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Principal Investigator: Kevin O'Connor
Organization: UNIV OF MASSACHUSETTS MED SCH WORCESTER
Fiscal Year: 2024
Award: $50,649
Funding agency: National Cancer Institute
PROJECT SUMMARY/ABSTRACT
Therapy resistance is a major barrier to long term remission in pediatric T-cell acute lymphoblastic leukemia (T-
ALL). The prognosis for children with relapsed or refractory disease is dismal. Leukemia-initiating cells (L-ICs)
regenerate disease upon transplantation into mice. They also recapitulate the immunophenotypic complexity of
the parent leukemia supporting that, as in normal hematopoiesis, there is a cellular hierarchy among leukemic
cells. Our laboratory has previously demonstrated that the L-IC is a committed thymocyte progenitor and resides
in the leukemic DN3 population, however, only a fraction of DN3 cells can give rise to disease. L-ICs rely on
NOTCH1-induced MYC signaling for survival. Recent studies identified dormant, therapy resistant L-ICs in both
murine models and T-ALL patient samples. The role of cell cycle restriction in L-IC latency is incompletely
understood. In an effort to uncover pathways that govern L-IC function, we performed single cell RNA-
sequencing on thymocytes at varying stages of T-cell leukemogenesis using our transgenic Tal1/Lmo2 model.
This approach identified a dormant DN3 cluster, marked by low Ki67 expression, which is observed in other
murine T-ALL samples. Dormant DN3 cells exhibit high Notch1, but low Myc expression. The transcriptional
signature of these cells shows enrichment of genes previously implicated in leukemia initiation or leukemia stem
cell function. Dormant DN3 cells show enrichment of the non-canonical Wnt receptor Ryk, which is reported to
maintain hematopoietic stem cell self-renewal by limiting proliferation and promoting quiescence. RYK is
overexpressed in primary pediatric T-ALL and in Tal1/Lmo2-induced murine T-ALL compared to healthy thymus.
This indicates that RYK may not be restricted to this rare subpopulation and moreover, there may be a
therapeutic window for RYK inhibition in relapsed T-ALL. The central hypothesis of this proposal is that dormant
DN3 cells are quiescent L-ICs that retain proliferative and differentiative capacity, which permits their therapy
tolerance and subsequent expansion during relapse. This proposal will identify a gene signature of dormant DN3
cells and uncover the potential role of these cells in T-ALL relapse by evaluating their L-IC function and
chemoresistance (Aim 1). Aim 2 will define the non-canonical WNT/RYK signaling network in T-ALL and uncover
the role of these pathways in dormant DN3 cells and L-IC function by testing whether inhibition of RYK reduces
the L-IC frequency of murine and patient T-ALL cells. Collectively, these studies will provide critical insight to T-
ALL heterogeneity and will lay the foundation for development of L-IC targeted therapy for relapsed disease.
Terms: <0-11 years old><Acute T Cell Leukemia><Acute T-Cell Lymphoblastic Leukemia><Acute T-Cell Lymphocytic Leukemia><Acute T-Lymphocytic Leukemia><Assay><Beta Cadherin-Associated Protein><Beta-1 Catenin><Bioassay><Biological Assay><Blood Precursor Cell><CUL-2><Calcineurin><Cell Body><Cell Communication and Signaling><Cell Cycle><Cell Division Cycle><Cell Function><Cell Isolation><Cell Physiology><Cell Process><Cell Segregation><Cell Separation><Cell Separation Technology><Cell Signaling><Cell surface><Cells><Cellular Function><Cellular Physiology><Cellular Process><Chemoresistance><Child><Child Youth><Childhood ALL><Childhood Acute Lymphoblastic Leukemia><Childhood Acute Lymphocytic Leukemia><Childhood Acute Lymphogenous Leukemia><Childhood Acute Lymphoid Leukemia><Childhood Precursor T Lymphoblastic Leukemia><Children (0-21)><Data><Data Bases><Databases><Development><Diagnosis><Disease><Disease remission><Disorder><Drosophila Homolog of NOTCH 1><Exhibits><Expression Signature><Failure><Foundations><Frequencies><GEM model><GEMM model><Gene Expression Profile><Gene Transcription><Genes><Genetic Transcription><Genetically Engineered Mouse><Goals><HSC quiescence><HSC regeneration><HSC self-renewal><Hematopoiesis><Hematopoietic Cellular Control Mechanisms><Hematopoietic Progenitor Cells><Hematopoietic stem