1
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Hao YH, Borenstein-Auerbach N, Grichuk A, Li L, Lafita-Navarro MC, Fang S, Nogueira P, Kim J, Xu L, Shay JW, Conacci-Sorrell M. MYC-Mediated Inhibition of ARNT2 Uncovers a Key Tumor Suppressor in Glioblastoma. RESEARCH SQUARE 2024:rs.3.rs-4810280. [PMID: 39184078 PMCID: PMC11343292 DOI: 10.21203/rs.3.rs-4810280/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Tumor initiation and progression rely on intricate cellular pathways that promote proliferation while suppressing differentiation, yet the importance of pathways inhibiting differentiation in cancer remains incompletely understood. Here, we reveal a novel mechanism centered on the repression of the neuronal-specific transcription factor ARNT2 by the MYC oncogene that governs the balance between proliferation and differentiation. We found that MYC coordinates the transcriptional repression of ARNT2 through the activity of polycomb repressive complex 2 (PRC2). Notably, ARNT2, highly and specifically expressed in the central nervous system, is diminished in glioblastoma, inversely correlating with patient survival. Utilizing in vitro and in vivo models, we demonstrate that ARNT2 knockout (KO) exerts no discernible effect on the in vitro proliferation of glioblastoma cells, but significantly enhances the growth of glioblastoma cells in vivo. Conversely, ARNT2 overexpression severely dampens the growth of fully transformed glioblastoma cells subcutaneously or orthotopically xenografted in mice. Mechanistically, ARNT2 depletion diminishes differentiation and enhances stemness of glioblastoma cells. Our findings provide new insights into the complex mechanisms used by oncogenes to limit differentiation in cancer cells and define ARNT2 as a tumor suppressor in glioblastoma.
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2
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Molina E, García-Gutiérrez L, Junco V, Perez-Olivares M, de Yébenes VG, Blanco R, Quevedo L, Acosta JC, Marín AV, Ulgiati D, Merino R, Delgado MD, Varela I, Regueiro JR, Moreno de Alborán I, Ramiro AR, León J. MYC directly transactivates CR2/CD21, the receptor of the Epstein-Barr virus, enhancing the viral infection of Burkitt lymphoma cells. Oncogene 2023; 42:3358-3370. [PMID: 37773203 DOI: 10.1038/s41388-023-02846-9] [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: 02/01/2023] [Revised: 09/12/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023]
Abstract
MYC is an oncogenic transcription factor dysregulated in about half of total human tumors. While transcriptomic studies reveal more than 1000 genes regulated by MYC, a much smaller fraction of genes is directly transactivated by MYC. Virtually all Burkitt lymphoma (BL) carry chromosomal translocations involving MYC oncogene. Most endemic BL and a fraction of sporadic BL are associated with Epstein-Barr virus (EBV) infection. The currently accepted mechanism is that EBV is the BL-causing agent inducing MYC translocation. Herein we show that the EBV receptor, CR2 (also called CD21), is a direct MYC target gene. This is based on several pieces of evidence: MYC induces CR2 expression in both proliferating and arrested cells and in the absence of protein synthesis, binds the CR2 promoter and transactivates CR2 in an E-box-dependent manner. Moreover, using mice with conditional MYC ablation we show that MYC induces CR2 in primary B cells. Importantly, modulation of MYC levels directly correlates with EBV's ability of infection in BL cells. Altogether, in contrast to the widely accepted hypothesis for the correlation between EBV and BL, we propose an alternative hypothesis in which MYC dysregulation could be the first event leading to the subsequent EBV infection.
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Affiliation(s)
- Ester Molina
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Lucía García-Gutiérrez
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Vanessa Junco
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Mercedes Perez-Olivares
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, Spain
| | - Virginia G de Yébenes
- Centro Nacional de Investigaciones Cardiovasculares-CNIC Carlos III, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, Universidad Complutense, School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Rosa Blanco
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Laura Quevedo
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Juan C Acosta
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Ana V Marín
- Department of Immunology, Ophthalmology and ENT, Universidad Complutense, School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Daniela Ulgiati
- School of Biomedical Sciences, The University of Western Australia, Crawley, WA, Australia
| | - Ramon Merino
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - M Dolores Delgado
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Ignacio Varela
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - José R Regueiro
- Department of Immunology, Ophthalmology and ENT, Universidad Complutense, School of Medicine and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | | | - Almudena R Ramiro
- Centro Nacional de Investigaciones Cardiovasculares-CNIC Carlos III, Madrid, Spain
| | - Javier León
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain.
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain.
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3
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Kawaharada M, Yamazaki M, Maruyama S, AbÉ T, Chan NN, Kitano T, Kobayashi T, Maeda T, Tanuma JI. Novel cytological model for the identification of early oral cancer diagnostic markers: The carcinoma sequence model. Oncol Lett 2022; 23:76. [PMID: 35111245 PMCID: PMC8771650 DOI: 10.3892/ol.2022.13196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 12/29/2021] [Indexed: 02/06/2023] Open
Abstract
Most oral squamous cell carcinomas (OSCCs) arise from a premalignant lesion, oral epithelial dysplasia; however, useful markers for the early detection of OSCC are lacking. The present study aimed to establish a novel experimental model to observe changes in the sequential expression patterns of mRNAs and proteins in a rat model of tongue cancer using liquid-based cytology techniques. Cytology specimens were collected at 2, 5, 8, 11, 14, 17 and 21 weeks from rats treated with 4-nitroquinoline 1-oxide to induce tongue cancer. The expression of candidate biomarkers was examined by performing immunocytochemistry and reverse transcription-quantitative PCR. The percentage of positively stained nuclei was calculated as the labeling index (LI). All rats developed OSCC of the tongue at 21 weeks. The mRNA expression levels of bromodomain protein 4 (Brd4), c-Myc and Tp53 were upregulated during the progression from negative for intraepithelial lesion or malignancy to squamous cell carcinoma (SCC). Brd4- and c-Myc-LI increased in low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion and SCC specimens. p53-LI was significantly increased in SCC specimens. This novel experimental model allowed the observation of sequential morphological changes and the expression patterns of mRNAs and proteins during carcinogenesis. Combining immunocytochemistry with cytology-based diagnoses may potentially improve the diagnostic accuracy of OSCC.
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Affiliation(s)
- Masami Kawaharada
- Division of Reconstructive Surgery for Oral and Maxillofacial Region, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan.,Division of Oral Pathology, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
| | - Manabu Yamazaki
- Division of Oral Pathology, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
| | - Satoshi Maruyama
- Oral Pathology Section, Department of Surgical Pathology, Niigata University Hospital, Chuo-ku, Niigata 951-8520, Japan
| | - Tatsuya AbÉ
- Division of Oral Pathology, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
| | - Nyein Nyein Chan
- Division of Reconstructive Surgery for Oral and Maxillofacial Region, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan.,Division of Oral Pathology, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
| | - Taiichi Kitano
- Oral Pathology Section, Department of Surgical Pathology, Niigata University Hospital, Chuo-ku, Niigata 951-8520, Japan
| | - Tadaharu Kobayashi
- Division of Reconstructive Surgery for Oral and Maxillofacial Region, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
| | - Takeyasu Maeda
- Research Center for Advanced Oral Science, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
| | - Jun-Ichi Tanuma
- Division of Oral Pathology, Faculty of Dentistry and Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
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4
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PBRM1 loss in kidney cancer unbalances the proximal tubule master transcription factor hub to repress proximal tubule differentiation. Cell Rep 2021; 36:109747. [PMID: 34551289 PMCID: PMC8561673 DOI: 10.1016/j.celrep.2021.109747] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 07/20/2021] [Accepted: 09/01/2021] [Indexed: 01/10/2023] Open
Abstract
PBRM1, a subunit of the PBAF coactivator complex that transcription factors use to activate target genes, is genetically inactivated in almost all clear cell renal cell cancers (RCCs). Using unbiased proteomic analyses, we find that PAX8, a master transcription factor driver of proximal tubule epithelial fates, recruits PBRM1/PBAF. Reverse analyses of the PAX8 interactome confirm recruitment specifically of PBRM1/PBAF and not functionally similar BAF. More conspicuous in the PAX8 hub in RCC cells, however, are corepressors, which functionally oppose coactivators. Accordingly, key PAX8 target genes are repressed in RCC versus normal kidneys, with the loss of histone lysine-27 acetylation, but intact lysine-4 trimethylation, activation marks. Re-introduction of PBRM1, or depletion of opposing corepressors using siRNA or drugs, redress coregulator imbalance and release RCC cells to terminal epithelial fates. These mechanisms thus explain RCC resemblance to the proximal tubule lineage but with suppression of the late-epithelial program that normally terminates lineage-precursor proliferation. Gu et al. identify that transcription factor PAX8 needs the PBRM1/PBAF coactivator to activate proximal tubule genes. PBRM1 mutation/deletion thus explains the resemblance of clear cell kidney cancer to proximal tubule tissue but with suppressed terminal epithelial markers. This oncogenic mechanism could be repaired using drugs to inhibit corepressors.
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5
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Ahmadi SE, Rahimi S, Zarandi B, Chegeni R, Safa M. MYC: a multipurpose oncogene with prognostic and therapeutic implications in blood malignancies. J Hematol Oncol 2021; 14:121. [PMID: 34372899 PMCID: PMC8351444 DOI: 10.1186/s13045-021-01111-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/12/2021] [Indexed: 12/17/2022] Open
Abstract
MYC oncogene is a transcription factor with a wide array of functions affecting cellular activities such as cell cycle, apoptosis, DNA damage response, and hematopoiesis. Due to the multi-functionality of MYC, its expression is regulated at multiple levels. Deregulation of this oncogene can give rise to a variety of cancers. In this review, MYC regulation and the mechanisms by which MYC adjusts cellular functions and its implication in hematologic malignancies are summarized. Further, we also discuss potential inhibitors of MYC that could be beneficial for treating hematologic malignancies.
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Affiliation(s)
- Seyed Esmaeil Ahmadi
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Samira Rahimi
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Bahman Zarandi
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Rouzbeh Chegeni
- Medical Laboratory Sciences Program, College of Health and Human Sciences, Northern Illinois University, DeKalb, IL, USA.
| | - Majid Safa
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran.
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.
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6
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Ultimate Precision: Targeting Cancer But Not Normal Self-Replication. Lung Cancer 2021. [DOI: 10.1007/978-3-030-74028-3_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Xu L, Wu F, Yang L, Wang F, Zhang T, Deng X, Zhang X, Yuan X, Yan Y, Li Y, Yang Z, Yu D. miR-144/451 inhibits c-Myc to promote erythroid differentiation. FASEB J 2020; 34:13194-13210. [PMID: 33319407 DOI: 10.1096/fj.202000941r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 07/01/2020] [Accepted: 07/08/2020] [Indexed: 12/12/2022]
Abstract
Ablation of miR-144/451 disrupts homeostasis of erythropoiesis. Myc, a protooncogenic protein, is essential for erythroblast proliferation but commits rapid downregulation during erythroid maturation. How erythroblasts orchestrate maturation processes through coding and non-coding genes is largely unknown. In this study, we use miR-144/451 knockout mice as in vivo model, G1E, MEL erythroblast lines and erythroblasts from fresh mouse fetal livers as in vitro systems to demonstrate that targeted depletion of miR-144/451 blocks erythroid nuclear condensation and enucleation. This is due, at least in part, to the continued high expression of Myc in erythroblasts when miR-144/451 is absent. Specifically, miR-144/451 directly inhibits Myc in erythroblasts. Loss of miR-144/451 locus derepresses, and thus, increases the expression of Myc. Sustained high levels of Myc in miR-144/451-depleted erythroblasts blocks erythroid differentiation. Moreover, Myc reversely regulates the expression of miR-144/451, forming a positive miR-144/451-Myc feedback to ensure the complete shutoff of Myc during erythropoiesis. Given that erythroid-specific transcription factor GATA1 activates miR-144/451 and inactivates Myc, our findings indicate that GATA1-miR-144/451-Myc network safeguards normal erythroid differentiation. Our findings also demonstrate that disruption of the miR-144/451-Myc crosstalk causes anemia, suggesting that miR-144/451 might be a potential therapeutic target in red cell diseases.
