Project description:Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a heterogeneous group of malignancies with poor outcome. Here we have identified a subgroup of SMARCB1 deficient PTCL-NOS, which is characterized by the lack of the SMARCB1 protein and is more common in young patients. Human and murine Smarcb1-negative PTCL-NOS from a corresponding mouse model show similar DNA methylation profiles, with hypermethylation of T-cell-related genes and hypomethylation of genes involved in myeloid development.
Project description:SMARCB1 (Snf5/Ini1/Baf47) is a potent tumor suppressor, the loss of which serves as the diagnostic feature in Malignant Rhabdoid Tumors (MRT) and Atypical Teratoid/Rhabdoid Tumors (AT/RT), two highly aggressive forms of pediatric neoplasms. Here, we restore Smarcb1 expression in cells derived from Smarcb1-deficient tumors which developed in Smarcb1-heterozygous p53-/- mice. Profiling Smarcb1 dependent gene expression we find genes which are dependent on Smarcb1 expression to be enriched for ECM and cell adhesion functions. We identify Igfbp7, which is related to the insulin-like growth factor binding proteins family, as a downstream target of Smarcb1 transcriptional activity, and show that re-introduction of Igfbp7 alone can hinder tumor development. Two cancer cell lines, 167 and 365, derived from Smarcb1-deficient tumors which developed in Smarcb1-heterozygous p53-/- mice were re-infected with a retro-viral vector for Smarcb1 re-expression or an empty retro-viral vector as control. Total-RNA was collected 3 days post infection so as to enrich for direct targets of Smarcb1 transcriptionaly regulated genes
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: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:SMARCB1 (Snf5/Ini1/Baf47) is a potent tumor suppressor, the loss of which serves as the diagnostic feature in Malignant Rhabdoid Tumors (MRT) and Atypical Teratoid/Rhabdoid Tumors (AT/RT), two highly aggressive forms of pediatric neoplasms. Here, we restore Smarcb1 expression in cells derived from Smarcb1-deficient tumors which developed in Smarcb1-heterozygous p53-/- mice. Profiling Smarcb1 dependent gene expression we find genes which are dependent on Smarcb1 expression to be enriched for ECM and cell adhesion functions. We identify Igfbp7, which is related to the insulin-like growth factor binding proteins family, as a downstream target of Smarcb1 transcriptional activity, and show that re-introduction of Igfbp7 alone can hinder tumor development.
Project description:Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a heterogeneous group of malignancies with poor outcome. Here we identified a subgroup, PTCL-NOS SMARCB1-, which is characterized by the lack of SMARCB1 protein expression and is more common in young patients under 25 years of age. To investigate the cellular heterogeneity of PTCL-NOS SMARCB1- and the role of its tumor microenvironment, we performed single-nuclei RNA sequencing (snRNA-seq) of five patient samples.
Project description:Ataxia-telangiectasia mutated (ATM) kinase plays a central role in maintaining genomic integrity. In both humans and mice, ATM deficiency is associated with an increased incidence of lymphoid cancers that are primarily T cell in origin. We demonstrate here that when T cells are removed as targets for lymphomagenesis and as mediators of immune surveillance, ATM-deficient mice exclusively develop early onset IgM+ B cell lymphomas that by histology and gene expression profiling resemble the activated B cell-like (ABC) subset of human diffuse large B cell lymphomas (DLBCL). These ATM-deficient B cell tumors show considerable chromosomal instability and a recurrent genomic amplification of a 4.48 Mb region on chromosome 18 that contains Malt1 and is orthologous to a region similarly amplified in human ABC-DLBCL. Further, the amplification of Malt1 in these lymphomas correlates with their dependence on NF-kB, MALT1, and BCR signaling for survival, paralleling human ABC-DLBCL. This study reveals that ATM protects against development of B cell lymphomas that model human ABC-DLBCL and identifies a role for T cells in preventing the emergence of these tumors.
Project description:SMARCB1, a subunit of the SWI/SNF chromatin remodeling complex, is the causative gene of rhabdoid tumors and epithelioid sarcomas. Here, we identify a paralog pair of CBP and p300 as a synthetic lethal target in SMARCB1-deficient cancers by using a dual siRNA screening method based on the “simultaneous inhibition of a paralog pair” concept. Treatment with CBP/p300 dual inhibitors suppresses growth of cell lines and tumor xenografts derived from SMARCB1-deficient cells but not from SMARCB1-proficient cells. SMARCB1-containing SWI/SNF complexes localize with H3K27me3 and its methyltransferase EZH2 at the promotor region of the KREMEN2 locus, resulting in transcriptional downregulation of KREMEN2. By contrast, SMARCB1 deficiency leads to localization of H3K27ac, and recruitment of its acetyltransferases CBP and p300, at the KREMEN2 locus, resulting in transcriptional upregulation of KREMEN2, which cooperates with the SMARCA1 chromatin remodeling complex. Simultaneous inhibition of CBP/p300 leads to transcriptional downregulation of KREMEN2, followed by apoptosis induction via monomerization of KREMEN1 due to a failure to interact with KREMEN2, which suppresses anti-apoptotic signaling pathways. Taken together, our findings indicate that simultaneous inhibitors of CBP/p300 could be promising therapeutic agents for SMARCB1-deficient cancers.