseco Difuso , Glioma , Adulto , Criança , Humanos , Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/terapia , Glioma Pontino Intrínseco Difuso/genética , Glioma Pontino Intrínseco Difuso/terapia , Glioma Pontino Intrínseco Difuso/patologia , Glioma/diagnóstico por imagem , Glioma/genética , Glioma/terapia , Imunoterapia , Ensaios Clínicos como AssuntoRESUMO
BACKGROUND: Neurodevelopmental disorders increase brain tumor risk, suggesting that normal brain development may have protective properties. Mutations in epigenetic regulators are common in pediatric brain tumors, highlighting a potentially central role for disrupted epigenetic regulation of normal brain development in tumorigenesis. For example, lysine 27 to methionine mutation (H3K27M) in the H3F3A gene occurs frequently in Diffuse Intrinsic Pontine Gliomas (DIPGs), the most aggressive pediatric glioma. As H3K27M mutation is necessary but insufficient to cause DIPGs, it is accompanied by additional mutations in tumors. However, how H3K27M alone increases vulnerability to DIPG tumorigenesis remains unclear. RESULTS: Here, we used human embryonic stem cell models with this mutation, in the absence of other DIPG contributory mutations, to investigate how H3K27M alters cellular proliferation and differentiation. We found that H3K27M increased stem cell proliferation and stem cell properties. It interfered with differentiation, promoting anomalous mesodermal and ectodermal gene expression during both multi-lineage and germ layer-specific cell specification, and blocking normal differentiation into neuroectoderm. H3K27M mutant clones exhibited transcriptomic diversity relative to the more homogeneous wildtype population, suggesting reduced fidelity of gene regulation, with aberrant expression of genes involved in stem cell regulation, differentiation, and tumorigenesis. These phenomena were associated with global loss of H3K27me3 and concordant loss of DNA methylation at specific genes in H3K27M-expressing cells. CONCLUSIONS: Together, these data suggest that H3K27M mutation disrupts normal differentiation, maintaining a partially differentiated state with elevated clonogenicity during early development. This disrupted response to early developmental cues could promote tissue properties that enable acquisition of additional mutations that cooperate with H3K27M mutation in genesis of DMG/DIPG. Therefore, this work demonstrates for the first time that H3K27M mutation confers vulnerability to gliomagenesis through persistent clonogenicity and aberrant differentiation and defines associated alterations of histone and DNA methylation.
Assuntos
Neoplasias do Tronco Encefálico , Epigênese Genética , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/metabolismo , Neoplasias do Tronco Encefálico/patologia , Carcinogênese/genética , Proliferação de Células , Criança , Histonas , Humanos , Mutação , Células-Tronco/metabolismoRESUMO
Diffuse intrinsic pontine gliomas (DIPG), the first cause of cerebral pediatric cancer death, will greatly benefit from specific and non-invasive biomarkers for patient follow-up and monitoring of drug efficacy. Since biopsies are challenging for brain tumors, molecular imaging may be a technique of choice to target and follow tumor evolution. So far, MR remains the imaging technique of reference for DIPG, although it often fails to define the extent of tumors, an essential parameter for therapeutic efficacy assessment. Thanks to its high sensitivity, positron emission tomography (PET) offers a unique way to target specific biomarkers in vivo. We demonstrated in a patient-derived orthotopic xenograft (PDOX) model in the rat that the translocator protein of 18 kDa (TSPO) may be a promising biomarker for monitoring DIPG tumors. We studied the distribution of 18F-DPA-714, a TSPO radioligand, in rats inoculated with HSJD-DIPG-007 cells. The primary DIPG human cell line HSJD-DIPG-007 highly represents this pediatric tumor, displaying the most prevalent DIPG mutations, H3F3A (K27M) and ACVR1 (R206H). Kinetic modeling and parametric imaging using the brain 18F-DPA-714 PET data enabled specific delineation of the DIPG tumor area, which is crucial for radiotherapy dose management.