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Affiliation(s)
- Lei Xu
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou, China.,Central Laboratory, Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Fan Wu
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou, China
| | - Lei Yang
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou, China
| | - Fangfang Wang
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou, China
| | - Tong Zhang
- Xinghua People's Hospital, Yangzhou University, Xinghua, China
| | - Xintao Deng
- Xinghua People's Hospital, Yangzhou University, Xinghua, China
| | - Xiumei Zhang
- Xinghua People's Hospital, Yangzhou University, Xinghua, China
| | - Xiaoling Yuan
- Yangzhou Maternal and Child Care Service Center, Yangzhou University, Yangzhou, China
| | - Ying Yan
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou, China
| | - Yaoyao Li
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou, China.,Central Laboratory, Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Zhangping Yang
- Department of Animal Science & Technology, Yangzhou University College of Animal Science and Technology, Yangzhou, China
| | - Duonan Yu
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou, China.,Central Laboratory, Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China.,Xinghua People's Hospital, Yangzhou University, Xinghua, China
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8
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García-Gutiérrez L, Bretones G, Molina E, Arechaga I, Symonds C, Acosta JC, Blanco R, Fernández A, Alonso L, Sicinski P, Barbacid M, Santamaría D, León J. Myc stimulates cell cycle progression through the activation of Cdk1 and phosphorylation of p27. Sci Rep 2019; 9:18693. [PMID: 31822694 PMCID: PMC6904551 DOI: 10.1038/s41598-019-54917-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/14/2019] [Indexed: 12/24/2022] Open
Abstract
Cell cycle stimulation is a major transforming mechanism of Myc oncoprotein. This is achieved through at least three concomitant mechanisms: upregulation of cyclins and Cdks, downregulation of the Cdk inhibitors p15 and p21 and the degradation of p27. The Myc-p27 antagonism has been shown to be relevant in human cancer. To be degraded, p27 must be phosphorylated at Thr-187 to be recognized by Skp2, a component of the ubiquitination complex. We previously described that Myc induces Skp2 expression. Here we show that not only Cdk2 but Cdk1 phosphorylates p27 at the Thr-187. Moreover, Myc induced p27 degradation in murine fibroblasts through Cdk1 activation, which was achieved by Myc-dependent cyclin A and B induction. In the absence of Cdk2, p27 phosphorylation at Thr-187 was mainly carried out by cyclin A2-Cdk1 and cyclin B1-Cdk1. We also show that Cdk1 inhibition was enough for the synthetic lethal interaction with Myc. This result is relevant because Cdk1 is the only Cdk strictly required for cell cycle and the reported synthetic lethal interaction between Cdk1 and Myc.
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Affiliation(s)
- Lucía García-Gutiérrez
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain.,Systems Biology Ireland, University College Dublin, Belfield, Dublin, Ireland
| | - Gabriel Bretones
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain.,Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006, Oviedo, Spain
| | - Ester Molina
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Ignacio Arechaga
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Catherine Symonds
- Experimental Oncology, Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain.,Global Oncology Franchise, EMD Serono, Rockland, Massachusetts, USA
| | - Juan C Acosta
- Edinburgh Cancer Research UK Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Rosa Blanco
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Adrián Fernández
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Leticia Alonso
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Piotr Sicinski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, USA
| | - Mariano Barbacid
- Experimental Oncology, Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain
| | - David Santamaría
- University of Bordeaux, INSERM U1218, ACTION Laboratory, IECB, Pessac, France
| | - Javier León
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, and Departmento de Biología Molecular, Universidad de Cantabria, Santander, Spain.
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9
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Velcheti V, Schrump D, Saunthararajah Y. Ultimate Precision: Targeting Cancer but Not Normal Self-replication. Am Soc Clin Oncol Educ Book 2018; 38:950-963. [PMID: 30231326 DOI: 10.1200/edbk_199753] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Self-replication is the engine that drives all biologic evolution, including neoplastic evolution. A key oncotherapy challenge is to target this, the heart of malignancy, while sparing the normal self-replication mandatory for health and life. Self-replication can be demystified: it is activation of replication, the most ancient of cell programs, uncoupled from activation of lineage-differentiation, metazoan programs more recent in origin. The uncoupling can be physiologic, as in normal tissue stem cells, or pathologic, as in cancer. Neoplastic evolution selects to disengage replication from forward-differentiation where intrinsic replication rates are the highest, in committed progenitors that have division times measured in hours versus weeks for tissue stem cells, via partial loss of function in master transcription factors that activate terminal-differentiation programs (e.g., GATA4) or in the coactivators they use for this purpose (e.g., ARID1A). These loss-of-function mutations bias master transcription factor circuits, which normally regulate corepressor versus coactivator recruitment, toward corepressors (e.g., DNMT1) that repress rather than activate terminal-differentiation genes. Pharmacologic inhibition of the corepressors rebalances to coactivator function, activating lineage-differentiation genes that dominantly antagonize MYC (the master transcription factor coordinator of replication) to terminate malignant self-replication. Physiologic self-replication continues, because the master transcription factors in tissue stem cells activate stem cell, not terminal-differentiation, programs. Druggable corepressor proteins are thus the barriers between self-replicating cancer cells and the terminal-differentiation fates intended by their master transcription factor content. This final common pathway to oncogenic self-replication, being separate and distinct from the normal, offers the favorable therapeutic indices needed for clinical progress.
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Affiliation(s)
- Vamsidhar Velcheti
- From the Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH; Thoracic Oncology, National Cancer Institute, Bethesda, MD
| | - David Schrump
- From the Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH; Thoracic Oncology, National Cancer Institute, Bethesda, MD
| | - Yogen Saunthararajah
- From the Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH; Thoracic Oncology, National Cancer Institute, Bethesda, MD
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10
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Tu WB, Shiah YJ, Lourenco C, Mullen PJ, Dingar D, Redel C, Tamachi A, Ba-Alawi W, Aman A, Al-Awar R, Cescon DW, Haibe-Kains B, Arrowsmith CH, Raught B, Boutros PC, Penn LZ. MYC Interacts with the G9a Histone Methyltransferase to Drive Transcriptional Repression and Tumorigenesis. Cancer Cell 2018; 34:579-595.e8. [PMID: 30300580 DOI: 10.1016/j.ccell.2018.09.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 06/30/2018] [Accepted: 09/04/2018] [Indexed: 12/22/2022]
Abstract
MYC is an oncogenic driver that regulates transcriptional activation and repression. Surprisingly, mechanisms by which MYC promotes malignant transformation remain unclear. We demonstrate that MYC interacts with the G9a H3K9-methyltransferase complex to control transcriptional repression. Inhibiting G9a hinders MYC chromatin binding at MYC-repressed genes and de-represses gene expression. By identifying the MYC box II region as essential for MYC-G9a interaction, a long-standing missing link between MYC transformation and gene repression is unveiled. Across breast cancer cell lines, the anti-proliferative response to G9a pharmacological inhibition correlates with MYC sensitivity and gene signatures. Consistently, genetically depleting G9a in vivo suppresses MYC-dependent tumor growth. These findings unveil G9a as an epigenetic regulator of MYC transcriptional repression and a therapeutic vulnerability in MYC-driven cancers.
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Affiliation(s)
- William B Tu
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada
| | - Yu-Jia Shiah
- Informatics and Biocomputing Program, Ontario Institute for Cancer Research, Toronto, ON M5G0A3, Canada
| | - Corey Lourenco
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada
| | - Peter J Mullen
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada
| | | | - Cornelia Redel
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada
| | - Aaliya Tamachi
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada
| | - Wail Ba-Alawi
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada
| | - Ahmed Aman
- Drug Discovery Program, Ontario Institute for Cancer Research, Toronto, ON M5G0A3, Canada
| | - Rima Al-Awar
- Drug Discovery Program, Ontario Institute for Cancer Research, Toronto, ON M5G0A3, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S1A8, Canada
| | - David W Cescon
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Division of Medical Oncology and Hematology, Department of Medicine, University of Toronto, Toronto, ON M5G2C4, Canada
| | - Benjamin Haibe-Kains
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada
| | - Cheryl H Arrowsmith
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada; Structural Genomics Consortium, Toronto, ON M5G1L7, Canada
| | - Brian Raught
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada
| | - Paul C Boutros
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada; Informatics and Biocomputing Program, Ontario Institute for Cancer Research, Toronto, ON M5G0A3, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Linda Z Penn
- Princess Margaret Cancer Centre, Toronto, ON M5G1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G1L7, Canada.
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11
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Enane FO, Saunthararajah Y, Korc M. Differentiation therapy and the mechanisms that terminate cancer cell proliferation without harming normal cells. Cell Death Dis 2018; 9:912. [PMID: 30190481 PMCID: PMC6127320 DOI: 10.1038/s41419-018-0919-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 12/24/2022]
Abstract
Chemotherapeutic drugs have a common intent to activate apoptosis in tumor cells. However, master regulators of apoptosis (e.g., p53, p16/CDKN2A) are frequently genetically inactivated in cancers, resulting in multidrug resistance. An alternative, p53-independent method for terminating malignant proliferation is to engage terminal-differentiation. Normally, the exponential proliferation of lineage-committed progenitors, coordinated by the master transcription factor (TF) MYC, is self-limited by forward-differentiation to terminal lineage-fates. In cancers, however, this exponential proliferation is disengaged from terminal-differentiation. The mechanisms underlying this decoupling are mostly unknown. We performed a systematic review of published literature (January 2007-June 2018) to identify gene pathways linked to differentiation-failure in three treatment-recalcitrant cancers: hepatocellular carcinoma (HCC), ovarian cancer (OVC), and pancreatic ductal adenocarcinoma (PDAC). We analyzed key gene alterations in various apoptosis, proliferation and differentiation pathways to determine whether it is possible to predict treatment outcomes and suggest novel therapies. Poorly differentiated tumors were linked to poorer survival across histologies. Our analyses suggested loss-of-function events to master TF drivers of lineage-fates and their cofactors as being linked to differentiation-failure: genomic data in TCGA and ICGC databases demonstrated frequent haploinsufficiency of lineage master TFs (e.g., GATA4/6) in poorly differentiated tumors; the coactivators that these TFs use to activate genes (e.g. ARID1A, PBRM1) were also frequently inactivated by genetic mutation and/or deletion. By contrast, corepressor components (e.g., DNMT1, EED, UHRF1, and BAZ1A/B), that oppose coactivators to repress or turn off genes, were frequently amplified instead, and the level of amplification was highest in poorly differentiated lesions. This selection by neoplastic evolution towards unbalanced activity of transcriptional corepressors suggests these enzymes as candidate targets for inhibition aiming to re-engage forward-differentiation. This notion is supported by both pre-clinical and clinical trial literature.
