Retinoic acid rewires the adrenergic core regulatory circuitry of neuroblastoma but can be subverted by enhancer hijacking of MYC or MYCN (RNA-Seq)
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ABSTRACT: Neuroblastoma cell identity depends on a core regulatory circuit (CRC) of transcription factors that incorporate MYCN to drive the oncogenic gene expression program. For neuroblastomas dependent on the adrenergic CRC, treatment with retinoids can inhibit cell growth and induce differentiation in both primary neuroblastomas and cell lines; however, the underlying mechanisms remain unclear. Here we show that when MYCN-amplified neuroblastomas cells are treated with all-trans retinoic acid (ATRA), they undergo modifications of histone H3K27 acetylation and methylation that decommission super-enhancers driving the expression of PHOX2B and GATA3, together with the activation of new super-enhancers that drive high levels of expression of MEIS1, HIC1 and SOX4. These findings indicate that treatment with ATRA can reprogram the enhancer landscape to collapse the adrenergic CRC, which downregulates MYCN expression, while upregulating a new “retino-sympathetic” CRC that causes proliferative arrest and sympathetic differentiation. Thus, we provide mechanisms that account for the beneficial effects of retinoids against high-risk neuroblastoma and explain the rapid downregulation of expression of MYCN despite massive levels of gene amplification.
Project description:Neuroblastoma cell identity depends on a core regulatory circuit (CRC) of transcription factors that incorporate MYCN to drive the oncogenic gene expression program. For neuroblastomas dependent on the adrenergic CRC, treatment with retinoids can inhibit cell growth and induce differentiation in both primary neuroblastomas and cell lines; however, the underlying mechanisms remain unclear. Here we show that when MYCN-amplified neuroblastomas cells are treated with all-trans retinoic acid (ATRA), they undergo modifications of histone H3K27 acetylation and methylation that decommission super-enhancers driving the expression of PHOX2B and GATA3, together with the activation of new super-enhancers that drive high levels of expression of MEIS1, HIC1 and SOX4. These findings indicate that treatment with ATRA can reprogram the enhancer landscape to collapse the adrenergic CRC, which downregulates MYCN expression, while upregulating a new “retino-sympathetic” CRC that causes proliferative arrest and sympathetic differentiation. Thus, we provide mechanisms that account for the beneficial effects of retinoids against high-risk neuroblastoma and explain the rapid downregulation of expression of MYCN despite massive levels of gene amplification.
Project description:Neuroblastoma cell identity depends on a core regulatory circuit (CRC) of transcription factors that incorporate MYCN to drive the oncogenic gene expression program. For neuroblastomas dependent on the adrenergic CRC, treatment with retinoids can inhibit cell growth and induce differentiation in both primary neuroblastomas and cell lines; however, the underlying mechanisms remain unclear. Here we show that when MYCN-amplified neuroblastomas cells are treated with all-trans retinoic acid (ATRA), they undergo modifications of histone H3K27 acetylation and methylation that decommission super-enhancers driving the expression of PHOX2B and GATA3, together with the activation of new super-enhancers that drive high levels of expression of MEIS1, HIC1 and SOX4. These findings indicate that treatment with ATRA can reprogram the enhancer landscape to collapse the adrenergic CRC, which downregulates MYCN expression, while upregulating a new “retino-sympathetic” CRC that causes proliferative arrest and sympathetic differentiation. Thus, we provide mechanisms that account for the beneficial effects of retinoids against high-risk neuroblastoma and explain the rapid downregulation of expression of MYCN despite massive levels of gene amplification.
