RESUMEN
Whereas oncogenes can potentially be inhibited with small molecules, the loss of tumour suppressors is more common and is problematic because the tumour-suppressor proteins are no longer present to be targeted. Notable examples include SMARCB1-mutant cancers, which are highly lethal malignancies driven by the inactivation of a subunit of SWI/SNF (also known as BAF) chromatin-remodelling complexes. Here, to generate mechanistic insights into the consequences of SMARCB1 mutation and to identify vulnerabilities, we contributed 14 SMARCB1-mutant cell lines to a near genome-wide CRISPR screen as part of the Cancer Dependency Map Project1-3. We report that the little-studied gene DDB1-CUL4-associated factor 5 (DCAF5) is required for the survival of SMARCB1-mutant cancers. We show that DCAF5 has a quality-control function for SWI/SNF complexes and promotes the degradation of incompletely assembled SWI/SNF complexes in the absence of SMARCB1. After depletion of DCAF5, SMARCB1-deficient SWI/SNF complexes reaccumulate, bind to target loci and restore SWI/SNF-mediated gene expression to levels that are sufficient to reverse the cancer state, including in vivo. Consequently, cancer results not from the loss of SMARCB1 function per se, but rather from DCAF5-mediated degradation of SWI/SNF complexes. These data indicate that therapeutic targeting of ubiquitin-mediated quality-control factors may effectively reverse the malignant state of some cancers driven by disruption of tumour suppressor complexes.
Asunto(s)
Complejos Multiproteicos , Mutación , Neoplasias , Proteína SMARCB1 , Animales , Femenino , Humanos , Masculino , Ratones , Línea Celular Tumoral , Sistemas CRISPR-Cas , Edición Génica , Neoplasias/genética , Neoplasias/metabolismo , Proteína SMARCB1/deficiencia , Proteína SMARCB1/genética , Proteína SMARCB1/metabolismo , Proteínas Supresoras de Tumor/deficiencia , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Complejos Multiproteicos/química , Complejos Multiproteicos/metabolismo , Proteolisis , Ubiquitina/metabolismoRESUMEN
Disruption of antagonism between SWI/SNF chromatin remodelers and polycomb repressor complexes drives the formation of numerous cancer types. Recently, an inhibitor of the polycomb protein EZH2 was approved for the treatment of a sarcoma mutant in the SWI/SNF subunit SMARCB1, but resistance occurs. Here, we performed CRISPR screens in SMARCB1-mutant rhabdoid tumor cells to identify genetic contributors to SWI/SNF-polycomb antagonism and potential resistance mechanisms. We found that loss of the H3K36 methyltransferase NSD1 caused resistance to EZH2 inhibition. We show that NSD1 antagonizes polycomb via cooperation with SWI/SNF and identify co-occurrence of NSD1 inactivation in SWI/SNF-defective cancers, indicating in vivo relevance. We demonstrate that H3K36me2 itself has an essential role in the activation of polycomb target genes as inhibition of the H3K36me2 demethylase KDM2A restores the efficacy of EZH2 inhibition in SWI/SNF-deficient cells lacking NSD1. Together our data expand the mechanistic understanding of SWI/SNF and polycomb interplay and identify NSD1 as the key for coordinating this transcriptional control.