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Affiliation(s)
- Francis O Enane
- Department of Medicine, Indiana University School of Medicine Indianapolis, Indianapolis, IN, 46202, USA.
| | - Yogen Saunthararajah
- Department of Hematology and Oncology, Taussig Cancer Center, Cleveland Clinic, Cleveland, OH, 44195, USA
- Department of Translational Hematology and Oncology Research, Taussig Cancer Center, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Murray Korc
- Department of Medicine, Indiana University School of Medicine Indianapolis, Indianapolis, IN, 46202, USA.
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- The Pancreatic Cancer Signature Center at Indiana University Purdue University Indianapolis and Indiana University Simon Cancer, Indianapolis, IN, 46202, USA.
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12
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Velcheti V, Radivoyevitch T, Saunthararajah Y. Higher-Level Pathway Objectives of Epigenetic Therapy: A Solution to the p53 Problem in Cancer. Am Soc Clin Oncol Educ Book 2017; 37:812-824. [PMID: 28561650 DOI: 10.1200/edbk_174175] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Searches for effective yet nontoxic oncotherapies are searches for exploitable differences between cancer and normal cells. In its core of cell division, cancer resembles normal life, coordinated by the master transcription factor MYC. Outside of this core, apoptosis and differentiation programs, which dominantly antagonize MYC to terminate cell division, necessarily differ between cancer and normal cells, as apoptosis is suppressed by biallelic inactivation of the master regulator of apoptosis, p53, or its cofactor p16/CDKN2A in approximately 80% of cancers. These genetic alterations impact therapy: conventional oncotherapy applies stress upstream of p53 to upregulate it and causes apoptosis (cytotoxicity)-a toxic, futile intent when it is absent or nonfunctional. Differentiation, on the other hand, cannot be completely suppressed because it is a continuum along which all cells exist. Neoplastic evolution stalls advances along this continuum at its most proliferative points-in lineage-committed progenitors that have division times measured in hours compared with weeks for tissue stem cells. This differentiation arrest is by mutations/deletions in differentiation-driving transcription factors or their coactivators that shift balances of gene-regulating protein complexes toward corepressors that repress instead of activate hundreds of terminal differentiation genes. That is, malignant proliferation without differentiation, also referred to as cancer "stem" cell self-renewal, hinges on druggable corepressors. Inhibiting these corepressors (e.g., DNMT1) releases p53-independent terminal differentiation in cancer stem cells but preserves self-renewal of normal stem cells that express stem cell transcription factors. Thus, epigenetic-differentiation therapies exploit a fundamental distinction between cancer and normal stem cell self-renewal and have a pathway of action downstream of genetic defects in cancer, affording favorable therapeutic indices needed for clinical progress.
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Affiliation(s)
- Vamsidhar Velcheti
- From the Department of Hematology & Medical Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH; Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH; Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH
| | - Tomas Radivoyevitch
- From the Department of Hematology & Medical Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH; Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH; Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH
| | - Yogen Saunthararajah
- From the Department of Hematology & Medical Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH; Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH; Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH
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13
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Perearnau A, Orlando S, Islam ABMMK, Gallastegui E, Martínez J, Jordan A, Bigas A, Aligué R, Pujol MJ, Bachs O. p27Kip1, PCAF and PAX5 cooperate in the transcriptional regulation of specific target genes. Nucleic Acids Res 2017; 45:5086-5099. [PMID: 28158851 PMCID: PMC5435914 DOI: 10.1093/nar/gkx075] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 01/26/2017] [Indexed: 12/13/2022] Open
Abstract
The cyclin-dependent kinase inhibitor p27Kip1 (p27) also behaves as a transcriptional repressor. Data showing that the p300/CBP-associated factor (PCAF) acetylates p27 inducing its degradation suggested that PCAF and p27 could collaborate in the regulation of transcription. However, this possibility remained to be explored. We analyzed here the transcriptional programs regulated by PCAF and p27 in the colon cancer cell line HCT116 by chromatin immunoprecipitation sequencing (ChIP-seq). We identified 269 protein-encoding genes that contain both p27 and PCAF binding sites being the majority of these sites different for PCAF and p27. PCAF or p27 knock down revealed that both regulate the expression of these genes, PCAF as an activator and p27 as a repressor. The double knock down of PCAF and p27 strongly reduced their expression indicating that the activating role of PCAF overrides the repressive effect of p27. We also observed that the transcription factor Pax5 interacts with both p27 and PCAF and that the knock down of Pax5 induces the expression of p27/PCAF target genes indicating that it also participates in the transcriptional regulation mediated by p27/PCAF. In summary, we report here a previously unknown mechanism of transcriptional regulation mediated by p27, Pax5 and PCAF.
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Affiliation(s)
- Anna Perearnau
- Department of Biomedical Sciences, University of Barcelona-IDIBAPS, CIBERONC, 08036 Barcelona, Spain
| | - Serena Orlando
- Department of Biomedical Sciences, University of Barcelona-IDIBAPS, CIBERONC, 08036 Barcelona, Spain
| | - Abul B M M K Islam
- Department of Genetic Engineering and Biotechnology University of Dhaka, Dhaka 1000, Bangladesh
| | - Edurne Gallastegui
- Department of Biomedical Sciences, University of Barcelona-IDIBAPS, CIBERONC, 08036 Barcelona, Spain
| | - Jonatan Martínez
- Department of Biomedical Sciences, University of Barcelona-IDIBAPS, CIBERONC, 08036 Barcelona, Spain
| | - Albert Jordan
- Department of Molecular Genomics, Molecular Biology Institute of Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), 08029 Barcelona, Spain
| | - Anna Bigas
- Program in Cancer Research, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), CIBERONC, 08003 Barcelona, Spain
| | - Rosa Aligué
- Department of Biomedical Sciences, University of Barcelona-IDIBAPS, CIBERONC, 08036 Barcelona, Spain
| | - Maria Jesús Pujol
- Department of Biomedical Sciences, University of Barcelona-IDIBAPS, CIBERONC, 08036 Barcelona, Spain
| | - Oriol Bachs
- Department of Biomedical Sciences, University of Barcelona-IDIBAPS, CIBERONC, 08036 Barcelona, Spain
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14
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Enane FO, Shuen WH, Gu X, Quteba E, Przychodzen B, Makishima H, Bodo J, Ng J, Chee CL, Ba R, Seng Koh L, Lim J, Cheong R, Teo M, Hu Z, Ng KP, Maciejewski J, Radivoyevitch T, Chung A, Ooi LL, Tan YM, Cheow PC, Chow P, Chan CY, Lim KH, Yerian L, Hsi E, Toh HC, Saunthararajah Y. GATA4 loss of function in liver cancer impedes precursor to hepatocyte transition. J Clin Invest 2017; 127:3527-3542. [PMID: 28758902 DOI: 10.1172/jci93488] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/08/2017] [Indexed: 12/18/2022] Open
Abstract
The most frequent chromosomal structural loss in hepatocellular carcinoma (HCC) is of the short arm of chromosome 8 (8p). Genes on the remaining homologous chromosome, however, are not recurrently mutated, and the identity of key 8p tumor-suppressor genes (TSG) is unknown. In this work, analysis of minimal commonly deleted 8p segments to identify candidate TSG implicated GATA4, a master transcription factor driver of hepatocyte epithelial lineage fate. In a murine model, liver-conditional deletion of 1 Gata4 allele to model the haploinsufficiency seen in HCC produced enlarged livers with a gene expression profile of persistent precursor proliferation and failed hepatocyte epithelial differentiation. HCC mimicked this gene expression profile, even in cases that were morphologically classified as well differentiated. HCC with intact chromosome 8p also featured GATA4 loss of function via GATA4 germline mutations that abrogated GATA4 interactions with a coactivator, MED12, or by inactivating mutations directly in GATA4 coactivators, including ARID1A. GATA4 reintroduction into GATA4-haploinsufficient HCC cells or ARID1A reintroduction into ARID1A-mutant/GATA4-intact HCC cells activated hundreds of hepatocyte genes and quenched the proliferative precursor program. Thus, disruption of GATA4-mediated transactivation in HCC suppresses hepatocyte epithelial differentiation to sustain replicative precursor phenotype.
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Affiliation(s)
- Francis O Enane
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Wai Ho Shuen
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Xiaorong Gu
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Ebrahem Quteba
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Bartlomiej Przychodzen
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Hideki Makishima
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Juraj Bodo
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Joanna Ng
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Chit Lai Chee
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Rebecca Ba
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Lip Seng Koh
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Janice Lim
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Rachael Cheong
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Marissa Teo
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Zhenbo Hu
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Kwok Peng Ng
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Jaroslaw Maciejewski
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Tomas Radivoyevitch
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio, USA
| | - Alexander Chung
- Department of Hepato-pancreato-biliary and Transplant Surgery and
| | | | - Yu Meng Tan
- Department of Hepato-pancreato-biliary and Transplant Surgery and
| | - Peng-Chung Cheow
- Department of Hepato-pancreato-biliary and Transplant Surgery and
| | - Pierce Chow
- Department of Hepato-pancreato-biliary and Transplant Surgery and
| | - Chung Yip Chan
- Department of Hepato-pancreato-biliary and Transplant Surgery and
| | - Kiat Hon Lim
- Department of Pathology, Singapore General Hospital, Singapore
| | - Lisa Yerian
- Clinical Pathology, Pathology Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Eric Hsi
- Clinical Pathology, Pathology Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Han Chong Toh
- Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Yogen Saunthararajah
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, USA
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15
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Transcriptome analysis of dominant-negative Brd4 mutants identifies Brd4-specific target genes of small molecule inhibitor JQ1. Sci Rep 2017; 7:1684. [PMID: 28490802 PMCID: PMC5431861 DOI: 10.1038/s41598-017-01943-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 04/05/2017] [Indexed: 01/02/2023] Open
Abstract
The bromodomain protein Brd4 is an epigenetic reader and plays a critical role in the development and maintenance of leukemia. Brd4 binds to acetylated histone tails and activates transcription by recruiting the positive elongation factor P-TEFb. Small molecule inhibitor JQ1 competitively binds the bromodomains of Brd4 and displaces the protein from acetylated histones. However, it remains unclear whether genes targeted by JQ1 are mainly regulated by Brd4 or by other bromodomain proteins such as Brd2 and Brd3. Here, we describe anti-proliferative dominant-negative Brd4 mutants that compete with the function of distinct Brd4 domains. We used these Brd4 mutants to compare the Brd4-specific transcriptome with the transcriptome of JQ1-treated cells. We found that most JQ1-regulated genes are also regulated by dominant-negative Brd4 mutants, including the mutant that competes with the P-TEFb recruitment function of Brd4. Importantly, JQ1 and dominant-negative Brd4 mutants regulated the same set of target genes of c-Myc, a key regulator of the JQ1 response in leukemia cells. Our results suggest that Brd4 mediates most of the anti-cancer effects of JQ1 and that the major function of Brd4 in this process is the recruitment of P-TEFb. In summary, our studies define the molecular targets of JQ1 in more detail.
