RESUMO
In this issue of Developmental Cell, Shiraishi et al. investigate the epigenetic changes occurring during the formation of SHH medulloblastoma and show that an epigenomic shift renders Nuclear Factor I family of transcription factors oncogenic.
Assuntos
Epigênese Genética , Proteínas Hedgehog , Meduloblastoma , Fatores de Transcrição NFI , Meduloblastoma/genética , Meduloblastoma/patologia , Meduloblastoma/metabolismo , Humanos , Proteínas Hedgehog/metabolismo , Proteínas Hedgehog/genética , Fatores de Transcrição NFI/metabolismo , Fatores de Transcrição NFI/genética , Animais , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/metabolismo , Neurofibromina 1/genética , Neurofibromina 1/metabolismo , CamundongosRESUMO
Sonic hedgehog subgroup of medulloblastoma (SHH-MB) is characterized by aberrant activation of the SHH signaling pathway. An inhibition of the positive SHH regulator Smoothened (SMO) has demonstrated promising clinical efficacy. Yet, primary and acquired resistance to SMO inhibitors limit their efficacy. An understanding of underlying molecular mechanisms of resistance to therapy is warranted to bridge this unmet need. Here, we make use of genome-wide CRISPR-Cas9 knockout screens in murine SMB21 and human DAOY cells, in order to unravel genetic dependencies and drug-related genetic interactors that could serve as alternative therapeutic targets for SHH-MB. Our screens reinforce SMB21 cells as a faithful model system for SHH-MB, as opposed to DAOY cells, and identify members of the epigenetic machinery including DNA methyltransferase 1 (DNMT1) as druggable targets in SHH-dependent tumors. We show that Dnmt1 plays a crucial role in normal murine cerebellar development and is required for SHH-MB growth in vivo. Additionally, DNMT1 pharmacological inhibition alone and in combination with SMO inhibition effectively inhibits tumor growth in murine and human SHH-MB cell models and prolongs survival of SHH-MB mouse models by inhibiting SHH signaling output downstream of SMO. In conclusion, our data highlight the potential of inhibiting epigenetic regulators as a novel therapeutic avenue in SMO-inhibitor sensitive as well as resistant SHH-MBs.
Assuntos
Sistemas CRISPR-Cas , Neoplasias Cerebelares , DNA (Citosina-5-)-Metiltransferase 1 , Proteínas Hedgehog , Meduloblastoma , Meduloblastoma/genética , Meduloblastoma/metabolismo , Meduloblastoma/patologia , Animais , DNA (Citosina-5-)-Metiltransferase 1/genética , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Proteínas Hedgehog/metabolismo , Proteínas Hedgehog/genética , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/patologia , Humanos , Camundongos , Linhagem Celular Tumoral , Receptor Smoothened/genética , Receptor Smoothened/metabolismo , Técnicas de Inativação de Genes/métodosRESUMO
Medulloblastoma, the most common malignant pediatric brain tumor, is classified into four main molecular subgroups, but group 3 and group 4 tumors are difficult to subclassify and have a poor prognosis. Rapid point-of-care diagnostic and prognostic assays are needed to improve medulloblastoma risk stratification and management. N6-methyladenosine (m6A) is a common RNA modification and long non-coding RNAs (lncRNAs) play a central role in tumor progression, but their impact on gene expression and associated clinical outcomes in medulloblastoma are unknown. Here we analyzed 469 medulloblastoma tumor transcriptomes to identify lncRNAs co-expressed with m6A regulators. Using LASSO-Cox analysis, we identified a five-gene m6A-associated lncRNA signature (M6LSig) significantly associated with overall survival, which was combined in a prognostic clinical nomogram. Using expression of the 67 m6A-associated lncRNAs, a subgroup classification model was generated using the XGBoost machine learning algorithm, which had a classification accuracy > 90%, including for group 3 and 4 samples. All M6LSig genes were significantly correlated with at least one immune cell type abundance in the tumor microenvironment, and the risk score was positively correlated with CD4+ naïve T cell abundance and negatively correlated with follicular helper T cells and eosinophils. Knockdown of key m6A writer genes METTL3 and METTL14 in a group 3 medulloblastoma cell line (D425-Med) decreased cell proliferation and upregulated many M6LSig genes identified in our in silico analysis, suggesting that the signature genes are functional in medulloblastoma. This study highlights a crucial role for m6A-dependent lncRNAs in medulloblastoma prognosis and immune responses and provides the foundation for practical clinical tools that can be rapidly deployed in clinical settings.
