Identification of common mechanisms underlying organ development and primary tumor formation should yield new insights into tumor biology and facilitate the generation of relevant cancer models. We have developed a novel method to project the gene expression profiles of medulloblastomas (MBs)human cerebellar tumorsonto a mouse cerebellar development sequence: postnatal days 1-60 (P1-P60). Genomically, human medulloblastomas were closest to mouse P1-P10 cerebella, and normal human cerebella were closest to mouse P30-P60 cerebella. Furthermore, metastatic MBs were highly associated with mouse P5 cerebella, suggesting that a clinically distinct subset of tumors is identifiable by molecular similarity to a precise developmental stage. Genewise, down- and up-regulated MB genes segregate to late and early stages of development, respectively. Comparable results for human lung cancer vis-a-vis the developing mouse lung suggest the generalizability of this multiscalar developmental perspective on tumor biology. Our findings indicate both a recapitulation of tissue-specific developmental programs in diverse solid tumors and the utility of tumor characterization on the developmental time axis for identifying novel aspects of clinical and biological behavior.
Conserved mechanisms across development and tumorigenesis revealed by a mouse development perspective of human cancers.
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Epigenetic antagonism between polycomb and SWI/SNF complexes during oncogenic transformation.
Specimen part
View SamplesEpigenetic alterations have been increasingly implicated in oncogenesis. Analysis of Drosophila mutants suggests that Polycomb and SWI/SNF complexes can serve antagonistic developmental roles. However, the relevance of this relationship to human disease is unclear. Here we have investigated functional relationships between these epigenetic regulators in oncogenic transformation. Mechanistically, we show that loss of the SNF5 tumor suppressor leads to elevated expression of the Polycomb gene EZH2 and that Polycomb targets are broadly H3K27-trimethylated and repressed in SNF5-deficient fibroblasts and cancers. Further, we show antagonism between SNF5 and EZH2 in the regulation of stem cell-associated programs and that Snf5 loss activates those programs. Finally, using conditional mouse models, we show that inactivation of Ezh2 blocks tumor formation driven by Snf5 loss.
Epigenetic antagonism between polycomb and SWI/SNF complexes during oncogenic transformation.
Specimen part
View SamplesNatural killer (NK) cells can be divided into phenotypic subsets based on the expression of receptors that bind self-MHC-I molecules with differing affinities; a concept termed licensing or education. Here we show that NK cell subsets exhibit markedly different migratory, effector, and immunoregulatory functions on dendritic cells and antigen-specific CD8+ T cell responses during influenza and murine cytomegalovirus infections. Shortly after infection, unlicensed NK cells preferentially trafficked to draining lymph nodes and produced GM-CSF, which promoted the expansion and activation of dendritic cells, and ultimately resulted in sustained antigen-specific CD8+ T cell responses. In contrast, licensed NK cells preferentially migrated to infected parenchymal tissues and produced greater levels of interferon- (IFN-). Importantly, human NK cell subsets exhibited similar phenotypic characteristics and patterns of cytokine production. Collectively, our studies demonstrate a critical demarcation between the functions of licensed and unlicensed NK cell subsets, with the former functioning as the classical effector subset in inflamed tissues and the latter as modulators of adaptive immunity helping to prime immune responses in draining lymph nodes.
Licensing delineates helper and effector NK cell subsets during viral infection.
Specimen part
View SamplesMedulloblastoma is the most frequent malignant pediatric brain tumor and is divided into at least four subgroups known as Wnt, SHH, Group 3 and Group 4. Here we characterized gene regulation mechanisms in the most aggressive subtype, Group 3 tumors, through genome-wide chromatin and expression profiling. Our results show that most active distal sites in these tumors are occupied by the transcription factor OTX2. Highly active OTX2 bound enhancers are often arranged as clusters of adjacent peaks and are also bound by the transcription factor NEUROD1. These sites are responsive to OTX2 and NEUROD1 knockdown and could also be generated de novo upon ectopic OTX2 expression in primary cells, showing that OTX2 cooperates with NEUROD1 and plays a major role in maintaining and possibly establishing regulatory elements as a pioneer factor. Among OTX2 target genes we identified the kinase NEK2, whose knockdown and pharmacological inhibition decreased cell viability. Our studies thus show that OTX2 controls the regulatory landscape of Group 3 medulloblastoma through cooperative activity at enhancer elements and contributes to the expression of critical target genes. Overall design: Primary Group 3 Medulloblastomas tumor samples were analyzed by RNA-seq. Group 3 medulloblastoma cell line (D341) was analyzed by RNA-seq. OTX2 was depleted by infection with lentiviral shRNAs (sh OTX2 and sh GFP control). Raw data not provided for primary Medulloblastoma samples due to patient privacy concerns. Submitter states that the raw data for these samples will be submitted to dbGaP.
OTX2 Activity at Distal Regulatory Elements Shapes the Chromatin Landscape of Group 3 Medulloblastoma.
