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Chamo M, Koren O, Goldstein O, Bujanover N, Keinan N, Scharff Y, Gazit R. Molecular Mechanisms in Murine Syngeneic Leukemia Stem Cells. Cancers (Basel) 2023; 15:cancers15030720. [PMID: 36765677 PMCID: PMC9913241 DOI: 10.3390/cancers15030720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/26/2023] Open
Abstract
Acute Myeloid Leukemia (AML) is a severe disease with a very high relapse rate. AML relapse may be attributable to leukemic stem cells (LSC). Notably, the "cancer stem cell" theory, which relates to LSCs, is controversial and criticized due to the technical peculiarities of the xenotransplant of human cells into mice. In this study, we searched for possible LSCs in an immunocompetent synergetic mice model. First, we found phenotypic heterogeneity in the ML23 leukemia line. We prospectively isolated a sub-population using the surface markers cKit+CD9-CD48+Mac1-/low, which have the potency to relapse the disease. Importantly, this sub-population can pass in syngeneic hosts and retrieve the heterogeneity of the parental ML23 leukemia line. The LSC sub-population resides in various organs. We present a unique gene expression signature of the LSC in the ML23 model compared to the other sub-populations. Interestingly, the ML23 LSC sub-population expresses therapeutic targeted genes such as CD47 and CD93. Taken together, we present the identification and molecular characterization of LSCs in a syngeneic murine model.
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2
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Barreto IV, Pessoa FMCDP, Machado CB, Pantoja LDC, Ribeiro RM, Lopes GS, Amaral de Moraes ME, de Moraes Filho MO, de Souza LEB, Burbano RMR, Khayat AS, Moreira-Nunes CA. Leukemic Stem Cell: A Mini-Review on Clinical Perspectives. Front Oncol 2022; 12:931050. [PMID: 35814466 PMCID: PMC9270022 DOI: 10.3389/fonc.2022.931050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 05/25/2022] [Indexed: 11/13/2022] Open
Abstract
Hematopoietic stem cells (HSCs) are known for their ability to proliferate and self-renew, thus being responsible for sustaining the hematopoietic system and residing in the bone marrow (BM). Leukemic stem cells (LSCs) are recognized by their stemness features such as drug resistance, self-renewal, and undifferentiated state. LSCs are also present in BM, being found in only 0.1%, approximately. This makes their identification and even their differentiation difficult since, despite the mutations, they are cells that still have many similarities with HSCs. Although the common characteristics, LSCs are heterogeneous cells and have different phenotypic characteristics, genetic mutations, and metabolic alterations. This whole set of alterations enables the cell to initiate the process of carcinogenesis, in addition to conferring drug resistance and providing relapses. The study of LSCs has been evolving and its application can help patients, where through its count as a biomarker, it can indicate a prognostic factor and reveal treatment results. The selection of a target to LSC therapy is fundamental. Ideally, the target chosen should be highly expressed by LSCs, highly selective, absence of expression on other cells, in particular HSC, and preferentially expressed by high numbers of patients. In view of the large number of similarities between LSCs and HSCs, it is not surprising that current treatment approaches are limited. In this mini review we seek to describe the immunophenotypic characteristics and mechanisms of resistance presented by LSCs, also approaching possible alternatives for the treatment of patients.
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Affiliation(s)
- Igor Valentim Barreto
- Department of Medicine, Pharmacogenetics Laboratory, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza, Brazil
| | - Flávia Melo Cunha de Pinho Pessoa
- Department of Medicine, Pharmacogenetics Laboratory, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza, Brazil
| | - Caio Bezerra Machado
- Department of Medicine, Pharmacogenetics Laboratory, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza, Brazil
| | - Laudreísa da Costa Pantoja
- Department of Pediatrics, Octávio Lobo Children’s Hospital, Belém, Brazil
- Department of Biological Sciences, Oncology Research Center, Federal University of Pará, Belém, Brazil
| | | | | | - Maria Elisabete Amaral de Moraes
- Department of Medicine, Pharmacogenetics Laboratory, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza, Brazil
| | - Manoel Odorico de Moraes Filho
- Department of Medicine, Pharmacogenetics Laboratory, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza, Brazil
| | | | | | - André Salim Khayat
- Department of Biological Sciences, Oncology Research Center, Federal University of Pará, Belém, Brazil
| | - Caroline Aquino Moreira-Nunes
- Department of Medicine, Pharmacogenetics Laboratory, Drug Research and Development Center (NPDM), Federal University of Ceará, Fortaleza, Brazil
- Department of Biological Sciences, Oncology Research Center, Federal University of Pará, Belém, Brazil
- Ceará State University, Northeast Biotechnology Network (RENORBIO), Fortaleza, Brazil
- *Correspondence: Caroline Aquino Moreira-Nunes,
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3
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Busse JE, Cuadrado S, Marciniak-Czochra A. Local asymptotic stability of a system of integro-differential equations describing clonal evolution of a self-renewing cell population under mutation. J Math Biol 2022; 84:10. [PMID: 34988700 DOI: 10.1007/s00285-021-01708-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 11/01/2021] [Accepted: 11/19/2021] [Indexed: 11/30/2022]
Abstract
In this paper we consider a system of non-linear integro-differential equations (IDEs) describing evolution of a clonally heterogeneous population of malignant white blood cells (leukemic cells) undergoing mutation and clonal selection. We prove existence and uniqueness of non-trivial steady states and study their asymptotic stability. The results are compared to those of the system without mutation. Existence of equilibria is proved by formulating the steady state problem as an eigenvalue problem and applying a version of the Krein-Rutmann theorem for Banach lattices. The stability at equilibrium is analysed using linearisation and the Weinstein-Aronszajn determinant which allows to conclude local asymptotic stability.