Asunto(s)
Proteína Potenciadora del Homólogo Zeste 2 , Proteínas F-Box , N-Metiltransferasa de Histona-Lisina , Histona Demetilasas con Dominio de Jumonji , Proteínas del Grupo Polycomb , Proteína SMARCB1 , Cromatina/genética , Cromatina/metabolismo , Proteína Potenciadora del Homólogo Zeste 2/antagonistas & inhibidores , Proteína Potenciadora del Homólogo Zeste 2/genética , Proteína Potenciadora del Homólogo Zeste 2/metabolismo , Proteínas F-Box/genética , Proteínas F-Box/metabolismo , N-Metiltransferasa de Histona-Lisina/genética , N-Metiltransferasa de Histona-Lisina/metabolismo , Histonas/genética , Histonas/metabolismo , Humanos , Histona Demetilasas con Dominio de Jumonji/genética , Histona Demetilasas con Dominio de Jumonji/metabolismo , Proteínas del Grupo Polycomb/genética , Proteínas del Grupo Polycomb/metabolismo , Tumor Rabdoide/genética , Tumor Rabdoide/metabolismo , Tumor Rabdoide/patología , Proteína SMARCB1/genética , Proteína SMARCB1/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Activación Transcripcional/genética , Células Tumorales Cultivadas/metabolismoRESUMEN
For cells to initiate and sustain a differentiated state, it is necessary that a 'memory' of this state is transmitted through mitosis to the daughter cells1-3. Mammalian switch/sucrose non-fermentable (SWI/SNF) complexes (also known as Brg1/Brg-associated factors, or BAF) control cell identity by modulating chromatin architecture to regulate gene expression4-7, but whether they participate in cell fate memory is unclear. Here we provide evidence that subunits of SWI/SNF act as mitotic bookmarks to safeguard cell identity during cell division. The SWI/SNF core subunits SMARCE1 and SMARCB1 are displaced from enhancers but are bound to promoters during mitosis, and we show that this binding is required for appropriate reactivation of bound genes after mitotic exit. Ablation of SMARCE1 during a single mitosis in mouse embryonic stem cells is sufficient to disrupt gene expression, impair the occupancy of several established bookmarks at a subset of their targets and cause aberrant neural differentiation. Thus, SWI/SNF subunit SMARCE1 has a mitotic bookmarking role and is essential for heritable epigenetic fidelity during transcriptional reprogramming.
Asunto(s)
Diferenciación Celular , Proteínas Cromosómicas no Histona , Epigénesis Genética , Mitosis , Animales , Ratones , Diferenciación Celular/genética , Cromatina/genética , Ensamble y Desensamble de Cromatina/genética , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Mitosis/genética , Proteínas Cromosómicas no Histona/deficiencia , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Subunidades de Proteína/metabolismo , Células Madre Embrionarias de Ratones/metabolismo , Elementos de Facilitación Genéticos/genética , Regiones Promotoras Genéticas/genética , División Celular/genética , Epigénesis Genética/genéticaRESUMEN
The identification of mechanisms to promote memory T (Tmem) cells has important implications for vaccination and anti-cancer immunotherapy1-4. Using a CRISPR-based screen for negative regulators of Tmem cell generation in vivo5, here we identify multiple components of the mammalian canonical BRG1/BRM-associated factor (cBAF)6,7. Several components of the cBAF complex are essential for the differentiation of activated CD8+ T cells into T effector (Teff) cells, and their loss promotes Tmem cell formation in vivo. During the first division of activated CD8+ T cells, cBAF and MYC8 frequently co-assort asymmetrically to the two daughter cells. Daughter cells with high MYC and high cBAF display a cell fate trajectory towards Teff cells, whereas those with low MYC and low cBAF preferentially differentiate towards Tmem cells. The cBAF complex and MYC physically interact to establish the chromatin landscape in activated CD8+ T cells. Treatment of naive CD8+ T cells with a putative cBAF inhibitor during the first 48 h of activation, before the generation of chimeric antigen receptor T (CAR-T) cells, markedly improves efficacy in a mouse solid tumour model. Our results establish cBAF as a negative determinant of Tmem cell fate and suggest that manipulation of cBAF early in T cell differentiation can improve cancer immunotherapy.
