Multi-functional barcoding enables high resolution study of clonal dynamics (scRNA-seq)
Ontology highlight
ABSTRACT: The remarkable evolutionary capacity of cancer poses major challenges to current therapeutic efforts, and results from the vast clonal heterogeneity and ability of individual cancer cells to adapt to diverse selective pressures. More complete mechanistic understanding of the basis of therapeutic resistance has been limited by difficulties in coupling information regarding genetic and epigenetic alterations present within individual cells to their respective transcriptomic and functional outputs. To this end, we developed a novel high-complexity expressed barcode system, ClonMapper, that integrates DNA barcoding with single-cell RNA-sequencing and clonal isolation to characterize thousands of clones within a mixed cancer cell population. In applying this system to the chronic lymphocytic leukemia cell line HG3 in the setting of resistance to fludarabine-based chemotherapy, we discover pretreatment sub-populations with distinct expression profiles (i.e. upregulated Wnt, Notch and CXCR4 signaling) that not only confer distinct treatment survivorship trajectories, but also provide the basis for long-term clonal equilibrium between co-existing clones in the absence of treatment. Characterization of individual clones comprising these sub-populations revealed remarkable genetic heterogeneity and the persistence of unique transcriptomic signatures throughout treatment exposure. These data reveal the diverse clonal characteristics and therapeutic responses of a heterogeneous cancer cell population and highlight the unprecedented resolution that can be achieved using ClonMapper.
Project description:The remarkable evolutionary capacity of cancer poses major challenges to current therapeutic efforts, and results from the vast clonal heterogeneity and ability of individual cancer cells to adapt to diverse selective pressures. More complete mechanistic understanding of the basis of therapeutic resistance has been limited by difficulties in coupling information regarding genetic and epigenetic alterations present within individual cells to their respective transcriptomic and functional outputs. To this end, we developed a novel high-complexity expressed barcode system, ClonMapper, that integrates DNA barcoding with single-cell RNA-sequencing and clonal isolation to characterize thousands of clones within a mixed cancer cell population. In applying this system to the chronic lymphocytic leukemia cell line HG3 in the setting of resistance to fludarabine-based chemotherapy, we discover pretreatment sub-populations with distinct expression profiles (i.e. upregulated Wnt, Notch and CXCR4 signaling) that not only confer distinct treatment survivorship trajectories, but also provide the basis for long-term clonal equilibrium between co-existing clones in the absence of treatment. Characterization of individual clones comprising these sub-populations revealed remarkable genetic heterogeneity and the persistence of unique transcriptomic signatures throughout treatment exposure. These data reveal the diverse clonal characteristics and therapeutic responses of a heterogeneous cancer cell population and highlight the unprecedented resolution that can be achieved using ClonMapper.
Project description:The remarkable evolutionary capacity of cancer poses major challenges to current therapeutic efforts, and results from the vast clonal heterogeneity and ability of individual cancer cells to adapt to diverse selective pressures. More complete mechanistic understanding of the basis of therapeutic resistance has been limited by difficulties in coupling information regarding genetic and epigenetic alterations present within individual cells to their respective transcriptomic and functional outputs. To this end, we developed a novel high-complexity expressed barcode system, ClonMapper, that integrates DNA barcoding with single-cell RNA-sequencing and clonal isolation to characterize thousands of clones within a mixed cancer cell population. In applying this system to the chronic lymphocytic leukemia cell line HG3 in the setting of resistance to fludarabine-based chemotherapy, we discover pretreatment sub-populations with distinct expression profiles (i.e. upregulated Wnt, Notch and CXCR4 signaling) that not only confer distinct treatment survivorship trajectories, but also provide the basis for long-term clonal equilibrium between co-existing clones in the absence of treatment. Characterization of individual clones comprising these sub-populations revealed remarkable genetic heterogeneity and the persistence of unique transcriptomic signatures throughout treatment exposure. These data reveal the diverse clonal characteristics and therapeutic responses of a heterogeneous cancer cell population and highlight the unprecedented resolution that can be achieved using ClonMapper.