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Affiliation(s)
- Jan-Erik Busse
- Institute of Applied Mathematics, Interdisciplinary Center for Scientific Computing (IWR) and BIOQUANT Center, Heidelberg, Germany
| | - Sílvia Cuadrado
- Departament de Matemàtiques, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, Interdisciplinary Center for Scientific Computing (IWR) and BIOQUANT Center, Heidelberg, Germany.
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4
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Stiehl T, Marciniak-Czochra A. Computational Reconstruction of Clonal Hierarchies From Bulk Sequencing Data of Acute Myeloid Leukemia Samples. Front Physiol 2021; 12:596194. [PMID: 34497529 PMCID: PMC8419336 DOI: 10.3389/fphys.2021.596194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 07/26/2021] [Indexed: 11/13/2022] Open
Abstract
Acute myeloid leukemia is an aggressive cancer of the blood forming system. The malignant cell population is composed of multiple clones that evolve over time. Clonal data reflect the mechanisms governing treatment response and relapse. Single cell sequencing provides most direct insights into the clonal composition of the leukemic cells, however it is still not routinely available in clinical practice. In this work we develop a computational algorithm that allows identifying all clonal hierarchies that are compatible with bulk variant allele frequencies measured in a patient sample. The clonal hierarchies represent descendance relations between the different clones and reveal the order in which mutations have been acquired. The proposed computational approach is tested using single cell sequencing data that allow comparing the outcome of the algorithm with the true structure of the clonal hierarchy. We investigate which problems occur during reconstruction of clonal hierarchies from bulk sequencing data. Our results suggest that in many cases only a small number of possible hierarchies fits the bulk data. This implies that bulk sequencing data can be used to obtain insights in clonal evolution.
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Affiliation(s)
- Thomas Stiehl
- Institute for Computational Biomedicine – Disease Modeling, RWTH Aachen University, Aachen, Germany
- Institute of Applied Mathematics, Interdisciplinary Center for Scientific Computing and Bioquant Center, Heidelberg University, Heidelberg, Germany
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, Interdisciplinary Center for Scientific Computing and Bioquant Center, Heidelberg University, Heidelberg, Germany
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5
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Saeed BR, Manta L, Raffel S, Pyl PT, Buss EC, Wang W, Eckstein V, Jauch A, Trumpp A, Huber W, Ho AD, Lutz C. Analysis of nonleukemic cellular subcompartments reconstructs clonal evolution of acute myeloid leukemia and identifies therapy-resistant preleukemic clones. Int J Cancer 2021; 148:2825-2838. [PMID: 33411954 DOI: 10.1002/ijc.33461] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 07/16/2020] [Accepted: 08/27/2020] [Indexed: 12/19/2022]
Abstract
To acquire a better understanding of clonal evolution of acute myeloid leukemia (AML) and to identify the clone(s) responsible for disease recurrence, we have comparatively studied leukemia-specific mutations by whole-exome-sequencing (WES) of both the leukemia and the nonleukemia compartments derived from the bone marrow of AML patients. The T-lymphocytes, B-lymphocytes and the functionally normal hematopoietic stem cells (HSC), that is, CD34+ /CD38- /ALDH+ cells for AML with rare-ALDH+ blasts (<1.9% ALDH+ cells) were defined as the nonleukemia compartments. WES identified 62 point-mutations in the leukemia compartment derived from 12 AML-patients at the time of diagnosis and 73 mutations in 3 matched relapse cases. Most patients (8/12) showed 4 to 6 point-mutations per sample at diagnosis. Other than the mutations in the recurrently mutated genes such as DNMT3A, NRAS and KIT, we were able to identify novel point-mutations that have not yet been described in AML. Some leukemia-specific mutations and cytogenetic abnormalities including DNMT3A(R882H), EZH2(I146T) and inversion(16) were also detectable in the respective T-lymphocytes, B-lymphocytes and HSC in 5/12 patients, suggesting that preleukemia HSC might represent the source of leukemogenesis for these cases. The leukemic evolution was reconstructed for five cases with detectable preleukemia clones, which were tracked in follow-up and relapse samples. Four of the five patients with detectable preleukemic mutations developed relapse. The presence of leukemia-specific mutations in these nonleukemia compartments, especially after chemotherapy or after allogeneic stem cell transplantation, is highly relevant, as these could be responsible for relapse. This discovery may facilitate the identification of novel targets for long-term cure.