Asunto(s)
Linfocitos T CD8-positivos , Diferenciación Celular , ADN Helicasas , Complejos Multiproteicos , Proteínas Nucleares , Proteínas Proto-Oncogénicas c-myc , Factores de Transcripción , Animales , Linfocitos T CD8-positivos/citología , ADN Helicasas/metabolismo , Modelos Animales de Enfermedad , Memoria Inmunológica , Inmunoterapia , Células T de Memoria/citología , Ratones , Complejos Multiproteicos/química , Complejos Multiproteicos/metabolismo , Neoplasias , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Receptores Quiméricos de Antígenos , Factores de Transcripción/metabolismoRESUMEN
Klein et al. (2020) demonstrate for the first time that small-molecule cancer therapeutics are selectively partitioned and concentrated within phase-separated nuclear condensates, providing new insights to drug efficacy and creating the opportunity for enhanced control of therapeutic targeting.
Asunto(s)
Núcleo Celular , Neoplasias , Desarrollo de Medicamentos , HumanosRESUMEN
Enhancer elements are genomic regulatory sequences that direct the selective expression of genes so that genetically identical cells can differentiate and acquire the highly specialized forms and functions required to build a functioning animal. To differentiate, cells must select from among the â¼106 enhancers encoded in the genome the thousands of enhancers that drive the gene programs that impart their distinct features. We used a genetic approach to identify transcription factors (TFs) required for enhancer selection in fibroblasts. This revealed that the broadly expressed, growth-factor-inducible TFs FOS/JUN (AP-1) play a central role in enhancer selection. FOS/JUN selects enhancers together with cell-type-specific TFs by collaboratively binding to nucleosomal enhancers and recruiting the SWI/SNF (BAF) chromatin remodeling complex to establish accessible chromatin. These experiments demonstrate how environmental signals acting via FOS/JUN and BAF coordinate with cell-type-specific TFs to select enhancer repertoires that enable differentiation during development.
Asunto(s)
Cromatina/metabolismo , Proteínas Cromosómicas no Histona/metabolismo , Elementos de Facilitación Genéticos , Proteínas Proto-Oncogénicas c-fos/fisiología , Factores de Transcripción/metabolismo , Factores de Transcripción/fisiología , Animales , Cromatina/genética , Proteínas Cromosómicas no Histona/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Nucleosomas , Regiones Promotoras Genéticas , Factores de Transcripción/genéticaRESUMEN
Malignant neoplasms evolve in response to changes in oncogenic signalling. Cancer cell plasticity in response to evolutionary pressures is fundamental to tumour progression and the development of therapeutic resistance. Here we determine the molecular and cellular mechanisms of cancer cell plasticity in a conditional oncogenic Kras mouse model of pancreatic ductal adenocarcinoma (PDAC), a malignancy that displays considerable phenotypic diversity and morphological heterogeneity. In this model, stochastic extinction of oncogenic Kras signalling and emergence of Kras-independent escaper populations (cells that acquire oncogenic properties) are associated with de-differentiation and aggressive biological behaviour. Transcriptomic and functional analyses of Kras-independent escapers reveal the presence of Smarcb1-Myc-network-driven mesenchymal reprogramming and independence from MAPK signalling. A somatic mosaic model of PDAC, which allows time-restricted perturbation of cell fate, shows that depletion of Smarcb1 activates the Myc network, driving an anabolic switch that increases protein metabolism and adaptive activation of endoplasmic-reticulum-stress-induced survival pathways. Increased protein turnover renders mesenchymal sub-populations highly susceptible to pharmacological and genetic perturbation of the cellular proteostatic machinery and the IRE1-α-MKK4 arm of the endoplasmic-reticulum-stress-response pathway. Specifically, combination regimens that impair the unfolded protein responses block the emergence of aggressive mesenchymal subpopulations in mouse and patient-derived PDAC models. These molecular and biological insights inform a potential therapeutic strategy for targeting aggressive mesenchymal features of PDAC.
