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Zhou Q, Yu B, Anderson C, Huang ZP, Hanus J, Zhang W, Han Y, Bhattacharjee PS, Srinivasan S, Zhang K, Wang DZ, Wang S. LncEGFL7OS regulates human angiogenesis by interacting with MAX at the EGFL7/miR-126 locus. eLife 2019; 8:e40470. [PMID: 30741632 PMCID: PMC6370342 DOI: 10.7554/elife.40470] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 01/11/2019] [Indexed: 01/02/2023] Open
Abstract
In an effort to identify human endothelial cell (EC)-enriched lncRNAs,~500 lncRNAs were shown to be highly restricted in primary human ECs. Among them, lncEGFL7OS, located in the opposite strand of the EGFL7/miR-126 gene, is regulated by ETS factors through a bidirectional promoter in ECs. It is enriched in highly vascularized human tissues, and upregulated in the hearts of dilated cardiomyopathy patients. LncEGFL7OS silencing impairs angiogenesis as shown by EC/fibroblast co-culture, in vitro/in vivo and ex vivo human choroid sprouting angiogenesis assays, while lncEGFL7OS overexpression has the opposite function. Mechanistically, lncEGFL7OS is required for MAPK and AKT pathway activation by regulating EGFL7/miR-126 expression. MAX protein was identified as a lncEGFL7OS-interacting protein that functions to regulate histone acetylation in the EGFL7/miR-126 promoter/enhancer. CRISPR-mediated targeting of EGLF7/miR-126/lncEGFL7OS locus inhibits angiogenesis, inciting therapeutic potential of targeting this locus. Our study establishes lncEGFL7OS as a human/primate-specific EC-restricted lncRNA critical for human angiogenesis.
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Affiliation(s)
- Qinbo Zhou
- Department of Cell and Molecular BiologyTulane UniversityNew OrleansUnited States
| | - Bo Yu
- Department of Cell and Molecular BiologyTulane UniversityNew OrleansUnited States
| | - Chastain Anderson
- Department of Cell and Molecular BiologyTulane UniversityNew OrleansUnited States
| | - Zhan-Peng Huang
- Department of CardiologyBoston Children’s Hospital, Harvard Medical SchoolBostonUnited States
| | - Jakub Hanus
- Department of Cell and Molecular BiologyTulane UniversityNew OrleansUnited States
| | - Wensheng Zhang
- Department of Computer ScienceXavier UniversityNew OrleansUnited States
| | - Yu Han
- Aab Cardiovascular Research InstituteUniversity of Rochester School of Medicine and DentistryRochesterUnited States
| | | | - Sathish Srinivasan
- Cardiovascular Biology Research ProgramOklahoma Medical Research FoundationOklahomaUnited States
| | - Kun Zhang
- Department of Computer ScienceXavier UniversityNew OrleansUnited States
| | - Da-zhi Wang
- Department of CardiologyBoston Children’s Hospital, Harvard Medical SchoolBostonUnited States
| | - Shusheng Wang
- Department of Cell and Molecular BiologyTulane UniversityNew OrleansUnited States
- Department of OphthalmologyTulane UniversityNew OrleansUnited States
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The Nutrient-Sensing Hexosamine Biosynthetic Pathway as the Hub of Cancer Metabolic Rewiring. Cells 2018; 7:cells7060053. [PMID: 29865240 PMCID: PMC6025041 DOI: 10.3390/cells7060053] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 05/29/2018] [Accepted: 05/31/2018] [Indexed: 12/12/2022] Open
Abstract
Alterations in glucose and glutamine utilizing pathways and in fatty acid metabolism are currently considered the most significant and prevalent metabolic changes observed in almost all types of tumors. Glucose, glutamine and fatty acids are the substrates for the hexosamine biosynthetic pathway (HBP). This metabolic pathway generates the “sensing molecule” UDP-N-Acetylglucosamine (UDP-GlcNAc). UDP-GlcNAc is the substrate for the enzymes involved in protein N- and O-glycosylation, two important post-translational modifications (PTMs) identified in several proteins localized in the extracellular space, on the cell membrane and in the cytoplasm, nucleus and mitochondria. Since protein glycosylation controls several key aspects of cell physiology, aberrant protein glycosylation has been associated with different human diseases, including cancer. Here we review recent evidence indicating the tight association between the HBP flux and cell metabolism, with particular emphasis on the post-transcriptional and transcriptional mechanisms regulated by the HBP that may cause the metabolic rewiring observed in cancer. We describe the implications of both protein O- and N-glycosylation in cancer cell metabolism and bioenergetics; focusing our attention on the effect of these PTMs on nutrient transport and on the transcriptional regulation and function of cancer-specific metabolic pathways.
