| 1. |
- Northcott, Paul A, et al.
(författare)
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Enhancer hijacking activates GFI1 family oncogenes in medulloblastoma.
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 511:7510, s. 428-428
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Tidskriftsartikel (refereegranskat)abstract
- Medulloblastoma is a highly malignant paediatric brain tumour currently treated with a combination of surgery, radiation and chemotherapy, posing a considerable burden of toxicity to the developing child. Genomics has illuminated the extensive intertumoral heterogeneity of medulloblastoma, identifying four distinct molecular subgroups. Group 3 and group 4 subgroup medulloblastomas account for most paediatric cases; yet, oncogenic drivers for these subtypes remain largely unidentified. Here we describe a series of prevalent, highly disparate genomic structural variants, restricted to groups 3 and 4, resulting in specific and mutually exclusive activation of the growth factor independent 1 family proto-oncogenes, GFI1 and GFI1B. Somatic structural variants juxtapose GFI1 or GFI1B coding sequences proximal to active enhancer elements, including super-enhancers, instigating oncogenic activity. Our results, supported by evidence from mouse models, identify GFI1 and GFI1B as prominent medulloblastoma oncogenes and implicate 'enhancer hijacking' as an efficient mechanism driving oncogene activation in a childhood cancer.
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| 2. |
- Bolin, Sara, 1988-, et al.
(författare)
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Dormant SOX9-positive cells behind MYC-driven medulloblastoma recurrence
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Tidskriftsartikel (refereegranskat)abstract
- Tumor recurrence is a slow biological process involving therapy resistance, immune escape, and metastasis and is the leading cause of death in medulloblastoma, the most frequent malignant pediatric brain tumor. By studying paired primary-recurrent patient samples and patient-derived xenografts we identified a significant accumulation of SOX9-positive cells in relapses and metastases. They exist as rare, quiescent cells in Group 3 and Group 4 patients that constitute two-thirds of medulloblastoma. To follow relapse at the single-cell level we developed an inducible dual Tet model of MYC-driven MB, where MYC can be directed from treatment-sensitive bulk cells to resistant, dormant SOX9-positive cells by doxycycline. SOX9 promoted immune es-cape, DNA repair suppression and was essential for recurrence. Tumor cell dormancy was non-hierarchical, migratory, and depended on MYC suppression by SOX9 to promote relapse. By using computational modeling and treatment we further showed how doxorubicin and MGMT inhibitors are specifically targeting relapsing cells.
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| 3. |
- Borgenvik, Anna, 1987-, et al.
(författare)
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Dormant SOX9-Positive Cells Facilitate MYC-Driven Recurrence of Medulloblastoma
- 2022
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Ingår i: Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 0008-5472 .- 1538-7445. ; 82:24, s. 4586-4603
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Tidskriftsartikel (refereegranskat)abstract
- Relapse is the leading cause of death in patients with medulloblas-toma, the most common malignant pediatric brain tumor. A better understanding of the mechanisms underlying recurrence could lead to more effective therapies for targeting tumor relapses. Here, we observed that SOX9, a transcription factor and stem cell/glial fate marker, is limited to rare, quiescent cells in high-risk medulloblastoma with MYC amplification. In paired primary-recurrent patient samples, SOX9-positive cells accumulated in medulloblastoma relapses. SOX9 expression anti-correlated with MYC expression in murine and human medulloblastoma cells. However, SOX9-positive cells were plastic and could give rise to a MYC high state. To follow relapse at the single-cell level, an inducible dual Tet model of medulloblastoma was developed, in which MYC expression was redirected in vivo from treatment-sensitive bulk cells to dormant SOX9-positive cells using doxycycline treatment. SOX9 was essential for relapse initiation and depended on suppression of MYC activity to promote therapy resistance, epithelial-mesenchymal transition, and immune escape. p53 and DNA repair pathways were downregulated in recurrent tumors, whereas MGMT was upregulated. Recurrent tumor cells were found to be sensitive to treatment with an MGMT inhibitor and doxorubicin. These findings suggest that recurrence-specific targeting coupled with DNA repair inhibition comprises a potential therapeutic strategy in patients affected by medulloblastoma relapse.Significance: SOX9 facilitates therapy escape and recurrence in medulloblastoma via temporal inhibition of MYC/MYCN genes, revealing a strategy to specifically target SOX9-positive cells to prevent tumor relapse.
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| 4. |
- Ferrucci, Veronica, et al.
