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Romano F, Di Porzio A, Iaccarino N, Riccardi G, Di Lorenzo R, Laneri S, Pagano B, Amato J, Randazzo A. G-quadruplexes in cancer-related gene promoters: from identification to therapeutic targeting. Expert Opin Ther Pat 2023; 33:745-773. [PMID: 37855085 DOI: 10.1080/13543776.2023.2271168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/11/2023] [Indexed: 10/20/2023]
Abstract
INTRODUCTION Guanine-rich DNA sequences can fold into four-stranded noncanonical secondary structures called G-quadruplexes (G4s) which are widely distributed in functional regions of the human genome, such as telomeres and gene promoter regions. Compelling evidence suggests their involvement in key genome functions such as gene expression and genome stability. Notably, the abundance of G4-forming sequences near transcription start sites suggests their potential involvement in regulating oncogenes. AREAS COVERED This review provides an overview of current knowledge on G4s in human oncogene promoters. The most representative G4-binding ligands have also been documented. The objective of this work is to present a comprehensive overview of the most promising targets for the development of novel and highly specific anticancer drugs capable of selectively impacting the expression of individual or a limited number of genes. EXPERT OPINION Modulation of G4 formation by specific ligands has been proposed as a powerful new tool to treat cancer through the control of oncogene expression. Actually, most of G4-binding small molecules seem to simultaneously target a range of gene promoter G4s, potentially influencing several critical driver genes in cancer, thus producing significant therapeutic benefits.
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Affiliation(s)
- Francesca Romano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Anna Di Porzio
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Nunzia Iaccarino
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | | | | | - Sonia Laneri
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
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Deng Z, Richardson DR. The Myc Family and the Metastasis Suppressor NDRG1: Targeting Key Molecular Interactions with Innovative Therapeutics. Pharmacol Rev 2023; 75:1007-1035. [PMID: 37280098 DOI: 10.1124/pharmrev.122.000795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 03/07/2023] [Accepted: 05/01/2023] [Indexed: 06/08/2023] Open
Abstract
Cancer is a leading cause of death worldwide, resulting in ∼10 million deaths in 2020. Major oncogenic effectors are the Myc proto-oncogene family, which consists of three members including c-Myc, N-Myc, and L-Myc. As a pertinent example of the role of the Myc family in tumorigenesis, amplification of MYCN in childhood neuroblastoma strongly correlates with poor patient prognosis. Complexes between Myc oncoproteins and their partners such as hypoxia-inducible factor-1α and Myc-associated protein X (MAX) result in proliferation arrest and pro-proliferative effects, respectively. Interactions with other proteins are also important for N-Myc activity. For instance, the enhancer of zest homolog 2 (EZH2) binds directly to N-Myc to stabilize it by acting as a competitor against the ubiquitin ligase, SCFFBXW7, which prevents proteasomal degradation. Heat shock protein 90 may also be involved in N-Myc stabilization since it binds to EZH2 and prevents its degradation. N-Myc downstream-regulated gene 1 (NDRG1) is downregulated by N-Myc and participates in the regulation of cellular proliferation via associating with other proteins, such as glycogen synthase kinase-3β and low-density lipoprotein receptor-related protein 6. These molecular interactions provide a better understanding of the biologic roles of N-Myc and NDRG1, which can be potentially used as therapeutic targets. In addition to directly targeting these proteins, disrupting their key interactions may also be a promising strategy for anti-cancer drug development. This review examines the interactions between the Myc proteins and other molecules, with a special focus on the relationship between N-Myc and NDRG1 and possible therapeutic interventions. SIGNIFICANCE STATEMENT: Neuroblastoma is one of the most common childhood solid tumors, with a dismal five-year survival rate. This problem makes it imperative to discover new and more effective therapeutics. The molecular interactions between major oncogenic drivers of the Myc family and other key proteins; for example, the metastasis suppressor, NDRG1, may potentially be used as targets for anti-neuroblastoma drug development. In addition to directly targeting these proteins, disrupting their key molecular interactions may also be promising for drug discovery.