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Yu Z, Li T, Wang C, Deng S, Zhang B, Huo X, Zhang B, Wang X, Zhong Y, Ma X. Gamabufotalin triggers c-Myc degradation via induction of WWP2 in multiple myeloma cells. Oncotarget 2017; 7:15725-37. [PMID: 26894970 PMCID: PMC4941272 DOI: 10.18632/oncotarget.7398] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 02/05/2016] [Indexed: 12/14/2022] Open
Abstract
Deciding appropriate therapy for multiple myeloma (MM) is challenging because of the occurrence of multiple chromosomal changes and the fatal nature of the disease. In the current study, gamabufotalin (GBT) was isolated from toad venom, and its tumor-specific cytotoxicity was investigated in human MM cells. We found GBT inhibited cell growth and induced apoptosis with the IC50 values <50 nM. Mechanistic studies using functional approaches identified GBT as an inhibitor of c-Myc. Further analysis showed that GBT especially evoked the ubiquitination and degradation of c-Myc protein, thereby globally repressing the expression of c-Myc target genes. GBT treatment inhibited ERK and AKT signals, while stimulating the activation of JNK cascade. An E3 ubiquitin-protein ligase, WWP2, was upregulated following JNK activation and played an important role in c-Myc ubiquitination and degradation through direct protein-protein interaction. The antitumor effect of GBT was validated in a xenograft mouse model and the suppression of MM-induced osteolysis was verified in a SCID-hu model in vivo. Taken together, our study identified the potential of GBT as a promising therapeutic agent in the treatment of MM.
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Affiliation(s)
- Zhenlong Yu
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Tao Li
- Department of Biology, College of Chemistry and Life Sciences, Zhejiang Normal University, Zhejiang, China
| | - Chao Wang
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Sa Deng
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Baojing Zhang
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Xiaokui Huo
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Bo Zhang
- Department of Neurosurgery, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Xiaobo Wang
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Yuping Zhong
- Department of Hematology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Xiaochi Ma
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
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4
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Noubissi FK, Nikiforov MA, Colburn N, Spiegelman VS. Transcriptional Regulation of CRD-BP by c-myc: Implications for c-myc Functions. Genes Cancer 2011; 1:1074-82. [PMID: 21779431 DOI: 10.1177/1947601910395581] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 11/19/2010] [Accepted: 11/29/2010] [Indexed: 11/15/2022] Open
Abstract
The coding region determinant binding protein, CRD-BP, is a multifunctional RNA binding protein involved in different processes such as mRNA turnover, translation control, and localization. It is mostly expressed in fetal and neonatal tissues, where it regulates many transcripts essential for normal embryonic development. CRD-BP is scarce or absent in normal adult tissues but reactivated and/or overexpressed in various neoplastic and preneoplastic tumors and in most cell lines. Its expression has been associated with the most aggressive form of some cancers. CRD-BP is an important regulator of different genes including a variety of oncogenes or proto-oncogenes (c-myc, β-TrCP1, GLI1, etc.). Regulation of CRD-BP expression is critical for proper control of its targets as its overexpression may play an important role in abnormal cell proliferation, suppression of apoptosis, invasion, and metastasis. Molecular bases of the regulatory mechanisms governing CRD-BP expression are still not completely elucidated. In this article, we have identified c-myc as a novel transcriptional regulator of CRD-BP. We show that c-myc binds to CRD-BP promoter and induces its transcription. This induction of CRD-BP expression contributes to the role of c-myc in the regulation of translation, increase in cell size, and acceleration of cell cycle progression via a mechanism involving upregulation of β-TrCP1 levels and activities and accelerated degradation of PDCD4.
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Affiliation(s)
- Felicite K Noubissi
- Department of Dermatology and Paul P. Carbone Comprehensive Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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Vallespinós M, Fernández D, Rodríguez L, Alvaro-Blanco J, Baena E, Ortiz M, Dukovska D, Martínez D, Rojas A, Campanero MR, Moreno de Alborán I. B Lymphocyte Commitment Program Is Driven by the Proto-Oncogene c-myc. THE JOURNAL OF IMMUNOLOGY 2011; 186:6726-36. [DOI: 10.4049/jimmunol.1002753] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Pfister A, Osman A. The VKORC1 promoter is occupied by c-Myc transcription factor in HepG2 cells. Thromb Res 2010; 126:e150-1. [PMID: 20163834 DOI: 10.1016/j.thromres.2010.01.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 01/27/2010] [Accepted: 01/29/2010] [Indexed: 10/19/2022]
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Rimpi S, Nilsson JA. Metabolic enzymes regulated by the Myc oncogene are possible targets for chemotherapy or chemoprevention. Biochem Soc Trans 2007; 35:305-10. [PMID: 17371266 DOI: 10.1042/bst0350305] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The Myc oncogenes are dysregulated in 70% of human cancers. They encode transcription factors that bind to E-box sequences in DNA, driving the expression of a vast amount of target genes. The biological outcome is enhanced proliferation (which is counteracted by apoptosis), angiogenesis and cancer. Based on the biological effects of Myc overexpression it was originally assumed that the important Myc target genes are those encoding components of the cell cycle machinery. Recent work has challenged this notion and indicates that Myc target genes encoding metabolic enzymes deserve attention, as they may be critical arbiters of Myc in cancer. Thus targeting metabolic enzymes encoded by Myc-target genes may provide a new means to treat cancer that have arisen in response to deregulated Myc oncogenes.