Assuntos
Adenosina , Neoplasias Cerebelares , Meduloblastoma , RNA Longo não Codificante , Transcriptoma , Humanos , Meduloblastoma/genética , Meduloblastoma/patologia , Meduloblastoma/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Adenosina/análogos & derivados , Adenosina/metabolismo , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/patologia , Prognóstico , Criança , Perfilação da Expressão Gênica/métodos , Masculino , Feminino , Microambiente Tumoral/genética , Microambiente Tumoral/imunologia , MetiltransferasesRESUMO
Hypothyroidism is commonly detected in patients with medulloblastoma (MB). However, whether thyroid hormone (TH) contributes to MB pathogenicity remains undetermined. Here, we find that TH plays a critical role in promoting tumor cell differentiation. Reduction in TH levels frees the TH receptor, TRα1, to bind to EZH2 and repress expression of NeuroD1, a transcription factor that drives tumor cell differentiation. Increased TH reverses EZH2-mediated repression of NeuroD1 by abrogating the binding of EZH2 and TRα1, thereby stimulating tumor cell differentiation and reducing MB growth. Importantly, TH-induced differentiation of tumor cells is not restricted by the molecular subgroup of MB, suggesting that TH can be used to broadly treat MB subgroups. These findings establish an unprecedented association between TH signaling and MB pathogenicity, providing solid evidence for TH as a promising modality for MB treatment.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos , Diferenciação Celular , Proteína Potenciadora do Homólogo 2 de Zeste , Meduloblastoma , Hormônios Tireóideos , Meduloblastoma/patologia , Meduloblastoma/metabolismo , Meduloblastoma/genética , Humanos , Diferenciação Celular/efeitos dos fármacos , Animais , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Camundongos , Hormônios Tireóideos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/tratamento farmacológico , Linhagem Celular Tumoral , Progressão da Doença , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Receptores alfa dos Hormônios Tireóideos/metabolismo , Receptores alfa dos Hormônios Tireóideos/genética , Transdução de Sinais/efeitos dos fármacosRESUMO
BACKGROUND: The current standard of care treatments for medulloblastoma are insufficient as these do not take tumor heterogeneity into account. Newer, safer, patient-specific treatment approaches are required to treat high-risk medulloblastoma patients who are not cured by the standard therapies. Immunotherapy is a promising treatment modality that could be key to improving survival and avoiding morbidity. For an effective immune response, appropriate tumor antigens must be targeted. While medulloblastoma patients with subgroup-specific genetic substitutions have been previously reported, the immunogenicity of these genetic alterations remains unknown. The aim of this study is to identify potential tumor rejection antigens for the development of antigen-directed cellular therapies for medulloblastoma. METHODS: We developed a cancer immunogenomics pipeline and performed a comprehensive analysis of medulloblastoma subgroup-specific transcription profiles (n = 170, 18 WNT, 46 SHH, 41 Group 3, and 65 Group 4 patient tumors) available through International Cancer Genome Consortium (ICGC) and European Genome-Phenome Archive (EGA). We performed in silico antigen prediction across a broad array of antigen classes including neoantigens, tumor-associated antigens (TAAs), and fusion proteins. Furthermore, we evaluated the antigen processing and presentation pathway in tumor cells and the immune infiltrating cell landscape using the latest computational deconvolution methods. RESULTS: Medulloblastoma patients were found to express multiple private and shared immunogenic antigens. The proportion of predicted TAAs was higher than neoantigens and gene fusions for all molecular subgroups, except for sonic hedgehog (SHH), which had a higher neoantigen burden. Importantly, cancer-testis antigens, as well as previously unappreciated neurodevelopmental antigens, were found to be expressed by most patients across all medulloblastoma subgroups. Despite being immunologically cold, medulloblastoma subgroups were found to have distinct immune cell gene signatures. CONCLUSIONS: Using a custom antigen prediction pipeline, we identified potential tumor rejection antigens with important implications for the development of immunotherapy for medulloblastoma.