Assuntos
Astrocitoma , Neoplasias do Tronco Encefálico , Glioma Pontino Intrínseco Difuso , Glioma , Criança , Animais , Humanos , Ratos , Glioma/diagnóstico por imagem , Glioma/genética , Glioma/metabolismo , Linhagem Celular Tumoral , Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/genética , Tomografia por Emissão de Pósitrons/métodos , Proteínas de Transporte , Modelos Animais de Doenças , Biomarcadores , Receptores de GABA/genética , Receptores de GABA/metabolismo , Receptores de GABA-ARESUMO
PURPOSE: CNS malignancies are currently the most common cause of disease related deaths in children. Although brainstem gliomas are invariably fatal cancers in children, clinical studies against this disease are limited. This review is to lead to a succinct collection of knowledge of known biological mechanisms of this disease and discuss available therapeutics. METHODS: A hallmark of brainstem gliomas are mutations in the histone H3.3 with the majority of cases expressing the mutation K27M on histone 3.3. Recent studies using whole genome sequencing have revealed other mutations associated with disease. Current standard clinical practice may merely involve radiation and/or chemotherapy with little hope for long term survival. Here we discuss the potential of new therapies. CONCLUSION: Despite the lack of treatment options using frequently practiced clinical techniques, immunotherapeutic strategies have recently been developed to target brainstem gliomas. To target brainstem gliomas, investigators are evaluating the use of broad non-targeted therapy with immune checkpoint inhibitors. Alternatively, others have begun to explore adoptive T cell strategies against these fatal malignancies.
Assuntos
Neoplasias do Tronco Encefálico , Glioma , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/terapia , Glioma/genética , Glioma/terapia , Histonas/genética , Humanos , MutaçãoRESUMO
OBJECTIVES: The diffuse intrinsic pontine gliomas (DIPGs) are now defined by the type of histone H3 mutated at lysine 27. We aimed to correlate the multimodal MRI features of DIPGs, H3K27M mutant, with their histological and molecular characteristics. METHODS: Twenty-seven treatment-naïve children with histopathologically confirmed DIPG H3K27M mutant were prospectively included. MRI performed prior to biopsy included multi-b-value diffusion-weighted imaging, ASL, and dynamic susceptibility contrast (DSC) perfusion imaging. The ADC and cerebral blood flow (CBF) and blood volume (CBV) were measured at the biopsy site. We assessed quantitative histological data, including microvascular density, nuclear density, and H3K27M-positive nuclear density. Gene expression profiling was also assessed in the samples. We compared imaging and histopathological data according to histone subgroup. We correlated MRI quantitative data with histological data and gene expression. RESULTS: H3.1K27M mutated tumors showed higher ADC values (median 3151 µm2/s vs 1741 µm2/s, p = 0.003), and lower perfusion values (DSC-rCBF median 0.71 vs 1.43, p = 0.002, and DSC-rCBV median 1.00 vs 1.71, p = 0.02) than H3.3K27M ones. They had similar microvascular and nuclear density, but lower H3K27M-positive nuclear density (p = 0.007). The DSC-rCBV was positively correlated to the H3K27M-positive nuclear density (rho = 0.74, p = 0.02). ADC values were not correlated with nuclear density nor perfusion values with microvascular density. The expression of gated channel activity-related genes tended to be inversely correlated with ADC values and positively correlated with DSC perfusion. CONCLUSIONS: H3.1K27M mutated tumors have higher ADC and lower perfusion values than H3.3K27M ones, without direct correlation with microvascular or nuclear density. This may be due to tissular edema possibly related to gated channel activity-related gene expression. KEY POINTS: ⢠H3.1K27M mutant DIPG had higher apparent diffusion coefficient (p = 0.003), lower α (p = 0.048), and lower relative cerebral blood volume (p = 0.02) than H3.3K27M mutant DIPG at their biopsy sites. ⢠Biopsy samples obtained within the tumor's enhancing portion showed higher microvascular density (p = 0.03) than samples obtained outside the tumor's enhancing portion, but similar H3K27M-positive nuclear density (p = 0.84). ⢠Relative cerebral blood volume measured at the biopsy site was significantly correlated with H3K27M-positive nuclear density (rho = 0.74, p = 0.02).