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Affiliation(s)
- S Rimpi
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden
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8
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Barsyte-Lovejoy D, Mao DYL, Penn LZ. c-Myc represses the proximal promoters of GADD45a and GADD153 by a post-RNA polymerase II recruitment mechanism. Oncogene 2004; 23:3481-6. [PMID: 15021909 DOI: 10.1038/sj.onc.1207487] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The c-Myc cellular oncogene has diverse activities, including transformation, proliferation, and apoptosis. These activities are dependent on the ability of c-Myc to regulate gene transcription. c-Myc downregulates the GADD45a and GADD153 (DDTI3) genes that are induced in response to genotoxic stresses and that encode protein products with antiproliferative activities. We show that c-Myc represses the expression of GADD45a and GADD153 in response to thapsigargin, a nongenotoxic stress, as well as other endoplasmic reticulum (ER) stress agents. c-Myc represses both the basal expression and the magnitude of ER stress induction of GADD gene transcription. This repression requires the minimal promoter region of GADD45a and GADD153 and is not dependent on the ER stress element or p53-binding sites in the regulatory regions of these genes. Further analysis by chromatin immunoprecipitation shows that c-Myc binds to the minimal promoter region of GADD45a and GADD153 in vivo. c-Myc-associated protein X (Max) is also bound to both GADD gene promoters, whereas c-Myc interacting zinc-finger protein 1 (Miz-1) is bound to the GADD153, but not GADD45a, promoter. RNA polymerase II (RNAPII) is recruited to the GADD gene promoters in the presence and absence of c-Myc, which suggests that c-Myc represses these genes through a post-RNAPII recruitment mechanism.
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Affiliation(s)
- Dalia Barsyte-Lovejoy
- Division of Cellular and Molecular Biology, Ontario Cancer Institute/Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada M5G 2M9
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Blume SW, Meng Z, Shrestha K, Snyder RC, Emanuel PD. The 5'-untranslated RNA of the human dhfr minor transcript alters transcription pre-initiation complex assembly at the major (core) promoter. J Cell Biochem 2003; 88:165-80. [PMID: 12461786 DOI: 10.1002/jcb.10326] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The human dhfr minor transcript is distinguished from the predominant dhfr mRNA by an approximately 400 nucleotide extension of the 5'-untranslated region, which corresponds to the major (core) promoter DNA (its template). Based on its unusual sequence composition, we hypothesized that the minor transcript 5'-UTR might be capable of altering transcription pre-initiation complex assembly at the core promoter, through direct interactions of the RNA with specific regulatory polypeptides or the promoter DNA itself. We found that the minor transcript 5'-UTR selectively sequesters transcription factor Sp3, and to a lesser extent Sp1, preventing their binding to the dhfr core promoter. This allows a third putative transcriptional regulatory protein, which is relatively resistant to sequestration by the minor transcript RNA, the opportunity to bind the dhfr core promoter. The selective sequestration of Sp3 > Sp1 by the minor transcript 5'-UTR involves an altered conformation of the RNA, and a structural domain of the protein distinct from that required for binding to DNA. As a consequence, the minor transcript 5'-UTR inhibits transcription from the core promoter in vitro (in trans) in a concentration-dependent manner. These results suggest that the dhfr minor transcript may function in vivo (in cis) to regulate the transcriptional activity of the major (core) promoter.
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Affiliation(s)
- Scott W Blume
- Department of Medicine and Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
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10
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Abstract
The activated product of the myc oncogene deregulates both cell growth and death check points and, in a permissive environment, rapidly accelerates the affected clone through the carcinogenic process. Advances in understanding the molecular mechanism of Myc action are highlighted in this review. With the revolutionary developments in molecular diagnostic technology, we have witnessed an unprecedented advance in detecting activated myc in its deregulated, oncogenic form in primary human cancers. These improvements provide new opportunities to appreciate the tumor subtypes harboring deregulated Myc expression, to identify the essential cooperating lesions, and to realize the therapeutic potential of targeting Myc. Knowledge of both the breadth and depth of the numerous biological activities controlled by Myc has also been an area of progress. Myc is a multifunctional protein that can regulate cell cycle, cell growth, differentiation, apoptosis, transformation, genomic instability, and angiogenesis. New insights into Myc's role in regulating these diverse activities are discussed. In addition, breakthroughs in understanding Myc as a regulator of gene transcription have revealed multiple mechanisms of Myc activation and repression of target genes. Moreover, the number of reported Myc regulated genes has expanded in the past few years, inspiring a need to focus on classifying and segregating bona fide targets. Finally, the identity of Myc-binding proteins has been difficult, yet has exploded in the past few years with a plethora of novel interactors. Their characterization and potential impact on Myc function are discussed. The rapidity and magnitude of recent progress in the Myc field strongly suggests that this marvelously complex molecule will soon be unmasked.
