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Hu H, Muntean AG. The YEATS domain epigenetic reader proteins ENL and AF9 and their therapeutic value in leukemia. Exp Hematol 2023; 124:15-21. [PMID: 37295550 PMCID: PMC10527611 DOI: 10.1016/j.exphem.2023.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/30/2023] [Accepted: 06/01/2023] [Indexed: 06/12/2023]
Abstract
Recent studies have uncovered similarities and differences between 2 highly homologous epigenetic reading proteins, namely, ENL (MLLT1) and AF9 (MLLT3) with therapeutic implications. The importance of these proteins has traditionally been exemplified by their involvement in chromosomal translocations with the mixed-lineage leukemia gene (MLL; aka KMT2a). MLL rearrangements occur in a subset of acute leukemias and generate potent oncogenic MLL-fusion proteins that impact epigenetic and transcriptional regulation. Leukemic patients with MLL rearrangements display intermediate-to-poor prognoses, necessitating further mechanistic research. Several protein complexes involved in regulating RNA polymerase II transcription and the epigenetic landscape are hijacked in MLL-r leukemia, which include ENL and AF9. Recent biochemical studies have defined a highly homologous YEATS domain in ENL and AF9 that binds acylated histones, which aids in the localization and retention of these proteins to transcriptional targets. In addition, detailed characterization of the homologous ANC-1 homology domain (AHD) on ENL and AF9 revealed differential association with transcriptional activating and repressing complexes. Importantly, CRISPR knockout screens have demonstrated a unique role for wild-type ENL in leukemic stem cell function, whereas AF9 appears important for normal hematopoietic stem cells. In this perspective, we examine the ENL and AF9 proteins with attention to recent work characterizing the epigenetic reading YEATS domains and AHD on both wild-type proteins and when fused to MLL. We summarized the drug development efforts and their therapeutic potential and assess ongoing research that has refined our understanding of how these proteins function, which continues to reveal new therapeutic avenues.
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Affiliation(s)
- Hsiangyu Hu
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI
| | - Andrew G Muntean
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI.
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Hu H, Saha N, Yang Y, Ahmad E, Lachowski L, Shrestha U, Premkumar V, Ropa J, Chen L, Teahan B, Grigsby S, Marschalek R, Nikolovska-Coleska Z, Muntean AG. The ENL YEATS epigenetic reader domain critically links MLL-ENL to leukemic stem cell frequency in t(11;19) Leukemia. Leukemia 2023; 37:190-201. [PMID: 36435883 PMCID: PMC11246743 DOI: 10.1038/s41375-022-01765-0] [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: 02/01/2022] [Accepted: 11/11/2022] [Indexed: 11/28/2022]
Abstract
MLL (KMT2a) translocations are found in ~10% of acute leukemia patients, giving rise to oncogenic MLL-fusion proteins. A common MLL translocation partner is ENL and associated with a poor prognosis in t(11;19) patients. ENL contains a highly conserved N-terminal YEATS domain that binds acetylated histones and interacts with the PAF1c, an epigenetic regulator protein complex essential for MLL-fusion leukemogenesis. Recently, wild-type ENL, and specifically the YEATS domain, was shown to be essential for leukemic cell growth. However, the inclusion and importance of the YEATS domain in MLL-ENL-mediated leukemogenesis remains unexplored. We found the YEATS domain is retained in 84.1% of MLL-ENL patients and crucial for MLL-ENL-mediated leukemogenesis in mouse models. Mechanistically, deletion of the YEATS domain impaired MLL-ENL fusion protein binding and decreased expression of pro-leukemic genes like Eya1 and Meis1. Point mutations that disrupt YEATS domain binding to acetylated histones decreased stem cell frequency and increased MLL-ENL-mediated leukemia latency. Therapeutically, YEATS containing MLL-ENL leukemic cells display increased sensitivity to the YEATS inhibitor SGC-iMLLT compared to control AML cells. Our results demonstrate that the YEATS domain is important for MLL-ENL fusion protein-mediated leukemogenesis and exposes an "Achilles heel" that may be therapeutically targeted for treating t(11;19) patients.
