Dissecting transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human retinoblastoma tumours by single cell sequencing
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE166175 | GEO | 2021/07/26
REPOSITORIES: GEO
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Project description:Background: Retinoblastoma (Rb) is a malignant neoplasm arising during retinal development from mutations in the RB1 gene. Loss or inactivation of both copies of RB1 results in initiation of retinoblastoma tumours, however additional genetic changes are needed for the continued growth and spread of the tumour. Ex vivo research has shown that in humans, retinoblastoma may initiate from Rb depleted cone precursors. Notwithstanding, it has not been possible to assess the full spectrum of clonal types within the tumour itself in vivo and the molecular changes occurring at the cells of origin, enabling their malignant conversion. To overcome these challenges, we have performed the first single cell (sc) RNA- and ATAC-Seq analyses of primary tumour tissues, enabling us to dissect the transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human Rb tumours. Methods: Two Rb tumours each characterised by two pathogenic RB1 mutations were dissociated to single cells and subjected to scRNA-Seq & scATAC-Seq using the 10x Genomics platform. In addition, nine embryonic and fetal retina samples were dissociated to single cells and subjected to scRNA- and ATAC-Seq analyses. The scRNA- and ATAC-Seq data were embedded using Uniform Manifold Approximation and Projection (UMAP) and clustered using Seurat graph based-clustering. Integrated scATAC-Seq analysis of Rb tumours and human embryonic/fetal retina samples was performed to identify Rb cone enriched subsets. Pseudotime analysis of proliferating cones in the Rb samples was performed with Monocle. Ingenuity Pathway Analysis (IPA) was used to identify the signalling pathway and upstream regulators in the Rb cone enriched subclusters. Results: Our single cell analyses revealed the predominant presence of cone precursors at different stages of the cell cycle in the Rb tumours and amongst those identified the G2/M subset as the cell type of origin. scATAC-Seq analysis identified two Rb enriched cone subsets, each characterised by activation of different upstream regulators and signalling pathways, leading proliferating cone precursors to escape cell cycle arrest and/or apoptosis. Conclusions: Our study provides evidence of Rb tumor heterogeneity and defines molecular pathways that can be targeted to define new treatment strategies
2021-07-26 | GSE166174 | GEO
Project description:Background: Retinoblastoma (Rb) is a malignant neoplasm arising during retinal development from mutations in the RB1 gene. Loss or inactivation of both copies of RB1 results in initiation of retinoblastoma tumours, however additional genetic changes are needed for the continued growth and spread of the tumour. Ex vivo research has shown that in humans, retinoblastoma may initiate from Rb depleted cone precursors. Notwithstanding, it has not been possible to assess the full spectrum of clonal types within the tumour itself in vivo and the molecular changes occurring at the cells of origin, enabling their malignant conversion. To overcome these challenges, we have performed the first single cell (sc) RNA- and ATAC-Seq analyses of primary tumour tissues, enabling us to dissect the transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human Rb tumours. Methods: Two Rb tumours each characterised by two pathogenic RB1 mutations were dissociated to single cells and subjected to scRNA-Seq & scATAC-Seq using the 10x Genomics platform. In addition, nine embryonic and fetal retina samples were dissociated to single cells and subjected to scRNA- and ATAC-Seq analyses. The scRNA- and ATAC-Seq data were embedded using Uniform Manifold Approximation and Projection (UMAP) and clustered using Seurat graph based-clustering. Integrated scATAC-Seq analysis of Rb tumours and human embryonic/fetal retina samples was performed to identify Rb cone enriched subsets. Pseudotime analysis of proliferating cones in the Rb samples was performed with Monocle. Ingenuity Pathway Analysis (IPA) was used to identify the signalling pathway and upstream regulators in the Rb cone enriched subclusters. Results: Our single cell analyses revealed the predominant presence of cone precursors at different stages of the cell cycle in the Rb tumours and amongst those identified the G2/M subset as the cell type of origin. scATAC-Seq analysis identified two Rb enriched cone subsets, each characterised by activation of different upstream regulators and signalling pathways, leading proliferating cone precursors to escape cell cycle arrest and/or apoptosis. Conclusions: Our study provides evidence of Rb tumor heterogeneity and defines molecular pathways that can be targeted to define new treatment strategies