Asunto(s)
Mesodermo/patología , Neoplasias Pancreáticas/patología , Animales , Carcinoma Ductal Pancreático/tratamiento farmacológico , Carcinoma Ductal Pancreático/metabolismo , Carcinoma Ductal Pancreático/patología , Desoxicitidina/análogos & derivados , Desoxicitidina/farmacología , Desoxicitidina/uso terapéutico , Estrés del Retículo Endoplásmico/genética , Femenino , Genes myc , Genes ras , Humanos , MAP Quinasa Quinasa 4/metabolismo , Sistema de Señalización de MAP Quinasas , Masculino , Mesodermo/metabolismo , Ratones , Mosaicismo , Proteína Oncogénica p55(v-myc)/metabolismo , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/metabolismo , Proteolisis , Proteínas Proto-Oncogénicas p21(ras)/genética , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Proteína SMARCB1/deficiencia , Proteína SMARCB1/metabolismo , Transcriptoma/genética , GemcitabinaRESUMEN
The new paradigm of mutations in chromatin-modifying genes as driver events in the development of cancers has proved challenging to resolve the complex influences over disease phenotypes. In particular, impaired activities of members of the SWI/SNF chromatin remodeling complex have appeared in an increasing variety of tumors. Mutations in SNF5, a member of this ubiquitously expressed complex, arise in almost all cases of malignant rhabdoid tumor in the absence of additional genetic alterations. Therefore, we studied how activation of additional oncogenic pathways might shift the phenotype of disease driven by SNF5 loss. With the use of a genetically engineered mouse model, we examined the effects of a hypomorphic Vhl2B allele on disease phenotype, with a modest up-regulation of the hypoxia response pathway. Snf5+/-;Vhl2B/+ mice did not demonstrate a substantial difference in overall survival or a change in malignant rhabdoid tumor development. However, a high percentage of female mice showed complex hemorrhagic ovarian cysts, a phenotype rarely found in either parental mouse strain. These lesions also showed mosaic expression of SNF5 by immunohistochemistry. Therefore, our studies implicate that modest changes in angiogenic regulation interact with perturbations of SWI/SNF complex activity to modulate disease phenotypes.
Asunto(s)
Hemorragia/patología , Mutación , Quistes Ováricos/patología , Proteína SMARCB1/fisiología , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/fisiología , Animales , Femenino , Hemorragia/etiología , Hemorragia/metabolismo , Ratones , Ratones Noqueados , Quistes Ováricos/etiología , Quistes Ováricos/metabolismo , FenotipoRESUMEN
Changes of histone modification status at critical lineage-specifying gene loci in multipotent precursors can influence cell fate commitment. The contribution of these epigenetic mechanisms to natural killer (NK) cell lineage determination from common lymphoid precursors is not understood. Here we investigate the impact of histone methylation repressive marks (H3 Lys27 trimethylation; H3K27(me3)) on early NK cell differentiation. We demonstrate that selective loss of the histone-lysine N-methyltransferase Ezh2 (enhancer of zeste homolog 2) or inhibition of its enzymatic activity with small molecules unexpectedly increased generation of the IL-15 receptor (IL-15R) CD122(+) NK precursors and mature NK progeny from both mouse and human hematopoietic stem and progenitor cells. Mechanistic studies revealed that enhanced NK cell expansion and cytotoxicity against tumor cells were associated with up-regulation of CD122 and the C-type lectin receptor NKG2D. Moreover, NKG2D deficiency diminished the positive effects of Ezh2 inhibitors on NK cell commitment. Identification of the contribution of Ezh2 to NK lineage specification and function reveals an epigenetic-based mechanism that regulates NK cell development and provides insight into the clinical application of Ezh2 inhibitors in NK-based cancer immunotherapies.