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Affiliation(s)
- Zhao Deng
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Australia (Z.D., D.R.R.), and Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya, Japan (D.R.R.)
| | - Des R Richardson
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Australia (Z.D., D.R.R.), and Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya, Japan (D.R.R.)
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Smith BAH, Deutzmann A, Correa KM, Delaveris CS, Dhanasekaran R, Dove CG, Sullivan DK, Wisnovsky S, Stark JC, Pluvinage JV, Swaminathan S, Riley NM, Rajan A, Majeti R, Felsher DW, Bertozzi CR. MYC-driven synthesis of Siglec ligands is a glycoimmune checkpoint. Proc Natl Acad Sci U S A 2023; 120:e2215376120. [PMID: 36897988 PMCID: PMC10089186 DOI: 10.1073/pnas.2215376120] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/06/2022] [Indexed: 03/12/2023] Open
Abstract
The Siglecs (sialic acid-binding immunoglobulin-like lectins) are glycoimmune checkpoint receptors that suppress immune cell activation upon engagement of cognate sialoglycan ligands. The cellular drivers underlying Siglec ligand production on cancer cells are poorly understood. We find the MYC oncogene causally regulates Siglec ligand production to enable tumor immune evasion. A combination of glycomics and RNA-sequencing of mouse tumors revealed the MYC oncogene controls expression of the sialyltransferase St6galnac4 and induces a glycan known as disialyl-T. Using in vivo models and primary human leukemias, we find that disialyl-T functions as a "don't eat me" signal by engaging macrophage Siglec-E in mice or the human ortholog Siglec-7, thereby preventing cancer cell clearance. Combined high expression of MYC and ST6GALNAC4 identifies patients with high-risk cancers and reduced tumor myeloid infiltration. MYC therefore regulates glycosylation to enable tumor immune evasion. We conclude that disialyl-T is a glycoimmune checkpoint ligand. Thus, disialyl-T is a candidate for antibody-based checkpoint blockade, and the disialyl-T synthase ST6GALNAC4 is a potential enzyme target for small molecule-mediated immune therapy.
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Affiliation(s)
- Benjamin A. H. Smith
- Sarafan ChEM-H, Stanford University, Stanford, CA94305
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA94305
| | - Anja Deutzmann
- Division of Oncology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | | | - Corleone S. Delaveris
- Sarafan ChEM-H, Stanford University, Stanford, CA94305
- Department of Chemistry, Stanford University, Stanford, CA94305
| | - Renumathy Dhanasekaran
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | - Christopher G. Dove
- Division of Hematology, Department of Medicine, Stanford University, Stanford, CA94305
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA94305
| | - Delaney K. Sullivan
- Division of Oncology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | - Simon Wisnovsky
- Faculty of Pharmaceutical Sciences, University of British Columbia, British Columbia, BC V6T 1Z3, Canada
| | - Jessica C. Stark
- Sarafan ChEM-H, Stanford University, Stanford, CA94305
- Department of Chemistry, Stanford University, Stanford, CA94305
| | - John V. Pluvinage
- Department of Neurology, University of California, San Francisco, CA94143
| | - Srividya Swaminathan
- Division of Oncology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA91016
- Department of Pediatrics, Beckman Research Institute of City of Hope, Duarte, CA91010
| | | | - Anand Rajan