Assuntos
Antígenos de Neoplasias , Meduloblastoma , Meduloblastoma/imunologia , Meduloblastoma/genética , Humanos , Antígenos de Neoplasias/imunologia , Antígenos de Neoplasias/genética , Neoplasias Cerebelares/imunologia , Neoplasias Cerebelares/genética , ImunoterapiaRESUMO
BACKGROUND: Von Hippel-Lindau (VHL) disease is a rare autosomal dominant disorder that predisposes patients to develop multiple cysts and tumors, such as hemangioblastomas (HBs) and clear cell renal cell carcinoma (ccRCC), due to mutations in the VHL tumor suppressor gene. While treatment of HBs varies based on their characteristics and has improved patient survival, it still involves high morbidity and mortality, leading to ongoing debates and studies to refine therapy strategies. Recent developments include the emergence of Belzutifan, a novel inhibitor targeting hypoxia-inducible factor 2α (HIF-2α), which has shown promising results in ongoing trials, particularly for patients not immediately requiring surgery. METHODS: This systematic review and meta-analysis aimed to comprehensively evaluate the efficacy and safety of Belzutifan for treating HBs associated with VHL disease. Search was conducted across Medline, Embase, Cochrane, and Web of Science databases. Statistical Analysis was performed, with proportions and 95 % confidence intervals. Statistical analyses were carried out using R Studio. RESULTS: Ten studies were selected, comprising 553 patients. The population mean age was 40 (24-65), and 50 % of the population was formed by males. In terms of proportion, 6 analyses were performed: Disease Stability of 31 % [95 %CI:14 %-47 %; I2 = 2 %]; Disease Progression of 2 %[95 %CI:0 %-9 %; I2 = 0 %]; Partial Response of 75 % [95 %CI:54 %-96 %; I2 = 58 %]. Complete response of 1 % [95 %CI:0 %-7 %; I2 = 0 %];and Side effects, anemia 81 % rate [95 % CI:54 %-100 %; I2 = 94 %], and fatigue rate of 79 % [95 % CI:54 %-100 %;I2 = 94 %]. CONCLUSION: Results indicate that Belzutifan effectively stabilizes disease, reduces tumor progression, and achieves significant therapeutic responses, although side effects like anemia and fatigue were noted.
Assuntos
Hemangioblastoma , Indenos , Doença de von Hippel-Lindau , Humanos , Neoplasias Cerebelares/diagnóstico , Neoplasias Cerebelares/tratamento farmacológico , Neoplasias Cerebelares/genética , Hemangioblastoma/diagnóstico , Hemangioblastoma/tratamento farmacológico , Hemangioblastoma/genética , Doença de von Hippel-Lindau/complicações , Doença de von Hippel-Lindau/tratamento farmacológico , Doença de von Hippel-Lindau/genética , Indenos/administração & dosagem , Indenos/efeitos adversos , Antineoplásicos/administração & dosagem , Antineoplásicos/efeitos adversosRESUMO
Effective and less toxic therapies for medulloblastoma have proved to be highly elusive. In this issue of Cancer Cell, Yang et al. show that thyroid hormone treatment leads to the activation of neurogenic differentiation factor 1 (NeuroD1) and differentiation of medulloblastoma cells through reversing EZH2-mediated transcriptional repression of NeuroD1.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos , Diferenciação Celular , Neoplasias Cerebelares , Proteína Potenciadora do Homólogo 2 de Zeste , Meduloblastoma , Meduloblastoma/patologia , Meduloblastoma/genética , Meduloblastoma/metabolismo , Humanos , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Complexo Repressor Polycomb 2/genética , Hormônios Tireóideos/metabolismo , Animais , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacosRESUMO
OTX2 is a transcription factor and known driver in medulloblastoma (MB), where it is amplified in a subset of tumours and overexpressed in most cases of group 3 and group 4 MB. Here we demonstrate a noncanonical role for OTX2 in group 3 MB alternative splicing. OTX2 associates with the large assembly of splicing regulators complex through protein-protein interactions and regulates a stem cell splicing program. OTX2 can directly or indirectly bind RNA and this may be partially independent of its DNA regulatory functions. OTX2 controls a pro-tumorigenic splicing program that is mirrored in human cerebellar rhombic lip origins. Among the OTX2-regulated differentially spliced genes, PPHLN1 is expressed in the most primitive rhombic lip stem cells, and targeting PPHLN1 splicing reduces tumour growth and enhances survival in vivo. These findings identify OTX2-mediated alternative splicing as a major determinant of cell fate decisions that drive group 3 MB progression.