Project description:Neuroblastoma with MYCN amplification (MNA) is a high-risk disease that requires long-term intensive multimodal therapies. Less than 50% survival rate of high-risk patients has prompted active and extensive studies to seek more effective therapies against MNA neuroblastomas but with few successes. We show that MYCN transdifferentiates the neuroblastoma cells from mesenchymal state to adrenergic state accompanied with induction of histone lysine demethylase 4 family members (KDM4A-C), all of which act in concert to control the expression of MYCN and adrenergic core regulatory transcription factors (CRC TF). Pharmacologic inhibition of KDM4 blocks expression of MYCN and adrenergic CRC transcriptome with genome-wide induction of transcriptionally repressive H3K9me3, resulting in potent anticancer activity against MNA neuroblastomas by inducing differentiation, apoptosis and type I interferon response. KDM4 inhibition in combination with chemotherapy leads to complete tumor response of MNA xenografts, without overt toxicity in animals. Thus, KDM4 blockade may be a transformative strategy to target the dependency of adrenergic CRC TFs in MNA neuroblastomas.
Project description:Neuroblastoma with MYCN amplification (MNA) is a high-risk disease that requires long-term intensive multimodal therapies. Despite this, high-risk patients have a poor survival rate, which has prompted extensive studies aimed at identifying more effective therapies against neuroblastomas with MNA. Neuroblastoma displays cellular heterogeneity, including more differentiated (adrenergic) and more primitive (mesenchymal) cellular states. Here, we demonstrate that MYCN oncoprotein can promote a cellular state switch in mesenchymal cells to an adrenergic state. This cellular state transition is accompanied by induction of histone lysine demethylase 4 family members (KDM4A-C), which act in concert to control the expression of MYCN and adrenergic core regulatory transcription factors (CRC TF). Pharmacologic inhibition of KDM4 blocks expression of MYCN and the adrenergic CRC transcriptome with genome-wide induction of transcriptionally repressive H3K9me3, resulting in potent anticancer activity against neuroblastomas with MNA by inducing neuroblastic differentiation, apoptosis, and a type I interferon response. Further, KDM4 inhibition in combination with conventional, cytotoxic chemotherapy results in complete tumor responses of xenografts with MNA, without overt toxicity in animals. Thus, KDM4 blockade may be a novel and transformative strategy to target the adrenergic CRC dependencies in MNA neuroblastomas.
Project description:Childhood neuroblastomas exhibit plasticity between an undifferentiated neural crest-like “mesenchymal” cell state and a more differentiated sympathetic “adrenergic” cell state. These cell states are governed by autoregulatory transcriptional loops called core regulatory circuitries (CRCs), which drive the early development of sympathetic neuronal progenitors from migratory neural crest cells during embryogenesis. The adrenergic cell identity of neuroblastoma requires LMO1 as a transcriptional co-factor. Both LMO1 expression levels and the risk of developing neuroblastoma in children are associated with a single nucleotide polymorphism G/T that affects a GATA motif in the first intron of LMO1. Here we showed that wild-type zebrafish with the GATA genotype developed adrenergic neuroblastoma, while knock-in of the protective TATA allele at this locus reduced the penetrance of MYCN-driven tumors, which were restricted to the mesenchymal cell state. Whole genome sequencing of childhood neuroblastomas demonstrated that TATA/TATA tumors also exhibited a mesenchymal cell state and were low risk at diagnosis. Thus, conversion of the regulatory GATA to a TATA allele in the first intron of LMO1 reduced the neuroblastoma initiation rate by preventing formation of the adrenergic cell state, a mechanism that was conserved over 400 million years of evolution separating zebrafish and humans.
Project description:The pediatric extra-cranial tumor neuroblastoma displays a low mutational burden while recurrent copy number alterations are present in most high-risk cases. We identify SOX11 as a dependency transcription factor in adrenergic neuroblastoma based on recurrent chromosome 2p focal gains and amplifications, specific expression in the normal sympatho-adrenal lineage and adrenergic neuroblastoma, regulation by multiple adrenergic specific (super-)enhancers and strong dependency on high SOX11 expression in adrenergic neuroblastomas. SOX11 regulated direct targets include genes implicated in epigenetic control, cytoskeleton and neurodevelopment. Most notably, SOX11 controls chromatin regulatory complexes, including 10 SWI/SNF core components among which SMARCC1, SMARCA4/BRG1 and ARID1A. Additionally, the histone deacetylase HDAC2, PRC1 complex component CBX2, chromatin-modifying enzyme KDM1A/LSD1 and pioneer factor c-MYB are regulated by SOX11. Finally, SOX11 is identified as a core transcription factor of the core regulatory circuitry (CRC) in adrenergic high-risk neuroblastoma with a potential role as epigenetic master regulator upstream of the CRC.