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Affiliation(s)
- Borhan R Saeed
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany
| | - Linda Manta
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany
| | - Simon Raffel
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Paul Theodor Pyl
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.,Division of Surgery, Oncology and Pathology, Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, Lund, Sweden
| | - Eike C Buss
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany
| | - Wenwen Wang
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany.,Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Volker Eckstein
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany
| | - Anna Jauch
- Institute of Human Genetics, Heidelberg University, Heidelberg, Germany
| | - Andreas Trumpp
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Wolfgang Huber
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Anthony D Ho
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany
| | - Christoph Lutz
- Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany.,Praxis for Hematology and Oncology Koblenz, Koblenz, Germany
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6
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Stiehl T. Using mathematical models to improve risk-scoring in acute myeloid leukemia. CHAOS (WOODBURY, N.Y.) 2020; 30:123150. [PMID: 33380018 DOI: 10.1063/5.0023830] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
Acute myeloid leukemia (AML) is an aggressive cancer of the blood forming (hematopoietic) system. Due to the high patient variability of disease dynamics, risk-scoring is an important part of its clinical management. AML is characterized by impaired blood cell formation and the accumulation of so-called leukemic blasts in the bone marrow of patients. Recently, it has been proposed to use counts of blood-producing (hematopoietic) stem cells (HSCs) as a biomarker for patient prognosis. In this work, we use a non-linear mathematical model to provide mechanistic evidence for the suitability of HSC counts as a prognostic marker. Using model analysis and computer simulations, we compare different risk-scores involving HSC quantification. We propose and validate a simple approach to improve risk prediction based on HSC and blast counts measured at the time of diagnosis.
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Affiliation(s)
- Thomas Stiehl
- Institute of Applied Mathematics, Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
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7
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Bessonov N, Pinna G, Minarsky A, Harel-Bellan A, Morozova N. Mathematical modeling reveals the factors involved in the phenomena of cancer stem cells stabilization. PLoS One 2019; 14:e0224787. [PMID: 31710617 PMCID: PMC6844488 DOI: 10.1371/journal.pone.0224787] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 10/22/2019] [Indexed: 12/15/2022] Open
Abstract
Cancer Stem Cells (CSC), a subset of cancer cells resembling normal stem cells with self-renewal and asymmetric division capabilities, are present at various but low proportions in many tumors and are thought to be responsible for tumor relapses following conventional cancer therapies. In vitro, most intriguingly, isolated CSCs rapidly regenerate the original population of stem and non-stem cells (non-CSCs) as shown by various investigators. This phenomenon still remains to be explained. We propose a mathematical model of cancer cell population dynamics, based on the main parameters of cell population growth, including the proliferation rates, the rates of cell death and the frequency of symmetric and asymmetric cell divisions both in CSCs and non-CSCs sub-populations, and taking into account the stabilization phenomenon. The analysis of the model allows determination of time-varying corridors of probabilities for different cell fates, given the particular dynamics of cancer cells populations; and determination of a cell-cell communication factors influencing these time-varying probabilities of cell behavior (division, transition) scenarios. Though the results of the model have to be experimentally confirmed, we can anticipate the development of several fundamental and practical applications based on the theoretical results of the model.