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Affiliation(s)
- Hsiangyu Hu
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nirmalya Saha
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Yuting Yang
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ejaz Ahmad
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Lauren Lachowski
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Uttar Shrestha
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Vidhya Premkumar
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - James Ropa
- Department of Microbiology and Immunology, Indiana University School of Medicine, 950 West Walnut Street, R2-302, Indianapolis, IN, 46202-5181, USA
| | - Lili Chen
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Blaine Teahan
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Sierrah Grigsby
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Rolf Marschalek
- Institute of Pharmaceutical Biology / Diagnostic Center of Acute Leukemia, University of Frankfurt, Frankfurt/Main, Germany
| | | | - Andrew G Muntean
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA.
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Yuen K, Liu Y, Zhou Y, Wang Y, Zhou D, Fang J, Xu L. Mutational landscape and clinical outcome of pediatric acute myeloid leukemia with 11q23/KMT2A rearrangements. Cancer Med 2022; 12:1418-1430. [PMID: 35833755 PMCID: PMC9883550 DOI: 10.1002/cam4.5026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 05/25/2022] [Accepted: 06/27/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Alterations of 11q23/KMT2A are the most prevalent cytogenetic abnormalities in acute myeloid leukemia (AML) and the prognostic significance of 11q23/KMT2A-rearranged AML based on various translocation partners varies among different studies. However, few studies evaluated the molecular characteristics of 11q23/KMT2A-rearranged pediatric AML. We aim to analyze the mutational landscape of 11q23/KMT2A-rearranged AML and assess their prognostic value in outcomes. METHODS The mutational landscape and clinical prognosis of 105 children with 11q23/KMT2A-rearranged AML in comparison with 277 children with non-11q23/KMT2A-rearranged AML were analyzed using publicly accessible next-generation sequencing data from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) dataset. RESULTS Pediatric AML patients with 11q23/KMT2A-rearrangements harbored a low number of mutations (Median, 1 mutation/patient, range, 1-22), 58% of which involved in RAS pathway mutations (KRAS, NRAS, and PTPN11) and 10.5% of which comprised of SETD2 mutations. Compared with non-11q23/KMT2A-rearranged AML, the incidence of KRAS (32.4% vs. 10.1%, P〈0.001) and SETD2 (10.5% vs. 1.4%, P=0.001) gene mutations in 11q23/KMT2A-rearranged AML was significantly higher. Both KRAS and SETD2 mutations occurred more often in t(10;11)(p12;q23). KRAS mutations were correlated with worse 5-year event-free survival [EFS] (Plog-rank = 0.001) and 5-year overall survival [OS] (Plog-rank = 0.009) and the presence of SETD2 mutations increases the 5-year relapse rate (PGray = 0.004). Multivariate analyses confirmed KRAS mutations in 11q23/KMT2A-rearranged AML as an independent predictor for poor EFS (hazard ratio [HR] = 2.10, P=0.05) and OS (HR = 2.39, P=0.054). CONCLUSION Our findings show that pediatric patients with 11q23/KMT2A rearrangements have characteristic mutation patterns and varying clinical outcomes depending on different translocation partners, which could be utilized to develop more accurate risk stratification and tailored therapies.
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Affiliation(s)
- Ka‐Yuk Yuen
- Department of PediatricsSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene RegulationSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina
| | - Yong Liu
- Department of PediatricsSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene RegulationSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina
| | - Yong‐Zhuo Zhou
- Department of Clinical LaboratorySun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina
| | - Yin Wang
- Department of PediatricsSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene RegulationSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina
| | - Dun‐Hua Zhou
- Department of PediatricsSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene RegulationSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina
| | - Jian‐Pei Fang
- Department of PediatricsSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene RegulationSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina
| | - Lu‐Hong Xu
- Department of PediatricsSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene RegulationSun Yat‐Sen Memorial Hospital, Sun Yat‐Sen UniversityGuangzhouGuangdong ProvinceChina
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Zhang M, Wang LF, Xu X, Du Y, Li L, Deng G, Feng Y, Ou Z, Wang K, Xu Y, Peng X, Chen F. The role of E2A in ATPR-induced cell differentiation and cycle arrest in acute myeloid leukaemia cells. J Cell Mol Med 2022; 26:1128-1143. [PMID: 35001521 PMCID: PMC8831953 DOI: 10.1111/jcmm.17166] [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: 09/16/2021] [Revised: 12/14/2021] [Accepted: 12/21/2021] [Indexed: 11/29/2022] Open
Abstract
Acute myeloid leukaemia (AML) is a biologically heterogeneous disease with an overall poor prognosis; thus, novel therapeutic approaches are needed. Our previous studies showed that 4-amino-2-trifluoromethyl-phenyl retinate (ATPR), a new derivative of all-trans retinoic acid (ATRA), could induce AML cell differentiation and cycle arrest. The current study aimed to determine the potential pharmacological mechanisms of ATPR therapies against AML. Our findings showed that E2A was overexpressed in AML specimens and cell lines, and mediate AML development by inactivating the P53 pathway. The findings indicated that E2A expression and activity decreased with ATPR treatment. Furthermore, we determined that E2A inhibition could enhance the effect of ATPR-induced AML cell differentiation and cycle arrest, whereas E2A overexpression could reverse this effect, suggesting that the E2A gene plays a crucial role in AML. We identified P53 and c-Myc were downstream pathways and targets for silencing E2A cells using RNA sequencing, which are involved in the progression of AML. Taken together, these results confirmed that ATPR inhibited the expression of E2A/c-Myc, which led to the activation of the P53 pathway, and induced cell differentiation and cycle arrest in AML.
