Project description:Neuroblastoma is a tumor of the peripheral sympathetic nervous system, derived from multipotent neural crest cells (NCCs). To define Core Regulatory Circuitries (CRCs) controlling the gene expression program of neuroblastoma, we established and analyzed the neuroblastoma super-enhancer landscape. We discovered three types of identity in neuroblastoma cell lines: a sympathetic noradrenergic identity defined by a CRC module including the PHOX2B, HAND2 and GATA3 transcription factors (TFs); an NCC-like identity, driven by a CRC module containing AP-1 family TFs; a mixed type further deconvoluted at the single cell level. Treatment of the mixed type with chemotherapeutic agents resulted in enrichment of NCC-like cells. The noradrenergic module was validated by ChIP-seq. Functional studies demonstrated dependency of neuroblastoma with noradrenergic identity on PHOX2B, evocative of lineage addiction. Most neuroblastoma primary tumors express TFs from the noradrenergic and NCC-like modules. Our data demonstrate a novel aspect of tumor heterogeneity relevant for neuroblastoma treatment strategies.
Project description:Two cell identities, noradrenergic and mesenchymal, have been characterized in neuroblastoma cell lines according to their epigenetic landscapes relying on specific circuitries of transcription factors. Yet, their relationship and relative contribution in patient tumors remain poorly defined. Our results now document spontaneous plasticity in several neuroblastoma models between noradrenergic and mesenchymal tumor states and show that this plasticity is reversible and relies on epigenetic reprogramming. We demonstrate that an in vivo microenvironment provides a powerful pressure towards a noradrenergic identity for these models. Interestingly, single-cell RNA-seq analyses of 18 tumor biopsies and 15 PDX models revealed that tumor cells systematically exhibit a noradrenergic identity. Yet, our data highlight a population of noradrenergic tumor cells with mesenchymal features, demonstrating that the plasticity described in cellular models between both identities is relevant in neuroblastoma patients. Our work also emphasizes that both external cues of the environment and intrinsic factors influence plasticity and cell identity in neuroblastoma.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
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.