cells><Heterogeneity><Human><Immunologic Subtyping><Immunophenotyping><Impairment><Intracellular Communication and Signaling><L1 Lymphocytic Leukemia><Label><Laboratories><Leukemic Cell><Leukemic progenitor and stem cell><Lymphoblastic Leukemia, Acute, L1><Mediating><Mice><Mice Mammals><Modeling><Modern Man><Murine><Mus><NOTCH1><NOTCH1 gene><PDX model><PP2B><PRO2286><Parents><Pathway interactions><Patient derived xenograft><Patients><Pediatric ALL><Pediatric Acute Lymphoblastic Leukemia><Pediatric Acute Lymphocytic Leukemia><Pediatric Acute Lymphogenous Leukemia><Pediatric Acute Lymphoid Leukemia><Population><Precursor T Lymphoblastic Leukemia><Progenitor Cells><Prognosis><Proliferating><Protein Phosphatase-2B><RNA Expression><RNA Seq><RNA sequencing><RNAseq><Radiation therapy><Radiotherapeutics><Radiotherapy><Receptor Protein><Recurrent disease><Refractory Disease><Relapse><Relapsed Disease><Remission><Reporting><Resistance><Role><SCL Transcription Factor><Sampling><Signal Pathway><Signal Transduction><Signal Transduction Systems><Signaling><Sorting><Stem Cell Leukemia Hematopoietic Transcription Factor><Stem Cell Protein><Subcellular Process><T leukemia cell><T-ALL cell><T-Cell Acute Lymphocytic Leukemia 1 Gene><T-Cell Childhood ALL><T-Cell Childhood Acute Lymphoblastic Leukemia><T-Cell Childhood Acute Lymphocytic Leukemia><T-Cell Pediatric ALL><T-Cell Pediatric Acute Lymphoblastic Leukemia><T-Cell Pediatric Acute Lymphocytic Leukemia><T-Cell Subsets><T-Cell Type Acute Leukemia><T-Cells><T-Lymphocyte><T-Lymphocyte Subsets><T-cell acute lymphocytic leukemia 1 protein><T-lineage acute lymphoblastic leukemia><TAL1><TAL1 Gene Product><TAL1 gene><TAN1><TCL5><Testing><Therapeutic><Thymus><Thymus Gland><Thymus Proper><Thymus Reticuloendothelial System><Transcription><Transgenic Organisms><Translocation-Associated NOTCH Homolog><Transplantation><WNT Signaling Pathway><WNT signaling><Work><acute T-cell lymphoblastic leukemia cell><acute T-cell lymphocytic leukemia cell><beta catenin><biological signal transduction><blood cell formation><blood cell progenitor><blood progenitor><blood stem cell><blood stem cell quiescence><blood stem cell self-renewal><blood-forming stem cell><cell regeneration><cell sorting><cellular regeneration><chemoresistant><chemotherapy><chemotherapy resistance><chemotherapy resistant><data base><developmental><differential expression><differentially expressed><gene expression pattern><gene expression signature><gene signatures><genetic signature><genetically engineered mouse model><genetically engineered murine model><hematopoietic progenitor><hematopoietic progenitor cell self-renewal><hematopoietic stem cell quiescence><hematopoietic stem cell regeneration><hematopoietic stem cell self-renewal><hematopoietic stem progenitor cell><hemopoietic progenitor><hemopoietic stem cell><human disease><immunophenotype><in vivo><infant ALL><insight><kids><leukemia><leukemia initiating cell><leukemia relapse><leukemia treatment><leukemic progenitor><leukemic stem cell><leukemic therapy><leukemogenesis><mouse model><murine model><overexpress><overexpression><parent><pathway><patient derived xenograft model><prevent><preventing><progenitor><progenitor cell function><progenitor cell population><progenitor cell proliferation><progenitor function><progenitor population><progenitor proliferation><programs><radiation treatment><receptor><regeneration potential><regenerative potential><resistance to therapy><resistant><resistant to therapy><scRNA-seq><single cell RNA-seq><single cell RNAseq><single cell expression profiling><single cell transcriptomic profiling><single-cell RNA sequencing><social role><stem and progenitor cell function><stem and progenitor cell population><stem and progenitor cell proliferation><stem and progenitor function><stem cell function><stem cell population><stem cell proliferation><stem cells><targeted drug therapy><targeted drug treatments><targeted therapeutic><targeted therapeutic agents><targeted therapy><targeted treatment><therapeutic resistance><therapy resistant><thymocyte><thymus derived lymphocyte><transcriptional differences><transcriptional profile><transcriptional signature><transcriptome sequencing><transcriptomic sequencing><transgenic><transplant><treatment resistance><treatment with radiation><youngster><β-catenin>