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Affiliation(s)
- Nikolay Bessonov
- Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, Saint-Petersburg, Russia
| | - Guillaume Pinna
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris‐Sud, University Paris‐Saclay, Gif‐sur‐Yvette, France
| | - Andrey Minarsky
- Saint-Petersburg Academic University, Russian Academy of Sciences, Saint-Petersburg, Russia
| | - Annick Harel-Bellan
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris‐Sud, University Paris‐Saclay, Gif‐sur‐Yvette, France
- Institut des Hautes Etudes Scientiques (IHES), Bures-sur-Yvette, France
| | - Nadya Morozova
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris‐Sud, University Paris‐Saclay, Gif‐sur‐Yvette, France
- Institut des Hautes Etudes Scientiques (IHES), Bures-sur-Yvette, France
- * E-mail:
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8
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Lorenzi T, Marciniak-Czochra A, Stiehl T. A structured population model of clonal selection in acute leukemias with multiple maturation stages. J Math Biol 2019; 79:1587-1621. [DOI: 10.1007/s00285-019-01404-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 07/05/2019] [Indexed: 12/19/2022]
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9
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Lo TH, Abadir E, Gasiorowski RE, Kabani K, Ramesh M, Orellana D, Fromm PD, Kupresanin F, Newman E, Cunningham I, Hart DNJ, Silveira PA, Clark GJ. Examination of CD302 as a potential therapeutic target for acute myeloid leukemia. PLoS One 2019; 14:e0216368. [PMID: 31075107 PMCID: PMC6510432 DOI: 10.1371/journal.pone.0216368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/18/2019] [Indexed: 01/03/2023] Open
Abstract
Acute myeloid leukemia (AML) is the most common form of adult acute leukemia with ~20,000 new cases yearly. The disease develops in people of all ages, but is more prominent in the elderly, who due to limited treatment options, have poor overall survival rates. Monoclonal antibodies (mAb) targeting specific cell surface molecules have proven to be safe and effective in different haematological malignancies. However, AML target molecules are currently limited so discovery of new targets would be highly beneficial to patients. We examined the C-type lectin receptor CD302 as a potential therapeutic target for AML due to its selective expression in myeloid immune populations. In a cohort of 33 AML patients with varied morphological and karyotypic classifications, 88% were found to express CD302 on the surface of blasts and 80% on the surface of CD34+ CD38- population enriched with leukemic stem cells. A mAb targeting human CD302 was effective in mediating antibody dependent cell cytotoxicity and was internalised, making it amenable to toxin conjugation. Targeting CD302 with antibody limited in vivo engraftment of the leukemic cell line HL-60 in NOD/SCID mice. While CD302 was expressed in a hepatic cell line, HepG2, this molecule was not detected on the surface of HepG2, nor could HepG2 be killed using a CD302 antibody-drug conjugate. Expression was however found on the surface of haematopoietic stem cells suggesting that targeting CD302 would be most effective prior to haematopoietic transplantation. These studies provide the foundation for examining CD302 as a potential therapeutic target for AML.
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MESH Headings
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Animals
- Antigens, Neoplasm/metabolism
- Antineoplastic Agents, Immunological/pharmacology
- Blast Crisis/drug therapy
- Blast Crisis/metabolism
- Blast Crisis/pathology
- Drug Delivery Systems
- Female
- HL-60 Cells
- Hematopoietic Stem Cell Transplantation
- Hep G2 Cells
- Humans
- Lectins, C-Type/metabolism
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Leukemia, Myeloid, Acute/therapy
- Male
- Mice
- Mice, Inbred NOD
- Mice, SCID
- Middle Aged
- Neoplastic Stem Cells/metabolism
- Neoplastic Stem Cells/pathology
- Receptors, Cell Surface/metabolism
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Tsun-Ho Lo
- Dendritic Cell Research, ANZAC Research Institute, Sydney, NSW, Australia
| | - Edward Abadir
- Dendritic Cell Research, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Robin E. Gasiorowski
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
- Department of Haematology, Concord Repatriation General Hospital, Sydney, NSW, Australia
| | - Karieshma Kabani
- Institute of Haematology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Murari Ramesh
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Daniel Orellana
- Institute of Haematology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Phillip D. Fromm
- Dendritic Cell Research, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Fiona Kupresanin
- Dendritic Cell Research, ANZAC Research Institute, Sydney, NSW, Australia
| | - Elizabeth Newman
- Department of Haematology, Concord Repatriation General Hospital, Sydney, NSW, Australia
| | - Ilona Cunningham
- Department of Haematology, Concord Repatriation General Hospital, Sydney, NSW, Australia
| | - Derek N. J. Hart
- Dendritic Cell Research, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
- Department of Haematology, Concord Repatriation General Hospital, Sydney, NSW, Australia
- Institute of Haematology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Pablo A. Silveira
- Dendritic Cell Research, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Georgina J. Clark
- Dendritic Cell Research, ANZAC Research Institute, Sydney, NSW, Australia
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia
- * E-mail:
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Fonseca ICCFE, da Luz FAC, Uehara IA, Silva MJB. Cell-adhesion molecules and their soluble forms: Promising predictors of "tumor progression" and relapse in leukemia. Tumour Biol 2018; 40:1010428318811525. [PMID: 30486756 DOI: 10.1177/1010428318811525] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Some surface markers are used to discriminate certain leukemic subpopulations that retain a greater oncogenic potential than others, and, for this reason, they were termed as leukemic stem cells, similar to the concept of cancer stem cells in carcinoma. Among these surface markers are proteins involved in cell-cell adhesion or cell-matrix adhesion, and they may play a role in the relapse of leukemia, similar to metastasis in carcinomas. The most important are epithelial cadherin, neural cadherin, epithelial cell-adhesion molecule, and CD44, which can be cleaved and released, and their soluble forms were found increased in serum levels of cancer patients, being implicated, in some cases, with progression, metastases, and relapse. In this review, we highlighted the role of these four adhesion molecules in carcinomas and hematological malignancies, mainly leukemia, and discuss if the serum levels of soluble forms can be correlated with the surface protein status on the leukemic cells. Accession of the soluble forms looks attractive, but their use as markers in cancer must be studied in association with other parameters, as there are significant changes in levels in other pathological conditions besides cancer. Studies correlating the levels of the forms with the status of the membrane-bound proteins in leukemic (stem) cells and correlating those parameters with relapse in leukemia may afford important knowledge and applicability of those serum markers in clinical practice. For instance, the expression of the membrane-bound forms of these adhesion proteins may have promising clinical use in leukemia and other hematological malignancies.