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Affiliation(s)
- Sara K Oster
- Division of Cellular and Molecular Biology, Ontario Cancer Institute, Princess Margaret Hospital, University of Toronto
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11
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Kuschak TI, Kuschak BC, Taylor CL, Wright JA, Wiener F, Mai S. c-Myc initiates illegitimate replication of the ribonucleotide reductase R2 gene. Oncogene 2002; 21:909-20. [PMID: 11840336 DOI: 10.1038/sj.onc.1205145] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2001] [Revised: 10/19/2001] [Accepted: 10/31/2001] [Indexed: 11/09/2022]
Abstract
The mechanisms through which the oncoprotein c-Myc initiates locus-specific gene amplification are not understood. When analysing the initiation mechanism of c-Myc-dependent amplification of the mouse ribonucleotide reductase R2 (R2) gene, we observe c-Myc-dependent initiation of illegitimate DNA replication of the R2 gene. We demonstrate multiple simultaneous c-Myc-induced R2 replication forks, whereas R2 normally replicates with a single fork. In contrast, cyclin C replicates with only a single replication fork irrespective of c-Myc deregulation. In addition to de novo replication forks, c-Myc also initiates bi-allelic replication of R2, abrogating its normal mono-allelic replication pattern. Moreover, several chromosomal regions also display c-Myc-induced illegitimate replication profiles. Thus, c-Myc can act as an illegitimate replication-licensing factor that promotes de novo replication initiation and illegitimate replication timing that adversely impacts upon genomic stability.
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Affiliation(s)
- T I Kuschak
- Department of Microbiology, Manitoba Institute of Cell Biology, The University of Manitoba, 675 McDermot Ave., Winnipeg, MB, R3E 0V9, Canada
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12
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Abstract
c-MYC is the prototype for oncogene activation by chromosomal translocation. In contrast to the tightly regulated expression of c-myc in normal cells, c-myc is frequently deregulated in human cancers. Herein, aspects of c-myc gene activation and the function of the c-Myc protein are reviewed. The c-myc gene produces an oncogenic transcription factor that affects diverse cellular processes involved in cell growth, cell proliferation, apoptosis and cellular metabolism. Complete removal of c-myc results in slowed cell growth and proliferation, suggesting that while c-myc is not required for cell proliferation, it acts as an integrator and accelerator of cellular metabolism and proliferation.
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Affiliation(s)
- L M Boxer
- Division of Hematology, Department of Medicine, Stanford University School of Medicine, Stanford, California CA 94305, USA
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Schuhmacher M, Kohlhuber F, Hölzel M, Kaiser C, Burtscher H, Jarsch M, Bornkamm GW, Laux G, Polack A, Weidle UH, Eick D. The transcriptional program of a human B cell line in response to Myc. Nucleic Acids Res 2001; 29:397-406. [PMID: 11139609 PMCID: PMC29676 DOI: 10.1093/nar/29.2.397] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The proto-oncogene c-myc (myc) encodes a transcription factor (Myc) that promotes growth, proliferation and apoptosis. Myc has been suggested to induce these effects by induction/repression of downstream genes. Here we report the identification of potential Myc target genes in a human B cell line that grows and proliferates depending on conditional myc expression. Oligonucleotide microarrays were applied to identify downstream genes of Myc at the level of cytoplasmic mRNA. In addition, we identified potential Myc target genes in nuclear run-on experiments by changes in their transcription rate. The identified genes belong to gene classes whose products are involved in amino acid/protein synthesis, lipid metabolism, protein turnover/folding, nucleotide/DNA synthesis, transport, nucleolus function/RNA binding, transcription and splicing, oxidative stress and signal transduction. The identified targets support our current view that myc acts as a master gene for growth control and increases transcription of a large variety of genes.
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Affiliation(s)
- M Schuhmacher
- GSF Research Centre, Institute of Clinical Molecular Biology, Marchioninistrasse 25, D-81377 Munich, Germany
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Abstract
The diagnostic category of Burkitt's lymphoma encompasses a closely related group of aggressive B-cell tumors that includes sporadic, endemic, and human immunodeficiency virus-associated subtypes. All subtypes are characterized by chromosomal rearrangements involving the c-myc proto-oncogene that lead to its inappropriate expression. This review focuses on the roles of c-myc dysregulation and Epstein-Barr virus infection in Burkitt's lymphoma. Although the normal function of c-Myc remains enigmatic, recent data indicate that it has a central role in several fundamental aspects of cellular biology, including proliferation, differentiation, metabolism, apoptosis, and telomere maintenance. We discuss new insights into the molecular mechanisms of these c-Myc activities and their potential relevance to the pathogenesis of Burkitt's lymphoma and speculate on the role of Epstein-Barr virus.
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Affiliation(s)
- J L Hecht
- Departments of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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15
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Dang CV, Resar LM, Emison E, Kim S, Li Q, Prescott JE, Wonsey D, Zeller K. Function of the c-Myc oncogenic transcription factor. Exp Cell Res 1999; 253:63-77. [PMID: 10579912 DOI: 10.1006/excr.1999.4686] [Citation(s) in RCA: 277] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The c-myc gene and the expression of the c-Myc protein are frequently altered in human cancers. The c-myc gene encodes the transcription factor c-Myc, which heterodimerizes with a partner protein, termed Max, to regulate gene expression. Max also heterodimerizes with the Mad family of proteins to repress transcription, antagonize c-Myc, and promote cellular differentiation. The constitutive activation of c-myc expression is key to the genesis of many cancers, and hence the understanding of c-Myc function depends on our understanding of its target genes. In this review, we attempt to place the putative target genes of c-Myc in the context of c-Myc-mediated phenotypes. From this perspective, c-Myc emerges as an oncogenic transcription factor that integrates the cell cycle machinery with cell adhesion, cellular metabolism, and the apoptotic pathways.