Asunto(s)
Diferenciación Celular/genética , N-Metiltransferasa de Histona-Lisina/genética , Células Asesinas Naturales/metabolismo , Complejo Represivo Polycomb 2/genética , Animales , Línea Celular Tumoral , Linaje de la Célula/genética , Proliferación Celular/genética , Supervivencia Celular/genética , Células Cultivadas , Proteína Potenciadora del Homólogo Zeste 2 , Citometría de Flujo , Perfilación de la Expresión Génica , Células Madre Hematopoyéticas/metabolismo , Histona Metiltransferasas , N-Metiltransferasa de Histona-Lisina/metabolismo , Humanos , Immunoblotting , Subunidad beta del Receptor de Interleucina-2/genética , Subunidad beta del Receptor de Interleucina-2/metabolismo , Células K562 , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Subfamilia K de Receptores Similares a Lectina de Células NK/genética , Subfamilia K de Receptores Similares a Lectina de Células NK/metabolismo , Complejo Represivo Polycomb 2/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Defects in epigenetic regulation play a fundamental role in the development of cancer, and epigenetic regulators have recently emerged as promising therapeutic candidates. We therefore set out to systematically interrogate epigenetic cancer dependencies by screening an epigenome-focused deep-coverage design shRNA (DECODER) library across 58 cancer cell lines. This screen identified BRM/SMARCA2, a DNA-dependent ATPase of the mammalian SWI/SNF (mSWI/SNF) chromatin remodeling complex, as being essential for the growth of tumor cells that harbor loss of function mutations in BRG1/SMARCA4. Depletion of BRM in BRG1-deficient cancer cells leads to a cell cycle arrest, induction of senescence, and increased levels of global H3K9me3. We further demonstrate the selective dependency of BRG1-mutant tumors on BRM in vivo. Genetic alterations of the mSWI/SNF chromatin remodeling complexes are the most frequent among chromatin regulators in cancers, with BRG1/SMARCA4 mutations occurring in â¼10-15% of lung adenocarcinomas. Our findings position BRM as an attractive therapeutic target for BRG1 mutated cancers. Because BRG1 and BRM function as mutually exclusive catalytic subunits of the mSWI/SNF complex, we propose that such synthetic lethality may be explained by paralog insufficiency, in which loss of one family member unveils critical dependence on paralogous subunits. This concept of "cancer-selective paralog dependency" may provide a more general strategy for targeting other tumor suppressor lesions/complexes with paralogous subunits.
Asunto(s)
ADN Helicasas/deficiencia , Epigénesis Genética/fisiología , Complejos Multiproteicos/genética , Neoplasias/genética , Proteínas Nucleares/deficiencia , Factores de Transcripción/deficiencia , Factores de Transcripción/genética , Western Blotting , Puntos de Control del Ciclo Celular/genética , Línea Celular Tumoral , Senescencia Celular/genética , Técnicas de Silenciamiento del Gen , Biblioteca de Genes , Histonas/metabolismo , Humanos , Inmunoprecipitación , Complejos Multiproteicos/metabolismo , ARN Interferente Pequeño/genética , Factores de Transcripción/metabolismoRESUMEN
Osteosarcoma is the most common primary bone tumor, yet there have been no substantial advances in treatment or survival in three decades. We examined 59 tumor/normal pairs by whole-exome, whole-genome, and RNA-sequencing. Only the TP53 gene was mutated at significant frequency across all samples. The mean nonsilent somatic mutation rate was 1.2 mutations per megabase, and there was a median of 230 somatic rearrangements per tumor. Complex chains of rearrangements and localized hypermutation were detected in almost all cases. Given the intertumor heterogeneity, the extent of genomic instability, and the difficulty in acquiring a large sample size in a rare tumor, we used several methods to identify genomic events contributing to osteosarcoma survival. Pathway analysis, a heuristic analytic algorithm, a comparative oncology approach, and an shRNA screen converged on the phosphatidylinositol 3-kinase/mammalian target of rapamycin (PI3K/mTOR) pathway as a central vulnerability for therapeutic exploitation in osteosarcoma. Osteosarcoma cell lines are responsive to pharmacologic and genetic inhibition of the PI3K/mTOR pathway both in vitro and in vivo.