- Department of Pathology, University of Iowa, Iowa City, IA52242
| | - Ravindra Majeti
- Division of Hematology, Department of Medicine, Stanford University, Stanford, CA94305
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA94305
| | - Dean W. Felsher
- Division of Oncology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Pathology, Stanford University School of Medicine, Stanford, CA94305
| | - Carolyn R. Bertozzi
- Sarafan ChEM-H, Stanford University, Stanford, CA94305
- Department of Chemistry, Stanford University, Stanford, CA94305
- Howard Hughes Medical Institute, Stanford University, Stanford, CA94305
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MNT suppresses T cell apoptosis via BIM and is critical for T lymphomagenesis. Cell Death Differ 2023; 30:1018-1032. [PMID: 36755068 PMCID: PMC10070419 DOI: 10.1038/s41418-023-01119-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 01/11/2023] [Accepted: 01/19/2023] [Indexed: 02/10/2023] Open
Abstract
The importance of c-MYC in regulating lymphopoiesis and promoting lymphomagenesis is well-established. Far less appreciated is the vital supporting role of MYC's relative MNT. Using Rag1Cre-mediated Mnt deletion in lymphoid progenitor cells, we show here that, during normal T cell development, MNT loss enhances apoptosis, at least in part by elevating expression of the pro-apoptotic BH3-only protein BIM. Moreover, using T lymphoma-prone VavP-MYC transgenic mice, we show that Mnt deletion reduces the pool of pre-malignant MYC-driven T lymphoid cells and abrogates thymic T lymphomagenesis. In addition, we establish that Mnt deletion prevents T lymphoma development in γ-irradiated mice, most likely by enhancing apoptosis of T lymphoid cells repopulating the depleted thymus. Taken together with our recent demonstration that MNT is vital for the survival of MYC-driven pre-malignant and malignant B lymphoid cells, these results suggest that MNT represents an important new drug target for both T and B lymphoid malignancies.
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Carratt SA, Kong GL, Curtiss BM, Schonrock Z, Maloney L, Maniaci BN, Blaylock HZ, Baris A, Druker BJ, Braun TP, Maxson JE. Mutated SETBP1 activates transcription of Myc programs to accelerate CSF3R-driven myeloproliferative neoplasms. Blood 2022; 140:644-658. [PMID: 35482940 PMCID: PMC9373012 DOI: 10.1182/blood.2021014777] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 04/15/2022] [Indexed: 11/20/2022] Open
Abstract
Colony stimulating factor 3 receptor (CSF3R) mutations lead to JAK pathway activation and are the molecular hallmark of chronic neutrophilic leukemia (CNL). Approximately half of patients with CNL also have mutations in SET binding protein 1 (SETBP1). In this study, we developed models of SETBP1-mutated leukemia to understand the role that SETBP1 plays in CNL. SETBP1 mutations promote self-renewal of CSF3R-mutated hematopoietic progenitors in vitro and prevent cells from undergoing terminal differentiation. In vivo, SETBP1 mutations accelerate leukemia progression, leading to the rapid development of hepatosplenomegaly and granulocytosis. Through transcriptomic and epigenomic profiling, we found that SETBP1 enhances progenitor-associated programs, most strongly upregulating Myc and Myc target genes. This upregulation of Myc can be reversed by LSD1 inhibitors. In summary, we found that SETBP1 mutations promote aggressive hematopoietic cell expansion when expressed with mutated CSF3R through the upregulation of Myc-associated gene expression programs.
