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1.
Nat Commun ; 15(1): 4325, 2024 May 21.
Article in English | MEDLINE | ID: mdl-38773071

ABSTRACT

Hematopoietic stem cell (HSC) mutations can result in clonal hematopoiesis (CH) with heterogeneous clinical outcomes. Here, we investigate how the cell state preceding Tet2 mutation impacts the pre-malignant phenotype. Using an inducible system for clonal analysis of myeloid progenitors, we find that the epigenetic features of clones at similar differentiation status are highly heterogeneous and functionally respond differently to Tet2 mutation. Cell differentiation stage also influences Tet2 mutation response indicating that the cell of origin's epigenome modulates clone-specific behaviors in CH. Molecular features associated with higher risk outcomes include Sox4 that sensitizes cells to Tet2 inactivation, inducing dedifferentiation, altered metabolism and increasing the in vivo clonal output of mutant cells, as confirmed in primary GMP and HSC models. Our findings validate the hypothesis that epigenetic features can predispose specific clones for dominance, explaining why identical genetic mutations can result in different phenotypes.


Subject(s)
DNA-Binding Proteins , Dioxygenases , Epigenesis, Genetic , Hematopoietic Stem Cells , Mutation , Proto-Oncogene Proteins , Dioxygenases/genetics , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Animals , Hematopoietic Stem Cells/metabolism , Hematopoietic Stem Cells/cytology , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins/metabolism , Humans , Hematopoiesis/genetics , Mice , Cell Differentiation/genetics
2.
J Vis Exp ; (203)2024 Jan 26.
Article in English | MEDLINE | ID: mdl-38345255

ABSTRACT

Single-cell sequencing has enabled the mapping of heterogeneous cell populations in the stroma of hematopoietic organs. These methodologies provide a lens through which to study previously unresolved heterogeneity at steady state, as well as changes in cell type representation induced by extrinsic stresses or during aging. Here, we present step-wise protocols for the isolation of high-quality stromal cell populations from murine and human thymus, as well as murine bone and bone marrow. Cells isolated through these protocols are suitable for generating high-quality single-cell multiomics datasets. The impacts of sample digestion, hematopoietic lineage depletion, FACS analysis/sorting, and how these factors influence compatibility with single-cell sequencing are discussed here. With examples of FACS profiles indicating successful and inefficient dissociation and downstream stromal cell yields in post-sequencing analysis, recognizable pointers for users are provided. Considering the specific requirements of stromal cells is crucial for acquiring high-quality and reproducible results that can advance knowledge in the field.


Subject(s)
Bone Marrow , Stromal Cells , Humans , Animals , Mice , Flow Cytometry , Stromal Cells/metabolism , Hematopoietic Stem Cells , Bone Marrow Cells/metabolism
3.
Haematologica ; 109(2): 422-430, 2024 Feb 01.
Article in English | MEDLINE | ID: mdl-37584291

ABSTRACT

Monosomy 7 is the most common cytogenetic abnormality in pediatric myelodysplastic syndrome (MDS) and associated with a high risk of disease progression. However, in young children, spontaneous loss of monosomy 7 with concomitant hematologic recovery has been described, especially in the presence of germline mutations in SAMD9 and SAMD9L genes. Here, we report on our experience of close surveillance instead of upfront hematopoietic stem cell transplantation (HSCT) in seven patients diagnosed with SAMD9L syndrome and monosomy 7 at a median age of 0.6 years (range, 0.4-2.9). Within 14 months from diagnosis, three children experienced spontaneous hematological remission accompanied by a decrease in monosomy 7 clone size. Subclones with somatic SAMD9L mutations in cis were identified in five patients, three of whom attained hematological remission. Two patients acquired RUNX1 and EZH2 mutations during the observation period, of whom one progressed to myelodysplastic syndrome with excess of blasts (MDS-EB). Four patients underwent allogeneic HSCT at a median time of 26 months (range, 14-40) from diagnosis for MDSEB, necrotizing granulomatous lymphadenitis, persistent monosomy 7, and severe neutropenia. At last follow-up, six patients were alive, while one passed away due to transplant-related causes. These data confirm previous observations that monosomy 7 can be transient in young children with SAMD9L syndrome. However, they also indicate that delaying HSCT poses a substantial risk of severe infection and disease progression. Finally, surveillance of patients with SAMD9L syndrome and monosomy 7 is critical to define the evolving genetic landscape and to determine the appropriate timing of HSCT (clinicaltrials gov. Identifier: NCT00662090).


Subject(s)
Chromosome Deletion , Myelodysplastic Syndromes , Humans , Child , Child, Preschool , Infant , Remission, Spontaneous , Myelodysplastic Syndromes/diagnosis , Myelodysplastic Syndromes/genetics , Myelodysplastic Syndromes/therapy , Disease Progression , Transcription Factors/genetics , Monosomy , Chromosomes, Human, Pair 7/genetics , Intracellular Signaling Peptides and Proteins/genetics
4.
Blood ; 142(24): 2079-2091, 2023 12 14.
Article in English | MEDLINE | ID: mdl-37595362