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Affiliation(s)
- C V Dang
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA.
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16
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Kuschak TI, Taylor C, McMillan-Ward E, Israels S, Henderson DW, Mushinski JF, Wright JA, Mai S. The ribonucleotide reductase R2 gene is a non-transcribed target of c-Myc-induced genomic instability. Gene 1999; 238:351-65. [PMID: 10570963 DOI: 10.1016/s0378-1119(99)00341-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The c-Myc oncoprotein is highly expressed in malignant cells of many cell types, but the mechanism by which it contributes to the transformation process is not fully understood. Here, we show for the first time that constitutive or activated overexpression of the c-myc gene in cultured mouse B lymphocytes is followed by chromosomal and extrachromosomal amplification as well as rearrangement of the ribonucleotide reductase R2 gene locus. Electron micrographs and fluorescent in situ hybridization (FISH) demonstrate the c-Myc-dependent generation of extrachromosomal elements, some of which contain R2 sequences. However, unlike other genes that have been shown to be targets of c-Myc-dependent genomic instability, amplification of the R2 gene is not associated with alterations in R2 mRNA or protein expression. These data suggest that c-Myc-dependent genomic instability involves a greater number of genes than previously anticipated, but not all of the genes that are amplified in this system are transcriptionally upregulated.
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Affiliation(s)
- T I Kuschak
- Manitoba Institute of Cell Biology and the Manitoba Cancer Treatment and Research Foundation, Winnipeg, Canada
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17
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Mai S, Hanley-Hyde J, Rainey GJ, Kuschak TI, Paul JT, Littlewood TD, Mischak H, Stevens LM, Henderson DW, Mushinski JF. Chromosomal and extrachromosomal instability of the cyclin D2 gene is induced by Myc overexpression. Neoplasia 1999; 1:241-52. [PMID: 10935479 PMCID: PMC1508077 DOI: 10.1038/sj.neo.7900030] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/1999] [Accepted: 05/25/1999] [Indexed: 11/08/2022]
Abstract
We examined the expression of cyclins D1, D2, D3, and E in mouse B-lymphocytic tumors. Cyclin D2 mRNA was consistently elevated in plasmacytomas, which characteristically contain Myc-activating chromosome translocations and constitutive c-Myc mRNA and protein expression. We examined the nature of cyclin D2 overexpression in plasmacytomas and other tumors. Human and mouse tumor cell lines that exhibited c-Myc dysregulation displayed instability of the cyclin D2 gene, detected by Southern blot, fluorescent in situ hybridization (FISH), and in extrachromosomal preparations (Hirt extracts). Cyclin D2 instability was not seen in cells with low levels of c-Myc protein. To unequivocally demonstrate a role of c-Myc in the instability of the cyclin D2 gene, a Myc-estrogen receptor chimera was activated in two mouse cell lines. After 3 to 4 days of Myc-ER activation, instability at the cyclin D2 locus was seen in the form of extrachromosomal elements, determined by FISH of metaphase and interphase nuclei and of purified extrachromosomal elements. At the same time points, Northern and Western blot analyses detected increased cyclin D2 mRNA and protein levels. These data suggest that Myc-induced genomic instability may contribute to neoplasia by increasing the levels of a cell cycle-regulating protein, cyclin D2, via intrachromosomal amplification of its gene or generation of extrachromosomal copies.
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Affiliation(s)
- S Mai
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Canada
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18
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Cheng M, Wang D, Roussel MF. Expression of c-Myc in response to colony-stimulating factor-1 requires mitogen-activated protein kinase kinase-1. J Biol Chem 1999; 274:6553-8. [PMID: 10037749 DOI: 10.1074/jbc.274.10.6553] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitogen-inducible gene c-myc is a key regulator of cell proliferation and transformation. Yet, the signaling pathway(s) that regulate its expression have remained largely unresolved. Using the mitogen-activated protein kinase kinase (MEK1/2) inhibitor PD98059 and dominant negative forms of Ras (N17) and ERK1 (K71R), we found that activation of Ras and extracellular signal-regulated kinase (ERK) is necessary for colony-stimulating factor-1 (CSF-1)-mediated c-Myc expression and DNA synthetic (S) phase entry. Quiescent NIH-3T3 cells expressing a partially defective CSF-1 receptor, CSF-1R (Y809F), exhibited impaired ERK1 activation and c-Myc expression and failed to enter the S phase of the cell division cycle in response to CSF-1 stimulation. Ectopic expression of a constitutively active form of MEK1 in cells expressing CSF-1R (Y809F) rescued c-Myc expression and S phase entry, but only in the presence of CSF-1-induced cooperating signals. Therefore, MEK1 participates in an obligate signaling pathway linking CSF-1R to c-Myc expression, but other signals from CSF-1R must cooperate with the MEK/ERK pathway to induce c-Myc expression and S phase entry in response to CSF-1 stimulation.