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Affiliation(s)
- Meiju Zhang
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Long-Fei Wang
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Xiaoling Xu
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Yan Du
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Lanlan Li
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Ge Deng
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Yubin Feng
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Ziyao Ou
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Ke Wang
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Yayun Xu
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Xiaoqing Peng
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
| | - Feihu Chen
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China
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Rogawski DS, Deng J, Li H, Miao H, Borkin D, Purohit T, Song J, Chase J, Li S, Ndoj J, Klossowski S, Kim E, Mao F, Zhou B, Ropa J, Krotoska MZ, Jin Z, Ernst P, Feng X, Huang G, Nishioka K, Kelly S, He M, Wen B, Sun D, Muntean A, Dou Y, Maillard I, Cierpicki T, Grembecka J. Discovery of first-in-class inhibitors of ASH1L histone methyltransferase with anti-leukemic activity. Nat Commun 2021; 12:2792. [PMID: 33990599 PMCID: PMC8121805 DOI: 10.1038/s41467-021-23152-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 04/13/2021] [Indexed: 02/06/2023] Open
Abstract
ASH1L histone methyltransferase plays a crucial role in the pathogenesis of different diseases, including acute leukemia. While ASH1L represents an attractive drug target, developing ASH1L inhibitors is challenging, as the catalytic SET domain adapts an inactive conformation with autoinhibitory loop blocking the access to the active site. Here, by applying fragment-based screening followed by medicinal chemistry and a structure-based design, we developed first-in-class small molecule inhibitors of the ASH1L SET domain. The crystal structures of ASH1L-inhibitor complexes reveal compound binding to the autoinhibitory loop region in the SET domain. When tested in MLL leukemia models, our lead compound, AS-99, blocks cell proliferation, induces apoptosis and differentiation, downregulates MLL fusion target genes, and reduces the leukemia burden in vivo. This work validates the ASH1L SET domain as a druggable target and provides a chemical probe to further study the biological functions of ASH1L as well as to develop therapeutic agents.
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Affiliation(s)
- David S Rogawski
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Jing Deng
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Hao Li
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Hongzhi Miao
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Dmitry Borkin
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Trupta Purohit
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Jiho Song
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Jennifer Chase
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Shuangjiang Li
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Juliano Ndoj
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | | | - EunGi Kim
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Fengbiao Mao
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Bo Zhou
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - James Ropa
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Marta Z Krotoska
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Zhuang Jin
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Patricia Ernst
- Department of Pediatrics, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Xiaomin Feng
- Department of Pathology and Laboratory Medicine, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Gang Huang
- Department of Pathology and Laboratory Medicine, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Kenichi Nishioka
- Department of Internal Medicine Musashimurayama Hospital, Enoki 1-1-5, Musashimurayama, Tokyo, Japan
| | - Samantha Kelly
- Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Miao He
- College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
| | - Bo Wen
- College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
| | - Duxin Sun
- College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
| | - Andrew Muntean
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Yali Dou
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Ivan Maillard
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Tomasz Cierpicki
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA.
| | - Jolanta Grembecka
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA.