ABSTRACT

PPM1D encodes a phosphatase that is recurrently activated across cancer, most notably in therapy-related myeloid neoplasms. However, the function of PPM1D in hematopoiesis and its contribution to tumor cell growth remain incompletely understood. Using conditional mouse models, we uncover a central role for Ppm1d in hematopoiesis and validate its potential as a therapeutic target. We find that Ppm1d regulates the competitive fitness and self-renewal of hematopoietic stem cells (HSCs) with and without exogenous genotoxic stresses. We also show that although Ppm1d activation confers cellular resistance to cytotoxic therapy, it does so to a lesser degree than p53 loss, informing the clonal competition phenotypes often observed in human studies. Notably, loss of Ppm1d sensitizes leukemias to cytotoxic therapies in vitro and in vivo, even in the absence of a Ppm1d mutation. Vulnerability to PPM1D inhibition is observed across many cancer types and dependent on p53 activity. Importantly, organism-wide loss of Ppm1d in adult mice is well tolerated, supporting the tolerability of pharmacologically targeting PPM1D. Our data link PPM1D gain-of-function mutations to the clonal expansion of HSCs, inform human genetic observations, and support the therapeutic targeting of PPM1D in cancer.


Subject(s)
DNA Damage , Tumor Suppressor Protein p53 , Adult , Humans , Animals , Mice , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism , Protein Phosphatase 2C , Mutation , Phosphoric Monoester Hydrolases/genetics , Cell Cycle
5.
J Natl Cancer Inst ; 115(8): 981-988, 2023 08 08.
Article in English | MEDLINE | ID: mdl-37042724

ABSTRACT

BACKGROUND: The expansion of hematopoietic stem cells carrying recurrent somatic mutations, termed clonal hematopoiesis (CH), is common in elderly individuals and is associated with increased risk of myeloid malignancy and all-cause mortality. Though chemotherapy is a known risk factor for developing CH, how myelosuppressive therapies affect the short-term dynamics of CH remains incompletely understood. Most studies have been limited by retrospective design, heterogeneous patient populations, varied techniques to identifying CH, and analysis of single timepoints. METHODS: We examined serial samples from 40 older women with triple-negative or hormone receptor-positive breast cancer treated on the prospective ADjuVANt Chemotherapy in the Elderly trial to evaluate the prevalence and dynamics of CH at baseline and throughout chemotherapy (6 and 12 weeks). RESULTS: CH was detected in 44% of patients at baseline and in 53% at any timepoint. Baseline patient characteristics were not associated with CH. Over the course of treatment, mutations exhibited a variety of dynamics, including emergence, expansion, contraction, and disappearance. All mutations in TP53 (n = 3) and PPM1D (n = 4), genes that regulate the DNA damage response, either became detectable or expanded over the course of treatment. Neutropenia was more common in patients with CH, particularly when the mutations became detectable during treatment, and CH was significantly associated with cyclophosphamide dose reductions and holds (P = .02). CONCLUSIONS: Our study shows that CH is common, dynamic, and of potential clinical significance in this population. Our results should stimulate larger efforts to understand the biological and clinical importance of CH in solid tumor malignancies. TRIAL REGISTRATION: ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT03858322). Clinical trial registration number: NCT03858322.


Subject(s)
Breast Neoplasms , Clonal Hematopoiesis , Humans , Female , Aged , Clonal Hematopoiesis/genetics , Breast Neoplasms/drug therapy , Breast Neoplasms/genetics , Retrospective Studies , Hematopoiesis/genetics , Mutation
6.
J Clin Med ; 10(14)2021 Jul 13.
Article in English | MEDLINE | ID: mdl-34300250

ABSTRACT

Juvenile myelomonocytic leukemia (JMML) is a rare pediatric leukemia characterized by mutations in five canonical RAS pathway genes. The diagnosis is made by typical clinical and hematological findings associated with a compatible mutation. Although this is sufficient for clinical decision-making in most JMML cases, more in-depth analysis can include DNA methylation class and panel sequencing analysis for secondary mutations. NRAS-initiated JMML is heterogeneous and adequate management ranges from watchful waiting to allogeneic hematopoietic stem cell transplantation (HSCT). Upfront azacitidine in KRAS patients can achieve long-term remissions without HSCT; if HSCT is required, a less toxic preparative regimen is recommended. Germline CBL patients often experience spontaneous resolution of the leukemia or exhibit stable mixed chimerism after HSCT. JMML driven by PTPN11 or NF1 is often rapidly progressive, requires swift HSCT and may benefit from pretransplant therapy with azacitidine. Because graft-versus-leukemia alloimmunity is central to cure high risk patients, the immunosuppressive regimen should be discontinued early after HSCT.

7.
Pediatr Hematol Oncol ; 37(6): 530-538, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32374222

ABSTRACT

PEG asparaginase is an important and established drug in the treatment of pediatric acute lymphoblastic leukemia (ALL). Severe hypertriglyceridemia is a rare complication of PEG asparaginase in combination with glucocorticoids. We report a case of excessive hypertriglyceridemia in a child during ALL induction therapy successfully treated by lipid apheresis and give a literature review on the management of hypertriglyceridemia in children treated for ALL.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/adverse effects , Blood Component Removal , Hypertriglyceridemia , Induction Chemotherapy/adverse effects , Precursor Cell Lymphoblastic Leukemia-Lymphoma , Adolescent , Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Asparaginase/administration & dosage , Asparaginase/adverse effects , Glucocorticoids/administration & dosage , Glucocorticoids/adverse effects , Humans , Hypertriglyceridemia/blood , Hypertriglyceridemia/chemically induced , Hypertriglyceridemia/therapy , Male , Precursor Cell Lymphoblastic Leukemia-Lymphoma/blood , Precursor Cell Lymphoblastic Leukemia-Lymphoma/therapy
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