RESUMO
Cell fate decisions are achieved with gene expression changes driven by lineage-specific transcription factors (TFs). These TFs depend on chromatin remodelers including the Brahma-related gene 1 (BRG1)-associated factor (BAF) complex to activate target genes. BAF complex subunits are essential for development and frequently mutated in cancer. Thus, interrogating how BAF complexes contribute to cell fate decisions is critical for human health. We examined the requirement for the catalytic BAF subunit BRG1 in neural progenitor cell (NPC) specification from human embryonic stem cells. During the earliest stages of differentiation, BRG1 was required to establish chromatin accessibility at neuroectoderm-specific enhancers. Depletion of BRG1 dorsalized NPCs and promoted precocious neural crest specification and enhanced neuronal differentiation. These findings demonstrate that BRG1 mediates NPC specification by ensuring proper expression of lineage-specific TFs and appropriate activation of their transcriptional programs.
Assuntos
Cromatina , Placa Neural , Humanos , Cromatina/genética , DNA Helicases/genética , DNA Helicases/metabolismo , Placa Neural/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismoRESUMO
Patient-derived tumor organoids (TOs) are emerging as high-fidelity models to study cancer biology and develop novel precision medicine therapeutics. However, utilizing TOs for systems-biology-based approaches has been limited by a lack of scalable and reproducible methods to develop and profile these models. We describe a robust pan-cancer TO platform with chemically defined media optimized on cultures acquired from over 1,000 patients. Crucially, we demonstrate tumor genetic and transcriptomic concordance utilizing this approach and further optimize defined minimal media for organoid initiation and propagation. Additionally, we demonstrate a neural-network-based high-throughput approach for label-free, light-microscopy-based drug assays capable of predicting patient-specific heterogeneity in drug responses with applicability across solid cancers. The pan-cancer platform, molecular data, and neural-network-based drug assay serve as resources to accelerate the broad implementation of organoid models in precision medicine research and personalized therapeutic profiling programs.
Assuntos
Neoplasias/patologia , Organoides/patologia , Medicina de Precisão , Proliferação de Células , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Fluorescência , Genômica , Antígenos HLA/genética , Humanos , Perda de Heterozigosidade , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Neoplasias/genética , Redes Neurais de Computação , Transcriptoma/genéticaRESUMO
The SWI/SNF complex is a critical regulator of pluripotency in human embryonic stem cells (hESCs), and individual subunits have varied and specific roles during development and in diseases. The core subunit SMARCB1 is required for early embryonic survival, and mutations can give rise to atypical teratoid/rhabdoid tumors (AT/RTs) in the pediatric central nervous system. We report that in contrast to other studied systems, SMARCB1 represses bivalent genes in hESCs and antagonizes chromatin accessibility at super-enhancers. Moreover, and consistent with its established role as a CNS tumor suppressor, we find that SMARCB1 is essential for neural induction but dispensable for mesodermal or endodermal differentiation. Mechanistically, we demonstrate that SMARCB1 is essential for hESC super-enhancer silencing in neural differentiation conditions. This genomic assessment of hESC chromatin regulation by SMARCB1 reveals a novel positive regulatory function at super-enhancers and a unique lineage-specific role in regulating hESC differentiation.
Assuntos
Células-Tronco Embrionárias/metabolismo , Elementos Facilitadores Genéticos/genética , Proteína SMARCB1/genética , Proteína SMARCB1/metabolismo , Diferenciação Celular/genética , Criança , Cromatina/genética , Endoderma , Técnicas de Silenciamento de Genes , Genes Supressores de Tumor , Humanos , Mesoderma , Mutação/genética , Tumor Rabdoide/genéticaAssuntos
Neoplasias , RNA Longo não Codificante/genética , Cálcio , Humanos , Hipóxia , Microambiente TumoralRESUMO
MicroRNAs and chromatin remodeling complexes represent powerful epigenetic mechanisms that regulate the pluripotent state. miR-302 is a strong inducer of pluripotency, which is characterized by a distinct chromatin architecture. This suggests that miR-302 regulates global chromatin structure; however, a direct relationship between miR-302 and chromatin remodelers has not been established. Here, we provide data to show that miR-302 regulates Brg1 chromatin remodeling complex composition in human embryonic stem cells (hESCs) through direct repression of the BAF53a and BAF170 subunits. With the subsequent overexpression of BAF170 in hESCs, we show that miR-302's inhibition of BAF170 protein levels can affect the expression of genes involved in cell proliferation. Furthermore, miR-302-mediated repression of BAF170 regulates pluripotency by positively influencing mesendodermal differentiation. Overexpression of BAF170 in hESCs led to biased differentiation toward the ectoderm lineage during EB formation and severely hindered directed definitive endoderm differentiation. Taken together, these data uncover a direct regulatory relationship between miR-302 and the Brg1 chromatin remodeling complex that controls gene expression and cell fate decisions in hESCs and suggests that similar mechanisms are at play during early human development.
Assuntos
Diferenciação Celular/genética , Montagem e Desmontagem da Cromatina/genética , DNA Helicases/genética , Células-Tronco Embrionárias/metabolismo , MicroRNAs/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Actinas/genética , Actinas/metabolismo , Proliferação de Células/genética , Cromatina/genética , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Endoderma/crescimento & desenvolvimento , Humanos , MicroRNAs/metabolismo , Proteínas Nucleares/metabolismo , Células-Tronco Pluripotentes , Fatores de Transcrição/metabolismoRESUMO
Breaking immune tolerance against tumor self-antigens is presently an area of intense research in the design of cancer therapies. One possible method to enhance immune system activation against tumor antigens is by blocking the inhibitory co-stimulatory signals mediated by cytotoxic T lymphocyte antigen 4, (CTLA-4) expressed on activated T cells. The fully human monoclonal antibodies that are directed against human CTLA-4, ipilimumab (Medarex/Bristol-Myers Squibb) and CP-675,206 (Pfizer/Abgenix, now Amgen), have demonstrated activity against metastatic melanoma, hormone refractory prostate cancer and other malignancies. They have also uncovered unusual immune-related adverse events manifesting as self-limiting inflammatory reactions of the bowel, skin and pituitary. This article reviews preclinical development and data generated from Phase I, II and III studies with regard to the end points reported and immune-related adverse events.