Cell line, Subject
View SamplesSMARCB1 (SNF5/INI1/BAF47), a core subunit of the SWI/SNF (BAF) chromatin remodeling complex, is inactivated in nearly all pediatric rhabdoid tumors. These aggressive cancers are among the most genomically stable, suggesting an epigenetic mechanism by which SMARCB1 loss drives transformation. Here, we show that despite indistinguishable mutational landscapes, human RTs show distinct enhancer H3K27ac signatures, which reveal remnants of differentiation programs. We show that SMARCB1 is required for the integrity of SWI/SNF complexes and that its loss alters enhancer targeting markedly impairing SWI/SNF binding to typical enhancers, particularly those required for differentiation, while maintaining SWI/SNF binding at super-enhancers. We show that these retained super-enhancers are essential for rhabdoid tumor survival, including some that are shared across all subtypes, such as SPRY1, and other lineage-specific super-enhancers like SOX2 in brain-derived RTs. Taken together, our findings reveal a novel chromatin-based epigenetic mechanism underlying the tumor suppressive activity of SMARCB1. Overall design: RNA-seq in six Smarcb1 deficient rhabdoid tumor cell lines, before and after Smarcb1 re-expression.
SMARCB1-mediated SWI/SNF complex function is essential for enhancer regulation.
No sample metadata fields
View SamplesSMARCB1 (SNF5/INI1/BAF47), a core subunit of the SWI/SNF (BAF) chromatin remodeling complex, is inactivated in nearly all pediatric rhabdoid tumors. These aggressive cancers are among the most genomically stable, suggesting an epigenetic mechanism by which SMARCB1 loss drives transformation. Here, we show that despite indistinguishable mutational landscapes, human RTs show distinct enhancer H3K27ac signatures, which reveal remnants of differentiation programs. We show that SMARCB1 is required for the integrity of SWI/SNF complexes and that its loss alters enhancer targeting markedly impairing SWI/SNF binding to typical enhancers, particularly those required for differentiation, while maintaining SWI/SNF binding at super-enhancers. We show that these retained super-enhancers are essential for rhabdoid tumor survival, including some that are shared across all subtypes, such as SPRY1, and other lineage-specific super-enhancers like SOX2 in brain-derived RTs. Taken together, our findings reveal a novel chromatin-based epigenetic mechanism underlying the tumor suppressive activity of SMARCB1. Overall design: RNA-seq for three primary Rhabdoid tumor samples
SMARCB1-mediated SWI/SNF complex function is essential for enhancer regulation.
No sample metadata fields
View SamplesNeuroanatomical methods enable high-resolution mapping of neural circuitry, but do not allow systematic molecular profiling of neurons based on their connectivity. Here, we report the development of a novel approach for molecularly profiling projective neurons. We show that ribosomes can be labeled with a camelid nanobody raised against GFP and that this system can be engineered to selectively capture translating mRNAs from cells expressing GFP. We generated a transgenic mouse encoding a nanobody-ribosomal protein fusion (Syn-NBL10) and used a retrograde virus (CAV) encoding GFP to immunoprecipitate ribosomes from projection neurons. This enabled us to profile neurons projecting to the nucleus accumbens. The current method provides a new means for profiling neurons based on their projections. Overall design: Translating mRNAs immunoprecipitated from neurons projecting to the nucleus accumbens. Each Input and IP sample corrspond to a pooled group of 6 mice.
Molecular profiling of neurons based on connectivity.
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The G protein α subunit Gαs is a tumor suppressor in Sonic hedgehog-driven medulloblastoma.
Specimen part
View SamplesMedulloblastoma, the most common malignant pediatric brain tumor, is highly heterogeneous with distinct molecular subtypes and cellular origins. Although current treatments improve survival rates, patients suffer severe treatment-related side effects and often relapse of tumors carrying resistance mutations, underscoring an urgent need for alternative targeted therapies. Currently, the genetic alterations underlying this disease are not fully understood. Here we identify GNAS, encoding the G-protein Gs-alpha, as a potent tumor suppressor gene in medulloblastoma. GNAS specifically defines a subset of aggressive Sonic Hedgehog (Shh)-group medulloblastomas. Gnas loss-of-function in distinct lineage progenitors of the developing hindbrain suffices to initiate medulloblastoma. We find that Gs-alpha is highly enriched at primary cilia of granule neuron precursors and suppresses Shh signaling not only by regulating classic cAMP-dependent pathway but also controlling ciliary trafficking of Smoothened. Concurrent cAMP elevation and Smoothened inhibition robustly arrests tumor cell growth in Gnas mutants. We further reveal oligodendrocyte progenitors as a novel cellular origin for anatomically-distinct Shh-associated medulloblastomas. Together, we identify a previously unrecognized tumor suppressor function of Gs-alpha in medulloblastoma partially mediated through inhibiting Shh signaling, and uncover Gs-alpha as a molecular link across disparate cells of origin among Shh-group medulloblastomas, pointing to G- protein modulation as a potential therapeutic avenue.
The G protein α subunit Gαs is a tumor suppressor in Sonic hedgehog-driven medulloblastoma.
Specimen part
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