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Li X, Song Y. Structure, function and inhibition of critical protein-protein interactions involving mixed lineage leukemia 1 and its fusion oncoproteins. J Hematol Oncol 2021; 14:56. [PMID: 33823889 PMCID: PMC8022399 DOI: 10.1186/s13045-021-01057-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/05/2021] [Indexed: 12/13/2022] Open
Abstract
Mixed lineage leukemia 1 (MLL1, also known as MLL or KMT2A) is an important transcription factor and histone-H3 lysine-4 (H3K4) methyltransferase. It is a master regulator for transcription of important genes (e.g., Hox genes) for embryonic development and hematopoiesis. However, it is largely dispensable in matured cells. Dysregulation of MLL1 leads to overexpression of certain Hox genes and eventually leukemia initiation. Chromosome translocations involving MLL1 cause ~ 75% of acute leukemia in infants and 5–10% in children and adults with a poor prognosis. Targeted therapeutics against oncogenic fusion MLL1 (onco-MLL1) are therefore needed. Onco-MLL1 consists of the N-terminal DNA-interacting domains of MLL1 fused with one of > 70 fusion partners, among which transcription cofactors AF4, AF9 and its paralog ENL, and ELL are the most frequent. Wild-type (WT)- and onco-MLL1 involve numerous protein–protein interactions (PPI), which play critical roles in regulating gene expression in normal physiology and leukemia. Moreover, WT-MLL1 has been found to be essential for MLL1-rearranged (MLL1-r) leukemia. Rigorous studies of such PPIs have been performed and much progress has been achieved in understanding their structures, structure–function relationships and the mechanisms for activating gene transcription as well as leukemic transformation. Inhibition of several critical PPIs by peptides, peptidomimetic or small-molecule compounds has been explored as a therapeutic approach for MLL1-r leukemia. This review summarizes the biological functions, biochemistry, structure and inhibition of the critical PPIs involving MLL1 and its fusion partner proteins. In addition, challenges and perspectives of drug discovery targeting these PPIs for the treatment of MLL1-r leukemia are discussed.
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Affiliation(s)
- Xin Li
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, 77030, USA
| | - Yongcheng Song
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, 77030, USA. .,Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, 77030, USA.
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7
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Ropa J, Saha N, Hu H, Peterson LF, Talpaz M, Muntean AG. SETDB1 mediated histone H3 lysine 9 methylation suppresses MLL-fusion target expression and leukemic transformation. Haematologica 2020; 105:2273-2285. [PMID: 33054052 PMCID: PMC7556517 DOI: 10.3324/haematol.2019.223883] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 09/25/2019] [Indexed: 11/23/2022] Open
Abstract
Epigenetic regulators play a critical role in normal and malignant hematopoiesis. Deregulation, including epigenetic deregulation, of the HOXA gene cluster drives transformation of about 50% of acute myeloid leukemia. We recently showed that the Histone 3 Lysine 9 methyltransferase SETDB1 negatively regulates the expression of the pro-leukemic genes Hoxa9 and its cofactor Meis1 through deposition of promoter H3K9 trimethylation in MLL-AF9 leukemia cells. Here, we investigated the biological impact of altered SETDB1 expression and changes in H3K9 methylation on acute myeloid leukemia. We demonstrate that SETDB1 expression is correlated to disease status and overall survival in acute myeloid leukemia patients. We recapitulated these findings in mice, where high expression of SETDB1 delayed MLL-AF9 mediated disease progression by promoting differentiation of leukemia cells. We also explored the biological impact of treating normal and malignant hematopoietic cells with an H3K9 methyltransferase inhibitor, UNC0638. While myeloid leukemia cells demonstrate cytotoxicity to UNC0638 treatment, normal bone marrow cells exhibit an expansion of cKit+ hematopoietic stem and progenitor cells. Consistent with these data, we show that bone marrow treated with UNC0638 is more amenable to transformation by MLL-AF9. Next generation sequencing of leukemia cells shows that high expression of SETDB1 induces repressive changes to the promoter epigenome and downregulation of genes linked with acute myeloid leukemia, including Dock1 and the MLL-AF9 target genes Hoxa9, Six1, and others. These data reveal novel targets of SETDB1 in leukemia that point to a role for SETDB1 in negatively regulating pro-leukemic target genes and suppressing acute myeloid leukemia.
