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Pendse S, Loeffler D. Decoding Clonal Hematopoiesis: Emerging Themes and Novel Mechanistic Insights. Cancers (Basel) 2024; 16:2634. [PMID: 39123361 PMCID: PMC11311828 DOI: 10.3390/cancers16152634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Revised: 07/22/2024] [Accepted: 07/22/2024] [Indexed: 08/12/2024] Open
Abstract
Clonal hematopoiesis (CH), the relative expansion of mutant clones, is derived from hematopoietic stem cells (HSCs) with acquired somatic or cytogenetic alterations that improve cellular fitness. Individuals with CH have a higher risk for hematological and non-hematological diseases, such as cardiovascular disease, and have an overall higher mortality rate. Originally thought to be restricted to a small fraction of elderly people, recent advances in single-cell sequencing and bioinformatics have revealed that CH with multiple expanded mutant clones is universal in the elderly population. Just a few years ago, phylogenetic reconstruction across the human lifespan and novel sensitive sequencing techniques showed that CH can start earlier in life, decades before it was thought possible. These studies also suggest that environmental factors acting through aberrant inflammation might be a common theme promoting clonal expansion and disease progression. However, numerous aspects of this phenomenon remain to be elucidated and the precise mechanisms, context-specific drivers, and pathways of clonal expansion remain to be established. Here, we review our current understanding of the cellular mechanisms driving CH and specifically focus on how pro-inflammatory factors affect normal and mutant HSC fates to promote clonal selection.
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Affiliation(s)
- Shalmali Pendse
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Comprehensive Cancer Center, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Department of Pathology & Laboratory Medicine, The University of Tennessee, Memphis, TN 37996, USA
| | - Dirk Loeffler
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Comprehensive Cancer Center, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Department of Pathology & Laboratory Medicine, The University of Tennessee, Memphis, TN 37996, USA
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Mistry JJ, Young KA, Colom Díaz PA, Maestre IF, Levine RL, Trowbridge JJ. Mesenchymal Stromal Cell Senescence Induced by Dnmt3a -Mutant Hematopoietic Cells is a Targetable Mechanism Driving Clonal Hematopoiesis and Initiation of Hematologic Malignancy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.28.587254. [PMID: 38585779 PMCID: PMC10996614 DOI: 10.1101/2024.03.28.587254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Clonal hematopoiesis (CH) can predispose to blood cancers due to enhanced fitness of mutant hematopoietic stem and progenitor cells (HSPCs), but the mechanisms driving this progression are not understood. We hypothesized that malignant progression is related to microenvironment-remodelling properties of CH-mutant HSPCs. Single-cell transcriptomic profiling of the bone marrow microenvironment in Dnmt3a R878H/+ mice revealed signatures of cellular senescence in mesenchymal stromal cells (MSCs). Dnmt3a R878H/+ HSPCs caused MSCs to upregulate the senescence markers SA-β-gal, BCL-2, BCL-xL, Cdkn1a (p21) and Cdkn2a (p16), ex vivo and in vivo . This effect was cell contact-independent and can be replicated by IL-6 or TNFα, which are produced by Dnmt3a R878H/+ HSPCs. Depletion of senescent MSCs in vivo reduced the fitness of Dnmt3a R878H/+ hematopoietic cells and the progression of CH to myeloid neoplasms using a sequentially inducible Dnmt3a ; Npm1 -mutant model. Thus, Dnmt3a -mutant HSPCs reprogram their microenvironment via senescence induction, creating a self-reinforcing niche favoring fitness and malignant progression. Statement of Significance Mesenchymal stromal cell senescence induced by Dnmt3a -mutant hematopoietic stem and progenitor cells drives clonal hematopoiesis and initiation of hematologic malignancy.
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Park E, Evans MA, Walsh K. Regulators of clonal hematopoiesis and physiological consequences of this condition. THE JOURNAL OF CARDIOVASCULAR AGING 2024; 4:3. [PMID: 39119355 PMCID: PMC11309374 DOI: 10.20517/jca.2023.39] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
Clonal hematopoiesis (CH) is a prevalent condition that results from somatic mutations in hematopoietic stem cells. When these mutations occur in "driver" genes, they can potentially confer fitness advantages to the affected cells, leading to a clonal expansion. While most clonal expansions of mutant cells are generally considered to be asymptomatic since they do not impact overall blood cell numbers, CH carriers face long-term risks of all-cause mortality and age-associated diseases, including cardiovascular disease and hematological malignancies. While considerable research has focused on understanding the association between CH and these diseases, less attention has been given to exploring the regulatory factors that contribute to the expansion of the driver gene clone. This review focuses on the association between environmental stressors and inherited genetic risk factors in the context of CH development. A better understanding of how these stressors impact CH development will facilitate mechanistic studies and potentially lead to new therapeutic avenues to treat individuals with this condition.
