The fibroblast epigenome underlies SS18::SSX-mediated transformation in synovial sarcoma
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PROVIDER: PRJNA895363 | ENA |
REPOSITORIES: ENA
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Project description:Synovial sarcoma (SyS) is an aggressive soft-tissue malignancy that is characterized by a pathognomonic t(X;18)(p11.2;q11.2) translocation, which produces the fusion oncogene named SS18::SSX. Despite recent advancements in our understanding of synovial sarcoma biology, the cell-of-origin remains undefined. Here we employ a mesenchymal stromal cell (MSC) specific CreERT2 line to express SS18::SSX in fibroblasts and related cell types, resulting in 100% penetrant synovial sarcoma development in mice, with a median latency period of 16.2 ± 2.8 weeks. Murine tumours exhibit high concordance with human synovial sarcoma subtypes at the histological and molecular levels1. Genetic refinement of the cell-of-origin reveal that synovial sarcomas derive from a rare Hic1+ Pdgfra+ Lgr5+ fibroblastic population. Furthermore, comparative transcriptomic analysis reveals the acquisition of a transformed phenotype initiated by the loss of a mature fibroblastic profile and subsequent unmasking of an epigenetically embedded embryonic MSC program. Adult and embryonic MSCs exhibite overlapping H2AK119ub and H3K4me3/H3K27me3 (bivalent) histone marks, while SS18::SSX-mediated transformation culminates in the widespread loss of H3K27me3 at these genes and their consequent transcription. Collectively, these studies define a rare MSC context, conducive for SS18::SSX-mediated transformation, and demonstrate that SyS tumorigenesis involves the induction and maintenance of an embryonic-like MSC phenotype.
2025-09-11 | GSE216769 | GEO
Project description:Synovial sarcoma (SyS) is an aggressive soft-tissue malignancy that is characterized by a pathognomonic t(X;18)(p11.2;q11.2) translocation, which produces the fusion oncogene named SS18::SSX. Despite recent advancements in our understanding of synovial sarcoma biology, the cell-of-origin remains undefined. Here we employ a mesenchymal stromal cell (MSC) specific CreERT2 line to express SS18::SSX in fibroblasts and related cell types, resulting in 100% penetrant synovial sarcoma development in mice, with a median latency period of 16.2 ± 2.8 weeks. Murine tumours exhibit high concordance with human synovial sarcoma subtypes at the histological and molecular levels1. Genetic refinement of the cell-of-origin reveal that synovial sarcomas derive from a rare Hic1+ Pdgfra+ Lgr5+ fibroblastic population. Furthermore, comparative transcriptomic analysis reveals the acquisition of a transformed phenotype initiated by the loss of a mature fibroblastic profile and subsequent unmasking of an epigenetically embedded embryonic MSC program. Adult and embryonic MSCs exhibite overlapping H2AK119ub and H3K4me3/H3K27me3 (bivalent) histone marks, while SS18::SSX-mediated transformation culminates in the widespread loss of H3K27me3 at these genes and their consequent transcription. Collectively, these studies define a rare MSC context, conducive for SS18::SSX-mediated transformation, and demonstrate that SyS tumorigenesis involves the induction and maintenance of an embryonic-like MSC phenotype.
2025-09-11 | GSE213265 | GEO
Project description:The fibroblast epigenome underlies SS18::SSX-mediated transformation in synovial sarcoma
| PRJNA880292 | ENA
Project description:We analyzed the effects of cellular context on the function of the synovial sarcoma-specific fusion protein, SS18-SSX, using human pluripotent stem cells containing the drug-inducible SS18-SSX gene. To investigate the cell-type-dependent effecfts of SS18-SSX, we performed gene expression profiling experiments. Comparison of global gene expressions of hPSCs, hPSC-NCCs, and hPSC-MSCs with or without the inductuion of SS18-SSX2
2016-04-13 | E-GEOD-63895 | biostudies-arrayexpress
Project description:Synovial Sarcoma (SS) is driven by the SS18::SSX fusion oncoprotein and is ultimately refractory to therapeutic approaches. SS18::SSX alters ATP-dependent chromatin remodeling BAF (mammalian SWI/SNF) complexes, leading to the degradation of canonical (cBAF) complex and amplified presence of an SS18::SSX-containing non-canonical BAF (ncBAF or GBAF) that drives an SS-specific transcription program and tumorigenesis. We demonstrate that SS18::SSX activates the SUMOylation program and SSs are sensitive to the small molecule SAE1/2 inhibitor, TAK-981. Mechanistically, TAK-981 de-SUMOylates the cBAF/PBAF component, SMARCE1, stabilizing and restoring cBAF on chromatin, shifting away from SS18::SSX-driven transcription, resulting in DNA damage, cell death and tumor inhibition across both human and mouse SS tumor models. TAK-981 synergized with cytotoxic chemotherapy through increased DNA damage, leading to tumor regression. Targeting the SUMOylation pathway in SS restores cBAF complexes and blocks the SS18::SSX transcriptome, identifying a therapeutic vulnerability in SS.