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Affiliation(s)
| | - Felipe Andrés Cordero da Luz
- 1 Laboratory of Tumor Biomarkers and Osteoimmunology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil
- 2 Nucleus of Cancer Prevention and Research, Cancer Hospital, Federal University of Uberlândia, Uberlândia, Brazil
| | - Isadora Akemi Uehara
- 1 Laboratory of Tumor Biomarkers and Osteoimmunology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil
| | - Marcelo José Barbosa Silva
- 1 Laboratory of Tumor Biomarkers and Osteoimmunology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil
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11
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Liu J, Qin YZ, Yang S, Wang Y, Chang YJ, Zhao T, Jiang Q, Huang XJ. Meis1 is critical to the maintenance of human acute myeloid leukemia cells independent of MLL rearrangements. Ann Hematol 2017; 96:567-574. [PMID: 28054140 DOI: 10.1007/s00277-016-2913-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/23/2016] [Indexed: 11/26/2022]
Abstract
Although the outcome of patients with acute myeloid leukemia (AML) has improved by optimized chemotherapy regimens and bone marrow transplantation, leukemia relapse remains one of the most challenging problems during therapy. Sustained existence of AML blasts is a fundamental determinant for the development of leukemia and resistance to therapy. Recent evidences suggest that Meis1 is tightly associated with the self-renewal capacity of normal hematopoietic stem cells. Meis1 was also found to be essential for the development of mixed lineage leukemia (MLL)-rearranged leukemia. Whether Meis1 functions independently of MLL abnormality in the context of leukemia is unclear. Herein, we identified a distinct expression pattern of Meis1 in patients with newly diagnosed AML without MLL abnormality. High levels of Meis1 expression were found in 64 of 95 (67.4%) AML patients; whereas, 31 of 95 (32.6%) patients showed dramatically lower levels of Meis1, compared with the median level of Meis1 in healthy donors. The whole cohort and subgroup analyses further demonstrated that high Meis1 expression levels were associated with a resistance to conventional chemotherapy, compared with the group with low Meis1 levels (P = 0.014 and P = 0.029, respectively). In vitro knockdown experiments highlighted a role of Meis1 in regulating maintenance and survival of human AML cells. These results implicate that Meis1 functions as an important regulator during the progression of human AML and could be a prognostic factor independent of MLL abnormality.
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Affiliation(s)
- Jiangying Liu
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China
| | - Ya-Zhen Qin
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China
| | - Shenmiao Yang
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China
| | - Yazhe Wang
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China
| | - Ying-Jun Chang
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China
| | - Ting Zhao
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China
| | - Qian Jiang
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China
| | - Xiao-Jun Huang
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, 11 Xizhimen South Street, Beijing, 100044, China.
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12
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Stahl M, Kim TK, Zeidan AM. Update on acute myeloid leukemia stem cells: New discoveries and therapeutic opportunities. World J Stem Cells 2016; 8:316-331. [PMID: 27822339 PMCID: PMC5080639 DOI: 10.4252/wjsc.v8.i10.316] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 08/11/2016] [Accepted: 08/29/2016] [Indexed: 02/06/2023] Open
Abstract
The existence of cancer stem cells has been well established in acute myeloid leukemia. Initial proof of the existence of leukemia stem cells (LSCs) was accomplished by functional studies in xenograft models making use of the key features shared with normal hematopoietic stem cells (HSCs) such as the capacity of self-renewal and the ability to initiate and sustain growth of progenitors in vivo. Significant progress has also been made in identifying the phenotype and signaling pathways specific for LSCs. Therapeutically, a multitude of drugs targeting LSCs are in different phases of preclinical and clinical development. This review focuses on recent discoveries which have advanced our understanding of LSC biology and provided rational targets for development of novel therapeutic agents. One of the major challenges is how to target the self-renewal pathways of LSCs without affecting normal HSCs significantly therefore providing an acceptable therapeutic window. Important issues pertinent to the successful design and conduct of clinical trials evaluating drugs targeting LSCs will be discussed as well.