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16
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Abstract
Therapy-induced senescence (TIS), a lasting chemotherapy-evoked proliferative arrest of tumor cells, has gained increasing attention by cancer researchers because of its' profound biological implications, and by clinical oncologists due to its potential contribution to the long-term outcome of cancer patients post-treatment. Although both apoptosis and senescence represent therapy-inducible, ultimate cell-cycle exit programs, mediated via DNA damage response signaling, apoptotic cell death as the faster and often quantitatively more prominent tumor response has been in the scientific focus for decades. The more recently recognized TIS as another "safeguard" response of cancer cells that were never primed for or failed to execute apoptosis, not only reflects a more complex "arrest-plus-other features" cell-autonomous condition but produces non-cell-autonomous phenotypes at the tumor site, collectively impinging on tumor control and clinical outcome. Hence, TIS research is gaining pivotal interest from both a tumor biological and a therapeutic perspective, and the development of non-DNA damaging, senescence-evoking therapeutics is about to become a major research objective. In this chapter, we describe a well-characterized, genetically controlled TIS model system based on primary BCL2-expressing Eμ-myc transgenic lymphoma cells harboring defined genetic lesions and provide protocols for co-staining of either senescence-associated β-galactosidase (SA-β-gal) activity or trimethylated lysine 9 of histone H3 (H3K9me3) together with Ki67 to detect the senescent status of therapy-exposed cancer cells.
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Affiliation(s)
- Dorothy N Y Fan
- Department of Hematology, Oncology and Tumor Immunology, Campus Virchow Clinic, Charité-University Medical Center, Berlin, Germany
| | - Clemens A Schmitt
- Department of Hematology, Oncology and Tumor Immunology, Campus Virchow Clinic, Charité-University Medical Center, Berlin, Germany.
- Molekulares Krebsforschungszentrum-MKFZ, Berlin, Germany.
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Str. 10, Berlin, 13125, Germany.
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17
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Zini R, Rossi C, Norfo R, Pennucci V, Barbieri G, Ruberti S, Rontauroli S, Salati S, Bianchi E, Manfredini R. miR-382-5p Controls Hematopoietic Stem Cell Differentiation Through the Downregulation of MXD1. Stem Cells Dev 2016; 25:1433-43. [DOI: 10.1089/scd.2016.0150] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Roberta Zini
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Chiara Rossi
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Ruggiero Norfo
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
- Haematopoietic Stem Cell Biology Laboratory, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Valentina Pennucci
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Greta Barbieri
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Samantha Ruberti
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Sebastiano Rontauroli
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Simona Salati
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Elisa Bianchi
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Rossella Manfredini
- Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
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18
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BPTF is required for c-MYC transcriptional activity and in vivo tumorigenesis. Nat Commun 2016; 7:10153. [PMID: 26729287 PMCID: PMC4728380 DOI: 10.1038/ncomms10153] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 11/06/2015] [Indexed: 01/06/2023] Open
Abstract
c-MYC oncogene is deregulated in most human tumours. Histone marks associated with transcriptionally active genes define high-affinity c-MYC targets. The mechanisms involved in their recognition by c-MYC are unknown. Here we report that c-MYC interacts with BPTF, a core subunit of the NURF chromatin-remodelling complex. BPTF is required for the activation of the full c-MYC transcriptional programme in fibroblasts. BPTF knockdown leads to decreased c-MYC recruitment to DNA and changes in chromatin accessibility. In Bptf-null MEFs, BPTF is necessary for c-MYC-driven proliferation, G1–S progression and replication stress, but not for c-MYC-driven apoptosis. Bioinformatics analyses unveil that BPTF levels correlate positively with c-MYC-driven transcriptional signatures. In vivo, Bptf inactivation in pre-neoplastic pancreatic acinar cells significantly delays tumour development and extends survival. Our findings uncover BPTF as a crucial c-MYC co-factor required for its biological activity and suggest that the BPTF-c-MYC axis is a potential therapeutic target in cancer. c-MYC genomic distribution is dictated by the epigenetic context but the mechanisms are unknown. Here, the authors show that c-MYC requires the chromatin reader BPTF to activate its transcriptional program and promote tumour development in vivo, suggesting that BPTF is a potential target for cancer therapy.
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19
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Morgado-Palacin L, Varetti G, Llanos S, Gómez-López G, Martinez D, Serrano M. Partial Loss of Rpl11 in Adult Mice Recapitulates Diamond-Blackfan Anemia and Promotes Lymphomagenesis. Cell Rep 2015; 13:712-722. [PMID: 26489471 DOI: 10.1016/j.celrep.2015.09.038] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 08/10/2015] [Accepted: 09/14/2015] [Indexed: 01/01/2023] Open
Abstract
Diamond-Blackfan anemia (DBA) is characterized by anemia and cancer susceptibility and is caused by mutations in ribosomal genes, including RPL11. Here, we report that Rpl11-heterozygous mouse embryos are not viable and that Rpl11 homozygous deletion in adult mice results in death within a few weeks, accompanied by bone marrow aplasia and intestinal atrophy. Importantly, Rpl11 heterozygous deletion in adult mice results in anemia associated with decreased erythroid progenitors and defective erythroid maturation. These defects are also present in mice transplanted with inducible heterozygous Rpl11 bone marrow and, therefore, are intrinsic to the hematopoietic system. Additionally, heterozygous Rpl11 mice present increased susceptibility to radiation-induced lymphomagenesis. In this regard, total or partial deletion of Rpl11 compromises p53 activation upon ribosomal stress or DNA damage in fibroblasts. Moreover, fibroblasts and hematopoietic tissues from heterozygous Rpl11 mice present higher basal cMYC levels. We conclude that Rpl11-deficient mice recapitulate DBA disorder, including cancer predisposition.
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Affiliation(s)
- Lucia Morgado-Palacin
- Tumor Suppression Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid E28029, Spain
| | - Gianluca Varetti
- Tumor Suppression Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid E28029, Spain
| | - Susana Llanos
- Tumor Suppression Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid E28029, Spain
| | - Gonzalo Gómez-López
- Bioniformatics Unit, Structural Biology and Biocomputing Programme, Spanish National Cancer Research Centre (CNIO), Madrid E28029, Spain
| | - Dolores Martinez
- Flow Cytometry Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), Madrid E28029, Spain
| | - Manuel Serrano
- Tumor Suppression Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid E28029, Spain.
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20
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Diolaiti D, McFerrin L, Carroll PA, Eisenman RN. Functional interactions among members of the MAX and MLX transcriptional network during oncogenesis. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1849:484-500. [PMID: 24857747 PMCID: PMC4241192 DOI: 10.1016/j.bbagrm.2014.05.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 04/23/2014] [Accepted: 05/14/2014] [Indexed: 01/27/2023]
Abstract
The transcription factor MYC and its related family members MYCN and MYCL have been implicated in the etiology of a wide spectrum of human cancers. Compared to other oncoproteins, such as RAS or SRC, MYC is unique because its protein coding region is rarely mutated. Instead, MYC's oncogenic properties are unleashed by regulatory mutations leading to unconstrained high levels of expression. Under both normal and pathological conditions MYC regulates multiple aspects of cellular physiology including proliferation, differentiation, apoptosis, growth and metabolism by controlling the expression of thousands of genes. How a single transcription factor exerts such broad effects remains a fascinating puzzle. Notably, MYC is part of a network of bHLHLZ proteins centered on the MYC heterodimeric partner MAX and its counterpart, the MAX-like protein MLX. This network includes MXD1-4, MNT, MGA, MONDOA and MONDOB proteins. With some exceptions, MXD proteins have been functionally linked to cell cycle arrest and differentiation, while MONDO proteins control cellular metabolism. Although the temporal expression patterns of many of these proteins can differ markedly they are frequently expressed simultaneously in the same cellular context, and potentially bind to the same, or similar DNA consensus sequence. Here we review the activities and interactions among these proteins and propose that the broad spectrum of phenotypes elicited by MYC deregulation is intimately connected to the functions and regulation of the other network members. Furthermore, we provide a meta-analysis of TCGA data suggesting that the coordinate regulation of the network is important in MYC driven tumorigenesis. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.
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Affiliation(s)
- Daniel Diolaiti
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA
| | - Lisa McFerrin
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA
| | - Patrick A Carroll
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA
| | - Robert N Eisenman
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA.
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21
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Jezkova J, Williams JS, Jones-Hutchins F, Sammut SJ, Gollins S, Cree I, Coupland S, McFarlane RJ, Wakeman JA. Brachyury regulates proliferation of cancer cells via a p27Kip1-dependent pathway. Oncotarget 2015; 5:3813-22. [PMID: 25003467 PMCID: PMC4116522 DOI: 10.18632/oncotarget.1999] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The T-box transcription factor Brachyury is expressed in a number of tumour types and has been demonstrated to have cancer inducing properties. To date, it has been linked to cancer associated induction of epithelial to mesenchymal transition, tumour metastasis and expression of markers for cancer stem-like cells. Taken together, these findings indicate that Brachyury plays an important role in the progression of cancer, although the mechanism through which it functions is poorly understood. Here we show that Brachyury regulates the potential of Brachyury-positive colorectal cancer cells to proliferate and reduced levels of Brachyury result in inhibition of proliferation, with features consistent with the cells entering a quiescent-like state. This inhibition of proliferation is dependent upon p27Kip1 demonstrating that Brachyury acts to modulate cellular proliferative fate in colorectal cancer cells in a p27Kip1-dependent manner. Analysis of patient derived colorectal tumours reveals a heterogeneous localisation of Brachyury (in the nucleolus, nucleus and cytoplasm) indicating the potential complexity of the regulatory role of Brachyury in solid colorectal tumours.
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Affiliation(s)
- Jana Jezkova
- North West Cancer Research Institute, College of Natural Sciences, Bangor, Gwynedd, UK
| | | | | | | | | | | | | | - Ramsay J McFarlane
- North West Cancer Research Institute, College of Natural Sciences, Bangor, Gwynedd, UK; NISCHR Cancer Genetics Biomedical Research Unit, Welsh Government, Cathays Park, Cardiff, UK
| | - Jane A Wakeman
- North West Cancer Research Institute, College of Natural Sciences, Bangor, Gwynedd, UK
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22
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Geiler C, Andrade I, Greenwald D. Exogenous c-Myc Blocks Differentiation and Improves Expansion of Human Erythroblasts In vitro. Int J Stem Cells 2014; 7:153-7. [PMID: 25473453 PMCID: PMC4249898 DOI: 10.15283/ijsc.2014.7.2.153] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2014] [Indexed: 11/15/2022] Open
Abstract
Background: Engineered blood has the greatest potential to combat a predicted future shortfall in the blood supply for transfusion treatment. The production of red blood cells from hematopoietic stem cells in the laboratory is possible but the mass production of red blood cells to the level present in a blood transfusion unit is currently not possible. The proliferation capacity of the immature red blood cell will need to be increased to enable mass production. This work focused on the hypothesis that exogenous c-Myc can delay the differentiation process of highly proliferative immature erythroblasts, and increase the proliferation capacity of erythroblast cell cultures. Objectives: The objective of this research effort was to improve in vitro erythropoiesis from stem cells without gene transfection with the eventual goal of producing blood for transfusion treatment in a manner that could be easily translated into clinical medicine. Methods: The hematopoietic stem cell containing mononuclear cell fraction of venous blood samples was cultured in a liquid media containing erythroblasts growth factors with and without exogenous c-Myc combined with a cell -penetrating peptide. The cells were maintained in the liquid culture media for 23 days. Viable cells were counted and analyzed with flow cytometry. Results: Our results show a 4 fold increase in expansion of the erythroblasts grown in the c-Myc containing growth media compared to the control. Eighty percent of these cells retained the CD117 surface receptor, indicating immature cells. Conclusion: Exogenous c-Myc blocks the differentiation and improves in vitro expansion of human erythroblasts.
