Project description:We report a previously unrecognized role of super-enhancer-associated TTC8 in neuroblastoma. To explore TTC8-dependent gene regulation, RNA-seq analysis was conducted and the differently expressed genes were revealed in the TTC8-knockdown SK-N-BE(2) cells in comparison to control group. We find that TTC8 activate the MAPK signaling pathway to promote the occurrence and development of neuroblastoma.
Project description:Bromodomain-containing protein 4 (BRD4) functions as an epigenetic reader and binds to so-called super-enhancer regions of driving oncogenes such as MYC in cancer. We investigated the possibility to target super-enhancer regulated genes in neuroblastoma and in MYCN amplified disease in particular. We used OTX015, the first small-molecule BRD4 inhibitor to enter clinical phase I/II trials in adults, to test the feasibility to specifically target super-enhancer regulated gene-expression in neuroblastoma. BRD4 inhibition lead to significant transcriptional down-regulation of genes that were associated with super-enhancers, supporting the notion that BRD4 preferentially acts at these chromatin sites. BRD4 inhibition not only attenuated MYCN transcription but most significantly affected MYCN-regulated transcriptional programs.
Project description:Intra-tumour heterogeneity is increasingly appreciated as a determinant of tumour recurrence. Several tumour types were recently found to include phenotypically divergent cell types, reflecting lineage development stages (1,2,3). Lineage identity has been proposed to ensue super-enhancer (SE)-associated transcription factor (TF) networks (4,5), but their role in intra-tumour heterogeneity is unknown. Neuroblastoma is a paediatric tumour of the adrenergic differentiation lineage. Here we show that most neuroblastoma tumors include two types of tumor cells with highly diverging gene expression profiles. The undifferentiated mesenchymal cells and more differentiated adrenergic cells can interconvert and may relate to normal lineage differentiation stages. ChIP-seq analysis of isogenic pairs of mesenchymal and adrenergic neuroblastoma cells revealed a distinct, highly consistent super-enhancer landscape for each cell type. Two SE-associated TF networks emerged that potentially master each cell type. Accordingly, the mesenchymal TF PRRX1 could reprogram the SE- and mRNA-profiles of adrenergic cells towards a mesenchymal state. To assess the clinical relevance of this bi-phasic system, we investigated chemo-sensitivity of both cell types. Mesenchymal cells were more resistant in vitro and were enriched in post-therapy and relapsed neuroblastoma in patients. Intra-tumor heterogeneity in neuroblastoma is therefore structured according to distinct SE-associated transcriptional programs that mediate a dynamic bi-phasic structure.
Project description:Transcriptional dysregulation plays a major role in the development and progression of human tumors such as pediatric neuroblastoma. Therefore, we sought to elucidate the relationship between genes required for neuroblastoma cell growth and survival and the transcriptional core regulatory circuitry (CRC) that controls the gene expression program. A genome-scale CRISPR-Cas9 screen for oncogenic dependencies revealed that 143 genes are essential for cell survival and growth in neuroblastoma relative to other cancers, including many super-enhancer (SE) regulated transcription factors. Genome-wide occupancy analysis of transcription factor binding demonstrated that at least six of these transcription factors were both dependency genes and components of the CRC in MYCN-amplified neuroblastoma including: HAND2, ISL1, PHOX2B, GATA3, TBX2, and MEIS2. Binding sites for these transcription factors were clustered within a few hundred base pairs in their own enhancers and the enhancers of downstream target genes, which surprisingly included 40% of the independently determined neuroblastoma dependency genes. This profound level of transcriptional control of oncogenesis through self-reinforcing transcriptional circuits led us to test combinatorial pharmacological inhibition of transcriptional initiation and elongation, which synergistically induced tumor cell death, supporting drugging transcription as a means to advance the treatment of high risk neuroblastoma.
Project description:Intra-tumour heterogeneity is increasingly appreciated as a determinant of tumour recurrence. Several tumour types were recently found to include phenotypically divergent cell types, reflecting lineage development stages (1,2,3). Lineage identity has been proposed to ensue super-enhancer (SE)-associated transcription factor (TF) networks (4,5), but their role in intra-tumour heterogeneity is unknown. Neuroblastoma is a paediatric tumour of the adrenergic differentiation lineage. Here we show that most neuroblastoma tumors include two types of tumor cells with highly diverging gene expression profiles. The undifferentiated mesenchymal cells and more differentiated adrenergic cells can interconvert and may relate to normal lineage differentiation stages. ChIP-seq analysis of isogenic pairs of mesenchymal and adrenergic neuroblastoma cells revealed a distinct, highly consistent super-enhancer landscape for each cell type. Two SE-associated TF networks emerged that potentially master each cell type. Accordingly, the mesenchymal TF PRRX1 could reprogram the SE- and mRNA-profiles of adrenergic cells towards a mesenchymal state. To assess the clinical relevance of this bi-phasic system, we investigated chemo-sensitivity of both cell types. Mesenchymal cells were more resistant in vitro and were enriched in post-therapy and relapsed neuroblastoma in patients. Intra-tumor heterogeneity in neuroblastoma is therefore structured according to distinct SE-associated transcriptional programs that mediate a dynamic bi-phasic structure.
