Project description:Medulloblastoma (MB) is the most prevalent pediatric cerebral cancer, but is rare in adults. The vast majority of MB arises sporadically but some few cases occur in association with germline alterations in genes such as PTCH1, SUFU, APC, and TP53. Additional genes are responsible for MB predisposition including some that have probably not been described so far either due to the rarity of the cases and/or to the low penetrance. Here we report the case of a 27 years old woman affected by Pitt Hopkins syndrome due to a heterozygous germline pathogenic variant in TCF4 who has developed a Sonic Hedgehog (SHH)-driven MB. Somatic loss of function variants of TCF4 have been identified in SHH MB especially among adults and this case raises the question of a predisposition to late-onset SHH MB associated with TCF4 germline alteration.
Project description:Germline loss-of-function (LOF) variants in Elongator complex protein 1 (ELP1) are the most prevalent predisposing genetic events in childhood medulloblastoma (MB), accounting for ~30% of the Sonic Hedgehog (SHH) 3 subtype. The underlying mechanism(s) by which germline ELP1 deficiency provokes SHH-MB pathogenesis remain unknown. Genetically engineered mice mimicking heterozygous germline Elp1 LOF (Elp1HET) seen in affected germline carriers exhibit hallmark features of cancer predisposition in cerebellar granule neuron progenitors (GNPs), including increased DNA replication stress, genomic instability, accelerated cell cycle, and stalled differentiation. Orthotopic transplantation of Elp1HET GNPs harboring somatic Ptch1 inactivation yielded SHH-MB-like tumors with compromised p53 signaling, providing an explanation for the exclusivity of ELP1-associated MBs in SHH-3 subtype. Preclinical treatment of ELP1-mutant patient-derived xenografts with an FDA-approved HDM2 inhibitor reactivated p53-dependent apoptosis and extended survival. Our findings functionally substantiate the role of ELP1 deficiency in SHH-MB predisposition and nominate therapeutics that overcome p53 inhibition as a rational treatment option.
Project description:Germline loss-of-function (LOF) variants in Elongator complex protein 1 (ELP1) are the most prevalent predisposing genetic events in childhood medulloblastoma (MB), accounting for ~30% of the Sonic Hedgehog (SHH) 3 subtype. The underlying mechanism(s) by which germline ELP1 deficiency provokes SHH-MB pathogenesis remain unknown. Genetically engineered mice mimicking heterozygous germline Elp1 LOF (Elp1HET) seen in affected germline carriers exhibit hallmark features of cancer predisposition in cerebellar granule neuron progenitors (GNPs), including increased DNA replication stress, genomic instability, accelerated cell cycle, and stalled differentiation. Orthotopic transplantation of Elp1HET GNPs harboring somatic Ptch1 inactivation yielded SHH-MB-like tumors with compromised p53 signaling, providing an explanation for the exclusivity of ELP1-associated MBs in SHH-3 subtype. Preclinical treatment of ELP1-mutant patient-derived xenografts with an FDA-approved HDM2 inhibitor reactivated p53-dependent apoptosis and extended survival. Our findings functionally substantiate the role of ELP1 deficiency in SHH-MB predisposition and nominate therapeutics that overcome p53 inhibition as a rational treatment option.
Project description:Germline loss-of-function (LOF) variants in Elongator complex protein 1 (ELP1) are the most prevalent predisposing genetic events in childhood medulloblastoma (MB), accounting for ~30% of the Sonic Hedgehog (SHH) 3 subtype. The underlying mechanism(s) by which germline ELP1 deficiency provokes SHH-MB pathogenesis remain unknown. Genetically engineered mice mimicking heterozygous Elp1 LOF (Elp1HET) seen in affected germline carriers exhibit hallmark features of cancer predisposition in cerebellar granule neuron progenitors (GNPs), including increased DNA replication stress, genomic instability, accelerated cell cycle, and stalled differentiation. Orthotopic transplantation of Elp1HET GNPs harboring somatic Ptch1 inactivation yielded SHH-MB-like tumors with compromised p53 signaling, providing an explanation for the exclusivity of ELP1-associated tumors in SHH-3. Preclinical treatment of ELP1-mutant patient-derived xenografts with an FDA-approved MDM2 inhibitor reactivated p53-dependent apoptosis and extended survival. Our findings functionally substantiate the role of ELP1 deficiency in SHH-MB predisposition and nominate therapeutics that overcome p53 inhibition as a rational treatment option.
Project description:Recurrent mutations in chromatin modifiers are specifically prevalent in adolescent or adult patients with Sonic Hedgehog-associated medulloblastoma (SHH MB). Here, we report that mutations in the acetyltransferase CREBBP have opposing effects during the development of the cerebellum, the primary site of origin of SHH MB. Our data reveal that loss of Crebbp in cerebellar granule neuron progenitors (GNPs) during embryonic development of mice compromises GNP development, in part by downregulation of brain-derived neurotrophic factor (Bdnf). Interestingly, concomitant cerebellar hypoplasia was also observed in patients with Rubinstein-Taybi syndrome, a congenital disorder caused by germline mutations of CREBBP. By contrast, loss of Crebbp in GNPs during postnatal development synergizes with oncogenic activation of SHH signaling to drive MB growth, thereby explaining the enrichment of somatic CREBBP mutations in SHH MB of adult patients. Together, our data provide novel insights into time-sensitive consequences of CREBBP mutations and corresponding associations with human diseases. We used microarrays to detail the global programme of gene expression underlying the knockout of Crebbp in murine Shh medulloblastoma, acutely induced at postnatal stages of development.
Project description:Medulloblastoma is the most common malignant brain tumor in children. Here we describe a medulloblastoma model using iPS cell-derived human neuroepithelial stem (NES) cells generated from a Gorlin syndrome patient carrying a germline mutation in the Sonic hedgehog (SHH) receptor PTCH1. We found that Gorlin NES cells formed tumors in mouse cerebellum mimicking human medulloblastoma. Re-transplantation of tumor-isolated NES (tNES) cells resulted in accelerated tumor formation, cells with reduced growth factor dependency, enhanced neurosphere formation in vitro, and increased sensitivity to Vismodegib. Using our model we identified LGALS1 to be a GLI target gene that is upregulated in both Gorlin tNES cells and SHH-subgroup of medulloblastoma patients. Taken together, we demonstrate that NES cells derived from Gorlin patients can be used as a resource to model medulloblastoma initiation and progression, and to identify novel putative targets.