2025-08-07 | PXD059936 | Pride
Project description:Gene fusions arising from chromosomal translocations are key oncogenic drivers in soft tissue sarcomas but little is known about how they exert their oncogenic effects. Our study explores the molecular mechanisms by which the SS18-SSX fusion oncoprotein subverts epigenetic mechanisms of gene regulation to drive synovial sarcoma. Using functional genomics, we identify KDM2B – a histone demethylase and core component of a non-canonical Polycomb Repressive Complex 1 (PRC1.1) – as selectively required for sustaining synovial sarcoma cell transformation. SS18-SSX physically interacts with PRC1.1 and co-associates with SWI/SNF and KDM2B complexes on unmethylated CpG islands genome-wide. Via KDM2B, SS18-SSX binds and aberrantly activates expression of a series of developmentally regulated transcription factors that would otherwise be targets of polycomb-mediated repression, which is restored upon KDM2B depletion leading to irreversible mesenchymal differentiation. Thus, SS18-SSX de-regulates developmental programs to drive transformation by hijacking a transcriptional repressive complex to aberrantly activate gene expression.
2018-03-01 | GSE108927 | GEO
Project description:Gene fusions arising from chromosomal translocations are key oncogenic drivers in soft tissue sarcomas but little is known about how they exert their oncogenic effects. Our study explores the molecular mechanisms by which the SS18-SSX fusion oncoprotein subverts epigenetic mechanisms of gene regulation to drive synovial sarcoma. Using functional genomics, we identify KDM2B – a histone demethylase and core component of a non-canonical Polycomb Repressive Complex 1 (PRC1.1) – as selectively required for sustaining synovial sarcoma cell transformation. SS18-SSX physically interacts with PRC1.1 and co-associates with SWI/SNF and KDM2B complexes on unmethylated CpG islands genome-wide. Via KDM2B, SS18-SSX binds and aberrantly activates expression of a series of developmentally regulated transcription factors that would otherwise be targets of polycomb-mediated repression, which is restored upon KDM2B depletion leading to irreversible mesenchymal differentiation. Thus, SS18-SSX de-regulates developmental programs to drive transformation by hijacking a transcriptional repressive complex to aberrantly activate gene expression.
2018-03-01 | GSE108928 | GEO
Project description:Gene fusions arising from chromosomal translocations are key oncogenic drivers in soft tissue sarcomas but little is known about how they exert their oncogenic effects. Our study explores the molecular mechanisms by which the SS18-SSX fusion oncoprotein subverts epigenetic mechanisms of gene regulation to drive synovial sarcoma. Using functional genomics, we identify KDM2B – a histone demethylase and core component of a non-canonical Polycomb Repressive Complex 1 (PRC1.1) – as selectively required for sustaining synovial sarcoma cell transformation. SS18-SSX physically interacts with PRC1.1 and co-associates with SWI/SNF and KDM2B complexes on unmethylated CpG islands genome-wide. Via KDM2B, SS18-SSX binds and aberrantly activates expression of a series of developmentally regulated transcription factors that would otherwise be targets of polycomb-mediated repression, which is restored upon KDM2B depletion leading to irreversible mesenchymal differentiation. Thus, SS18-SSX de-regulates developmental programs to drive transformation by hijacking a transcriptional repressive complex to aberrantly activate gene expression.
2018-03-01 | GSE108926 | GEO
Project description:Synovial sarcoma (SS) is defined by the hallmark SS18-SSX fusion oncoprotein, which renders BAF complexes aberrant in two manners: gain of SSX to the SS18 subunit and concomitant loss of BAF47 subunit assembly. Here we demonstrate that SS18-SSX globally hijacks BAF complexes on chromatin to activate a SS transcriptional signature we define using primary tumors and cell lines. Specifically, SS18-SSX retargets BAF complexes from enhancers to broad polycomb domains to oppose PRC2-mediated repression and activate bivalent genes. Upon suppression of SS18-SSX, reassembly of BAF47 restores enhancer activation, but is not required for proliferative arrest. These results establish a global hijacking mechanism for SS18-SSX on chromatin, and define the distinct contributions of two concurrent BAF complex perturbations.
2018-05-31 | GSE108025 | GEO
Project description:Synovial sarcoma (SS) is defined by the hallmark SS18-SSX fusion oncoprotein, which renders BAF complexes aberrant in two manners: gain of SSX to the SS18 subunit and concomitant loss of BAF47 subunit assembly. Here we demonstrate that SS18-SSX globally hijacks BAF complexes on chromatin to activate a SS transcriptional signature we define using primary tumors and cell lines. Specifically, SS18-SSX retargets BAF complexes from enhancers to broad polycomb domains to oppose PRC2-mediated repression and activate bivalent genes. Upon suppression of SS18-SSX, reassembly of BAF47 restores enhancer activation, but is not required for proliferative arrest. These results establish a global hijacking mechanism for SS18-SSX on chromatin, and define the distinct contributions of two concurrent BAF complex perturbations.
2018-05-31 | GSE114487 | GEO