Project description:The remarkable evolutionary capacity of cancer poses major challenges to current therapeutic efforts, and results from the vast clonal heterogeneity and ability of individual cancer cells to adapt to diverse selective pressures. More complete mechanistic understanding of the basis of therapeutic resistance has been limited by difficulties in coupling information regarding genetic and epigenetic alterations present within individual cells to their respective transcriptomic and functional outputs. To this end, we developed a novel high-complexity expressed barcode system, ClonMapper, that integrates DNA barcoding with single-cell RNA-sequencing and clonal isolation to characterize thousands of clones within a mixed cancer cell population. In applying this system to the chronic lymphocytic leukemia cell line HG3 in the setting of resistance to fludarabine-based chemotherapy, we discover pretreatment sub-populations with distinct expression profiles (i.e. upregulated Wnt, Notch and CXCR4 signaling) that not only confer distinct treatment survivorship trajectories, but also provide the basis for long-term clonal equilibrium between co-existing clones in the absence of treatment. Characterization of individual clones comprising these sub-populations revealed remarkable genetic heterogeneity and the persistence of unique transcriptomic signatures throughout treatment exposure. These data reveal the diverse clonal characteristics and therapeutic responses of a heterogeneous cancer cell population and highlight the unprecedented resolution that can be achieved using ClonMapper.
Project description:Little is known of the genetic architecture of cancer at the subclonal and single cell level or in the stem-like cells responsible for cancer clone maintenance and propagation. We have examined this issue in ALL in which ETV6-RUNX1 gene fuson is an early or initiating genetic lesion followed by a modest number of driver copy number alterations. By multiplexing FISH probes for these mutations, up to eight genetic abnormalities can be detected in single cells, a genetic signature of sub-clones identified and a composite picture of sub-clonal architecture and putative ancestral trees assembled. Sub-clones in ALL have variegated genetics and complex, non-linear or branching evolutionary histories. CNA are independently and recurrently acquired in sub-clones of individual patients, and in no preferential order. Clonal architecture is dynamic and changes in the lead up to a diagnosis and in relapse. Leukaemic stem cells, assayed by transplantation in NOD/SCID IL2Rgamma deficient mice, are also genetically variegated, mirroring sub-clonal patterns. These findings have significant implications for the cancer stem cell concept, for interpretation of cancer genome data and for therapeutic targetting in cancer.
Project description:Little is known of the genetic architecture of cancer at the subclonal and single cell level or in the stem-like cells responsible for cancer clone maintenance and propagation. We have examined this issue in ALL in which ETV6-RUNX1 gene fuson is an early or initiating genetic lesion followed by a modest number of driver copy number alterations. By multiplexing FISH probes for these mutations, up to eight genetic abnormalities can be detected in single cells, a genetic signature of sub-clones identified and a composite picture of sub-clonal architecture and putative ancestral trees assembled. Sub-clones in ALL have variegated genetics and complex, non-linear or branching evolutionary histories. CNA are independently and recurrently acquired in sub-clones of individual patients, and in no preferential order. Clonal architecture is dynamic and changes in the lead up to a diagnosis and in relapse. Leukaemic stem cells, assayed by transplantation in NOD/SCID IL2Rgamma deficient mice, are also genetically variegated, mirroring sub-clonal patterns. These findings have significant implications for the cancer stem cell concept, for interpretation of cancer genome data and for therapeutic targetting in cancer. Mononuclear cells were isolated at diagnosis of ALL for patient #3 and #7. Transplantation of 2 000 - 2 000 000 unsorted leukaemia cells was performed by intra-tibial injection into 7 - 14 week old NOD/SCID IL2Rgamma deficient mice. Mice were sacrificed when peripheral blood engraftment was >2%. An equivalent of 2 000 - 200 000 CD45 cells were used for serial transplantation. DNA was extracted from mononuclear cells at initial diagnosis and after second transplantation. Copy number analysis of Affymetrix 500K SNP arrays was performed in CNAG 3.0 for patients #3 and #7 at initial diagnosis and after second transplantation. Reference files were 9 samples from leukemia in remission.