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Stiehl T, Lutz C, Marciniak-Czochra A. Emergence of heterogeneity in acute leukemias. Biol Direct 2016; 11:51. [PMID: 27733173 PMCID: PMC5062896 DOI: 10.1186/s13062-016-0154-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/29/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Leukemias are malignant proliferative disorders of the blood forming system. Sequencing studies demonstrate that the leukemic cell population consists of multiple clones. The genetic relationship between the different clones, referred to as the clonal hierarchy, shows high interindividual variability. So far, the source of this heterogeneity and its clinical relevance remain unknown. We propose a mathematical model to study the emergence and evolution of clonal heterogeneity in acute leukemias. The model allows linking properties of leukemic clones in terms of self-renewal and proliferation rates to the structure of the clonal hierarchy. RESULTS Computer simulations imply that the self-renewal potential of the first emerging leukemic clone has a major impact on the total number of leukemic clones and on the structure of their hierarchy. With increasing depth of the clonal hierarchy the self-renewal of leukemic clones increases, whereas the proliferation rates do not change significantly. The emergence of deep clonal hierarchies is a complex process that is facilitated by a cooperativity of different mutations. CONCLUSION Comparison of patient data and simulation results suggests that the self-renewal of leukemic clones increases with the emergence of clonal heterogeneity. The structure of the clonal hierarchy may serve as a marker for patient prognosis. REVIEWERS This article was reviewed by Marek Kimmel, Tommaso Lorenzi and Tomasz Lipniacki.
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Affiliation(s)
- Thomas Stiehl
- Institute of Applied Mathematics, Heidelberg University, Im Neuenheimer Feld 205, Heidelberg, 69120, Germany. .,Interdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, Heidelberg, 69120, Germany. .,Bioquant Center, Heidelberg University, Im Neuenheimer Feld 297, Heidelberg, 69120, Germany.
| | - Christoph Lutz
- Department of Medicine V, Heidelberg University, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, Heidelberg University, Im Neuenheimer Feld 205, Heidelberg, 69120, Germany.,Interdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, Heidelberg, 69120, Germany.,Bioquant Center, Heidelberg University, Im Neuenheimer Feld 297, Heidelberg, 69120, Germany
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14
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Busse JE, Gwiazda P, Marciniak-Czochra A. Mass concentration in a nonlocal model of clonal selection. J Math Biol 2016; 73:1001-33. [PMID: 26936033 PMCID: PMC5018043 DOI: 10.1007/s00285-016-0979-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 01/05/2016] [Indexed: 02/08/2023]
Abstract
Self-renewal is a constitutive property of stem cells. Testing the cancer stem cell hypothesis requires investigation of the impact of self-renewal on cancer expansion. To better understand this impact, we propose a mathematical model describing the dynamics of a continuum of cell clones structured by the self-renewal potential. The model is an extension of the finite multi-compartment models of interactions between normal and cancer cells in acute leukemias. It takes a form of a system of integro-differential equations with a nonlinear and nonlocal coupling which describes regulatory feedback loops of cell proliferation and differentiation. We show that this coupling leads to mass concentration in points corresponding to the maxima of the self-renewal potential and the solutions of the model tend asymptotically to Dirac measures multiplied by positive constants. Furthermore, using a Lyapunov function constructed for the finite dimensional counterpart of the model, we prove that the total mass of the solution converges to a globally stable equilibrium. Additionally, we show stability of the model in the space of positive Radon measures equipped with the flat metric (bounded Lipschitz distance). Analytical results are illustrated by numerical simulations.
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Affiliation(s)
- J-E Busse
- Institute of Applied Mathematics, BIOQUANT, University of Heidelberg, Im Neuenheimer Feld 294, 69120, Heidelberg, Germany
| | - P Gwiazda
- Institute of Applied Mathematics and Mechanics, University of Warsaw, ul. Banacha 2, 02-097, Warsaw, Poland.,Institute of Mathematics, Polish Academy of Science, Śniadeckich 8, 00-656, Warszawa, Poland
| | - A Marciniak-Czochra
- Institute of Applied Mathematics, BIOQUANT, University of Heidelberg, Im Neuenheimer Feld 294, 69120, Heidelberg, Germany. .,Interdisciplinary Center of Scientific Computing (IWR), University of Heidelberg, Im Neuenheimer Feld 205, 69120, Heidelberg, Germany. .,Bioquant, University of Heidelberg, Im Neuenheimer Feld 205, 69120, Heidelberg, Germany.