Assuntos
Neoplasias Encefálicas , Neoplasias do Tronco Encefálico , Glioma Pontino Intrínseco Difuso , Glioma , Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/genética , Criança , Glioma/diagnóstico por imagem , Glioma/genética , Histonas/genética , Humanos , Imageamento por Ressonância MagnéticaRESUMO
BACKGROUND AND PURPOSE: Adult brainstem gliomas are rare primary brain tumours with heterogeneous clinical course. The low frequency of these tumours makes it difficult to achieve high-quality evidence regarding prognostic factors, adequate therapeutic approach and outcome in such patients. METHODS: In this retrospective study, we analysed clinical, radiological, molecular, prognostic and therapeutic factors in a series of 47 histologically proven adult brainstem gliomas recruited over a 20-year period (1998-2018). RESULTS: Twenty-two patients were male, 25 female with median age of 39 years. The tumour involved one brainstem segment in 20 cases and 2 or more segments in 27. Contrast enhancement was reported in 28 cases. Surgical procedures included biopsy in 26 cases and partial/total resection in the remaining 21. Histological diagnosis was of low-grade glioma in 23 patients, high-grade glioma in 22 and non-diagnostic in 2 cases. Data regarding molecular biology were available for 22 patients. Median overall survival was 35 months, in particular 16 months in high-grade glioma and 84 months in low-grade glioma. At univariate analysis, tumour grade was the only factor with a statistically significant impact on survival time (p = 0,003), whereas younger age, better performance status and total/subtotal resection showed a trend to more prolonged survival. This study also confirms safety of biopsy/surgery in adult brainstem glioma patients and shows a clear trend to a more frequent assessment of molecular biology data. CONCLUSIONS: Further prospective multicentre efforts, and hopefully clinical trials, are necessary to improve outcome in this neglected glioma patient population.
Assuntos
Neoplasias Encefálicas , Neoplasias do Tronco Encefálico , Glioma , Adulto , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/terapia , Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/terapia , Feminino , Glioma/diagnóstico por imagem , Glioma/genética , Glioma/terapia , Humanos , Itália/epidemiologia , Masculino , Prognóstico , Estudos RetrospectivosRESUMO
Histones form chromatin and play a key role in the regulation of gene expression. As an epigenetic information form, histone modifications such as methylation, phosphorylation, acetylation, and ubiquitination are closely related to the regulation of genes. In the last two decades, cancer scientists discovered that some histone modifications, including acetylation and methylation, are perturbed in cancer diseases. Recurrent histone mutations, which hinder histone methylation and are implicated in oncogenesis, are recently identified in several cancer disease and called oncohistones. Well-known oncohistones, with mutations on both H3.1 and H3.3, include H3K36M in chondroblastoma, H3K27M in glioma, and H3G34 mutations that exist in bone cancers and gliomas. Oncohistone expression can lead to epigenome/transcriptome reprogramming and eventually to oncogenesis. The H3K27M, H3G34V/R, and H3K36M histone mutations can lead to the substitution of amino acid(s) at or near a lysine residue, which is a methylation target. H3K27M characteristically exists in diffuse intrinsic pontine glioma (pediatric DIPG), and its expression can cause a global decrease of the methylation of histone at the lysine residue. Uncovering the molecular mechanisms of H3K27M-driven tumorigenesis has recently led to the identification of some potential therapeutic targets in diffuse intrinsic pontine glioma. In this chapter, we will review and summarize recent studies on the H3K27M-driven tumorigenic mechanisms and properties and the role of H3.1K27M and H3.3K27M oncohistones in brain tumors.
Assuntos
Neoplasias do Tronco Encefálico , Glioma , Histonas/genética , Mutação , Neoplasias do Tronco Encefálico/genética , Cromatina , Glioma/genética , HumanosRESUMO
Diffuse intrinsic pontine glioma (DIPG) is a lethal midline brainstem tumor that most commonly occurs in children and is genetically defined by substitution of methionine for lysine at site 27 of histone 3 (H3K27M) in the majority of cases. This mutation has since been shown to exert an influence on the posttranslational epigenetic landscape of this disease, with the loss of trimethylation at lysine 27 (H3K27me3) the most common alteration. Based on these findings, a number of drugs targeting these epigenetic changes have been proposed, specifically that alter histone trimethylation, acetylation, or phosphorylation. Various mechanisms have been explored, including inhibition of H327 demethylase and methyltransferase to target trimethylation, inhibition of histone deacetylase (HDAC) and bromodomain and extraterminal (BET) to target acetylation, and inhibition of phosphatase-related enzymes to target phosphorylation. This chapter reviews the current rationales and progress made to date in epigenetically targeting DIPG via these mechanisms.