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Affiliation(s)
- Sarah A Carratt
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Garth L Kong
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Brittany M Curtiss
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Zachary Schonrock
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Lauren Maloney
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Breanna N Maniaci
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Hunter Z Blaylock
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Adrian Baris
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Brian J Druker
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Theodore P Braun
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
| | - Julia E Maxson
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR
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Ding H, Li Z, Li X, Yang X, Zhao J, Guo J, Lu W, Liu H, Wang J. FTO Alleviates CdCl 2-Induced Apoptosis and Oxidative Stress via the AKT/Nrf2 Pathway in Bovine Granulosa Cells. Int J Mol Sci 2022; 23:ijms23094948. [PMID: 35563339 PMCID: PMC9101166 DOI: 10.3390/ijms23094948] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 04/25/2022] [Accepted: 04/27/2022] [Indexed: 12/15/2022] Open
Abstract
Cadmium (Cd) is a common environmental heavy metal contaminant of reproduction toxicity. Cd accumulation in animals leads to the damage of granulosa cells. However, its mechanism needs to be elucidated. This research found that treating granulosa cells with Cd resulted in reduced cell viability. The flow cytometry results showed that Cd increased the degree of apoptosis and level of superoxide anion (O2-) in granulosa cells. Further analysis showed that Cd treatment resulted in reduced expression levels of nuclear factor erythroid 2-related factor-2 (Nrf2), superoxide dismutase (SOD), catalase (CAT) and NAD(P)H: quinone oxidoreductase 1 (NQO1), and an increased expression level of malondialdehyde (MDA); the expression levels of Bcl-2 associated X (Bax) and caspase-3 increased, whereas that of B-cell lymphoma 2 (Bcl-2) decreased. Changes in m6A methylation-related enzymes were noted with Cd-induced damage to granulosa cells. The results of transcriptome and MeRIP sequencing revealed that the AKT pathway participated in Cd-induced damage in granulosa cells, and the MAX network transcriptional repressor (MNT) may be a potential target gene of fat mass and obesity-associated protein (FTO). FTO and YTH domain family member 2 (YTHDF2) regulated MNT expression through m6A modification. FTO overexpression alleviated Cd-induced apoptosis and oxidative stress through the activation of the AKT/Nrf2 pathway; this process could be reversed using siMNT. Overall, these findings associated m6A with Cd-induced damage to granulosa cells and provided insights into Cd-induced granulosa cell cytotoxicity from a new perspective centered on m6A modification.
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Affiliation(s)
- He Ding
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Zhiqiang Li
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Xin Li
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Xiaorui Yang
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Jing Zhao
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Jing Guo
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Wenfa Lu
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Hongyu Liu
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
- Correspondence: (H.L.); (J.W.)
| | - Jun Wang
- Joint Laboratory of Modern Agricultural Technology International Cooperation, Ministry of Education, Jilin Agricultural University, Changchun 130118, China; (H.D.); (Z.L.); (X.L.); (X.Y.); (J.Z.); (J.G.); (W.L.)
- Key Lab of Animal Production, Product Quality and Security, Ministry of Education, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
- Correspondence: (H.L.); (J.W.)
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Prochownik EV, Wang H. Normal and Neoplastic Growth Suppression by the Extended Myc Network. Cells 2022; 11:747. [PMID: 35203395 PMCID: PMC8870482 DOI: 10.3390/cells11040747] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/09/2022] [Accepted: 02/15/2022] [Indexed: 12/20/2022] Open
Abstract
Among the first discovered and most prominent cellular oncogenes is MYC, which encodes a bHLH-ZIP transcription factor (Myc) that both activates and suppresses numerous genes involved in proliferation, energy production, metabolism and translation. Myc belongs to a small group of bHLH-ZIP transcriptional regulators (the Myc Network) that includes its obligate heterodimerization partner Max and six "Mxd proteins" (Mxd1-4, Mnt and Mga), each of which heterodimerizes with Max and largely opposes Myc's functions. More recently, a second group of bHLH-ZIP proteins (the Mlx Network) has emerged that bears many parallels with the Myc Network. It is comprised of the Myc-like factors ChREBP and MondoA, which, in association with the Max-like member Mlx, regulate smaller and more functionally restricted repertoires of target genes, some of which are shared with Myc. Opposing ChREBP and MondoA are heterodimers comprised of Mlx and Mxd1, Mxd4 and Mnt, which also structurally and operationally link the two Networks. We discuss here the functions of these "Extended Myc Network" members, with particular emphasis on their roles in suppressing normal and neoplastic growth. These roles are complex due to the temporal- and tissue-restricted expression of Extended Myc Network proteins in normal cells, their regulation of both common and unique target genes and, in some cases, their functional redundancy.