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15
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Tian C, You MJ, Yu Y, Zhu L, Zheng G, Zhang Y. MicroRNA-9 promotes proliferation of leukemia cells in adult CD34-positive acute myeloid leukemia with normal karyotype by downregulation of Hes1. Tumour Biol 2015; 37:7461-71. [PMID: 26678889 DOI: 10.1007/s13277-015-4581-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 12/02/2015] [Indexed: 11/28/2022] Open
Abstract
Acute myeloid leukemia (AML) is a group of heterogeneous hematopoietic malignancies sustained by leukemic stem cells (LSCs) that can resist treatment. Previously, we found that low expression of Hes1 was a poor prognostic factor for AML. However, the activation status of Hes1 and its regulation in LSCs and leukemic progenitors (LPs) as well as normal hematopoietic stem cells (HSCs) in Hes1-low AML patients have not been elucidated. In this study, the expression of Hes1 in LSCs and LPs was analyzed in adult CD34(+) Hes1-low AML with normal karyotype and the upstream microRNA (miRNA) regulators were screened. Our results showed that the level of either Hes1 or p21 was lower in LSCs or LPs than in HSCs whereas the level of miR-9 was highest in LPs and lowest in HSCs. An inverse correlation was observed in the expression of Hes1 and miR-9. Furthermore, we validated miR-9 as one of the regulators of Hes1 by reporter gene analysis. Knockdown of miR-9 by lentivirus infection suppressed the proliferation of AML cells by the induction of G0 arrest and apoptosis in vitro. Moreover, knockdown of miR-9 resulted in decreased circulating leukemic cell counts in peripheral blood and bone marrow, attenuated splenomegaly, and prolonged survival in a xenotransplant mouse model. Our results indicate that the miR-9 plays an important role in supporting AML cell growth and survival by downregulation of Hes1 and that miR-9 has potential as a therapeutic target for treating AML.
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MESH Headings
- Adult
- Aged
- Animals
- Antigens, CD34/metabolism
- Apoptosis
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Blotting, Western
- Cell Cycle
- Cell Proliferation
- Down-Regulation
- Female
- Follow-Up Studies
- Hematopoietic Stem Cells/metabolism
- Hematopoietic Stem Cells/pathology
- Humans
- Karyotype
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Male
- Mice
- Mice, Inbred NOD
- Mice, SCID
- MicroRNAs/genetics
- Middle Aged
- Neoplasm Staging
- Neoplastic Stem Cells/metabolism
- Neoplastic Stem Cells/pathology
- Prognosis
- RNA, Messenger/genetics
- Real-Time Polymerase Chain Reaction
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription Factor HES-1/genetics
- Transcription Factor HES-1/metabolism
- Tumor Cells, Cultured
- Xenograft Model Antitumor Assays
- Young Adult
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Affiliation(s)
- Chen Tian
- Department of Hematology, Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, 300060, People's Republic of China
| | - M James You
- Department of Hematopathology, Division of Pathology and Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Yong Yu
- Department of Hematology, Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, 300060, People's Republic of China
| | - Lei Zhu
- Department of Hematology, Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, 300060, People's Republic of China
| | - Guoguang Zheng
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300020, People's Republic of China.
| | - Yizhuo Zhang
- Department of Hematology, Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, 300060, People's Republic of China.
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16
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Leukemic progenitor cells are susceptible to targeting by stimulated cytotoxic T cells against immunogenic leukemia-associated antigens. Int J Cancer 2015; 137:2083-92. [DOI: 10.1002/ijc.29583] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 03/30/2015] [Indexed: 12/30/2022]
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17
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Zhou J, Ching YQ, Chng WJ. Aberrant nuclear factor-kappa B activity in acute myeloid leukemia: from molecular pathogenesis to therapeutic target. Oncotarget 2015; 6:5490-500. [PMID: 25823927 PMCID: PMC4467382 DOI: 10.18632/oncotarget.3545] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 02/15/2015] [Indexed: 02/07/2023] Open
Abstract
The overall survival of patients with acute myeloid leukemia (AML) has not been improved significantly over the last decade. Molecularly targeted agents hold promise to change the therapeutic landscape in AML. The nuclear factor kappa B (NF-κB) controls a plethora of biological process through switching on and off its long list of target genes. In AML, constitutive NF-κB has been detected in 40% of cases and its aberrant activity enable leukemia cells to evade apoptosis and stimulate proliferation. These facts suggest that NF-κB signaling pathway plays a fundamental role in the development of AML and it represents an attractive target for the intervention of AML. This review summarizes our current knowledge of NF-κB signaling transduction including canonical and non-canonical NF-κB pathways. Then we specifically highlight what factors contribute to the aberrant activation of NF-κB activity in AML, followed by an overview of 8 important clinical trials of the first FDA approved proteasome inhibitor, Bortezomib (Velcade), which is a NF-κB inhibitor too, in combination with other therapeutic agents in patients with AML. Finally, this review discusses the future directions of NF-κB inhibitor in treatment of AML, especially in targeting leukemia stem cells (LSCs).