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Affiliation(s)
- Cristopher Geiler
- Department of Basic Science Research, Cellologi, LLC ; Santa Barbara Cottage Hospital, Santa Barbara, USA
| | - Inez Andrade
- Department of Basic Science Research, Cellologi, LLC
| | - Daniel Greenwald
- Department of Basic Science Research, Cellologi, LLC ; Santa Barbara Cottage Hospital, Santa Barbara, USA
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23
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Caraballo JM, Acosta JC, Cortés MA, Albajar M, Gómez-Casares MT, Batlle-López A, Cuadrado MA, Onaindia A, Bretones G, Llorca J, Piris MA, Colomer D, León J. High p27 protein levels in chronic lymphocytic leukemia are associated to low Myc and Skp2 expression, confer resistance to apoptosis and antagonize Myc effects on cell cycle. Oncotarget 2014; 5:4694-708. [PMID: 25051361 PMCID: PMC4148092 DOI: 10.18632/oncotarget.2100] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 06/09/2014] [Indexed: 12/29/2022] Open
Abstract
Myc (c-Myc) counteracts p27 effects, and low p27 usually correlates with high Myc expression in human cancer. However there is no information on the co-expression of both genes in chronic lymphocytic leukemia (CLL). We found a lack of correlation between RNA and protein levels of p27 and Myc in CLL cells, so we determined the protein levels by immunoblot in 107 cases of CLL. We observed a high p27 protein expression in CLL compared to normal B cells. Ectopic p27 expression in a CLL-derived cell line resulted in cell death resistance. Surprisingly, Myc expression was very low or undetectable in most CLL cases analyzed, with a clear correlation between high p27 and low Myc protein levels. This was associated with low Skp2 expression, which is consistent with the Skp2 role in p27 degradation and with SKP2 being a Myc target gene. High Myc expression did not correlate with leukemia progression, despite that cell cycle-related Myc target genes were upregulated. However, biochemical analysis showed that the high p27 levels inhibited cyclin-Cdk complexes even in Myc expressing CLL cells. Our data suggest that the combination of high p27 and low Myc is a marker of CLL cells which is mediated by Skp2.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Apoptosis/genetics
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Cell Cycle/genetics
- Cell Line, Tumor
- Cyclin-Dependent Kinase Inhibitor p27/genetics
- Cyclin-Dependent Kinase Inhibitor p27/metabolism
- Cyclins/genetics
- Cyclins/metabolism
- Drug Resistance, Neoplasm/genetics
- Female
- Gene Expression Regulation, Leukemic
- Humans
- Immunoblotting
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- Male
- Microscopy, Fluorescence
- Middle Aged
- Proto-Oncogene Proteins c-myb/genetics
- Proto-Oncogene Proteins c-myb/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- S-Phase Kinase-Associated Proteins/genetics
- S-Phase Kinase-Associated Proteins/metabolism
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Affiliation(s)
- Juan M. Caraballo
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria-Sodercan, and Dpt. of. Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Juan C. Acosta
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria-Sodercan, and Dpt. of. Biología Molecular, Universidad de Cantabria, Santander, Spain
- Present address: Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, UK
| | | | - Marta Albajar
- Servicio de Hematologia, Hospital Marqués de Valdecilla and Instituto de Investigación Marqués de Valdecilla (IDIVAL), Santander, Spain
| | | | - Ana Batlle-López
- Servicio de Hematologia, Hospital Marqués de Valdecilla and Instituto de Investigación Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - M. Angeles Cuadrado
- Servicio de Hematologia, Hospital Marqués de Valdecilla and Instituto de Investigación Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - Arantza Onaindia
- Servicio de Anatomía Patológica, Hospital Marqués de Valdecilla and Instituto de Investigación Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - Gabriel Bretones
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria-Sodercan, and Dpt. of. Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Javier Llorca
- Group of Epidemiology and Computational Biology, Universidad de Cantabria-IDIVAL, Santander, Spain and CIBER Epidemiología y Salud Pública (CIBERESP), Spain
| | - Miguel A. Piris
- Servicio de Anatomía Patológica, Hospital Marqués de Valdecilla and Instituto de Investigación Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - Dolors Colomer
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Barcelona, Spain
| | - Javier León
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria-Sodercan, and Dpt. of. Biología Molecular, Universidad de Cantabria, Santander, Spain
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24
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Bretones G, Delgado MD, León J. Myc and cell cycle control. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:506-16. [PMID: 24704206 DOI: 10.1016/j.bbagrm.2014.03.013] [Citation(s) in RCA: 483] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/18/2014] [Accepted: 03/23/2014] [Indexed: 12/12/2022]
Abstract
Soon after the discovery of the Myc gene (c-Myc), it became clear that Myc expression levels tightly correlate to cell proliferation. The entry in cell cycle of quiescent cells upon Myc enforced expression has been described in many models. Also, the downregulation or inactivation of Myc results in the impairment of cell cycle progression. Given the frequent deregulation of Myc oncogene in human cancer it is important to dissect out the mechanisms underlying the role of Myc on cell cycle control. Several parallel mechanisms account for Myc-mediated stimulation of the cell cycle. First, most of the critical positive cell cycle regulators are encoded by genes induced by Myc. These Myc target genes include Cdks, cyclins and E2F transcription factors. Apart from its direct effects on the transcription, Myc is able to hyperactivate cyclin/Cdk complexes through the induction of Cdk activating kinase (CAK) and Cdc25 phosphatases. Moreover, Myc antagonizes the activity of cell cycle inhibitors as p21 and p27 through different mechanisms. Thus, Myc is able to block p21 transcription or to induce Skp2, a protein involved in p27 degradation. Finally, Myc induces DNA replication by binding to replication origins and by upregulating genes encoding proteins required for replication initiation. Myc also regulates genes involved in the mitotic control. A promising approach to treat tumors with deregulated Myc is the synthetic lethality based on the inhibition of Cdks. Thus, the knowledge of the Myc-dependent cell cycle regulatory mechanisms will help to discover new therapeutic approaches directed against malignancies with deregulated Myc. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.
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Affiliation(s)
- Gabriel Bretones
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria-SODERCAN and Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - M Dolores Delgado
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria-SODERCAN and Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | - Javier León
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria-SODERCAN and Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain.
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25
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Abstract
Epigenetic regulatory mechanisms are implicated in the pathogenesis of acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). Recent progress suggests that proteins involved in epigenetic control are amenable to drug intervention, but little is known about the cancer-specific dependency on epigenetic regulators for cell survival and proliferation. We used a mouse model of human AML induced by the MLL-AF9 fusion oncogene and an epigenetic short hairpin RNA (shRNA) library to screen for novel potential drug targets. As a counter-screen for general toxicity of shRNAs, we used normal mouse bone marrow cells. One of the best candidate drug targets identified in these screens was Jmjd1c. Depletion of Jmjd1c impairs growth and colony formation of mouse MLL-AF9 cells in vitro as well as establishment of leukemia after transplantation. Depletion of JMJD1C impairs expansion and colony formation of human leukemic cell lines, with the strongest effect observed in the MLL-rearranged ALL cell line SEM. In both mouse and human leukemic cells, the growth defect upon JMJD1C depletion appears to be primarily due to increased apoptosis, which implicates JMJD1C as a potential therapeutic target in leukemia.
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26
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Ma J, Hu Y, Guo M, Huang Z, Li W, Wu Y. hERG potassium channel blockage by scorpion toxin BmKKx2 enhances erythroid differentiation of human leukemia cells K562. PLoS One 2013; 8:e84903. [PMID: 24386436 PMCID: PMC3873423 DOI: 10.1371/journal.pone.0084903] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 11/28/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The hERG potassium channel can modulate the proliferation of the chronic myelogenous leukemic K562 cells, and its role in the erythroid differentiation of K562 cells still remains unclear. PRINCIPAL FINDINGS The hERG potassium channel blockage by a new 36-residue scorpion toxin BmKKx2, a potent hERG channel blocker with IC50 of 6.7 ± 1.7 nM, enhanced the erythroid differentiation of K562 cells. The mean values of GPA (CD235a) fluorescence intensity in the group of K562 cells pretreated by the toxin for 24 h and followed by cytosine arabinoside (Ara-C) treatment for 72 h were about 2-fold stronger than those of K562 cells induced by Ara-C alone. Such unique role of hERG potassium channel was also supported by the evidence that the effect of the toxin BmKKx2 on cell differentiation was nullified in hERG-deficient cell lines. During the K562 cell differentiation, BmKKx2 could also suppress the expression of hERG channels at both mRNA and protein levels. Besides the function of differentiation enhancement, BmKKx2 was also found to promote the differentiation-dependent apoptosis during the differentiation process of K562 cells. In addition, the blockage of hERG potassium channel by toxin BmKKx2 was able to decrease the intracellular Ca(2+) concentration during the K562 cell differentiation, providing an insight into the mechanism of hERG potassium channel regulating this cellular process. CONCLUSIONS/SIGNIFICANCE Our results revealed scorpion toxin BmKKx2 could enhance the erythroid differentiation of leukemic K562 cells via inhibiting hERG potassium channel currents. These findings would not only accelerate the functional research of hERG channel in different leukemic cells, but also present the prospects of natural scorpion toxins as anti-leukemic drugs.
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Affiliation(s)
- Jian Ma
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Youtian Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Mingxiong Guo
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Zan Huang
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
- * E-mail: (WL); (YW)
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
- * E-mail: (WL); (YW)
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27
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Hirose SI, Takayama N, Nakamura S, Nagasawa K, Ochi K, Hirata S, Yamazaki S, Yamaguchi T, Otsu M, Sano S, Takahashi N, Sawaguchi A, Ito M, Kato T, Nakauchi H, Eto K. Immortalization of erythroblasts by c-MYC and BCL-XL enables large-scale erythrocyte production from human pluripotent stem cells. Stem Cell Reports 2013; 1:499-508. [PMID: 24371805 PMCID: PMC3871399 DOI: 10.1016/j.stemcr.2013.10.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 10/22/2013] [Accepted: 10/22/2013] [Indexed: 02/08/2023] Open
Abstract
The lack of knowledge about the mechanism of erythrocyte biogenesis through self-replication makes the in vitro generation of large quantities of cells difficult. We show that transduction of c-MYC and BCL-XL into multipotent hematopoietic progenitor cells derived from pluripotent stem cells and gene overexpression enable sustained exponential self-replication of glycophorin A(+) erythroblasts, which we term immortalized erythrocyte progenitor cells (imERYPCs). In an inducible expression system, turning off the overexpression of c-MYC and BCL-XL enabled imERYPCs to mature with chromatin condensation and reduced cell size, hemoglobin synthesis, downregulation of GCN5, upregulation of GATA1, and endogenous BCL-XL and RAF1, all of which appeared to recapitulate normal erythropoiesis. imERYPCs mostly displayed fetal-type hemoglobin and normal oxygen dissociation in vitro and circulation in immunodeficient mice following transfusion. Using critical factors to induce imERYPCs provides a model of erythrocyte biogenesis that could potentially contribute to a stable supply of erythrocytes for donor-independent transfusion.
