ABSTRACT: An observational experiment to methylation profile 23 SMARCB1 negative primary tumours from patients diagnosed with Malignant Rhabdoid Tumours.
Project description:Extracranial rhabdoid tumours (ECRT) are an aggressive malignancy of infancy and early childhood. The vast majority of cases demonstrate inactivation of SMARCB1 (ECRT_SMARCB1) but, rarely, ECRT can harbour the alternative inactivation of SMARCA4 (ECRT_SMARCA4) instead of SMARCB1. To explore the place of ECRTSMARCA4 in the "rhabdoid tumour" spectrum, we generated and collected from previous studies genome-wide DNA methylation array data (n = 85) from Atypical/Teratoid Rhabdoid Tumours (ATRT), ECRT_SMARCB1, ECRT_SMARCA4 and small cell carcinomas of the ovary, hypercalcaemic type (SCCOHT) tumours. Using dimensionality reduction and unsupervised clustering approaches, our results demonstrate that ECRT_SMARCA4 display an intermediate DNA methylation profile between SCCOHT and ECRT_SMARCB1.
Project description:Rhabdoid Tumors (RT) are highly aggressive tumors that are frequently localized in the central nervous system (CNS) where they are termed atypical teratoid and rhabdoid tumors (ATRT). We generated conditional Smarcb1-deficient mouse model leads to CNS Smarcb1-deficient tumors. We used microarrays to compared gene expression profilings of various human and mouse tumors. Our data demonstrate that the Smarcb1-deficient mouse model recapitulates the diversity of human RT.
Project description:Germline mutations of the SMARCB1 gene predispose to two distinct tumor syndromes: rhabdoid tumor predisposition syndrome, with malignant pediatric tumors mostly developing in brain and kidney, and familial schwannomatosis, with adulthood benign tumors involving cranial and peripheral nerves. The mechanisms by which SMARCB1 germline mutations predispose to rhabdoid tumors versus schwannomas are still unknown. Here, to understand the origin of these two types of SMARCB1-associated tumors, we generated different tissue- and developmental stage-specific conditional knockout mice carrying Smarcb1 and/or Nf2 deletion. Smarcb1 loss in early neural crest was necessary to initiate tumorigenesis in the cranial nerves and meninges with typical histological features and molecular profiles of human rhabdoid tumors. By inducing Smarcb1 loss at later developmental stage in the Schwann cell lineage, in addition to biallelic Nf2 gene inactivation, we generated the first mouse model developing schwannomas with the same underlying gene mutations found in schwannomatosis patients.
Project description:Atypical teratoid rhabdoid tumour (ATRT) is a rare but highly aggressive undifferentiated solid tumour arising in the central nervous system and predominantly affecting infants and young children. ATRT is exclusively characterised by the inactivation of SMARCB1, a member of the SWI/SNF chromatin remodelling complex that is essential for the regulation of large sets of genes required for normal development and differentiation. Histone deacetylase inhibitors (HDACi) are a promising anticancer therapy and are able to mimic the normal acetylation functions of SMARCB1 in SMARCB1-deficient cells and drive multilineage differentiation in extracranial rhabdoid tumours. However, the potential efficacy of HDACi in ATRT is unknown. Here, we show that human ATRT cells are highly responsive to the HDACi panobinostat and that sustained treatment leads to growth arrest, increased cell senescence, decreased clonogenicity and induction of a neurogenesis gene expression profile. Furthermore, in an orthotopic ATRT xenograft model, continuous panobinostat treatment inhibits tumour growth, increases survival and drives neuronal differentiation as shown by the expression of the neuronal marker, TUJ1. Collectively, this preclinical study supports the therapeutic potential of panobinostat-mediated differentiation therapy for ATRT.
Project description:We have generated DNA methylation profiles for patient-derived malignant rhabdoid tumor organoids and re-expressed SMARCB1 to assess SMARCB1-dependent changes in DNA methylation
Project description:SMARCA4-deficient rhabdoid tumours show intermediate molecular features between SMARCB1-deficient rhabdoid tumours and small cell carcinomas of the ovary, hypercalcaemic type.