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Affiliation(s)
- James Ropa
- Department of Pathology, University of Michigan Medical School
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School
| | - Nirmalya Saha
- Department of Pathology, University of Michigan Medical School
| | - Hsiangyu Hu
- Department of Pathology, University of Michigan Medical School
| | - Luke F. Peterson
- Department of Internal Medicine/Division of Hematology/Oncology, University of Michigan School of Medicine and Comprehensive Cancer Center, Ann Abor, MI, USA
| | - Moshe Talpaz
- Department of Internal Medicine/Division of Hematology/Oncology, University of Michigan School of Medicine and Comprehensive Cancer Center, Ann Abor, MI, USA
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The PAF1c Subunit CDC73 Is Required for Mouse Hematopoietic Stem Cell Maintenance but Displays Leukemia-Specific Gene Regulation. Stem Cell Reports 2019; 12:1069-1083. [PMID: 31031188 PMCID: PMC6524170 DOI: 10.1016/j.stemcr.2019.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 03/25/2019] [Accepted: 03/26/2019] [Indexed: 12/21/2022] Open
Abstract
The Polymerase Associated Factor 1 complex (PAF1c) functions at the interface of epigenetics and gene transcription. The PAF1c is required for MLL fusion-driven acute myeloid leukemia (AML) through direct regulation of pro-leukemic target genes such as Hoxa9 and Meis1. However, the role of the PAF1c in normal hematopoiesis is unknown. Here, we discovered that the PAF1c subunit, CDC73, is required for both fetal and adult hematopoiesis. Loss of Cdc73 in hematopoietic cells is lethal because of extensive bone marrow failure. Cdc73 has an essential cell-autonomous role for adult hematopoietic stem cell function in vivo, and deletion of Cdc73 results in cell-cycle defects in hematopoietic progenitors. Gene expression profiling indicated a differential regulation of Hoxa9/Meis1 gene programs by CDC73 in progenitors compared with AML cells, suggesting disease-specific functions. Thus, the PAF1c subunit, CDC73 is essential for hematopoietic stem cell function but exhibits leukemia-specific regulation of self-renewal gene programs in AML cells. CDC73 is necessary for embryonic and adult hematopoietic stem cell function Proliferation and survival of cKIT+ hematopoietic progenitors require CDC73 CDC73 regulates unique gene programs in leukemia and hematopoietic progenitor cells
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Ropa J, Saha N, Chen Z, Serio J, Chen W, Mellacheruvu D, Zhao L, Basrur V, Nesvizhskii AI, Muntean AG. PAF1 complex interactions with SETDB1 mediate promoter H3K9 methylation and transcriptional repression of Hoxa9 and Meis1 in acute myeloid leukemia. Oncotarget 2018; 9:22123-22136. [PMID: 29774127 PMCID: PMC5955148 DOI: 10.18632/oncotarget.25204] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 04/04/2018] [Indexed: 12/30/2022] Open
Abstract
The Polymerase Associated Factor 1 complex (PAF1c) is an epigenetic co-modifying complex that directly contacts RNA polymerase II (RNAPII) and several epigenetic regulating proteins. Mutations, overexpression and loss of expression of subunits of the PAF1c are observed in various forms of cancer suggesting proper regulation is needed for cellular development. However, the biochemical interactions with the PAF1c that allow dynamic gene regulation are unclear. We and others have shown that the PAF1c makes a direct interaction with MLL fusion proteins, which are potent oncogenic drivers of acute myeloid leukemia (AML). This interaction is critical for the maintenance of MLL translocation driven AML by targeting MLL fusion proteins to the target genes Meis1 and Hoxa9. Here, we use a proteomics approach to identify protein-protein interactions with the PAF1c subunit CDC73 that regulate the function of the PAF1c. We identified a novel interaction with a histone H3 lysine 9 (H3K9) methyltransferase protein, SETDB1. This interaction is stabilized with a mutant CDC73 that is incapable of supporting AML cell growth. Importantly, transcription of Meis1 and Hoxa9 is reduced and promoter H3K9 trimethylation (H3K9me3) increased by overexpression of SETDB1 or stabilization of the PAF1c-SETDB1 interaction in AML cells. These findings were corroborated in human AML patients where increased SETDB1 expression was associated with reduced HOXA9 and MEIS1. To our knowledge, this is the first proteomics approach to search for CDC73 protein-protein interactions in AML, and demonstrates that the PAF1c may play a role in H3K9me3-mediated transcriptional repression in AML.