Asunto(s)
Neoplasias Óseas/metabolismo , Genoma Humano , Osteosarcoma/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Neoplasias Óseas/genética , Neoplasias Óseas/patología , Línea Celular Tumoral , Proliferación Celular , Heterogeneidad Genética , Mutación de Línea Germinal , Humanos , Osteosarcoma/genética , Osteosarcoma/patología , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Precise nucleosome-positioning patterns at promoters are thought to be crucial for faithful transcriptional regulation. However, the mechanisms by which these patterns are established, are dynamically maintained, and subsequently contribute to transcriptional control are poorly understood. The switch/sucrose non-fermentable chromatin remodeling complex, also known as the Brg1 associated factors complex, is a master developmental regulator and tumor suppressor capable of mobilizing nucleosomes in biochemical assays. However, its role in establishing the nucleosome landscape in vivo is unclear. Here we have inactivated Snf5 and Brg1, core subunits of the mammalian Swi/Snf complex, to evaluate their effects on chromatin structure and transcription levels genomewide. We find that inactivation of either subunit leads to disruptions of specific nucleosome patterning combined with a loss of overall nucleosome occupancy at a large number of promoters, regardless of their association with CpG islands. These rearrangements are accompanied by gene expression changes that promote cell proliferation. Collectively, these findings define a direct relationship between chromatin-remodeling complexes, chromatin structure, and transcriptional regulation.
Asunto(s)
Proteínas Cromosómicas no Histona/metabolismo , ADN Helicasas/metabolismo , Proteínas Nucleares/metabolismo , Nucleosomas/metabolismo , Regiones Promotoras Genéticas/fisiología , Factores de Transcripción/metabolismo , Animales , Proliferación Celular , Cromatina/fisiología , Proteínas Cromosómicas no Histona/genética , Islas de CpG/fisiología , ADN Helicasas/genética , Fibroblastos/citología , Fibroblastos/fisiología , Regulación Neoplásica de la Expresión Génica/fisiología , Técnicas de Silenciamiento del Gen , Ratones , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patología , Proteínas Nucleares/genética , Nucleosomas/genética , Cultivo Primario de Células , Unión Proteica/fisiología , Proteína SMARCB1 , Factores de Transcripción/genética , Activación Transcripcional/fisiologíaRESUMEN
Large-scale cancer genome sequencing studies have revealed that chromatin regulators are frequently mutated in cancer. In particular, more than 20% of cancers harbour mutations in genes that encode subunits of SWI/SNF (BAF) chromatin remodelling complexes. Additional links of SWI/SNF complexes to disease have emerged with the findings that some oncogenes drive transformation by co-opting SWI/SNF function and that germline mutations in select SWI/SNF subunits are the basis of several neurodevelopmental disorders. Other chromatin remodellers, including members of the ISWI, CHD and INO80/SWR complexes, have also been linked to cancer and developmental disorders. Consequently, therapeutic manipulation of SWI/SNF and other remodelling complexes has become of great interest, and drugs that target SWI/SNF subunits have entered clinical trials. Genome-wide perturbation screens in cancer cell lines with SWI/SNF mutations have identified additional synthetic lethal targets and led to further compounds in clinical trials, including one that has progressed to FDA approval. Here, we review the progress in understanding the structure and function of SWI/SNF and other chromatin remodelling complexes, mechanisms by which SWI/SNF mutations cause cancer and neurological diseases, vulnerabilities that arise because of these mutations and efforts to target SWI/SNF complexes and synthetic lethal targets for therapeutic benefit.
RESUMEN
In the past two decades, technological advances have brought unprecedented insights into the paediatric cancer genome revealing characteristics distinct from those of adult cancer. Originating from developing tissues, paediatric cancers generally have low mutation burden and are driven by variants that disrupt the transcriptional activity, chromatin state, non-coding cis-regulatory regions and other biological functions. Within each tumour, there are multiple populations of cells with varying states, and the lineages of some can be tracked to their fetal origins. Genome-wide genetic screening has identified vulnerabilities associated with both the cell of origin and transcription deregulation in paediatric cancer, which have become a valuable resource for designing new therapeutic approaches including those for small molecules, immunotherapy and targeted protein degradation. In this Review, we present recent findings on these facets of paediatric cancer from a pan-cancer perspective and provide an outlook on future investigations.