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Affiliation(s)
- Sho-Ichi Hirose
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Naoya Takayama
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan ; Clinical Application Department, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Sou Nakamura
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan ; Clinical Application Department, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Kazumichi Nagasawa
- Graduate School of Advanced Science and Engineering, Center for Advanced Life and Medical Science, Waseda University, Tokyo 162-8480, Japan
| | - Kiyosumi Ochi
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan ; Clinical Application Department, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Shinji Hirata
- Clinical Application Department, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Satoshi Yamazaki
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Tomoyuki Yamaguchi
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Makoto Otsu
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Shinya Sano
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Nobuyasu Takahashi
- Department of Anatomy, Ultrastructural Cell Biology, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Akira Sawaguchi
- Department of Anatomy, Ultrastructural Cell Biology, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Mamoru Ito
- Central Institute for Experimental Animals, Kawasaki 210-0821, Japan
| | - Takashi Kato
- Department of Anatomy, Ultrastructural Cell Biology, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Hiromitsu Nakauchi
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Koji Eto
- Laboratory of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan ; Clinical Application Department, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
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28
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Zhang J, Seet CS, Sun C, Li J, You D, Volk A, Breslin P, Li X, Wei W, Qian Z, Zeleznik-Le NJ, Zhang Z, Zhang J. p27kip1 maintains a subset of leukemia stem cells in the quiescent state in murine MLL-leukemia. Mol Oncol 2013; 7:1069-82. [PMID: 23988911 DOI: 10.1016/j.molonc.2013.07.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/22/2013] [Accepted: 07/31/2013] [Indexed: 12/14/2022] Open
Abstract
MLL (mixed-lineage leukemia)-fusion genes induce the development of leukemia through deregulation of normal MLL target genes, such as HOXA9 and MEIS1. Both HOXA9 and MEIS1 are required for MLL-fusion gene-induced leukemogenesis. Co-expression of HOXA9 and MEIS1 induces acute myeloid leukemia (AML) similar to that seen in mice in which MLL-fusion genes are over-expressed. p27(kip1) (p27 hereafter), a negative regulator of the cell cycle, has also been defined as an MLL target, the expression of which is up-regulated in MLL leukemic cells (LCs). To investigate whether p27 plays a role in the pathogenesis of MLL-leukemia, we examined the effects of p27 deletion (p27(-/-)) on MLL-AF9 (MA9)-induced murine AML development. HOXA9/MEIS1 (H/M)-induced, p27 wild-type (p27(+/+)) and p27(-/-) AML were studied in parallel as controls. We found that LCs from both MA9-AML and H/M-AML can be separated into three fractions, a CD117(-)CD11b(hi) differentiated fraction as well as CD117(+)CD11b(hi) and CD117(+)CD11b(lo), two less differentiated fractions. The CD117(+)CD11b(lo) fraction, comprising only 1-3% of total LCs, expresses higher levels of early hematopoietic progenitor markers but lower levels of mature myeloid cell markers compared to other populations of LCs. p27 is expressed and is required for maintaining the quiescent and drug-resistant states of the CD117(+)CD11b(lo) fraction of MA9-LCs but not of H/M-LCs. p27 deletion significantly compromises the leukemogenic capacity of CD117(+)CD11b(lo) MA9-LCs by reducing the frequency of leukemic stem cells (LSCs) but does not do so in H/M-LCs. In addition, we found that p27 is highly expressed and required for cell cycle arrest in the CD117(-)CD11b(hi) fraction in both types of LCs. Furthermore, we found that c-Myc expression is required for maintaining LCs in an undifferentiated state independently of proliferation. We concluded that p27 represses the proliferation of LCs, which is specifically required for maintaining the quiescent and drug-resistant states of a small subset of MA9-LSCs in collaboration with the differentiation blockage function of c-Myc.
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Affiliation(s)
- Jun Zhang
- Department of Biology, College of Life and Environment Science, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, PR China; Oncology Institute, Cardinal Bernardin Cancer Center and Department of Pathology, Loyola University Chicago, Maywood, IL 60153, United States
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29
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Ng YP, Chen Y, Hu Y, Ip FCF, Ip NY. Olean-12-eno[2,3-c] [1,2,5]oxadiazol-28-oic acid (OEOA) induces G1 cell cycle arrest and differentiation in human leukemia cell lines. PLoS One 2013; 8:e63580. [PMID: 23696836 PMCID: PMC3656051 DOI: 10.1371/journal.pone.0063580] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 04/04/2013] [Indexed: 01/01/2023] Open
Abstract
Oleanolic acid (3β-hydroxy-olea-12-en-28-oic acid) is a natural pentacyclic triterpenoic acid found in many fruits, herbs and medicinal plants. In the past decade, increasing evidence has suggested that oleanolic acid exhibits inhibitory activities against different types of cancer including skin cancer and colon cancer, but not leukemia. We report here that a derivative of oleanolic acid, olean-12-eno[2,3-c] [1], [2], [5]oxadiazol-28-oic acid (designated OEOA) effectively blocks the proliferation of human leukemia cells. OEOA significantly reduces cell proliferation without inducing cell death in three types of leukemia cell lines, including K562, HEL and Jurket. Moreover, exposure of K562 cells to OEOA results in G1 cell cycle arrest, with a concomitant induction of cyclin-dependent kinase inhibitor p27 and downregulation of cyclins and Cdks that are essential for cell cycle progression. Interestingly, OEOA also enhances erythroid differentiation in K562 cells through suppressing the expression of Bcr-Abl and phosphorylation of Erk1/2. These findings identify a novel chemical entity for further development as therapeutics against leukemia.
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Affiliation(s)
- Yu Pong Ng
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yuewen Chen
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- JNU-HKUST Joint Lab, Ji-Nan University, Guangzhou, Guang Dong, China
| | - Yueqing Hu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Fanny C. F. Ip
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- JNU-HKUST Joint Lab, Ji-Nan University, Guangzhou, Guang Dong, China
| | - Nancy Y. Ip
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- JNU-HKUST Joint Lab, Ji-Nan University, Guangzhou, Guang Dong, China
- * E-mail:
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30
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MYC, a downstream target of BRD-NUT, is necessary and sufficient for the blockade of differentiation in NUT midline carcinoma. Oncogene 2013; 33:1736-1742. [PMID: 23604113 DOI: 10.1038/onc.2013.126] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 02/21/2013] [Accepted: 02/25/2013] [Indexed: 11/08/2022]
Abstract
NUT midline carcinoma (NMC) is an aggressive type of squamous cell carcinoma that is defined by the presence of BRD-NUT fusion oncogenes, which encode chimeric proteins that block differentiation and maintain tumor growth. BRD-NUT oncoproteins contain two bromodomains whose binding to acetylated histones is required for the blockade of differentiation in NMC, but the mechanisms by which BRD-NUT act remain uncertain. Here, we provide evidence that MYC is a key downstream target of BRD4-NUT. Expression profiling of NMCs shows that the set of genes whose expression is maintained by BRD4-NUT is highly enriched for MYC upregulated genes, and MYC and BRD4-NUT protein expression is strongly correlated in primary NMCs. More directly, we find that BRD4-NUT associates with the MYC promoter and is required to maintain MYC expression in NMC cell lines. Moreover, both siRNA knockdown of MYC and a dominant-negative form of MYC, omomyc, induce differentiation of NMC cells. Conversely, differentiation of NMC cells induced by knockdown of BRD4-NUT is abrogated by enforced expression of MYC. Together, these findings suggest that MYC is a downstream target of BRD4-NUT that is required for maintenance of NMC cells in an undifferentiated, proliferative state. Our findings support a model in which dysregulation of MYC by BRD-NUT fusion proteins has a central role in the pathogenesis of NMC.
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Shen LJ, Chen FY, Zhang Y, Cao LF, Kuang Y, Zhong M, Wang T, Zhong H. MYCN transgenic zebrafish model with the characterization of acute myeloid leukemia and altered hematopoiesis. PLoS One 2013; 8:e59070. [PMID: 23554972 PMCID: PMC3598662 DOI: 10.1371/journal.pone.0059070] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 02/11/2013] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Amplification of MYCN (N-Myc) oncogene has been reported as a frequent event and a poor prognostic marker in human acute myeloid leukemia (AML). The molecular mechanisms and transcriptional networks by which MYCN exerts its influence in AML are largely unknown. METHODOLOGY/PRINCIPAL FINDINGS We introduced murine MYCN gene into embryonic zebrafish through a heat-shock promoter and established the stable germline Tg(MYCN:HSE:EGFP) zebrafish. N-Myc downstream regulated gene 1 (NDRG1), negatively controlled by MYCN in human and functionally involved in neutrophil maturation, was significantly under-expressed in this model. Using peripheral blood smear detection, histological section and flow cytometric analysis of single cell suspension from kidney and spleen, we found that MYCN overexpression promoted cell proliferation, enhanced the repopulating activity of myeloid cells and the accumulation of immature hematopoietic blast cells. MYCN enhanced primitive hematopoiesis by upregulating scl and lmo2 expression and promoted myelopoiesis by inhibiting gata1 expression and inducing pu.1, mpo expression. Microarray analysis identified that cell cycle, glycolysis/gluconeogenesis, MAPK/Ras, and p53-mediated apoptosis pathways were upregulated. In addition, mismatch repair, transforming and growth factor β (TGFβ) were downregulated in MYCN-overexpressing blood cells (p<0.01). All of these signaling pathways are critical in the proliferation and malignant transformation of blood cells. CONCLUSION/SIGNIFICANCE The above results induced by overexpression of MYCN closely resemble the main aspects of human AML, suggesting that MYCN plays a role in the etiology of AML. MYCN reprograms hematopoietic cell fate by regulating NDRG1 and several lineage-specific hematopoietic transcription factors. Therefore, this MYCN transgenic zebrafish model facilitates dissection of MYCN-mediated signaling in vivo, and enables high-throughput scale screens to identify the potential therapeutic targets.
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Affiliation(s)
- Li-Jing Shen
- Department of Hematology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fang-Yuan Chen
- Department of Hematology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail:
| | - Yong Zhang
- Department of Hematology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lan-Fang Cao
- Department of Pediatric, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ying Kuang
- Shanghai Research Center for Biomodel Organisms, Shanghai, China
| | - Min Zhong
- Department of Hematology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ting Wang
- Department of Hematology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hua Zhong
- Department of Hematology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Delgado MD, Albajar M, Gomez-Casares MT, Batlle A, León J. MYC oncogene in myeloid neoplasias. Clin Transl Oncol 2012; 15:87-94. [PMID: 22911553 DOI: 10.1007/s12094-012-0926-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 07/24/2012] [Indexed: 01/13/2023]
Abstract
MYC is a transcription factor that regulates many critical genes for cell proliferation, differentiation, and biomass accumulation. MYC is one of the most prevalent oncogenes found to be altered in human cancer, being deregulated in about 50 % of tumors. Although MYC deregulation has been more frequently associated to lymphoma and lymphoblastic leukemia than to myeloid malignancies, a body of evidence has been gathered showing that MYC plays a relevant role in malignancies derived from the myeloid compartment. The myeloid leukemogenic activity of MYC has been demonstrated in different murine models. Not surprisingly, MYC has been found to be amplified or/and deregulated in the three major types of myeloid neoplasms: acute myeloid leukemia, myelodysplastic syndromes, and myeloproliferative neoplasms, including chronic myeloid leukemia. Here, we review the recent literature describing the involvement of MYC in myeloid tumors.