2021-07-26 | GSE166173 | GEO
Project description:PurposeRetinoblastoma (Rb) is a malignant neoplasm arising during retinal development from mutations in the RB1 gene. Loss or inactivation of both copies of RB1 results in initiation of retinoblastoma tumors; however, additional genetic changes are needed for the continued growth and spread of the tumor. Ex vivo research has shown that in humans, retinoblastoma may initiate from RB1-depleted cone precursors. Notwithstanding, it has not been possible to assess the full spectrum of clonal types within the tumor itself in vivo and the molecular changes occurring at the cells of origin, enabling their malignant conversion. To overcome these challenges, we have performed the first single cell (sc) RNA- and ATAC-Seq analyses of primary tumor tissues, enabling us to dissect the transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human Rb tumors.MethodsTwo Rb tumors each characterized by two pathogenic RB1 mutations were dissociated to single cells and subjected to scRNA-Seq and scATAC-Seq using the 10× Genomics platform. In addition, nine human embryonic and fetal retina samples were dissociated to single cells and subjected to scRNA- and ATAC-Seq analyses. The scRNA- and ATAC-Seq data were embedded using Uniform Manifold Approximation and Projection and clustered with Seurat graph-based clustering. Integrated scATAC-Seq analysis of Rb tumors and human embryonic/fetal retina samples was performed to identify Rb cone enriched subclusters. Pseudo time analysis of proliferating cones in the Rb samples was performed with Monocle. Ingenuity Pathway Analysis was used to identify the signaling pathway and upstream regulators in the Rb cone-enriched subclusters.ResultsOur single cell analyses revealed the predominant presence of cone precursors at different stages of the cell cycle in the Rb tumors and among those identified the G2/M subset as the cell type of origin. scATAC-Seq analysis identified two Rb enriched cone subclusters, each characterized by activation of different upstream regulators and signaling pathways, enabling proliferating cone precursors to escape cell cycle arrest and/or apoptosis.ConclusionsOur study provides evidence of Rb tumor heterogeneity and defines molecular pathways that can be targeted to define new treatment strategies.
| S-EPMC8132003 | biostudies-literature
Project description:Dissecting transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human retinoblastoma tumours by single cell sequencing
| PRJNA699531 | ENA
Project description:Dissecting transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human retinoblastoma tumours by single cell sequencing [scRNA-seq]
| PRJNA699542 | ENA
Project description:Dissecting transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human retinoblastoma tumours by single cell sequencing [scATAC-seq]
| PRJNA699543 | ENA
Project description:Retinoblastoma is a childhood retinal tumour that initiates in response to biallelic RB1 inactivation and loss of functional retinoblastoma (Rb) protein. Although Rb has diverse tumour-suppressor functions and is inactivated in many cancers, germline RB1 mutations predispose to retinoblastoma far more strongly than to other malignancies. This tropism suggests that retinal cell-type-specific circuitry sensitizes to Rb loss, yet the nature of the circuitry and the cell type in which it operates have been unclear. Here we show that post-mitotic human cone precursors are uniquely sensitive to Rb depletion. Rb knockdown induced cone precursor proliferation in prospectively isolated populations and in intact retina. Proliferation followed the induction of E2F-regulated genes, and depended on factors having strong expression in maturing cone precursors and crucial roles in retinoblastoma cell proliferation, including MYCN and MDM2. Proliferation of Rb-depleted cones and retinoblastoma cells also depended on the Rb-related protein p107, SKP2, and a p27 downregulation associated with cone precursor maturation. Moreover, Rb-depleted cone precursors formed tumours in orthotopic xenografts with histological features and protein expression typical of human retinoblastoma. These findings provide a compelling molecular rationale for a cone precursor origin of retinoblastoma. More generally, they demonstrate that cell-type-specific circuitry can collaborate with an initiating oncogenic mutation to enable tumorigenesis.