Assuntos
Processamento Alternativo , Neoplasias Cerebelares , Meduloblastoma , Células-Tronco Neoplásicas , Fatores de Transcrição Otx , Fatores de Transcrição Otx/metabolismo , Fatores de Transcrição Otx/genética , Meduloblastoma/genética , Meduloblastoma/patologia , Meduloblastoma/metabolismo , Processamento Alternativo/genética , Humanos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/metabolismo , Animais , Regulação Neoplásica da Expressão Gênica , Linhagem Celular Tumoral , Camundongos , Proliferação de CélulasRESUMO
Medulloblastoma (MB) is the most common malignant brain tumor in children and is stratified into three major subgroups. The Sonic hedgehog (SHH) subgroup represents â¼30% of all MB cases and has significant survival disparity depending upon TP53 status. Here, we describe a zebrafish model of SHH MB using CRISPR to create mutant ptch1, the primary genetic driver of human SHH MB. In these animals, tumors rapidly arise in the cerebellum and resemble human SHH MB by histology and comparative onco-genomics. Similar to human patients, MB tumors with loss of both ptch1 and tp53 have aggressive tumor histology and significantly worse survival outcomes. The simplicity and scalability of the ptch1-crispant MB model makes it highly amenable to CRISPR-based genome-editing screens to identify genes required for SHH MB tumor formation in vivo, and here we identify the gene encoding Grk3 kinase as one such target.
Assuntos
Modelos Animais de Doenças , Proteínas Hedgehog , Meduloblastoma , Receptor Patched-1 , Proteínas de Peixe-Zebra , Peixe-Zebra , Meduloblastoma/genética , Meduloblastoma/patologia , Meduloblastoma/metabolismo , Animais , Proteínas Hedgehog/metabolismo , Proteínas Hedgehog/genética , Proteínas de Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/genética , Receptor Patched-1/genética , Receptor Patched-1/metabolismo , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/metabolismo , Humanos , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/genética , Sistemas CRISPR-Cas/genéticaRESUMO
SNCAIP duplication may promote Group 4 medulloblastoma via induction of PRDM6, a poorly characterized member of the PRDF1 and RIZ1 homology domain-containing (PRDM) family of transcription factors. Here, we investigated the function of PRDM6 in human hindbrain neuroepithelial stem cells and tested PRDM6 as a driver of Group 4 medulloblastoma. We report that human PRDM6 localizes predominantly to the nucleus, where it causes widespread repression of chromatin accessibility and complex alterations of gene expression patterns. Genome-wide mapping of PRDM6 binding reveals that PRDM6 binds to chromatin regions marked by histone H3 lysine 27 trimethylation that are located within, or proximal to, genes. Moreover, we show that PRDM6 expression in neuroepithelial stem cells promotes medulloblastoma. Surprisingly, medulloblastomas derived from PRDM6-expressing neuroepithelial stem cells match human Group 3, but not Group 4, medulloblastoma. We conclude that PRDM6 expression has oncogenic potential but is insufficient to drive Group 4 medulloblastoma from neuroepithelial stem cells. We propose that both PRDM6 and additional factors, such as specific cell-of-origin features, are required for Group 4 medulloblastoma. Given the lack of PRDM6 expression in normal tissues and its oncogenic potential shown here, we suggest that PRDM6 inhibition may have therapeutic value in PRDM6-expressing medulloblastomas.