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Affiliation(s)
- M Dolores Delgado
- Group of Transcriptional Control and Cancer, Departamento de Biología Molecular, Facultad de Medicina, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, CSIC, SODERCAN, Avda Cardenal Herrera Oria s/n, 39011, Santander, Spain
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Valdés A, Simó C, Ibáñez C, Rocamora-Reverte L, Ferragut JA, García-Cañas V, Cifuentes A. Effect of dietary polyphenols on K562 leukemia cells: A Foodomics approach. Electrophoresis 2012; 33:2314-27. [DOI: 10.1002/elps.201200133] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | | | - Clara Ibáñez
- Laboratory of Foodomics; CIAL (CSIC); Madrid; Spain
| | - Lourdes Rocamora-Reverte
- Institute of Molecular and Cellular Biology; Miguel Hernández University; Elche, Alicante; Spain
| | - José Antonio Ferragut
- Institute of Molecular and Cellular Biology; Miguel Hernández University; Elche, Alicante; Spain
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Gómez-Casares MT, García-Alegria E, López-Jorge CE, Ferrándiz N, Blanco R, Alvarez S, Vaqué JP, Bretones G, Caraballo JM, Sánchez-Bailón P, Delgado MD, Martín-Perez J, Cigudosa JC, León J. MYC antagonizes the differentiation induced by imatinib in chronic myeloid leukemia cells through downregulation of p27(KIP1.). Oncogene 2012; 32:2239-46. [PMID: 22710719 DOI: 10.1038/onc.2012.246] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic myeloid leukemia (CML) progresses from a chronic to a blastic phase where the leukemic cells are proliferative and undifferentiated. The CML is nowadays successfully treated with BCR-ABL kinase inhibitors as imatinib and dasatinib. In the CML-derived K562 cell line, low concentrations of imatinib induce proliferative arrest and erythroid differentiation. We found that imatinib upregulated the cell cycle inhibitor p27(KIP1) (p27) in a time- and -concentration dependent manner, and that the extent of imatinib-mediated differentiation was severely decreased in cells with depleted p27. MYC (c-Myc) is a transcription factor frequently deregulated in human cancer. MYC is overexpressed in untreated CML and is associated to poor response to imatinib. Using K562 sublines with conditional MYC expression (induced by Zn(2+) or activated by 4-hydroxy-tamoxifen) we show that MYC prevented the erythroid differentiation induced by imatinib and dasatinib. The differentiation inhibition is not due to increased proliferation of MYC-expressing clones or enhanced apoptosis of differentiated cells. As p27 overexpression is reported to induce erythroid differentiation in K562, we explored the effect of MYC on imatinib-dependent induction of p27. We show that MYC abrogated the imatinib-induced upregulation of p27 concomitantly with the differentiation inhibition, suggesting that MYC inhibits differentiation by antagonizing the imatinib-mediated upregulation of p27. This effect occurs mainly by p27 protein destabilization. This was in part due to MYC-dependent induction of SKP2, a component of the ubiquitin ligase complex that targets p27 for degradation. The results suggest that, although MYC deregulation does not directly confer resistance to imatinib, it might be a factor that contributes to progression of CML through the inhibition of differentiation.
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Affiliation(s)
- M T Gómez-Casares
- Servicio de Hematología and Unidad de Investigación, Hospital Universitario Dr Negrín, Las Palmas, Spain
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Kruppel-like factor 1 (KLF1), KLF2, and Myc control a regulatory network essential for embryonic erythropoiesis. Mol Cell Biol 2012; 32:2628-44. [PMID: 22566683 DOI: 10.1128/mcb.00104-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Krüppel-like factor 1 (KLF1) and KLF2 positively regulate embryonic β-globin expression and have additional overlapping roles in embryonic (primitive) erythropoiesis. KLF1(-/-) KLF2(-/-) double knockout mice are anemic at embryonic day 10.5 (E10.5) and die by E11.5, in contrast to single knockouts. To investigate the combined roles of KLF1 and KLF2 in primitive erythropoiesis, expression profiling of E9.5 erythroid cells was performed. A limited number of genes had a significantly decreasing trend of expression in wild-type, KLF1(-/-), and KLF1(-/-) KLF2(-/-) mice. Among these, the gene for Myc (c-Myc) emerged as a central node in the most significant gene network. The expression of the Myc gene is synergistically regulated by KLF1 and KLF2, and both factors bind the Myc promoters. To characterize the role of Myc in primitive erythropoiesis, ablation was performed specifically in mouse embryonic proerythroblast cells. After E9.5, these embryos exhibit an arrest in the normal expansion of circulating red cells and develop anemia, analogous to KLF1(-/-) KLF2(-/-) embryos. In the absence of Myc, circulating erythroid cells do not show the normal increase in α- and β-like globin gene expression but, interestingly, have accelerated erythroid cell maturation between E9.5 and E11.5. This study reveals a novel regulatory network by which KLF1 and KLF2 regulate Myc to control the primitive erythropoietic program.
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Muñoz-Alonso MJ, Ceballos L, Bretones G, Frade P, León J, Gandarillas A. MYC accelerates p21CIP-induced megakaryocytic differentiation involving early mitosis arrest in leukemia cells. J Cell Physiol 2012; 227:2069-78. [DOI: 10.1002/jcp.22935] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Pippa R, Espinosa L, Gundem G, García-Escudero R, Dominguez A, Orlando S, Gallastegui E, Saiz C, Besson A, Pujol MJ, López-Bigas N, Paramio JM, Bigas A, Bachs O. p27Kip1 represses transcription by direct interaction with p130/E2F4 at the promoters of target genes. Oncogene 2011; 31:4207-20. [DOI: 10.1038/onc.2011.582] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Abstract
Hematopoiesis is a process capable of generating millions of cells every second, as distributed in many cell types. The process is regulated by a number of transcription factors that regulate the differentiation along the distinct lineages and dictate the genetic program that defines each mature phenotype. Myc was first discovered as the oncogene of avian leukemogenic retroviruses; it was later found translocated in human lymphoma. From then on, evidence accumulated showing that c-Myc is one of the transcription factors playing a major role in hematopoiesis. The study of genetically modified mice with overexpression or deletion of Myc has shown that c-Myc is required for the correct balance between self-renewal and differentiation of hematopoietic stem cells (HSCs). Enforced Myc expression in mice leads to reduced HSC pools owing to loss of self-renewal activity at the expense of increased proliferation of progenitor cells and differentiation. c-Myc deficiency consistently results in the accumulation of HSCs. Other models with conditional Myc deletion have demonstrated that different lineages of hematopoietic cells differ in their requirement for c-Myc to regulate their proliferation and differentiation. When transgenic mice overexpress c-Myc or N-Myc in mature cells from the lymphoid or myeloid lineages, the result is lymphoma or leukemia. In agreement, enforced expression of c-Myc blocks the differentiation in several leukemia-derived cell lines capable of differentiating in culture. Not surprising, MYC deregulation is recurrently found in many types of human lymphoma and leukemia. Whereas MYC is deregulated by translocation in Burkitt lymphoma and, less frequently, other types of lymphoma, MYC is frequently overexpressed in acute lymphoblastic and myeloid leukemia, through mechanisms unrelated to chromosomal translocation, and is often associated with disease progression.
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Affiliation(s)
- M Dolores Delgado
- Departamento de Biología Molecular, Facultad de Medicina and Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC, Santander, Spain
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Lüscher B. MAD1 and its life as a MYC antagonist: an update. Eur J Cell Biol 2011; 91:506-14. [PMID: 21917351 DOI: 10.1016/j.ejcb.2011.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Revised: 07/21/2011] [Accepted: 07/25/2011] [Indexed: 12/16/2022] Open
Abstract
The MYC/MAX/MAD network is of central importance for controlling cell physiology. The network is compiled of transcriptional regulators that form different heterodimers, which can either activate or repress the expression of target genes. Thus these proteins function as a molecular switch to control gene expression. MAD1, a member of this network, acts as a transcriptional repressor. It interacts with MAX to form the OFF position of the switch, antagonizing MYC/MAX complexes that define the ON position. MAD1 regulates cell proliferation and apoptosis through a number of target genes. In addition recent evidence indicates that the expression and activity of MAD1 are regulated at multiple levels. Here the recent developments are summarized, in comparison to MYC, of our understanding how the expression of the MAD1 gene and protein are controlled and what the functional consequences and downstream effectors of MAD1 are, which relay its activity as a transcriptional regulator.
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Affiliation(s)
- Bernhard Lüscher
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, 52057 Aachen, Germany.
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40
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Albajar M, Gómez-Casares MT, Llorca J, Mauleon I, Vaqué JP, Acosta JC, Bermúdez A, Donato N, Delgado MD, León J. MYC in chronic myeloid leukemia: induction of aberrant DNA synthesis and association with poor response to imatinib. Mol Cancer Res 2011; 9:564-76. [PMID: 21460180 DOI: 10.1158/1541-7786.mcr-10-0356] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Untreated chronic myeloid leukemia (CML) progresses from chronic phase to blastic crisis (BC). Increased genomic instability, deregulated proliferation, and loss of differentiation appear associated to BC, but the molecular alterations underlying the progression of CML are poorly characterized. MYC oncogene is frequently deregulated in human cancer, often associated with tumor progression. Genomic instability and induction of aberrant DNA replication are described as effects of MYC. In this report, we studied MYC activities in CML cell lines with conditional MYC expression with and without exposure to imatinib, the front-line drug in CML therapy. In cells with conditional MYC expression, MYC did not rescue the proliferation arrest mediated by imatinib but provoked aberrant DNA synthesis and accumulation of cells with 4C content. We studied MYC mRNA expression in 66 CML patients at different phases of the disease, and we found that MYC expression was higher in CML patients at diagnosis than control bone marrows or in patients responding to imatinib. Further, high MYC levels at diagnosis correlated with a poor response to imatinib. MYC expression did not directly correlate with BCR-ABL levels in patients treated with imatinib. Overall our study suggests that, as in other tumor models, MYC-induced aberrant DNA synthesis in CML cells is consistent with MYC overexpression in untreated CML patients and nonresponding patients and supports a role for MYC in CML progression, possibly through promotion of genomic instability.