| S-EPMC4232224 | biostudies-literature
Project description:The presence of genome-wide DNA hypermethylation is a hallmark of lower grade gliomas (LGG) with isocitrate dehydrogenase (IDH) mutations. Further molecular classification of IDH mutant gliomas is defined by the presence (IDHmut-codel) or absence (IDHmut-noncodel) of hemizygous codeletion of chromosome arms 1p and 19q. Despite the DNA hypermethylation seen in bulk tumors, intra-tumoral heterogeneity at the epigenetic level has not been thoroughly analyzed. To address this question, we performed the first epigenetic profiling of single cells in a cohort of 5 gliomas with IDH1 mutation using single nucleus Assay for Transposase-Accessible Chromatin with high-throughput sequencing (snATAC-seq). Using the Fluidigm HT IFC microfluidics platform, we generated chromatin accessibility maps from 336 individual nuclei, and identified variable promoter accessibility of non-coding RNAs in LGGs. Interestingly, local chromatin structures of several non-coding RNAs are significant factors that contribute to heterogeneity, and show increased promoter accessibility in IDHmut-noncodel samples. As an example for clinical significance of this result, we identify CYTOR as a poor prognosis factor in gliomas with IDH mutation. Open chromatin assay points to differential accessibility of non-coding RNAs as an important source of epigenetic heterogeneity within individual tumors and between molecular subgroups. Rare populations of nuclei that resemble either IDH mutant molecular group co-exist within IDHmut-noncodel and IDHmut-codel groups, and along with non-coding RNAs may be an important issue to consider for future studies, as they may help guide predict treatment response and relapse.A web-based explorer for the data is available at shiny.turcanlab.org.
| S-EPMC6896263 | biostudies-literature
Project description:The integration of single cell transcriptome and chromatin accessibility datasets enables a deeper understanding of cell heterogeneity. We performed single nucleus ATAC (snATAC-seq) and RNA (snRNA-seq) sequencing to generate paired, cell-type-specific chromatin accessibility and transcriptional profiles of the adult human kidney. We demonstrate that snATAC-seq is comparable to snRNA-seq in the assignment of cell identity and can further refine our understanding of functional heterogeneity in the nephron. The majority of differentially accessible chromatin regions are localized to promoters and a significant proportion are closely associated with differentially expressed genes. Cell-type-specific enrichment of transcription factor binding motifs implicates the activation of NF-κB that promotes VCAM1 expression and drives transition between a subpopulation of proximal tubule epithelial cells. Our multi-omics approach improves the ability to detect unique cell states within the kidney and redefines cellular heterogeneity in the proximal tubule and thick ascending limb.
| S-EPMC8044133 | biostudies-literature
Project description:BackgroundMutations in TP53 not only affect its tumour suppressor activity but also exerts oncogenic gain-of-function activity. While the genome-wide mutant p53 binding sites have been identified in cancer cell lines, the chromatin accessibility landscape driven by mutant p53 in primary tumours is unknown. Here, we leveraged the chromatin accessibility data of primary tumours from The Cancer Genome Atlas (TCGA) to identify differentially accessible regions in mutant p53 tumours compared to wild-type p53 tumours, especially in breast and colon cancers.ResultsWe identified 1587 lost and 984 gained accessible chromatin regions in breast, and 1143 lost and 640 gained regions in colon cancers. However, only less than half of those regions in both cancer types contain sequence motifs for wild-type or mutant p53 binding. Whereas, the remaining showed enrichment for master transcriptional regulators, such as FOX-Family TFs and NF-kB in lost and SMAD and KLF TFs in gained regions of breast. In colon, ATF3 and FOS/JUN TFs were enriched in lost, and CDX family TFs and HNF4A in gained regions. By integrating the gene expression data, we identified known and novel target genes regulated by the mutant p53.ConclusionThis study reveals the direct and indirect mechanisms by which gain-of-function mutant p53 targets the chromatin and subsequent gene expression patterns in a tumour-type specific manner. This furthers our understanding of the impact of mutant p53 in cancer development.
| S-EPMC8180165 | biostudies-literature