Assuntos
Cromatina , Meduloblastoma , Animais , Humanos , Linhagem Celular Tumoral , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/patologia , Cromatina/metabolismo , Cromatina/genética , Regulação Neoplásica da Expressão Gênica , Histona-Lisina N-Metiltransferase/metabolismo , Histona-Lisina N-Metiltransferase/genética , Histonas/metabolismo , Meduloblastoma/genética , Meduloblastoma/metabolismo , Meduloblastoma/patologia , Células Neuroepiteliais/metabolismoRESUMO
Survival of Medulloblastoma (MB) depends on various factors, including the gene expression profiles of MB tumor tissues. In this study, we identified 967 MB survival-related genes (SRGs) using a gene expression dataset and the Cox proportional hazards regression model. Notably, the SRGs were over-represented on chromosomes 6 and 17, known for the abnormalities monosomy 6 and isochromosome 17 in MB. The most significant SRG was HMGA1 (high mobility group AT-hook 1) on chromosome 6, which is a known oncogene and a histone H1 competitor. High expression of HMGA1 was associated with worse survival, primarily in the Group 3γ subtype. The high expression of HMGA1 was unrelated to any known somatic copy number alteration. Most SRGs on chromosome 17p were associated with low expression in Group 4ß, the MB subtype, with 93% deletion of 17p and 98% copy gain of 17q. GO enrichment analysis showed that both chromosomes 6 and 17 included SRGs related to telomere maintenance and provided a rationale for testing telomerase inhibitors in Group 3 MBs. We conclude that HMGA1, along with other SRGs on chromosomes 6 and 17, warrant further investigation as potential therapeutic targets in selected subgroups or subtypes of MB.
Assuntos
Cromossomos Humanos Par 17 , Cromossomos Humanos Par 6 , Meduloblastoma , Humanos , Meduloblastoma/genética , Meduloblastoma/mortalidade , Meduloblastoma/patologia , Cromossomos Humanos Par 17/genética , Cromossomos Humanos Par 6/genética , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/mortalidade , Neoplasias Cerebelares/patologia , Regulação Neoplásica da Expressão Gênica , Variações do Número de Cópias de DNA , Proteína HMGA1a/genética , Proteína HMGA1a/metabolismo , Feminino , Perfilação da Expressão GênicaRESUMO
Recent incorporation of the four primary medulloblastoma subgroups into the WHO Classification of Central Nervous System Tumors necessitates globally accessible methods to discern subgroups. In this issue of Cancer Cell, Wang et al. develop a rapid and reliable machine learning workflow for pre-operative subgroup determination using routine magnetic resonance imaging.
Assuntos
Neoplasias Cerebelares , Meduloblastoma , Meduloblastoma/patologia , Meduloblastoma/classificação , Meduloblastoma/genética , Meduloblastoma/diagnóstico por imagem , Humanos , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/classificação , Neoplasias Cerebelares/diagnóstico por imagem , Neoplasias Cerebelares/genética , Imageamento por Ressonância Magnética/métodos , Aprendizado de MáquinaRESUMO
Medulloblastomas (MBs) are malignant pediatric brain tumors that are molecularly and clinically heterogenous. The application of omics technologies-mainly studying nucleic acids-has significantly improved MB classification and stratification, but treatment options are still unsatisfactory. The proteome and their N-glycans hold the potential to discover clinically relevant phenotypes and targetable pathways. We compile a harmonized proteome dataset of 167 MBs and integrate findings with DNA methylome, transcriptome and N-glycome data. We show six proteome MB subtypes, that can be assigned to two main molecular programs: transcription/translation (pSHHt, pWNT and pG3myc), and synapses/immunological processes (pSHHs, pG3 and pG4). Multiomic analysis reveals different conservation levels of proteome features across MB subtypes at the DNA methylome level. Aggressive pGroup3myc MBs and favorable pWNT MBs are most similar in cluster hierarchies concerning overall proteome patterns but show different protein abundances of the vincristine resistance-associated multiprotein complex TriC/CCT and of N-glycan turnover-associated factors. The N-glycome reflects proteome subtypes and complex-bisecting N-glycans characterize pGroup3myc tumors. Our results shed light on targetable alterations in MB and set a foundation for potential immunotherapies targeting glycan structures.