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Affiliation(s)
- James Ropa
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Nirmalya Saha
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Zhiling Chen
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Justin Serio
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Wei Chen
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Dattatreya Mellacheruvu
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Lili Zhao
- Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - Venkatesha Basrur
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Alexey I. Nesvizhskii
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Andrew G. Muntean
- Department of Pathology and The University of Michigan Medical School, Ann Arbor, Michigan, USA
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10
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El Ashkar S, Schwaller J, Pieters T, Goossens S, Demeulemeester J, Christ F, Van Belle S, Juge S, Boeckx N, Engelman A, Van Vlierberghe P, Debyser Z, De Rijck J. LEDGF/p75 is dispensable for hematopoiesis but essential for MLL-rearranged leukemogenesis. Blood 2018; 131:95-107. [PMID: 29084774 PMCID: PMC5755044 DOI: 10.1182/blood-2017-05-786962] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 10/20/2017] [Indexed: 12/31/2022] Open
Abstract
Mixed lineage leukemia (MLL) represents a genetically distinct and aggressive subset of human acute leukemia carrying chromosomal translocations of the MLL gene. These translocations result in oncogenic fusions that mediate aberrant recruitment of the transcription machinery to MLL target genes. The N-terminus of MLL and MLL-fusions form a complex with lens epithelium-derived growth factor (LEDGF/p75; encoded by the PSIP1 gene) and MENIN. This complex contributes to the association of MLL and MLL-fusion multiprotein complexes with the chromatin. Several studies have shown that both MENIN and LEDGF/p75 are required for efficient MLL-fusion-mediated transformation and for the expression of downstream MLL-regulated genes such as HOXA9 and MEIS1 In light of developing a therapeutic strategy targeting this complex, understanding the function of LEDGF/p75 in normal hematopoiesis is crucial. We generated a conditional Psip1 knockout mouse model in the hematopoietic compartment and examined the effects of LEDGF/p75 depletion in postnatal hematopoiesis and the initiation of MLL leukemogenesis. Psip1 knockout mice were viable but showed several defects in hematopoiesis, reduced colony-forming activity in vitro, decreased expression of Hox genes in the hematopoietic stem cells, and decreased MLL occupancy at MLL target genes. Finally, in vitro and in vivo experiments showed that LEDGF/p75 is dispensable for steady-state hematopoiesis but essential for the initiation of MLL-mediated leukemia. These data corroborate the MLL-LEDGF/p75 interaction as novel target for the treatment of MLL-rearranged leukemia.
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Affiliation(s)
- Sara El Ashkar
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
| | - Juerg Schwaller
- Department of Biomedicine, University Children's Hospital (UKBB), University of Basel, Basel, Switzerland
| | - Tim Pieters
- Center for Medical Genetics, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Steven Goossens
- Center for Medical Genetics, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Jonas Demeulemeester
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
| | - Frauke Christ
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
| | - Siska Van Belle
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
| | - Sabine Juge
- Department of Biomedicine, University Children's Hospital (UKBB), University of Basel, Basel, Switzerland
| | - Nancy Boeckx
- Department of Laboratory Medicine, University Hospital Leuven, Leuven, Belgium
- Department of Oncology, KU Leuven, Leuven, Belgium; and
| | - Alan Engelman
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Pieter Van Vlierberghe
- Center for Medical Genetics, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Zeger Debyser
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
| | - Jan De Rijck
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
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11
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The PAF complex regulation of Prmt5 facilitates the progression and maintenance of MLL fusion leukemia. Oncogene 2017; 37:450-460. [PMID: 28945229 PMCID: PMC5785415 DOI: 10.1038/onc.2017.337] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 07/20/2017] [Accepted: 07/31/2017] [Indexed: 02/06/2023]
Abstract
Acute myeloid leukemia (AML) is a disease associated with epigenetic dysregulation. 11q23 translocations involving the H3K4 methyltransferase MLL1 (KMT2A) generate oncogenic fusion proteins with deregulated transcriptional potential. The Polymerase Associated Factor complex (PAFc) is an epigenetic co-activator complex that makes direct contact with MLL fusion proteins and is involved in AML, however its functions are not well understood. Here, we explored the transcriptional targets regulated by the PAFc that facilitate leukemia by performing RNA-sequencing after conditional loss of the PAFc subunit Cdc73. We found Cdc73 promotes expression of an early hematopoietic progenitor gene program that prevents differentiation. Among the target genes, we confirmed the protein arginine methyltransferase Prmt5 is a direct target that is positively regulated by a transcriptional unit that includes the PAFc, MLL1, HOXA9 and STAT5 in leukemic cells. We observed reduced PRMT5-mediated H4R3me2s following excision of Cdc73 placing this histone modification downstream of the PAFc and revealing a novel mechanism between the PAFc and Prmt5. Knock down or pharmacologic inhibition of Prmt5 causes a G1 arrest and reduced proliferation resulting in extended leukemic disease latency in vivo. Overall, we demonstrate the PAFc regulates Prmt5 to facilitate leukemic progression and is a potential therapeutic target for AMLs.