(författare)
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Metastatic group 3 medulloblastoma is driven by PRUNE1 targeting NME1–TGF-β–OTX2–SNAIL via PTEN inhibitio
- 2018
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 141:5, s. 1300-1319
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Tidskriftsartikel (refereegranskat)abstract
- Genetic modifications during development of paediatric groups 3 and 4 medulloblastoma are responsible for their highly metastatic properties and poor patient survival rates. PRUNE1 is highly expressed in metastatic medulloblastoma group 3, which is characterized by TGF-β signalling activation, c-MYC amplification, and OTX2 expression. We describe the process of activation of the PRUNE1 signalling pathway that includes its binding to NME1, TGF-β activation, OTX2 upregulation, SNAIL (SNAI1) upregulation, and PTEN inhibition. The newly identified small molecule pyrimido-pyrimidine derivative AA7.1 enhances PRUNE1 degradation, inhibits this activation network, and augments PTEN expression. Both AA7.1 and a competitive permeable peptide that impairs PRUNE1/NME1 complex formation, impair tumour growth and metastatic dissemination in orthotopic xenograft models with a metastatic medulloblastoma group 3 cell line (D425-Med cells). Using whole exome sequencing technology in metastatic medulloblastoma primary tumour cells, we also define 23 common ‘non-synonymous homozygous’ deleterious gene variants as part of the protein molecular network of relevance for metastatic processes. This PRUNE1/TGF-β/OTX2/PTEN axis, together with the medulloblastoma-driver mutations, is of relevance for future rational and targeted therapies for metastatic medulloblastoma group 3.
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| 5. |
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| 6. |
- Gudrunardottir, Thora, et al.
(författare)
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Treatment developments and the unfolding of the quality of life discussion in childhood medulloblastoma: a review.
- 2014
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Ingår i: Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery. - : Springer Science and Business Media LLC. - 1433-0350. ; 30:6, s. 979-990
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Forskningsöversikt (refereegranskat)abstract
- To describe how the quality of life (QOL) discussion in childhood medulloblastoma (MB) relates to treatment developments, survival and sequelae from 1920 to 2014. Articles containing "childhood medulloblastoma" and "quality of life" were identified in PubMed. Those containing phrases pertaining to psychological, emotional, behavioral or social adjustment in the title, abstract or keywords were selected. Inclusion of relevant older publications was assured by cross-checking references. 1920-1930s: suction, electro-surgery, kilovolt (KV) irradiation. Survival = months. Focus on operative mortality, symptoms and survival. 1940s: radiotherapy improved. 1950s: chemotherapy and intubation. Survival = years. Opinions oscillated between optimism/awareness of physical sequelae of radiotherapy. 1960s: magnified vision, ventriculo-peritoneal (VP) shunts, megavolt (MV) irradiation. Long-term survival shifted the attention towards neurological problems, disability and carcinogenesis of radiotherapy. 1970s: CT, microscope, bipolar coagulation, shunt filters, neuroanesthesia, chemotherapy trials and staging studies. Operative mortality decreased and many patients (re)entered school; emphasis on neuropsychological sequelae, IQ and academic performance. 1980s: magnetic resonance imaging (MRI), Cavitron ultrasonic aspiration (CUSA), laser surgery, hyper-fractionated radiotherapy (HFRT). Cerebellar mutism, psychological and social issues. 1990s: pediatric neurosurgery, proton beams, stem cell rescue. Reflections on QOL as such. 21st century: molecular genetics. Premature aging, patterns of decline, risk- and resilience factors. QOL is a critical outcome measure. Focus depends on survival and sequelae, determined after years of follow-up. Detailed measurements are limited by time, money and human resources, and self-reporting questionnaires represent a crude measure limited by subjectivity. Therapeutic improvements raise the question of QOL versus cure. QOL is a potential primary research endpoint; multicenter international studies are needed, as are web-based tools that work across cultures.
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| 7. |
- Mangerel, Joshua, et al.