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Affiliation(s)
- Jianbiao Zhou
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Centre for Translational Medicine, Singapore, Republic of Singapore
| | - Ying Qing Ching
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Centre for Translational Medicine, Singapore, Republic of Singapore
| | - Wee-Joo Chng
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Centre for Translational Medicine, Singapore, Republic of Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
- Department of Hematology-Oncology, National University Cancer Institute of Singapore (NCIS), The National University Health System (NUHS), Singapore, Republic of Singapore
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Stiehl T, Baran N, Ho AD, Marciniak-Czochra A. Cell division patterns in acute myeloid leukemia stem-like cells determine clinical course: a model to predict patient survival. Cancer Res 2015; 75:940-9. [PMID: 25614516 DOI: 10.1158/0008-5472.can-14-2508] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Acute myeloid leukemia (AML) is a heterogeneous disease in which a variety of distinct genetic alterations might occur. Recent attempts to identify the leukemia stem-like cells (LSC) have also indicated heterogeneity of these cells. On the basis of mathematical modeling and computer simulations, we have provided evidence that proliferation and self-renewal rates of the LSC population have greater impact on the course of disease than proliferation and self-renewal rates of leukemia blast populations, that is, leukemia progenitor cells. The modeling approach has enabled us to estimate the LSC properties of 31 individuals with relapsed AML and to link them to patient survival. On the basis of the estimated LSC properties, the patients can be divided into two prognostic groups that differ significantly with respect to overall survival after first relapse. The results suggest that high LSC self-renewal and proliferation rates are indicators of poor prognosis. Nevertheless, high LSC self-renewal rate may partially compensate for slow LSC proliferation and vice versa. Thus, model-based interpretation of clinical data allows estimation of prognostic factors that cannot be measured directly. This may have clinical implications for designing treatment strategies.
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Affiliation(s)
- Thomas Stiehl
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany. Bioquant Center, University of Heidelberg, Heidelberg, Germany. Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany.
| | - Natalia Baran
- Department of Medicine V, Medical Center, University of Heidelberg, Heidelberg, Germany
| | - Anthony D Ho
- Department of Medicine V, Medical Center, University of Heidelberg, Heidelberg, Germany
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany. Bioquant Center, University of Heidelberg, Heidelberg, Germany. Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany
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Stiehl T, Baran N, Ho AD, Marciniak-Czochra A. Clonal selection and therapy resistance in acute leukaemias: mathematical modelling explains different proliferation patterns at diagnosis and relapse. J R Soc Interface 2014; 11:20140079. [PMID: 24621818 PMCID: PMC3973374 DOI: 10.1098/rsif.2014.0079] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Recent experimental evidence suggests that acute myeloid leukaemias may originate from multiple clones of malignant cells. Nevertheless, it is not known how the observed clones may differ with respect to cell properties, such as proliferation and self-renewal. There are scarcely any data on how these cell properties change due to chemotherapy and relapse. We propose a new mathematical model to investigate the impact of cell properties on the multi-clonal composition of leukaemias. Model results imply that enhanced self-renewal may be a key mechanism in the clonal selection process. Simulations suggest that fast proliferating and highly self-renewing cells dominate at primary diagnosis, while relapse following therapy-induced remission is triggered mostly by highly self-renewing but slowly proliferating cells. Comparison of simulation results to patient data demonstrates that the proposed model is consistent with clinically observed dynamics based on a clonal selection process.
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Affiliation(s)
- Thomas Stiehl
- Institute of Applied Mathematics, BIOQUANT and IWR, Im Neuenheimer Feld 294, University of Heidelberg, , 69120 Heidelberg, Germany
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A combination of temsirolimus, an allosteric mTOR inhibitor, with clofarabine as a new therapeutic option for patients with acute myeloid leukemia. Oncotarget 2013; 3:1615-28. [PMID: 23271044 PMCID: PMC3681499 DOI: 10.18632/oncotarget.762] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Signaling through the phosphatidylinositol 3-kinase (PI3K) pathway and its downstream effectors, Akt and mechanistic target of rapamycin (mTOR), is aberrantly activated in acute myeloid leukemia (AML) patients, where it contributes to leukemic cell proliferation, survival, and drug-resistance. Thus, inhibiting mTOR signaling in AML blasts could enhance their sensitivity to cytotoxic agents. Preclinical data also suggest that allosteric mTOR inhibition with rapamycin impaired leukemia initiating cells (LICs) function. In this study, we assessed the therapeutic potential of a combination consisting of temsirolimus [an allosteric mTOR complex 1 (mTORC1) inhibitor] with clofarabine, a nucleoside analogue with potent inhibitory effects on both ribonucleotide reductase and DNA polymerase. The drug combination (CLO-TOR) displayed synergistic cytotoxic effects against a panel of AML cell lines and primary cells from AML patients. Treatment with CLO-TOR induced a G₀/G₁-phase cell cycle arrest, apoptosis, and autophagy. CLO-TOR was pro-apoptotic in an AML patient blast subset (CD34⁺/CD38⁻/CD123⁺), which is enriched in putative leukemia initiating cells (LICs). In summary, the CLO-TOR combination could represent a novel valuable treatment for AML patients, also in light of its efficacy against LICs.
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