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Affiliation(s)
- M Cheng
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105-2794, USA
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Affiliation(s)
- C V Dang
- Department of Medicine, The Johns Hopkins Oncology Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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20
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Boyd KE, Wells J, Gutman J, Bartley SM, Farnham PJ. c-Myc target gene specificity is determined by a post-DNAbinding mechanism. Proc Natl Acad Sci U S A 1998; 95:13887-92. [PMID: 9811896 PMCID: PMC24949 DOI: 10.1073/pnas.95.23.13887] [Citation(s) in RCA: 239] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/1998] [Indexed: 11/18/2022] Open
Abstract
Uncertainty as to which member of a family of DNA-binding transcription factors regulates a specific promoter in intact cells is a problem common to many investigators. Determining target gene specificity requires both an analysis of protein binding to the endogenous promoter as well as a characterization of the functional consequences of transcription factor binding. By using a formaldehyde crosslinking procedure and Gal4 fusion proteins, we have analyzed the timing and functional consequences of binding of Myc and upstream stimulatory factor (USF)1 to endogenous cellular genes. We demonstrate that the endogenous cad promoter can be immunoprecipitated with antibodies against Myc and USF1. We further demonstrate that although both Myc and USF1 can bind to cad, the cad promoter can respond only to the Myc transactivation domain. We also show that the amount of Myc bound to the cad promoter fluctuates in a growth-dependent manner. Thus, our data analyzing both DNA binding and promoter activity in intact cells suggest that cad is a Myc target gene. In addition, we show that Myc binding can occur at many sites in vivo but that the position of the binding site determines the functional consequences of this binding. Our data indicate that a post-DNA-binding mechanism determines Myc target gene specificity. Importantly, we have demonstrated the feasibility of analyzing the binding of site-specific transcription factors in vivo to single copy mammalian genes.
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Affiliation(s)
- K E Boyd
- McArdle Laboratory for Cancer Research, University of Wisconsin Medical School, Madison, WI 53706, USA
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21
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Taylor C, Mai S. c-Myc-associated genomic instability of the dihydrofolate reductase locus in vivo. CANCER DETECTION AND PREVENTION 1998; 22:350-6. [PMID: 9674878 DOI: 10.1046/j.1525-1500.1998.cdoa36.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
c-Myc overexpression is associated with the locus-specific amplification and rearrangement of the dihydrofolate reductase (DHFR) gene. This has been shown in lymphoid and nonlymphoid cell lines. Furthermore, c-Myc-dependent DHFR gene amplification occurs independent of species origins; it has been described in rat, hamster, mouse, and human cell lines. Here, we report on c-Myc-dependent amplification of the DHFR gene in vivo, using an animal model of c-Myc-dependent neoplasia, the mouse plasmacytoma.
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Affiliation(s)
- C Taylor
- Manitoba Institute of Cell Biology and the University of Manitoba, Winnipeg, Canada
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22
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Dang C, Lewis B. Role of Oncogenic Transcription Factor c-Myc in Cell Cycle Regulation, Apoptosis and Metabolism. J Biomed Sci 1997; 4:269-278. [PMID: 12386373 DOI: 10.1007/bf02258350] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The myc gene was initially discovered as a prototypical retrovirally transduced oncogene. Over the decades, abundant evidence has emerged to support a causal role for the activated cellular gene, c-myc, in animal and human tumors. The gene encodes an oncogenic helix-loop-helix leucine zipper transcription factor that acts as a heterodimer with its partner protein, Max, to activate genes regulating the cell cycle machinery as well as critical metabolic enzymes. The additional ability of c-Myc to repress transcription of differentiation-related genes suggest that c-Myc is a central and key molecular integrator of cell proliferation, differentiation and metabolism.
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Affiliation(s)
- C.V. Dang
- Departments of Medicine, Oncology, Pathology, and Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Md., USA
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23
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Shichiri M, Adachi S, Sedivy JM, Marumo F, Hirata Y. Biphasic regulation of the preproendothelin-1 gene by c-myc. Endocrinology 1997; 138:4584-90. [PMID: 9348182 DOI: 10.1210/endo.138.11.5538] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Endothelin-1 (ET-1), a potent vasoconstrictive/mitogenic peptide originally isolated from vascular endothelium, stimulates the expression of immediate early response genes such as c-myc. The c-myc protooncogene participates in regulating the cascade of events that follow mitogenic stimulation of quiescent cells. Using a panel of isogenic fibroblast cell lines with differential c-myc expression levels (obtained by disrupting one c-myc gene copy with targeted homologous recombination and subsequently stably transfecting the heterozygous cells with an exogenous c-myc transgene), we demonstrate that c-Myc protein regulates ET-1 gene transcription in a biphasic fashion: as an activator at low concentrations and as a repressor at high concentrations. Using rat endothelial cells treated with antisense c-myc oligodeoxynucleotides, we also show that c-myc regulates ET-1 synthesis and secretion in a biphasic manner. The present report, therefore, demonstrates the existence of a signal transduction pathway that regulates the synthesis and secretion of ET-1 via the immediate early transcription factor, c-Myc.