Asunto(s)
Neoplasias , Humanos , Neoplasias/genética , Neoplasias/patología , Niño , Mutación , Genoma Humano , Regulación Neoplásica de la Expresión GénicaRESUMEN
Genes encoding subunits of SWI/SNF (BAF) chromatin remodeling complexes are mutated in nearly 25% of cancers. To gain insight into the mechanisms by which SWI/SNF mutations drive cancer, we contributed ten rhabdoid tumor (RT) cell lines mutant for SWI/SNF subunit SMARCB1 to a genome-scale CRISPR-Cas9 depletion screen performed across 896 cell lines. We identify PHF6 as specifically essential for RT cell survival and demonstrate that dependency on Phf6 extends to Smarcb1-deficient cancers in vivo. As mutations in either SWI/SNF or PHF6 can cause the neurodevelopmental disorder Coffin-Siris syndrome, our findings of a dependency suggest a previously unrecognized functional link. We demonstrate that PHF6 co-localizes with SWI/SNF complexes at promoters, where it is essential for maintenance of an active chromatin state. We show that in the absence of SMARCB1, PHF6 loss disrupts the recruitment and stability of residual SWI/SNF complex members, collectively resulting in the loss of active chromatin at promoters and stalling of RNA Polymerase II progression. Our work establishes a mechanistic basis for the shared syndromic features of SWI/SNF and PHF6 mutations in CSS and the basis for selective dependency on PHF6 in SMARCB1-mutant cancers.
Asunto(s)
Micrognatismo , Regiones Promotoras Genéticas , Proteínas Represoras , Tumor Rabdoide , Proteína SMARCB1 , Factores de Transcripción , Humanos , Proteína SMARCB1/metabolismo , Proteína SMARCB1/genética , Tumor Rabdoide/genética , Tumor Rabdoide/metabolismo , Tumor Rabdoide/patología , Micrognatismo/genética , Micrognatismo/metabolismo , Línea Celular Tumoral , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Proteínas Represoras/metabolismo , Proteínas Represoras/genética , Regiones Promotoras Genéticas/genética , Cara/anomalías , Cromatina/metabolismo , Discapacidad Intelectual/genética , Discapacidad Intelectual/metabolismo , Ensamble y Desensamble de Cromatina , Mutación , Deformidades Congénitas del Pie/genética , Deformidades Congénitas del Pie/metabolismo , Proteínas Cromosómicas no Histona/metabolismo , Proteínas Cromosómicas no Histona/genética , Sistemas CRISPR-Cas , Transcripción Genética , Animales , Ratones , Anomalías Múltiples , Deformidades Congénitas de la Mano , Cuello/anomalíasRESUMEN
Malignant rhabdoid tumors (MRTs) are rare, aggressive cancers occuring in young children primarily through inactivation of the SNF5(INI1, SMARCB1) tumor suppressor gene. We and others have demonstrated that mice heterozygous for a Snf5 null allele develop MRTs with partial penetrance. We have also shown that Snf5(+/-) mice that lack expression of the pRb family, due to TgT121 transgene expression, develop MRTs with increased penetrance and decreased latency. Here, we report that altering the genetic background has substantial effects upon MRT development in Snf5(+/--) and TgT121 ;Snf5(+/-) mice, with a mixed F1 background resulting in increased latency and the appearance of brain tumors. We also report the establishment of the first mouse MRT cell lines that recapitulate many features of their human counterparts. Our studies provide further insight into the genetic influences on MRT development as well as provide valuable new cell culture and genetically engineered mouse models for the study of CNS-MRT etiology.