Assuntos
Meduloblastoma , Polissacarídeos , Proteoma , Meduloblastoma/metabolismo , Meduloblastoma/genética , Humanos , Polissacarídeos/metabolismo , Proteoma/metabolismo , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/genética , Metilação de DNA , Transcriptoma , Criança , Proteômica/métodos , Feminino , Regulação Neoplásica da Expressão Gênica , Masculino , Pré-Escolar , Perfilação da Expressão Gênica/métodosRESUMO
Medulloblastoma is the most common pediatric brain cancer, with about five cases per million in the pediatric population. Current treatment strategies have a 5-year survival rate of 70% or more but frequently lead to long-term neurocognitive defects, and recurrence is relatively high. Genomic sequencing of medulloblastoma patients has shown that DDX3X, which encodes an RNA helicase involved in the process of translation initiation, is among the most commonly mutated genes in medulloblastoma. The identified mutations are 42 single-point amino acid substitutions and are mostly not complete loss-of-function mutations. The pathological mechanism of DDX3X mutations in the causation of medulloblastoma is poorly understood, but several studies have examined their role in promoting cancer progression. This review first discusses the known roles of DDX3X and its yeast ortholog Ded1 in translation initiation, cellular stress responses, viral replication, innate immunity, inflammatory programmed cell death, Wnt signaling, and brain development. It then examines our current understanding of the oncogenic mechanism of the DDX3X mutations in medulloblastoma, including the effect of these DDX3X mutations on growth, biochemical functions, translation, and stress responses. Further research on DDX3X's mechanism and targets is required to therapeutically target DDX3X and/or its downstream effects in medulloblastoma progression.
Assuntos
RNA Helicases DEAD-box , Progressão da Doença , Meduloblastoma , Mutação , Humanos , Meduloblastoma/genética , Meduloblastoma/patologia , Meduloblastoma/metabolismo , RNA Helicases DEAD-box/genética , RNA Helicases DEAD-box/metabolismo , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/metabolismo , Animais , Proteínas de Saccharomyces cerevisiaeRESUMO
Carbon ion radiotherapy (CIRT) for pediatric cancer is currently limited because of the unknown risk of induction of secondary cancers. Medulloblastoma of Ptch1+/- mice offers a unique experimental system for radiation-induced carcinogenesis, in which tumors are classified into spontaneous and radiation-induced subtypes based on their features of loss of heterozygosity (LOH) that affect the wild-type Ptch1 allele. The present study aims to investigate in young Ptch1+/- mice the carcinogenic effect, and its age dependence, of the low-linear energy transfer (LET, â¼13 keV/µm) carbon ions, to which normal tissues in front of the tumor are exposed during therapy. We irradiated Ptch1+/- mice at postnatal day (P) 1, 4, or 10 with 290 MeV/u carbon ions (0.05-0.5 Gy; LET, 13 keV/µm) and monitored them for medulloblastoma development. Loss of heterozygosity of seven genetic markers on chromosome 13 (where Ptch1 resides) was studied to classify the tumors. Carbon ion exposure induced medulloblastoma most effectively at P1. The LOH patterns of tumors were either telomeric or interstitial, the latter occurring almost exclusively in the irradiated groups, allowing the use of interstitial LOH as a biomarker of radiation-induced tumors. Radiation-induced tumors developed during a narrow age window (most strongly at P1 and only moderately at P4, with suppressed tumorigenesis at P10). Calculated using previous results using 137Cs gamma rays, the values for relative biological effectiveness (RBE) regarding radiation-induced tumors were 4.1 (3.4, 4.8) and 4.3 (3.3, 5.2) (mean and 95% confidence interval) for exposure at P1 and 4, respectively. Thus, the RBE of carbon ions for medulloblastoma induction in Ptch1+/- mice was higher than the generally recognized RBE of 1-2 for cell killing, chromosome aberrations, and skin reactions.