(författare)
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Alternative lengthening of telomerases is enriched in, and impacts survival of TP53 mutant pediatric malignant brain tumors
- 2014
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Ingår i: Acta Neuropathologica. - : Springer Science and Business Media LLC. - 0001-6322 .- 1432-0533. ; 128:6, s. 853-862
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Tidskriftsartikel (refereegranskat)abstract
- Although telomeres are maintained in most cancers by telomerase activation, a subset of tumors utilize alternative lengthening of telomeres (ALT) to sustain self-renewal capacity. In order to study the prevalence and significance of ALT in childhood brain tumors we screened 517 pediatric brain tumors using the novel C-circle assay. We examined the association of ALT with alterations in genes found to segregate with specific histological phenotypes and with clinical outcome. ALT was detected almost exclusively in malignant tumors (p = 0.001). ALT was highly enriched in primitive neuroectodermal tumors (12 %), choroid plexus carcinomas (23 %) and high-grade gliomas (22 %). Furthermore, in contrast to adult gliomas, pediatric low grade gliomas which progressed to high-grade tumors did not exhibit the ALT phenotype. Somatic but not germline TP53 mutations were highly associated with ALT (p = 1.01 × 10(-8)). Of the other alterations examined, only ATRX point mutations and reduced expression were associated with the ALT phenotype (p = 0.0005). Interestingly, ALT attenuated the poor outcome conferred by TP53 mutations in specific pediatric brain tumors. Due to very poor prognosis, one year overall survival was quantified in malignant gliomas, while in children with choroid plexus carcinoma, five year overall survival was investigated. For children with TP53 mutant malignant gliomas, one year overall survival was 63 ± 12 and 23 ± 10 % for ALT positive and negative tumors, respectively (p = 0.03), while for children with TP53 mutant choroid plexus carcinomas, 5 years overall survival was 67 ± 19 and 27 ± 13 % for ALT positive and negative tumors, respectively (p = 0.07). These observations suggest that the presence of ALT is limited to a specific group of childhood brain cancers which harbor somatic TP53 mutations and may influence the outcome of these patients. Analysis of ALT may contribute to risk stratification and targeted therapies to improve outcome for these children.
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| 8. |
- Niklison-Chirou, Maria Victoria, et al.
(författare)
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TAp73 is a marker of glutamine addiction in medulloblastoma
- 2017
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Ingår i: Genes & Development. - : COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT. - 0890-9369 .- 1549-5477. ; 31:17, s. 1738-1753
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Tidskriftsartikel (refereegranskat)abstract
- Medulloblastoma is the most common solid primary brain tumor in children. Remarkable advancements in the understanding of the genetic and epigenetic basis of these tumors have informed their recent molecular classification. However, the genotype/phenotype correlation of the subgroups remains largely uncharacterized. In particular, the metabolic phenotype is of great interest because of its druggability, which could lead to the development of novel and more tailored therapies for a subset of medulloblastoma. p73 plays a critical role in a range of cellular metabolic processes. We show overexpression of p73 in a proportion of non-WNT medulloblastoma. In these tumors, p73 sustains cell growth and proliferation via regulation of glutamine metabolism. We validated our results in a xenograft model in which we observed an increase in survival time in mice on a glutamine restriction diet. Notably, glutamine starvation has a synergistic effect with cisplatin, a component of the current medulloblastoma chemotherapy. These findings raise the possibility that glutamine depletion can be used as an adjuvant treatment for p73-expressing medulloblastoma.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Zhukova, Nataliya, et al.
(författare)
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WNT activation by lithium abrogates TP53 mutation associated radiation resistance in medulloblastoma
- 2014
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Ingår i: Acta neuropathologica communications. - : Springer Science and Business Media LLC. - 2051-5960. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- TP53 mutations confer subgroup specific poor survival for children with medulloblastoma. We hypothesized that WNT activation which is associated with improved survival for such children abrogates TP53 related radioresistance and can be used to sensitize TP53 mutant tumors for radiation. We examined the subgroup-specific role of TP53 mutations in a cohort of 314 patients treated with radiation. TP53 wild-type or mutant human medulloblastoma cell-lines and normal neural stem cells were used to test radioresistance of TP53 mutations and the radiosensitizing effect of WNT activation on tumors and the developing brain. Children with WNT/TP53 mutant medulloblastoma had higher 5-year survival than those with SHH/TP53 mutant tumours (100% and 36.6%±8.7%, respectively (p<0.001)). Introduction of TP53 mutation into medulloblastoma cells induced radioresistance (survival fractions at 2Gy (SF2) of 89%±2% vs. 57.4%±1.8% (p<0.01)). In contrast, beta-catenin mutation sensitized TP53 mutant cells to radiation (p<0.05). Lithium, an activator of the WNT pathway, sensitized TP53 mutant medulloblastoma to radiation (SF2 of 43.5%±1.5% in lithium treated cells vs. 56.6±3% (p<0.01)) accompanied by increased number of gammaH2AX foci. Normal neural stem cells were protected from lithium induced radiation damage (SF2 of 33%±8% for lithium treated cells vs. 27%±3% for untreated controls (p=0.05). Poor survival of patients with TP53 mutant medulloblastoma may be related to radiation resistance. Since constitutive activation of the WNT pathway by lithium sensitizes TP53 mutant medulloblastoma cells and protect normal neural stem cells from radiation, this oral drug may represent an attractive novel therapy for high-risk medulloblastomas.
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