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12
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Chen L, Chen W, Mysliwski M, Serio J, Ropa J, Abulwerdi FA, Chan RJ, Patel JP, Tallman MS, Paietta E, Melnick A, Levine RL, Abdel-Wahab O, Nikolovska-Coleska Z, Muntean AG. Mutated Ptpn11 alters leukemic stem cell frequency and reduces the sensitivity of acute myeloid leukemia cells to Mcl1 inhibition. Leukemia 2015; 29:1290-300. [PMID: 25650089 PMCID: PMC4456293 DOI: 10.1038/leu.2015.18] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 01/05/2015] [Accepted: 01/29/2015] [Indexed: 02/07/2023]
Abstract
PTPN11 encodes the Shp2 non-receptor protein-tyrosine phosphatase implicated in several signaling pathways. Activating mutations in Shp2 are commonly associated with juvenile myelomonocytic leukemia (JMML) but are not as well defined in other neoplasms. Here we report that Shp2 mutations occur in human acute myeloid leukemia (AML) at a rate of 6.6% (6/91) in the ECOG E1900 dataset. We examined the role of mutated Shp2 in leukemias harboring MLL translocations which co-occur in human AML. The hyperactive Shp2E76K mutant, commonly observed in leukemia patients, significantly accelerated MLL-AF9 mediated leukemogenesis in vivo. Shp2E76K increased leukemic stem cell frequency and affords MLL-AF9 leukemic cells IL3 cytokine hypersensitivity. As Shp2 is reported to regulate anti-apoptotic genes, we investigated Bcl2, Bcl-xL and Mcl1 expression in MLL-AF9 leukemic cells with and without Shp2E76K. While the Bcl2 family of genes was upregulated in Shp2E76K cells, Mcl1 showed the highest upregulation in MLL-AF9 cells in response to Shp2E76K. Indeed, expression of Mcl1 in MLL-AF9 cells phenocopies expression of Shp2E76K suggesting Shp2 mutations cooperate through activation of anti-apoptotic genes. Finally, we show Shp2E76K mutations reduce sensitivity of AML cells to small molecule mediated Mcl1 inhibition suggesting reduced efficacy of drugs targeting MCL1 in patients with hyperactive Shp2.
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Affiliation(s)
- L Chen
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Department of Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - W Chen
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Department of Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - M Mysliwski
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Department of Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - J Serio
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Department of Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - J Ropa
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Department of Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - F A Abulwerdi
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Interdepartmental Program in Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
| | - R J Chan
- 1] Herman B Wells Center for Pediatric Research, Department of Medical and Molecular Genetics, University School of Medicine, Indianapolis, IN, USA [2] Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - J P Patel
- Human Oncology and Pathogenesis Program and Leukemia Service, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - M S Tallman
- Human Oncology and Pathogenesis Program and Leukemia Service, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - E Paietta
- Montefiore Medical Center-North Division, Immunology Laboratory, Cancer Center, Bronx, NY, USA
| | - A Melnick
- 1] Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medical College, New York, NY, USA [2] Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA
| | - R L Levine
- Human Oncology and Pathogenesis Program and Leukemia Service, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - O Abdel-Wahab
- Human Oncology and Pathogenesis Program and Leukemia Service, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Z Nikolovska-Coleska
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Department of Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - A G Muntean
- 1] Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA [2] Department of Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
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13
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Li BE, Ernst P. Two decades of leukemia oncoprotein epistasis: the MLL1 paradigm for epigenetic deregulation in leukemia. Exp Hematol 2014; 42:995-1012. [PMID: 25264566 PMCID: PMC4307938 DOI: 10.1016/j.exphem.2014.09.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 09/16/2014] [Indexed: 12/12/2022]
Abstract
MLL1, located on human chromosome 11, is disrupted in distinct recurrent chromosomal translocations in several leukemia subsets. Studying the MLL1 gene and its oncogenic variants has provided a paradigm for understanding cancer initiation and maintenance through aberrant epigenetic gene regulation. Here we review the historical development of model systems to recapitulate oncogenic MLL1-rearrangement (MLL-r) alleles encoding mixed-lineage leukemia fusion proteins (MLL-FPs) or internal gene rearrangement products. These largely mouse and human cell/xenograft systems have been generated and used to understand how MLL-r alleles affect diverse pathways to result in a highly penetrant, drug-resistant leukemia. The particular features of the animal models influenced the conclusions of mechanisms of transformation. We discuss significant downstream enablers, inhibitors, effectors, and collaborators of MLL-r leukemia, including molecules that directly interact with MLL-FPs and endogenous mixed-lineage leukemia protein, direct target genes of MLL-FPs, and other pathways that have proven to be influential in supporting or suppressing the leukemogenic activity of MLL-FPs. The use of animal models has been complemented with patient sample, genome-wide analyses to delineate the important genomic and epigenomic changes that occur in distinct subsets of MLL-r leukemia. Collectively, these studies have resulted in rapid progress toward developing new strategies for targeting MLL-r leukemia and general cell-biological principles that may broadly inform targeting aberrant epigenetic regulators in other cancers.
