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: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 an embryonic malignancy originating from early nerve cells. Neuroblastoma retains plasticity, interconverting between the mesenchymal (MES) and adrenergic (ADRN) states, which are controlled by different sets of transcription factors forming the core regulatory circuit (CRC). However, their functional roles and cooperative mechanisms in neuroblastoma pathogenesis are poorly understood. Here, we demonstrate that overexpression of ASCL1 in MES neuroblastoma cells opens closed chromatin at the promoters of key ADRN genes, accompanied by epigenetic activation and establishment of enhancer-promoter interactions, thereby initiating subtype switching. ASCL1 inhibits the TGFb-SMAD2/3 pathway but activates the BMP-SMAD1-ID3/4 pathway, serving as negative feedback to balance the function of ASCL1-TCF12 dimers. ASCL1 and other ADRN CRC members potentiate each other’s activity, increasing the expression of the original targets and inducing a new set of genes, thereby promoting conversion to ADRN neuroblastoma. Thus, via its pioneer factor function, ASCL1 serves as a master regulator that characterizes ADRN neuroblastoma.
Project description:PRRX1 is expressed in mesenchymal-type neuroblastoma cells. Over-expression of PRRX1 in adrenergic-type cell line was used to study reprogramming towards a mesenchymal lineage.
Project description:GD2 is a disialoganglioside that is highly expressed on the surface of neuroblastoma cells. Immunotherapy with anti-GD2 antibodies has revolutionized the treatment of children with high-risk neuroblastoma, but nearly half of patients relapse and little is known about mechanisms of resistance to anti-GD2. Neuroblastomas harbor intrinsic transcriptional plasticity by co-opting divergent lineage-specific developmental programs between adrenergic and mesenchymal cell states. We found that reduced GD2 expression was significantly correlated with the adrenergic cell state in neuroblastoma and that an Adrenergic-to-Mesenchymal Transition (AMT) conferred downregulation of GD2 and resistance to anti-GD2 antibody. Induced reprogramming of adrenergic cells with the master AMT regulator PRRX1 was sufficient to promote transcriptional rewiring in isogenic models and downregulate GD2 expression. Mechanistically, low-GD2 expressing cell lines demonstrate significantly reduced expression of the ganglioside synthesis enzyme ST8SIA1 (GD3 synthase), resulting in a bottlenecking of GD2 synthesis. Primary neuroblastoma tumors enriched for mesenchymal features show demonstrably lower GD3 synthase expression as compared to adrenergic tumors. Pharmacologic inhibition of EZH2 resulted in epigenetic rewiring of mesenchymal neuroblastoma cells and re-expression of ST8SIA1, restoring surface expression of GD2 and sensitivity to an anti-GD2 antibody. These data identify developmental lineage as a key determinant of sensitivity to anti-GD2 based immunotherapies and credential EZH2 inhibitors for clinical testing in combination with anti-GD2 antibody to enhance outcomes for children with neuroblastoma.
Project description:GD2 is a disialoganglioside that is highly expressed on the surface of neuroblastoma cells. Immunotherapy with anti-GD2 antibodies has revolutionized the treatment of children with high-risk neuroblastoma, but nearly half of patients relapse and little is known about mechanisms of resistance to anti-GD2. Neuroblastomas harbor intrinsic transcriptional plasticity by co-opting divergent lineage-specific developmental programs between adrenergic and mesenchymal cell states. We found that reduced GD2 expression was significantly correlated with the adrenergic cell state in neuroblastoma and that an Adrenergic-to-Mesenchymal Transition (AMT) conferred downregulation of GD2 and resistance to anti-GD2 antibody. Induced reprogramming of adrenergic cells with the master AMT regulator PRRX1 was sufficient to promote transcriptional rewiring in isogenic models and downregulate GD2 expression. Mechanistically, low-GD2 expressing cell lines demonstrate significantly reduced expression of the ganglioside synthesis enzyme ST8SIA1 (GD3 synthase), resulting in a bottlenecking of GD2 synthesis. Primary neuroblastoma tumors enriched for mesenchymal features show demonstrably lower GD3 synthase expression as compared to adrenergic tumors. Pharmacologic inhibition of EZH2 resulted in epigenetic rewiring of mesenchymal neuroblastoma cells and re-expression of ST8SIA1, restoring surface expression of GD2 and sensitivity to an anti-GD2 antibody. These data identify developmental lineage as a key determinant of sensitivity to anti-GD2 based immunotherapies and credential EZH2 inhibitors for clinical testing in combination with anti-GD2 antibody to enhance outcomes for children with neuroblastoma.