Project description:Triple-negative breast cancer, characterized by aggressive growth and high intratumor heterogeneity, presents a significant clinical challenge. Here, we use a lineage-tracing system, ClonMapper, which couples heritable clonal identifying tags with single-cell RNA-sequencing (scRNA-seq), to better elucidate the response to doxorubicin in a model of TNBC. We demonstrate that, while there is a dose-dependent reduction in overall clonal diversity, there is no pre-existing resistance signature among surviving clones. Separately, we found the existence of two transcriptomically distinct clonal subpopulations that remain through the course of treatment. Among clones persisting across multiple samples we identified divergent phenotypes, suggesting a response to treatment independent of clonal identity. Finally, a subset of clones harbor novel changes in expression following treatment. The clone and sample specific responses to treatment identified herein highlight the need for better personalized treatment strategies to overcome tumor heterogeneity.
Project description:Triple-negative breast cancer, characterized by aggressive growth and high intratumor heterogeneity, presents a significant clinical challenge. Here, we use a lineage-tracing system, ClonMapper, which couples heritable clonal identifying tags with single-cell RNA-sequencing (scRNA-seq), to better elucidate the response to doxorubicin in a model of TNBC. We demonstrate that, while there is a dose-dependent reduction in overall clonal diversity, there is no pre-existing resistance signature among surviving clones. Separately, we found the existence of two transcriptomically distinct clonal subpopulations that remain through the course of treatment. Among clones persisting across multiple samples we identified divergent phenotypes, suggesting a response to treatment independent of clonal identity. Finally, a subset of clones harbor novel changes in expression following treatment. The clone and sample specific responses to treatment identified herein highlight the need for better personalized treatment strategies to overcome tumor heterogeneity.
Project description:Genetic heterogeneity though common in tumors has been rarely documented in cell lines. To examine how often B-lymphoma cell lines are comprised of subclones, we performed immunoglobulin (Ig) heavy chain hypermutation analysis. Revealing that subclones are not rare in B-cell lymphoma cell lines, 6/49 Ig hypermutated cell lines (12%) consisted of subclones with individual Ig mutations. Subclones were also identified in 2/284 leukemia/lymphoma cell lines exhibiting bimodal CD marker expression. We successfully isolated 10 subclones from four cell lines HG3, SU-DHL-5, TMD-8, U-2932). Whole exome sequencing was performed to molecularly characterize these subclones. We in detail describe the clonal structure of cell line HG3, derived from chronic lymphocytic leukemia. HG3 consists of three lineages each bearing clone-specific aberrations, gene expression and DNA methylation patterns. While donor patient leukemic cells were CD5+, two of three HG3 subclones had independently lost this marker. CD5 on HG3 cells was regulated by epigenetic/transcriptional mechanisms rather than by alternative splicing as reported hitherto. In conclusion, we show that the presence of subclones in cell lines carrying individual mutations and characterized by sets of differentially expressed genes is not uncommon. We show also that these subclones can be useful isogenic models for regulatory and functional studies.
Project description:Genetic heterogeneity though common in tumors has been rarely documented in cell lines. To examine how often B-lymphoma cell lines are comprised of subclones, we performed immunoglobulin (Ig) heavy chain hypermutation analysis. Revealing that subclones are not rare in B-cell lymphoma cell lines, 6/49 Ig hypermutated cell lines (12%) consisted of subclones with individual Ig mutations. Subclones were also identified in 2/284 leukemia/lymphoma cell lines exhibiting bimodal CD marker expression. We successfully isolated 10 subclones from four cell lines HG3, SU-DHL-5, TMD-8, U-2932). Whole exome sequencing was performed to molecularly characterize these subclones. We in detail describe the clonal structure of cell line HG3, derived from chronic lymphocytic leukemia. HG3 consists of three lineages each bearing clone-specific aberrations, gene expression and DNA methylation patterns. While donor patient leukemic cells were CD5+ , two of three HG3 subclones had independently lost this marker. CD5 on HG3 cells was regulated by epigenetic/transcriptional mechanisms rather than by alternative splicing as reported hitherto. In conclusion, we show that the presence of subclones in cell lines carrying individual mutations and characterized by sets of differentially expressed genes is not uncommon. We show also that these subclones can be useful isogenic models for regulatory and functional studies.