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Affiliation(s)
- M Shichiri
- Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
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24
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Shim H, Lewis BC, Dolde C, Li Q, Wu CS, Chun YS, Dang CV. Myc target genes in neoplastic transformation. Curr Top Microbiol Immunol 1997; 224:181-90. [PMID: 9308241 DOI: 10.1007/978-3-642-60801-8_18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- H Shim
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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25
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Taylor C, Jalava A, Mai S. c-Myc dependent initiation of genomic instability during neoplastic transformation. Curr Top Microbiol Immunol 1997; 224:201-7. [PMID: 9308243 DOI: 10.1007/978-3-642-60801-8_20] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The dihydrofolate reductase (DHFR) gene is a target of c-Myc in genomic instability. The induced overexpression of c-Myc in cell lines is followed by the amplification and rearrangement of the DHFR gene. Furthermore, the constitutive upregulation of c-Myc protein coincides with genomic instability of the DHFR gene in lymphoid, non-lymphoid and in tumor lines. The amplification of the DHFR gene is locus-specific and independent of species origins. We have now addressed the question whether inducible deregulation of c-Myc is followed by DHFR gene amplification in vivo. We show that the DHFR gene is a target of c-Myc-dependent neoplasia in vivo and propose a role for genomic instability during the initiation of neoplastic transformation.
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Affiliation(s)
- C Taylor
- Manitoba Institute of Cell Biology, Winnipeg, Canada
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26
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Lewis BC, Shim H, Li Q, Wu CS, Lee LA, Maity A, Dang CV. Identification of putative c-Myc-responsive genes: characterization of rcl, a novel growth-related gene. Mol Cell Biol 1997; 17:4967-78. [PMID: 9271375 PMCID: PMC232348 DOI: 10.1128/mcb.17.9.4967] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The c-Myc protein is a helix-loop-helix leucine zipper oncogenic transcription factor that participates in the regulation of cell proliferation, differentiation, and apoptosis. The biochemical function of c-Myc has been well described, yet the identities of downstream effectors are just beginning to emerge. We describe the identification of a set of c-Myc-responsive genes in the Rat1a fibroblast through the application of cDNA representational difference analysis (RDA) to cDNAs isolated from nonadherent Rat1a and Rat1a-myc cells. In this system, c-Myc overexpression is sufficient to induce the transformed phenotype of anchorage-independent growth. We identified 20 differentially expressed cDNAs, several of which represent novel cDNA sequences. We further characterized one of the novel cDNAs identified in this screen, termed rcl. rcl expression is (i) directly stimulated by c-Myc; (ii) stimulated in the in vivo growth system of regenerating rat liver, as is c-myc; and (iii) elevated in human lymphoid cells that overexpress c-myc. By using an anti-Rcl antibody, immunoblot analysis, and immunofluorescence microscopy, the Rcl protein was found to be a 23-kDa nuclear protein. Ectopic expression of the protein encoded by the rcl cDNA induces anchorage-independent growth in Rat1a fibroblasts, albeit to a diminished extent compared to ectopic c-Myc expression. These data suggest a role for rcl during cellular proliferation and c-Myc-mediated transformation.
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Affiliation(s)
- B C Lewis
- Department of Medicine, Program in Human Genetics and Molecular Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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27
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Lücke-Huhle C, Mai S, Moll J. C-myc overexpression facilitates radiation-induced DHFR gene amplification. Int J Radiat Biol 1997; 71:167-75. [PMID: 9120352 DOI: 10.1080/095530097144283] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To investigate the role of myc-overexpression on radiation-induced amplification of the dihydrofolate reductase gene (DHFR) we compared diploid Chinese hamster ovary cells (CHO-9) to cells of the same line that had been stably transfected with a dexamethasone-inducible c-myc cDNA. The application of flow-cytofluorometry and fluorescent in situ hybridization (FISH) allowed the evaluation of an increase in DHFR gene copy number following radiation treatment without the use of a preceding selection procedure. We show that DHFR gene amplification may occur independently of p53 status in cells overexpressing c-myc.
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Affiliation(s)
- C Lücke-Huhle
- Research Center Karlsruhe, Institute of Genetics, Germany
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28
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Shrivastava A, Yu J, Artandi S, Calame K. YY1 and c-Myc associate in vivo in a manner that depends on c-Myc levels. Proc Natl Acad Sci U S A 1996; 93:10638-41. [PMID: 8855231 PMCID: PMC38206 DOI: 10.1073/pnas.93.20.10638] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The c-Myc oncoprotein has previously been shown to associate with transcription regulator YY1 and to inhibit its activity. We show herein that endogenous c-Myc and YY1 associate in vivo and that changes in c-Myc levels, which accompany mitogenic stimulation or differentiation of cultured cells, affect the ratio of free to c-Myc-associated YY1. We have also investigated the mechanism by which association with c-Myc inhibits YY1's ability to regulate transcription. c-Myc does not block binding of YY1 to DNA. However, protein association studies suggest that c-Myc interferes with the ability of YY1 to contact basal transcription proteins TATA-binding protein and TFIIB.