Project description:Neuroblastoma is a pediatric tumor that accounts for more than 15% of cancer-related deaths in children. Survival chances for high-risk patients are less than 50%. Retinoic acid treatment is part of the maintenance therapy given to neuroblastoma patients; however, not all tumors respond to retinoic acid-mediated differentiation. Among neuroblastoma tumors, two phenotypically distinct cell types-adrenergic (ADRN) and mesenchymal (MES), have been identified based on their super-enhancer landscape and transcriptional core regulatory circuitries. We hypothesized that distinct super-enhancers in these different tumor cells could mediate differential response to retinoic acid. To this end, we treated four different neuroblastoma cell lines, comprising both ADRN (MYCN amplified and non-amplified) and MES subtypes, with retinoic acid and studied the super-enhancer landscape upon treatment and after removal of retinoic acid. Using H3K27ac ChIP-seq paired with RNA-seq, we compared the super-enhancers in cells that respond to retinoic acid-mediated differentiation versus those that fail to differentiate. We identified unique super-enhancers associated with cells differentiation; however, even among cells that respond to treatment, there was heterogeneity upon removal of retinoic acid, with MYCN amplified cells remaining differentiated whereas MYCN non-amplified cells reverted to a proliferative state. This study identifies regulatory super-enhancers as a plausible mechanism behind the differential response to retinoic acid-mediated differentiation.
Project description:Neuroblastoma is a pediatric tumor that accounts for more than 15% of cancer-related deaths in children. Survival chances for high-risk patients are less than 50%. Retinoic acid treatment is part of the maintenance therapy given to neuroblastoma patients; however, not all tumors respond to retinoic acid-mediated differentiation. Among neuroblastoma tumors, two phenotypically distinct cell types-adrenergic (ADRN) and mesenchymal (MES), have been identified based on their super-enhancer landscape and transcriptional core regulatory circuitries. We hypothesized that distinct super-enhancers in these different tumor cells could mediate differential response to retinoic acid. To this end, we treated four different neuroblastoma cell lines, comprising both ADRN (MYCN amplified and non-amplified) and MES subtypes, with retinoic acid and studied the super-enhancer landscape upon treatment and after removal of retinoic acid. Using H3K27ac ChIP-seq paired with RNA-seq, we compared the super-enhancers in cells that respond to retinoic acid-mediated differentiation versus those that fail to differentiate. We identified unique super-enhancers associated with cells differentiation; however, even among cells that respond to treatment, there was heterogeneity upon removal of retinoic acid, with MYCN amplified cells remaining differentiated whereas MYCN non-amplified cells reverted to a proliferative state. This study identifies regulatory super-enhancers as a plausible mechanism behind the differential response to retinoic acid-mediated differentiation.
Project description:Transcriptional dysregulation plays a major role in the development and progression of human tumors such as pediatric neuroblastoma. Therefore, we sought to elucidate the relationship between genes required for neuroblastoma cell growth and survival and the transcriptional core regulatory circuitry (CRC) that controls the gene expression program. A genome-scale CRISPR-Cas9 screen for oncogenic dependencies revealed that 143 genes are essential for cell survival and growth in neuroblastoma relative to other cancers, including many super-enhancer (SE) regulated transcription factors. Genome-wide occupancy analysis of transcription factor binding demonstrated that at least six of these transcription factors were both dependency genes and components of the CRC in MYCN-amplified neuroblastoma including: HAND2, ISL1, PHOX2B, GATA3, TBX2, and MEIS2. Binding sites for these transcription factors were clustered within a few hundred base pairs in their own enhancers and the enhancers of downstream target genes, which surprisingly included 40% of the independently determined neuroblastoma dependency genes. This profound level of transcriptional control of oncogenesis through self-reinforcing transcriptional circuits led us to test combinatorial pharmacological inhibition of transcriptional initiation and elongation, which synergistically induced tumor cell death, supporting Òdrugging transcriptionÓ as a means to advance the treatment of high risk neuroblastoma.