Project description:GD2 is a disialoganglioside that is highly expressed on the surface of neuroblastoma cells. Immunotherapy with anti-GD2 antibodies has revolutionized the treatment of children with high-risk neuroblastoma, but nearly half of patients relapse and little is known about mechanisms of resistance to anti-GD2. Neuroblastomas harbor intrinsic transcriptional plasticity by co-opting divergent lineage-specific developmental programs between adrenergic and mesenchymal cell states. We found that reduced GD2 expression was significantly correlated with the adrenergic cell state in neuroblastoma and that an Adrenergic-to-Mesenchymal Transition (AMT) conferred downregulation of GD2 and resistance to anti-GD2 antibody. Induced reprogramming of adrenergic cells with the master AMT regulator PRRX1 was sufficient to promote transcriptional rewiring in isogenic models and downregulate GD2 expression. Mechanistically, low-GD2 expressing cell lines demonstrate significantly reduced expression of the ganglioside synthesis enzyme ST8SIA1 (GD3 synthase), resulting in a bottlenecking of GD2 synthesis. Primary neuroblastoma tumors enriched for mesenchymal features show demonstrably lower GD3 synthase expression as compared to adrenergic tumors. Pharmacologic inhibition of EZH2 resulted in epigenetic rewiring of mesenchymal neuroblastoma cells and re-expression of ST8SIA1, restoring surface expression of GD2 and sensitivity to an anti-GD2 antibody. These data identify developmental lineage as a key determinant of sensitivity to anti-GD2 based immunotherapies and credential EZH2 inhibitors for clinical testing in combination with anti-GD2 antibody to enhance outcomes for children with neuroblastoma.
Project description:GD2 is a disialoganglioside that is highly expressed on the surface of neuroblastoma cells. Immunotherapy with anti-GD2 antibodies has revolutionized the treatment of children with high-risk neuroblastoma, but nearly half of patients relapse and little is known about mechanisms of resistance to anti-GD2. Neuroblastomas harbor intrinsic transcriptional plasticity by co-opting divergent lineage-specific developmental programs between adrenergic and mesenchymal cell states. We found that reduced GD2 expression was significantly correlated with the adrenergic cell state in neuroblastoma and that an Adrenergic-to-Mesenchymal Transition (AMT) conferred downregulation of GD2 and resistance to anti-GD2 antibody. Induced reprogramming of adrenergic cells with the master AMT regulator PRRX1 was sufficient to promote transcriptional rewiring in isogenic models and downregulate GD2 expression. Mechanistically, low-GD2 expressing cell lines demonstrate significantly reduced expression of the ganglioside synthesis enzyme ST8SIA1 (GD3 synthase), resulting in a bottlenecking of GD2 synthesis. Primary neuroblastoma tumors enriched for mesenchymal features show demonstrably lower GD3 synthase expression as compared to adrenergic tumors. Pharmacologic inhibition of EZH2 resulted in epigenetic rewiring of mesenchymal neuroblastoma cells and re-expression of ST8SIA1, restoring surface expression of GD2 and sensitivity to an anti-GD2 antibody. These data identify developmental lineage as a key determinant of sensitivity to anti-GD2 based immunotherapies and credential EZH2 inhibitors for clinical testing in combination with anti-GD2 antibody to enhance outcomes for children with neuroblastoma.