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Affiliation(s)
- A Shrivastava
- Department of Biochemistry and Molecular Biophysics, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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29
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Mai S, Fluri M, Siwarski D, Huppi K. Genomic instability in MycER-activated Rat1A-MycER cells. Chromosome Res 1996; 4:365-71. [PMID: 8871825 DOI: 10.1007/bf02257272] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The deregulated expression of c-Myc protein is associated with the non-random locus-specific amplification of the dihydrofolate reductase (DHFR) gene. This study was performed to determine whether additional chromosomal aberrations occur when c-Myc protein levels are up-regulated for prolonged periods. To this end, we have used Rat1A-MycER cells, which allow the experimental regulation of Myc protein levels. We examined the genomic stability of Rat1A-MycER cells cultivated in either the absence or the presence of estrogen, which reportedly activates the chimeric MycER protein in these cells. Following prolonged periods of MycER activation, Rat1A-Mycer cells exhibited irreversible chromosomal aberrations. The aberrations included numerical changes, chromosome breakage, the formation of circular chromosomal structures, chromosome fusions, and extrachromosomal elements.
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Affiliation(s)
- S Mai
- Manitoba Institute of Cell Biology, Winnipeg, Canada.
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30
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Watson PH, Singh R, Hole AK. Influence of c-myc on the progression of human breast cancer. Curr Top Microbiol Immunol 1996; 213 ( Pt 2):267-83. [PMID: 9053295 DOI: 10.1007/978-3-642-61109-4_13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- P H Watson
- Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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31
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Lemaitre JM, Buckle RS, Méchali M. c-Myc in the control of cell proliferation and embryonic development. Adv Cancer Res 1996; 70:95-144. [PMID: 8902055 DOI: 10.1016/s0065-230x(08)60873-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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32
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Affiliation(s)
- D Dubik
- Department of Physiology, University of Manitoba, Winnipeg, Canada
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33
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Mai S, Hanley-Hyde J, Coleman A, Siwarski D, Huppi K. Amplified extrachromosomal elements containing c-Myc and Pvt 1 in a mouse plasmacytoma. Genome 1995; 38:780-5. [PMID: 7672608 DOI: 10.1139/g95-099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
After adaptation of a mouse plasma cell tumor, MOPC265, to culture, we have found several unique chromosomal alterations in addition to the T(12;15) translocation and trisomy 11 frequently observed in plasmacytomas. Among these alterations is a specific coamplification of the c-Myc and Pvt 1 gene loci from mouse chromosome 15. Further analysis by fluorescence in situ hybridization demonstrates that the amplicons of c-Myc and Pvt 1 exist as extrachromosomal elements as well as within intact chromosomes. Most importantly, the presence of both Pvt 1 and c-Myc in these extrachromosomal elements indicates ongoing coselection for these loci in the propagation of MOPC265.
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Affiliation(s)
- S Mai
- Basel Institute for Immunology, Switzerland
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34
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Abstract
The lambda 5 promoter initiates transcription at multiple sites and confers expression in all cell types. Two lambda 5 promoter-derived oligonucleotides (Inr lambda 5:1 and Inr lambda 5:2), each with a transcription start site, could promote transcription in transient transfection assays. In contrast, a third oligonucleotide (+90 lambda 5), without a transcription initiation site, was inactive. The Inr lambda 5:1 and Inr lambda 5:2 oligonucleotides formed a major DNA-protein complex B' in gel retardation analyses; no protein-DNA complexes were observed with the inactive +90 lambda 5 oligonucleotide. The B' complexes of Inr lambda 5:1 and Inr lambda 5:2 each contained c-myc and myn (murine homologue of Max) proteins. The c-myc and myn proteins were also found to bind the TdT initiator (InrTdT). Using mutated oligonucleotides, we found that the c-myc/myn proteins bound to the transcription initiation site of both Inr lambda 5:1 and InrTdT, however, these mutated oligonucleotides were inactive in transfection assays. This suggested that, in this system, transcription depended both on a transcription initiation site and appropriate flanking sequences. The significance of c-myc binding to the respective initiator was analysed by overexpressing c-myc in co-transfection assays. Under these conditions the transcriptional activity of both the lambda 5 and the TdT initiator was repressed.
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Affiliation(s)
- S Mai
- Basel Institute for Immunology, Switzerland
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35
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Abstract
An experimentally inducible model system was generated in which Chinese hamster ovary cells (CHO-9) were stably transfected with an inducible c-myc cDNA. The induction of c-myc in these transfectants is followed by the enhanced binding of c-Myc/Max-containing protein complexes to 5'flanking E-box sequences of the gene encoding dihydrofolate reductase (DHFR). Moreover, DHFR is transiently amplified. The inappropriate overproduction of the oncoprotein, therefore, seems to plays a role in induced DHFR amplification.
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Affiliation(s)
- S Mai
- Basel Institute for Immunology, Switzerland
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