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Affiliation(s)
- Marta Albajar
- Departamento de Biología Molecular, Facultad de Medicina, Instituto de Biomedicina y Biotecnología de Cantabria, Avda Cardenal Herrera Oria s/n, 39011 Santander, Spain
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Role of helix-loop-helix proteins during differentiation of erythroid cells. Mol Cell Biol 2011; 31:1332-43. [PMID: 21282467 DOI: 10.1128/mcb.01186-10] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Helix-loop-helix (HLH) proteins play a profound role in the process of development and cellular differentiation. Among the HLH proteins expressed in differentiating erythroid cells are the ubiquitous proteins Myc, USF1, USF2, and TFII-I, as well as the hematopoiesis-specific transcription factor Tal1/SCL. All of these HLH proteins exhibit distinct functions during the differentiation of erythroid cells. For example, Myc stimulates the proliferation of erythroid progenitor cells, while the USF proteins and Tal1 regulate genes that specify the differentiated phenotype. This minireview summarizes the known activities of Myc, USF, TFII-I, and Tal11/SCL and discusses how they may function sequentially, cooperatively, or antagonistically in regulating expression programs during the differentiation of erythroid cells.
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Bretones G, Acosta JC, Caraballo JM, Ferrándiz N, Gómez-Casares MT, Albajar M, Blanco R, Ruiz P, Hung WC, Albero MP, Perez-Roger I, León J. SKP2 oncogene is a direct MYC target gene and MYC down-regulates p27(KIP1) through SKP2 in human leukemia cells. J Biol Chem 2011; 286:9815-25. [PMID: 21245140 DOI: 10.1074/jbc.m110.165977] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SKP2 is the ubiquitin ligase subunit that targets p27(KIP1) (p27) for degradation. SKP2 is induced in the G(1)-S transit of the cell cycle, is frequently overexpressed in human cancer, and displays transformation activity in experimental models. Here we show that MYC induces SKP2 expression at the mRNA and protein levels in human myeloid leukemia K562 cells with conditional MYC expression. Importantly, in these systems, induction of MYC did not activate cell proliferation, ruling out SKP2 up-regulation as a consequence of cell cycle entry. MYC-dependent SKP2 expression was also detected in other cell types such as lymphoid, fibroblastic, and epithelial cell lines. MYC induced SKP2 mRNA expression in the absence of protein synthesis and activated the SKP2 promoter in luciferase reporter assays. With chromatin immunoprecipitation assays, MYC was detected bound to a region of human SKP2 gene promoter that includes E-boxes. The K562 cell line derives from human chronic myeloid leukemia. In a cohort of chronic myeloid leukemia bone marrow samples, we found a correlation between MYC and SKP2 mRNA levels. Analysis of cancer expression databases also indicated a correlation between MYC and SKP2 expression in lymphoma. Finally, MYC-induced SKP2 expression resulted in a decrease in p27 protein in K562 cells. Moreover, silencing of SKP2 abrogated the MYC-mediated down-regulation of p27. Our data show that SKP2 is a direct MYC target gene and that MYC-mediated SKP2 induction leads to reduced p27 levels. The results suggest the induction of SKP2 oncogene as a new mechanism for MYC-dependent transformation.
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Affiliation(s)
- Gabriel Bretones
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, Consejo Superior de Investigaciones Científicas, SODERCAN (Sociedad para el Desarrollo de Cantabria), 39011 Santander, Spain
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Jayapal SR, Lee KL, Ji P, Kaldis P, Lim B, Lodish HF. Down-regulation of Myc is essential for terminal erythroid maturation. J Biol Chem 2010; 285:40252-65. [PMID: 20940306 PMCID: PMC3001006 DOI: 10.1074/jbc.m110.181073] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Indexed: 02/06/2023] Open
Abstract
Terminal differentiation of mammalian erythroid progenitors involves 4-5 cell divisions and induction of many erythroid important genes followed by chromatin and nuclear condensation and enucleation. The protein levels of c-Myc (Myc) are reduced dramatically during late stage erythroid maturation, coinciding with cell cycle arrest in G(1) phase and enucleation, suggesting possible roles for c-Myc in either or both of these processes. Here we demonstrate that ectopic Myc expression affects terminal erythroid maturation in a dose-dependent manner. Expression of Myc at physiological levels did not affect erythroid differentiation or cell cycle shutdown but specifically blocked erythroid nuclear condensation and enucleation. Continued Myc expression prevented deacetylation of several lysine residues in histones H3 and H4 that are normally deacetylated during erythroid maturation. The histone acetyltransferase Gcn5 was up-regulated by Myc, and ectopic Gcn5 expression partially blocked enucleation and inhibited the late stage erythroid nuclear condensation and histone deacetylation. When overexpressed at levels higher than the physiological range, Myc blocked erythroid differentiation, and the cells continued to proliferate in cytokine-free, serum-containing culture medium with an early erythroblast morphology. Gene expression analysis demonstrated the dysregulation of erythropoietin signaling pathway and the up-regulation of several positive regulators of G(1)-S cell cycle checkpoint by supraphysiological levels of Myc. These results reveal an important dose-dependent function of Myc in regulating terminal maturation in mammalian erythroid cells.
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Affiliation(s)
- Senthil Raja Jayapal
- From the Computation and Systems Biology, Singapore-Massachusetts Institute of Technology Alliance, 4 Engineering Drive 3, Singapore 117576
- the Genome Institute of Singapore, 60 Biopolis Street, Genome, Singapore 138672
| | - Kian Leong Lee
- the Cancer Science Institute of Singapore, National University of Singapore, Centre for Life Sciences, 28 Medical Drive, Singapore 117456
| | - Peng Ji
- the Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
| | - Philipp Kaldis
- the Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, and
| | - Bing Lim
- From the Computation and Systems Biology, Singapore-Massachusetts Institute of Technology Alliance, 4 Engineering Drive 3, Singapore 117576
- the Genome Institute of Singapore, 60 Biopolis Street, Genome, Singapore 138672
- the Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Harvey F. Lodish
- From the Computation and Systems Biology, Singapore-Massachusetts Institute of Technology Alliance, 4 Engineering Drive 3, Singapore 117576
- the Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
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Abstract
The enigmatic MYC oncogene, which participates broadly in cancers, revealed itself recently as the maestro of an unfolding symphony of cell growth, proliferation, death, and metabolism. The study of MYC is arguably most challenging to its students but at the same time exhilarating when MYC reveals its deeply held secrets. It is the excitement of our richer understanding of MYC that is captured in each review of this special issue of Genes & Cancer. Collectively, our deeper understanding of MYC reveals that it is a symphony conductor, controlling a large orchestra of target genes. Although MYC controls many orchestra sections, which are necessary but not sufficient for Myc function, ribosome biogenesis stands out to reveal Myc's primordial function particularly in fruit flies. Because ribosome biogenesis and the associated translational machinery are bioenergetically demanding, Myc's other target genes involved in energy metabolism must be coupled with energy demand to ensure that cells can replicate their genome and produce daughter cells. Normal cells have feedback loops that diminish MYC expression when nutrients are scarce. On the other hand, when deregulated Myc transforms cells, their constitutive bioenergetic demand can trigger cell death when energy is unavailable. This special issue captures the unfolding symphony of MYC-mediated tumorigenesis through reviews that span from a timeline of MYC research, fundamental understanding of how the MYC gene itself is regulated, the study of Myc in model organisms, Myc function, and target genes to translational research in search of new therapeutic modalities for the treatment of cancer.
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Affiliation(s)
- Chi V Dang
- Division of Hematology, Department of Medicine, and Departments of Cell Biology, Oncology, Pathology, and Molecular Biology & Genetics, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Tatard VM, Xiang C, Biegel JA, Dahmane N. ZNF238 is expressed in postmitotic brain cells and inhibits brain tumor growth. Cancer Res 2010; 70:1236-46. [PMID: 20103640 DOI: 10.1158/0008-5472.can-09-2249] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Brain tumors such as medulloblastoma (MB) and glioblastoma multiforme (GBM) can derive from neural precursors. For instance, many MBs are thought to arise from the uncontrolled proliferation of cerebellar granule neuron precursors (GNP). GNPs normally proliferate in early postnatal stages in mice but then they become postmitotic and differentiate into granule neurons. The proliferation of neural precursors, GNPs, as well as at least subsets of GBM and MB depends on Hedgehog signaling. However, the gene functions that are lost or suppressed in brain tumors and that normally promote the proliferation arrest and differentiation of precursors remain unclear. Here we have identified a member of the BTB-POZ and zinc finger family, ZNF238, as a factor highly expressed in postmitotic GNPs and differentiated neurons. In contrast, proliferating GNPs as well as MB and GBM express low or no ZNF238. Functionally, inhibition of ZNF238 expression in mouse GNPs decreases the expression of the neuronal differentiation markers MAP2 and NeuN and downregulates the expression of the cell cycle arrest protein p27, a regulator of GNP differentiation. Conversely, reinstating ZNF238 expression in MB and GBM cells drastically decreases their proliferation and promotes cell death. It also downregulates cyclin D1 while increasing MAP2 and p27 protein levels. Importantly, ZNF238 antagonizes MB and GBM tumor growth in vivo in xenografts. We propose that the antiproliferative functions of ZNF238 in normal GNPs and possibly other neural precursors counteract brain tumor formation. ZNF238 is thus a novel brain tumor suppressor and its reactivation in tumors could open a novel anticancer strategy.
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Laurent B, Randrianarison-Huetz V, Kadri Z, Roméo PH, Porteu F, Duménil D. Gfi-1B promoter remains associated with active chromatin marks throughout erythroid differentiation of human primary progenitor cells. Stem Cells 2009; 27:2153-62. [PMID: 19522008 PMCID: PMC2962905 DOI: 10.1002/stem.151] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Growth Factor Independent-1B (Gfi-1B) is a transcriptional repressor that plays critical roles in the control of erythropoiesis and megakaryopoiesis. Gfi-1B expression was described to be repressed by an autoregulatory feedback control loop. Here, we show that Gfi-1 transcription is positively regulated early after induction of erythroid differentiation and remains highly active to late erythroblasts. Using chromatin immunoprecipitation assays in CD34+ cells from human cord blood, we found that Gfi-1 and GATA-2 in immature progenitors and then Gfi-1B and GATA-1 in erythroblasts are bound to the Gfi-1B promoter as well as to the promoter of c-myc, a known Gfi-1B target gene. Surprisingly, this Gfi-1/GATA-2–Gfi-1B/GATA-1 switch observed at erythroblast stages is associated to an increase in the Gfi-1B transcription whereas it triggers repression of c-myc transcription. Accordingly, analysis of chromatin modification patterns shows that HDAC, CoREST, and LSD1 are recruited to the c-myc promoter leading to appearance of repressive chromatin marks. In contrast, the Gfi-1B promoter remains associated with a transcriptionally active chromatin configuration as highlighted by an increase in histone H3 acetylation and concomitant release of the LSD1 and CoREST corepressors. The repressive function of Gfi-1B therefore depends on the nature of the proteins recruited to the target gene promoters and on chromatin modifications. We conclude that Gfi-1B behaves as a lineage-affiliated gene with an open chromatin configuration in multipotent progenitors and sustained activation as cells progress throughout erythroid differentiation.
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Affiliation(s)
- Benoît Laurent
- Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (UMR 8104), Paris, France
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Lu H, Li Y, Shu M, Tang J, Huang Y, Zhou Y, Liang Y, Yan G. Hypoxia-inducible factor-1α blocks differentiation of malignant gliomas. FEBS J 2009; 276:7291-304. [DOI: 10.1111/j.1742-4658.2009.07441.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Microarray study of mechanism of trichostatin a inducing apoptosis of Molt-4 cells. ACTA ACUST UNITED AC 2009; 29:445-50. [DOI: 10.1007/s11596-009-0411-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Indexed: 12/26/2022]
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