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Affiliation(s)
- Eunbee Park
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Megan A. Evans
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Kenneth Walsh
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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Muto T, Walker CS, Agarwal P, Vick E, Sampson A, Choi K, Niederkorn M, Ishikawa C, Hueneman K, Varney M, Starczynowski DT. Inactivation of p53 provides a competitive advantage to del(5q) myelodysplastic syndrome hematopoietic stem cells during inflammation. Haematologica 2023; 108:2715-2729. [PMID: 37102608 PMCID: PMC10542836 DOI: 10.3324/haematol.2022.282349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 04/17/2023] [Indexed: 04/28/2023] Open
Abstract
Inflammation is associated with the pathogenesis of myelodysplastic syndromes (MDS) and emerging evidence suggests that MDS hematopoietic stem and progenitor cells (HSPC) exhibit an altered response to inflammation. Deletion of chromosome 5 (del(5q)) is the most common chromosomal abnormality in MDS. Although this MDS subtype contains several haploinsufficient genes that impact innate immune signaling, the effects of inflammation on del(5q) MDS HSPC remains undefined. Utilizing a model of del(5q)-like MDS, inhibiting the IRAK1/4-TRAF6 axis improved cytopenias, suggesting that activation of innate immune pathways contributes to certain clinical features underlying the pathogenesis of low-risk MDS. However, low-grade inflammation in the del(5q)-like MDS model did not contribute to more severe disease but instead impaired the del(5q)-like HSPC as indicated by their diminished numbers, premature attrition and increased p53 expression. Del(5q)-like HSPC exposed to inflammation became less quiescent, but without affecting cell viability. Unexpectedly, the reduced cellular quiescence of del(5q) HSPC exposed to inflammation was restored by p53 deletion. These findings uncovered that inflammation confers a competitive advantage of functionally defective del(5q) HSPC upon loss of p53. Since TP53 mutations are enriched in del(5q) AML following an MDS diagnosis, increased p53 activation in del(5q) MDS HSPC due to inflammation may create a selective pressure for genetic inactivation of p53 or expansion of a pre-existing TP53-mutant clone.
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Affiliation(s)
- Tomoya Muto
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; Department of Hematology, Chiba University Hospital, Chiba.
| | - Callum S Walker
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Puneet Agarwal
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Eric Vick
- Division of Hematology and Oncology, University of Cincinnati, Cincinnati, OH
| | - Avery Sampson
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Kwangmin Choi
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Madeline Niederkorn
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Chiharu Ishikawa
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; Department of Cancer Biology, University of Cincinnati, Cincinnati, OH
| | - Kathleen Hueneman
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Melinda Varney
- Department of Pharmaceutical Science and Research, Marshall University, Huntington, WV
| | - Daniel T Starczynowski
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; Department of Cancer Biology, University of Cincinnati, Cincinnati, OH; Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; UC Cancer Center, Cincinnati, OH.
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Ktena YP, Dionysiou M, Gondek LP, Cooke KR. The impact of epigenetic modifications on allogeneic hematopoietic stem cell transplantation. Front Immunol 2023; 14:1188853. [PMID: 37325668 PMCID: PMC10264773 DOI: 10.3389/fimmu.2023.1188853] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 05/18/2023] [Indexed: 06/17/2023] Open
Abstract
The field of epigenetics studies the complex processes that regulate gene expression without altering the DNA sequence itself. It is well established that epigenetic modifications are crucial to cellular homeostasis and differentiation and play a vital role in hematopoiesis and immunity. Epigenetic marks can be mitotically and/or meiotically heritable upon cell division, forming the basis of cellular memory, and have the potential to be reversed between cellular fate transitions. Hence, over the past decade, there has been increasing interest in the role that epigenetic modifications may have on the outcomes of allogeneic hematopoietic transplantation and growing enthusiasm in the therapeutic potential these pathways may hold. In this brief review, we provide a basic overview of the types of epigenetic modifications and their biological functions, summarizing the current literature with a focus on hematopoiesis and immunity specifically in the context of allogeneic hematopoietic stem cell transplantation.