Assuntos
Deleção Cromossômica , Meduloblastoma , Receptor Patched-1 , Eficiência Biológica Relativa , Animais , Meduloblastoma/radioterapia , Meduloblastoma/genética , Meduloblastoma/patologia , Receptor Patched-1/genética , Camundongos , Radioterapia com Íons Pesados , Neoplasias Induzidas por Radiação/genética , Transferência Linear de Energia , Perda de Heterozigosidade/efeitos da radiação , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/radioterapia , Neoplasias Cerebelares/patologia , CarbonoRESUMO
Development of the cerebellum requires precise regulation of granule neuron progenitor (GNP) proliferation. Although it is known that primary cilia are necessary to support GNP proliferation, the exact molecular mechanism governing primary cilia dynamics within GNPs remains elusive. Here, we establish the pivotal roles for the centrosomal kinase TTBK2 (Tau tubulin kinase-2) and the E3 ubiquitin ligase HUWE1 in GNP proliferation. We show that TTBK2 is highly expressed in proliferating GNPs under Sonic Hedgehog (SHH) signaling, coinciding with active GNP proliferation and the presence of primary cilia. TTBK2 stabilizes primary cilia by inhibiting their disassembly, thereby promoting GNP proliferation in response to SHH. Mechanistically, we identify HUWE1 as a novel centrosomal E3 ligase that facilitates primary cilia disassembly by targeting TTBK2 degradation. Disassembly of primary cilia serves as a trigger for GNP differentiation, allowing their migration from the external granule layer (EGL) of the cerebellum to the internal granule layer (IGL) for subsequent maturation. Moreover, we have established a link between TTBK2 and SHH-type medulloblastoma (SHH-MB), a tumor characterized by uncontrolled GNP proliferation. TTBK2 depletion inhibits SHH-MB proliferation, indicating that TTBK2 may be a potential therapeutic target for this cancer type. In summary, our findings reveal the mechanism governing cerebellar development and highlight a potential anti-cancer strategy for SHH-MB.
Assuntos
Proliferação de Células , Cerebelo , Cílios , Proteínas Hedgehog , Meduloblastoma , Proteínas Serina-Treonina Quinases , Proteínas Supressoras de Tumor , Ubiquitina-Proteína Ligases , Meduloblastoma/patologia , Meduloblastoma/metabolismo , Meduloblastoma/genética , Cílios/metabolismo , Animais , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genética , Cerebelo/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Humanos , Proteínas Hedgehog/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Proteínas Supressoras de Tumor/genética , Camundongos , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/genética , Diferenciação Celular , Células-Tronco Neurais/metabolismoRESUMO
Medulloblastoma (MB) stands as one of the prevalent malignant brain tumors among pediatric patients. Despite its prevalence, the intricate interplay between the regulatory program driving malignancy in MB cells and their interactions with the microenvironment remains insufficiently understood. Leveraging the capabilities of single-cell Assay for Transposase-Accessible Chromatin sequencing (scATAC-seq), the chromatin accessibility landscape is unveiled across 59,015 distinct MB cells. This expansive dataset encompasses cells belonging to discrete molecular subgroups, namely SHH, WNT, Group3, and Group4. Within these chromatin accessibility profiles, specific regulatory elements tied to individual subgroups are uncovered, shedding light on the distinct activities of transcription factors (TFs) that likely orchestrate the tumorigenesis process. Moreover, it is found that certain neurotransmitter receptors (NTRs) are subgroup-specific and can predict MB subgroup classification when combined with their associated transcription factors. Notably, targeting essential NTRs within tumors influences both the in vitro sphere-forming capability and the in vivo tumorigenic capacity of MB cells. These findings collectively provide fresh insights into comprehending the regulatory networks and cellular dynamics within MBs. Furthermore, the significance of the TF-NTR regulatory circuits is underscored as prospective biomarkers and viable therapeutic targets.