Project description:The pediatric extra-cranial tumor neuroblastoma displays a low mutational burden while recurrent copy number alterations are present in most high-risk cases. We identify SOX11 as a dependency transcription factor in adrenergic neuroblastoma based on recurrent chromosome 2p focal gains and amplifications, specific expression in the normal sympatho-adrenal lineage and adrenergic neuroblastoma, regulation by multiple adrenergic specific (super-)enhancers and strong dependency on high SOX11 expression in adrenergic neuroblastomas. SOX11 regulated direct targets include genes implicated in epigenetic control, cytoskeleton and neurodevelopment. Most notably, SOX11 controls chromatin regulatory complexes, including 10 SWI/SNF core components among which SMARCC1, SMARCA4/BRG1 and ARID1A. Additionally, the histone deacetylase HDAC2, PRC1 complex component CBX2, chromatin-modifying enzyme KDM1A/LSD1 and pioneer factor c-MYB are regulated by SOX11. Finally, SOX11 is identified as a core transcription factor of the core regulatory circuitry (CRC) in adrenergic high-risk neuroblastoma with a potential role as epigenetic master regulator upstream of the CRC.
Project description:The pediatric extra-cranial tumor neuroblastoma displays a low mutational burden while recurrent copy number alterations are present in most high-risk cases. We identify SOX11 as a dependency transcription factor in adrenergic neuroblastoma based on recurrent chromosome 2p focal gains and amplifications, specific expression in the normal sympatho-adrenal lineage and adrenergic neuroblastoma, regulation by multiple adrenergic specific (super-)enhancers and strong dependency on high SOX11 expression in adrenergic neuroblastomas. SOX11 regulated direct targets include genes implicated in epigenetic control, cytoskeleton and neurodevelopment. Most notably, SOX11 controls chromatin regulatory complexes, including 10 SWI/SNF core components among which SMARCC1, SMARCA4/BRG1 and ARID1A. Additionally, the histone deacetylase HDAC2, PRC1 complex component CBX2, chromatin-modifying enzyme KDM1A/LSD1 and pioneer factor c-MYB are regulated by SOX11. Finally, SOX11 is identified as a core transcription factor of the core regulatory circuitry (CRC) in adrenergic high-risk neuroblastoma with a potential role as epigenetic master regulator upstream of the CRC.
Project description:MYCN amplification in neuroblastoma leads to aberrant expression of MYCN oncoprotein, which binds active genes promoting transcriptional amplification. Yet how MYCN coordinates transcription elongation to meet productive transcriptional amplification and which elongation machinery represents MYCN-driven vulnerability remain to be identified. We conducted a targeted screen of transcription elongation factors and identified the super elongation complex (SEC) as a unique vulnerability in MYCN-amplified neuroblastomas. MYCN directly binds EAF1 and recruits SEC to enhance processive transcription elongation. Depletion of EAF1 or AFF1/AFF4, another core subunit of SEC, leads to a global reduction in transcription elongation and elicits selective apoptosis of MYCN-amplified neuroblastoma cells. A combination screen reveals SEC inhibition synergistically potentiates the therapeutic efficacies of FDA-approved BCL2 antagonist ABT-199, in part due to suppression of MCL1 expression, both in MYCN-amplified neuroblastoma cells and in patient-derived xenografts. These findings identify disruption of the MYCN-SEC regulatory axis as a promising therapeutic strategy in neuroblastoma.
Project description:Neuroblastoma is a pediatric tumor of the developing sympathetic nervous system. We investigate developmental origins of neuroblastoma, the role of oncogenic MYCN in blocking normal differentiation and evaluate therapeutic interventions to overcome differentiation blocks. Here, we provide expression profiles of SK-N-BE(2)C cells upon treatment with ATRA or solvent control.