Assuntos
Neoplasias do Tronco Encefálico , Epigênese Genética , Glioma , Histonas/genética , Neoplasias do Tronco Encefálico/genética , Criança , Glioma/tratamento farmacológico , Glioma/genética , Histonas/metabolismo , Humanos , Mutação , Processamento de Proteína Pós-TraducionalRESUMO
Diffuse intrinsic pontine glioma (DIPG) is an incurable paediatric malignancy. Identifying the molecular drivers of DIPG progression is of the utmost importance. Long non-coding RNAs (lncRNAs) represent a large family of disease- and tissue-specific transcripts, whose functions have not yet been elucidated in DIPG. Herein, we studied the oncogenic role of the development-associated H19 lncRNA in DIPG. Bioinformatic analyses of clinical datasets were used to measure the expression of H19 lncRNA in paediatric high-grade gliomas (pedHGGs). The expression and sub-cellular location of H19 lncRNA were validated in DIPG cell lines. Locked nucleic acid antisense oligonucleotides were designed to test the function of H19 in DIPG cells. We found that H19 expression was higher in DIPG vs. normal brain tissue and other pedHGGs. H19 knockdown resulted in decreased cell proliferation and survival in DIPG cells. Mechanistically, H19 buffers let-7 microRNAs, resulting in the up-regulation of oncogenic let-7 target (e.g., SULF2 and OSMR). H19 is the first functionally characterized lncRNA in DIPG and a promising therapeutic candidate for treating this incurable cancer.
Assuntos
Neoplasias do Tronco Encefálico/genética , Proliferação de Células , Glioma/genética , RNA Longo não Codificante/metabolismo , Neoplasias do Tronco Encefálico/metabolismo , Neoplasias do Tronco Encefálico/patologia , Células Cultivadas , Regulação Neoplásica da Expressão Gênica , Glioma/metabolismo , Glioma/patologia , Histonas/metabolismo , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , Mutação , RNA Longo não Codificante/genéticaRESUMO
Dysregulation of the homeostatic balance of histone H3 di- and tri-methyl lysine 27 (H3K27me2/3) levels caused by the mis-sense mutation of histone H3 (H3K27M) is reported to be associated with various types of cancers. In this study, we found that reduction in H3K27me2/3 caused by H3.1K27M, a mutation of H3 variants found in patients with diffuse intrinsic pontine glioma (DIPG), dramatically attenuated the presence of 53BP1 (also known as TP53BP1) foci and the capability of non-homologous end joining (NHEJ) in human dermal fibroblasts. H3.1K27M mutant cells showed increased rates of genomic insertions/deletions and copy number variations, as well as an increase in p53-dependent apoptosis. We further showed that both hypo-H3K27me2/3 and H3.1K27M interacted with FANCD2, a central player in the choice of DNA repair pathway. H3.1K27M triggered the accumulation of FANCD2 on chromatin, suggesting an interaction between H3.1K27M and FANCD2. Interestingly, knockdown of FANCD2 in H3.1K27M cells recovered the number of 53BP1-positive foci, NHEJ efficiency and apoptosis rate. Although these findings in HDF cells may differ from the endogenous regulation of the H3.1K27M mutant in the specific tumor context of DIPG, our results suggest a new model by which H3K27me2/3 facilitates NHEJ and the maintenance of genome stability.This article has an associated First Person interview with the first author of the paper.