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Affiliation(s)
- Bin E Li
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Patricia Ernst
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH, USA; Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA; Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Hanover, NH, USA; Department of Pediatrics Hematology/Oncology/BMT, University of Colorado Anschutz Medical Center, Aurora, CO, USA.
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14
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Ballabio E, Milne TA. Epigenetic control of gene expression in leukemogenesis: Cooperation between wild type MLL and MLL fusion proteins. Mol Cell Oncol 2014; 1:e955330. [PMID: 27308325 PMCID: PMC4905190 DOI: 10.1080/23723548.2014.955330] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/14/2014] [Accepted: 07/17/2014] [Indexed: 12/17/2022]
Abstract
Although there has been great progress in the treatment of human cancers, especially leukemias, many remain resistant to treatment. A major current focus is the development of so-called epigenetic drugs. Epigenetic states are stable enough to persist through multiple cell divisions, but by their very nature are reversible and thus are amenable to therapeutic manipulation. Exciting work in this area has produced a new breed of highly specific small molecules designed to inhibit epigenetic proteins, some of which have entered clinical trials. The current and future development of epigenetic drugs is greatly aided by highly detailed information about normal and aberrant epigenetic changes at the molecular level. In this review we focus on a class of aggressive acute leukemias caused by mutations in the Mixed Lineage Leukemia (MLL) gene. We provide an overview of how detailed molecular analysis of MLL leukemias has provided several early-stage epigenetic drugs and propose that further study of MLL leukemogenesis may continue to provide molecular details that potentially have a wider range of applications in human cancers.
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Affiliation(s)
- Erica Ballabio
- MRC Molecular Hematology Unit; Weatherall Institute of Molecular Medicine; University of Oxford ; Oxford, UK
| | - Thomas A Milne
- MRC Molecular Hematology Unit; Weatherall Institute of Molecular Medicine; University of Oxford ; Oxford, UK
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15
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Downregulation of RUNX1/CBFβ by MLL fusion proteins enhances hematopoietic stem cell self-renewal. Blood 2014; 123:1729-38. [PMID: 24449215 DOI: 10.1182/blood-2013-03-489575] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
RUNX1/CBFβ (core binding factor [CBF]) is a heterodimeric transcription factor complex that is frequently involved in chromosomal translocations, point mutations, or deletions in acute leukemia. The mixed lineage leukemia (MLL) gene is also frequently involved in chromosomal translocations or partial tandem duplication in acute leukemia. The MLL protein interacts with RUNX1 and prevents RUNX1 from ubiquitin-mediated degradation. RUNX1/CBFβ recruits MLL to regulate downstream target genes. However, the functional consequence of MLL fusions on RUNX1/CBFβ activity has not been fully understood. In this report, we show that MLL fusion proteins and the N-terminal MLL portion of MLL fusions downregulate RUNX1 and CBFβ protein expression via the MLL CXXC domain and flanking regions. We confirmed this finding in Mll-Af9 knock-in mice and human M4/M5 acute myeloid leukemia (AML) cell lines, with or without MLL translocations, showing that MLL translocations cause a hypomorph phenotype of RUNX1/CBFβ. Overexpression of RUNX1 inhibits the development of AML in Mll-Af9 knock-in mice; conversely, further reducing Runx1/Cbfβ levels accelerates MLL-AF9-mediated AML in bone marrow transplantation assays. These data reveal a newly defined negative regulation of RUNX1/CBFβ by MLL fusion proteins and suggest that targeting RUNX1/CBFβ levels may be a potential therapy for MLLs.
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