Asunto(s)
Línea Celular Tumoral , Tumor Rabdoide/genética , Animales , Proliferación Celular , Transformación Celular Neoplásica/genética , Neoplasias del Plexo Coroideo/genética , Neoplasias del Plexo Coroideo/patología , Proteínas Cromosómicas no Histona/genética , Modelos Animales de Enfermedad , Genotipo , Humanos , Cariotipo , Ratones , Ratones Transgénicos , Fenotipo , Tumor Rabdoide/patología , Proteína SMARCB1RESUMEN
Data-driven basic, translational, and clinical research has resulted in improved outcomes for children, adolescents, and young adults (AYAs) with pediatric cancers. However, challenges in sharing data between institutions, particularly in research, prevent addressing substantial unmet needs in children and AYA patients diagnosed with certain pediatric cancers. Systematically collecting and sharing data from every child and AYA can enable greater understanding of pediatric cancers, improve survivorship, and accelerate development of new and more effective therapies. To accomplish this goal, the Childhood Cancer Data Initiative (CCDI) was launched in 2019 at the National Cancer Institute. CCDI is a collaborative community endeavor supported by a 10-year, $50-million (in US dollars) annual federal investment. CCDI aims to learn from every patient diagnosed with a pediatric cancer by designing and building a data ecosystem that facilitates data collection, sharing, and analysis for researchers, clinicians, and patients across the cancer community. For example, CCDI's Molecular Characterization Initiative provides comprehensive clinical molecular characterization for children and AYAs with newly diagnosed cancers. Through these efforts, the CCDI strives to provide clinical benefit to patients and improvements in diagnosis and care through data-focused research support and to build expandable, sustainable data resources and workflows to advance research well past the planned 10 years of the initiative. Importantly, if CCDI demonstrates the success of this model for pediatric cancers, similar approaches can be applied to adults, transforming both clinical research and treatment to improve outcomes for all patients with cancer.
Asunto(s)
Neoplasias , Adolescente , Estados Unidos/epidemiología , Humanos , Niño , Adulto Joven , Neoplasias/terapia , Ecosistema , Recolección de Datos , National Cancer Institute (U.S.)RESUMEN
BACKGROUND: Rhabdoid tumors (also called atypical teratoid/rhabdoid tumor (AT/RT) in the brain), are highly malignant, poor prognosis lesions arising in the kidneys, soft tissues, and central nervous system. Targeted therapy in this disease would benefit from advanced technologies detecting relevant actionable mutations. PROCEDURE: Here we report on the evaluation of 25 tumors, all with known SMARCB1/INI1 alterations, for the presence of 983 different mutations in 115 oncogenes and tumor-suppressor genes using OncoMap, a mass spectrometric method of allele detection. RESULTS: Other than mutations in SMARCB1, our results identified a single activating mutation in NRAS and complete absence of oncogenic mutations in all other genes tested. CONCLUSION: The absence of mutations in canonical pathways critical for development and progression of adult cancers suggests that distinct mechanisms drive these highly malignant pediatric tumors. This may limit the therapeutic utility of available targeted therapies and require a refocusing toward developmental and epigenetic pathways.
Asunto(s)
Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN/genética , Mutación , Tumor Rabdoide/genética , Transducción de Señal/genética , Factores de Transcripción/genética , Niño , Preescolar , Femenino , Genes Supresores de Tumor , Técnicas de Genotipaje , Humanos , Lactante , Masculino , Espectrometría de Masas , Oncogenes/genética , Proteína SMARCB1RESUMEN
Recent data suggest the SWI/SNF chromatin remodeling complex may also act as a tumor suppressor. Utilizing a reversibly inactivating conditional allele, we demonstrate that loss of Snf5/Ini1/Baf47/SmarcB1, a core subunit of SWI/SNF, results in highly penetrant cancer predisposition with 100% of mice developing mature CD8(+) T cell lymphoma or rare rhabdoid tumors with a median onset of only 11 weeks. Notably, while loss of Snf5 predisposes to aggressive cancers, it is also required for survival of virtually all nonmalignant cells in vivo. Reversible gene targeting demonstrates a critical and specific role for Snf5 in tumor suppression, provides a novel system in which to explore the genetic pathways involved in tumor suppression by Swi/Snf, and should be of wide use in evaluating other essential tumor suppressor genes.