Assuntos
Cromatina/metabolismo , Reparo do DNA por Junção de Extremidades , Enzimas Reparadoras do DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/metabolismo , Histonas/metabolismo , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/metabolismo , Linhagem Celular , Cromatina/genética , Reparo do DNA , Enzimas Reparadoras do DNA/genética , Proteínas de Ligação a DNA/genética , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/genética , Fibroblastos , Instabilidade Genômica , Glioma/genética , Glioma/metabolismo , Células HEK293 , Histonas/genética , Humanos , Metilação , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/genética , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/metabolismoRESUMO
PURPOSE: Our understanding of diffuse midline glioma (DMG) biology inclusive of diffuse intrinsic pontine glioma has been revolutionized by the discovery of novel mutations on the tails of histone 3, leading to the reclassification in 2016 of 'diffuse midline glioma, H3 K27M-mutant.' Given the abundance of basic, translational, and clinical information put forth in recent years, a review of the epigenetics of diffuse midline glioma is warranted. METHODS: Literature for the epigenetics of diffuse midline glioma published from 1989 to 2019 was reviewed by searching PubMed using the terms "diffuse intrinsic pontine glioma", "pontine glioma", or "midline glioma". The final references list was generated on the basis of originality and relevance to the broad scope of our review. RESULTS: The effects of H3K27M-mutation, while better understood, suggest multiple consequences on the chromatin landscape and DNA modification states, contributed to the progression of DMG. A rapid pace of translational development is occurring for epigenetic modifiers, and several classes of inhibitors have already made their way into clinical trial testing. As more agents become clinically accessible, immense effort is underway to understand the target effects, tumor penetration, and immune microenvironmental changes of epigenetic modification. CONCLUSION: We continue to seek a comprehensive understanding of the mechanisms that govern chromatin dysregulation and DNA modification in DMG, and in parallel we forge ahead with clinical testing of epigenetic modifiers. The determined efforts from bench to bedside, along with collaborative mindset and unified mission, will ultimately result in improved outcomes for DMG.
Assuntos
Neoplasias do Tronco Encefálico , Glioma , Neoplasias do Tronco Encefálico/genética , Cromatina , DNA , Epigênese Genética , Glioma/genética , HumanosRESUMO
Diffuse intrinsic pontine glioma (DIPG) is characterized by a short history of brainstem symptoms and well-known magnetic resonance imaging features with a fatal outcome. However, we report three unusual cases of brainstem tumors with an initial indolent and protracted course, which subsequently developed the classical imaging and clinical features of DIPG. Our findings support this notion that K27M is an early event in development and suggest that the emergence of additional events resulted in rapid progression after a long period of latency. Identification of such markers of aggressive behavior in the context of an indolent course is needed for better characterization and treatment management.
Assuntos
Neoplasias do Tronco Encefálico/patologia , Glioma Pontino Intrínseco Difuso/patologia , Histonas/genética , Mutação , Neoplasias do Tronco Encefálico/genética , Neoplasias do Tronco Encefálico/terapia , Criança , Pré-Escolar , Glioma Pontino Intrínseco Difuso/genética , Glioma Pontino Intrínseco Difuso/terapia , Feminino , Humanos , Lactente , Masculino , PrognósticoRESUMO
PURPOSE: The diagnosis of diffuse intrinsic pontine glioma (DIPG) is based largely on a combination of clinical and radiological findings due to the difficulty of obtaining a biopsy. An accurate evaluation of magnetic resonance imaging (MRI) scans is consequently essential. Recent analyses on the genomic landscape of DIPG revealed recurrent mutations in the H3F3A and HIST1H3B histone genes. We reviewed cases with available tumor tissue from institutional DIPG series to ascertain the consistency between their histo-molecular findings and clinical-radiological features. METHODS: We conducted a radiological and pathological central review of 22 cases enrolled in institutional DIPG trials. We performed immunohistochemical analyses to detect H3F3A/HIST1H3B K27M mutations, histone trimethylation, and EZH2 expression. Mutational analysis was performed for ACVR1, H3F3A, and HIST1H3B genes. RESULTS: Patients' median age at diagnosis was 8 years, and their median overall survival was 11 months. Nineteen/22 cases (86%) showed evidence of K27M mutation on immunohistochemistry and/or mutation analysis. Histone trimethylation expression was low or lacking in these mutated cases. Sequence analysis revealed 13 cases with H3F3A and 1 case with HIST1H3B K27M mutation. There was no significant difference in EZH2 expression between the K27M mutant and wild-type DIPGs. Upon external, blinded MRI re-evaluation one lesion not consistent with DIPG showed no evidence of K27M mutation and retained histone trimethylation expression. CONCLUSION: In conclusion, our study demonstrates a high frequency of histone K27M mutations in DIPG when MRI features are carefully assessed, thus confirming the consistency of imaging with biological markers in our institutional series of DIPG.