Assuntos
Neoplasias Cerebelares , Cromatina , Meduloblastoma , Análise de Célula Única , Fatores de Transcrição , Meduloblastoma/genética , Meduloblastoma/metabolismo , Humanos , Análise de Célula Única/métodos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Cromatina/metabolismo , Cromatina/genética , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/patologia , Camundongos , Animais , Linhagem Celular TumoralRESUMO
BACKGROUND: Central nervous system hemangioblastomas are the most prevalent manifestation of von Hippel-Lindau (VHL) disease and remain the main cause of mortality. Surgical resection is the primary treatment strategy, but is not always possible, and should be used as restrictively as possible. There is an unmet need for less invasive treatment strategies, such as targeted therapy. Expression of somatostatin receptor 2A (SSTR2A) in VHL-related hemangioblastomas has been described earlier, but the extent of expression in a larger population has yet to be determined. The authors hypothesize that a substantial subset of VHL-related hemangioblastomas show SSTR2A expression, which may serve as a potential new treatment target. METHODS: Patients who were surgically treated for a VHL-related hemangioblastoma from 1990 until 2021 at the UMC Utrecht were included. Clinical data was derived from a clinical database. Tissue samples were histopathologically examined with use of hematoxylin and eosin staining, and immunohistochemical analysis of SSTR2A expression was performed. RESULTS: Forty-three tissue samples were obtained from 26 patients. Nine showed strong positivity for SSTR2A expression, whereas 13 showed moderate and 15 sparse expression. Three samples showed no expression of SSTR2A. The distribution showed right-skewedness favoring a strong expression. SSTR2A expression colocalized with endothelial markers and not with stromal cells. Additionally, within-patient variability for SSTR2A expression was described in 14 patients. CONCLUSION: SSTR2A is expressed in varying degrees in the majority of VHL-related hemangioblastomas. Future treatment with somatostatin analogues or even peptide receptor radionuclide treatment may be considered for SSTR2A-positive cases.
Assuntos
Hemangioblastoma , Receptores de Somatostatina , Doença de von Hippel-Lindau , Humanos , Receptores de Somatostatina/metabolismo , Hemangioblastoma/metabolismo , Hemangioblastoma/patologia , Doença de von Hippel-Lindau/complicações , Doença de von Hippel-Lindau/patologia , Doença de von Hippel-Lindau/genética , Doença de von Hippel-Lindau/metabolismo , Feminino , Adulto , Masculino , Pessoa de Meia-Idade , Idoso , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/patologia , Neoplasias Cerebelares/genética , Adulto Jovem , Imuno-HistoquímicaRESUMO
BACKGROUND: Certain paediatric nervous system malignancies have dismal prognoses. Retinoic acid (RA) is used in neuroblastoma treatment, and preclinical data indicate potential benefit in selected paediatric brain tumour entities. However, limited single-agent efficacy necessitates combination treatment approaches. METHODS: We performed drug sensitivity profiling of 76 clinically relevant drugs in combination with RA in 16 models (including patient-derived tumouroids) of the most common paediatric nervous system tumours. Drug responses were assessed by viability assays, high-content imaging, and apoptosis assays and RA relevant pathways by RNAseq from treated models and patient samples obtained through the precision oncology programme INFORM (n = 2288). Immunoprecipitation detected BCL-2 family interactions, and zebrafish embryo xenografts were used for in vivo efficacy testing. RESULTS: Group 3 medulloblastoma (MBG3) and neuroblastoma models were highly sensitive to RA treatment. RA induced differentiation and regulated apoptotic genes. RNAseq analysis revealed high expression of BCL2L1 in MBG3 and BCL2 in neuroblastomas. Co-treatments with RA and BCL-2/XL inhibitor navitoclax synergistically decreased viability at clinically achievable concentrations. The combination of RA with navitoclax disrupted the binding of BIM to BCL-XL in MBG3 and to BCL-2 in neuroblastoma, inducing apoptosis in vitro and in vivo. CONCLUSIONS: RA treatment primes MBG3 and NB cells for apoptosis, triggered by navitoclax cotreatment.