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Affiliation(s)
- Yiouli P. Ktena
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Yamatani Y, Nakai K. Comprehensive comparison of gene expression diversity among a variety of human stem cells. NAR Genom Bioinform 2022; 4:lqac087. [PMCID: PMC9706419 DOI: 10.1093/nargab/lqac087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 10/26/2022] [Accepted: 11/08/2022] [Indexed: 12/02/2022] Open
Abstract
Several factors, including tissue origins and culture conditions, affect the gene expression of undifferentiated stem cells. However, understanding the basic identity across different stem cells has not been pursued well despite its importance in stem cell biology. Thus, we aimed to rank the relative importance of multiple factors to gene expression profile among undifferentiated human stem cells by analyzing publicly available RNA-seq datasets. We first conducted batch effect correction to avoid undefined variance in the dataset as possible. Then, we highlighted the relative impact of biological and technical factors among undifferentiated stem cell types: a more influence on tissue origins in induced pluripotent stem cells than in other stem cell types; a stronger impact of culture condition in embryonic stem cells and somatic stem cell types, including mesenchymal stem cells and hematopoietic stem cells. In addition, we found that a characteristic gene module, enriched in histones, exhibits higher expression across different stem cell types that were annotated by specific culture conditions. This tendency was also observed in mouse stem cell RNA-seq data. Our findings would help to obtain general insights into stem cell quality, such as the balance of differentiation potentials that undifferentiated stem cells possess.
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Affiliation(s)
- Yukiyo Yamatani
- Department of Computational Biology and Medical Sciences, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan
| | - Kenta Nakai
- To whom correspondence should be addressed. Tel: +81 3 5449 5131; Fax: +81 3 5449 5133;
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Florez MA, Tran BT, Wathan TK, DeGregori J, Pietras EM, King KY. Clonal hematopoiesis: Mutation-specific adaptation to environmental change. Cell Stem Cell 2022; 29:882-904. [PMID: 35659875 PMCID: PMC9202417 DOI: 10.1016/j.stem.2022.05.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Clonal hematopoiesis of indeterminate potential (CHIP) describes a widespread expansion of genetically variant hematopoietic cells that increases exponentially with age and is associated with increased risks of cancers, cardiovascular disease, and other maladies. Here, we discuss how environmental contexts associated with CHIP, such as old age, infections, chemotherapy, or cigarette smoking, alter tissue microenvironments to facilitate the selection and expansion of specific CHIP mutant clones. Further, we consider major remaining gaps in knowledge, including intrinsic effects, clone size thresholds, and factors affecting clonal competition, that will determine future application of this field in transplant and preventive medicine.
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Affiliation(s)
- Marcus A Florez
- Medical Scientist Training Program and Program in Translational Biology and Molecular Medicine, Graduate School of Biomedical Sciences, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA; Division of Infectious Disease, Department of Pediatrics, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA
| | - Brandon T Tran
- Graduate School of Biomedical Sciences, Program in Cancer and Cell Biology, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA; Division of Infectious Disease, Department of Pediatrics, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA
| | - Trisha K Wathan
- Division of Infectious Disease, Department of Pediatrics, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Division of Hematology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Microbiology and Immunology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Eric M Pietras
- Division of Hematology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Microbiology and Immunology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Katherine Y King
- Medical Scientist Training Program and Program in Translational Biology and Molecular Medicine, Graduate School of Biomedical Sciences, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA; Graduate School of Biomedical Sciences, Program in Cancer and Cell Biology, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA; Division of Infectious Disease, Department of Pediatrics, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA; Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, 1102 Bates Street, Suite 1150, Houston, TX 77030, USA.
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De Dominici M, DeGregori J. Dnmt3a-Mutant Hematopoietic Stem Cell Rewire IFNγ Signaling to Gain Clonal Advantage. Blood Cancer Discov 2022; 3:178-180. [PMID: 35394495 DOI: 10.1158/2643-3230.bcd-22-0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
SUMMARY Dnmt3a-mutant stem cells gain a competitive advantage via upregulation of a Txnip-p53-p21 axis and protection from IFNγ induced exhaustion. See related article by Zhang et al., (5) .
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Affiliation(s)
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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