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Affiliation(s)
- Edward V. Prochownik
- Division of Hematology/Oncology, The Department of Pediatrics, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA 15224, USA;
- The Department of Microbiology and Molecular Genetics, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
- The Hillman Cancer Center of UPMC, Pittsburgh, PA 15224, USA
- The Pittsburgh Liver Research Center, Pittsburgh, PA 15224, USA
| | - Huabo Wang
- Division of Hematology/Oncology, The Department of Pediatrics, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA 15224, USA;
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Stephan OOH. Interactions, structural aspects, and evolutionary perspectives of the yeast 'START'-regulatory network. FEMS Yeast Res 2021; 22:6461095. [PMID: 34905017 DOI: 10.1093/femsyr/foab064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 12/11/2021] [Indexed: 11/12/2022] Open
Abstract
Molecular signal transduction networks which conduct transcription at the G1 to S phase transition of the eukaryotic cell division cycle have been identified in diverse taxa from mammals to baker´s yeast with analogous functional organization. However, regarding some network components, such as the transcriptional regulators STB1 and WHI5, only few orthologs exist which are confined to individual Saccharomycotina species. While Whi5 has been characterized as yeast analog of human Rb protein, in the particular case of Stb1 (Sin three binding protein 1) identification of functional analogs emerges as difficult because to date its exact functionality still remains obscured. By aiming to resolve Stb1´s enigmatic role this Perspectives article especially surveys works covering relations between Cyclin/CDKs, the heteromeric transcription factor complexes SBF (Swi4/Swi6) and MBF (Mbp1/Swi6), as well as additional coregulators (Whi5, Sin3, Rpd3, Nrm1) which are collectively associated with the orderly transcription at 'Start' of the Saccharomyces cerevisiae cell cycle. In this context, interaction capacities of the Sin3-scaffold protein are widely surveyed because its four PAH domains (Paired Amphiphatic Helix) represent a 'recruitment-code' for gene-specific targeting of repressive histone deacetylase activity (Rpd3) via different transcription factors. Here Stb1 plays a role in Sin3´s action on transcription at the G1/S-boundary. Through bioinformatic analyses a potential Sin3-interaction domain (SID) was detected in Stb1, and beyond that, connections within the G1/S-regulatory network are discussed in structural and evolutionary context thereby providing conceptual perspectives.
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Affiliation(s)
- Octavian O H Stephan
- Department of Biology, Friedrich-Alexander University of Erlangen-Nuremberg, Staudtstr. 5, 91058 Erlangen, Bavaria, Germany
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9
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Mnt Represses Epithelial Identity To Promote Epithelial-to-Mesenchymal Transition. Mol Cell Biol 2021; 41:e0018321. [PMID: 34460331 DOI: 10.1128/mcb.00183-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The multistep process of epithelial-to-mesenchymal transition (EMT), whereby static epithelial cells become migratory mesenchymal cells, plays a critical role during various developmental contexts, wound healing, and pathological conditions such as cancer metastasis. Despite the established function of basic helix-loop-helix (bHLH) transcription factors (TFs) in cell fate determination, only a few have been examined for their role in EMT. Here, using transcriptome analysis of distinct stages during stepwise progression of transforming growth factor beta (TGFβ)-induced EMT in mammary epithelial cells, we revealed distinct categories of bHLH TFs that show differential expression kinetics during EMT. Using a short interfering RNA-mediated functional screen for bHLH TFs during EMT, we found Max network transcription repressor (MNT) to be essential for EMT in mammary epithelial cells. We show that the depletion of MNT blocks TGFβ-induced morphological changes during EMT, and this is accompanied by derepression of a large number of epithelial genes. We show that MNT mediates the repression of epithelial identity genes during EMT by recruiting HDAC1 and mediating the loss of H3K27ac and chromatin accessibility. Lastly, we show that MNT is expressed at higher levels in EMT-High breast cancer cells and is required for their migration. Taken together, these findings establish MNT as a critical regulator of cell fate changes during mammary EMT. IMPORTANCE The bHLH TF Mnt promotes epithelial to mesenchymal transition through epigenetic repression of the epithelial gene expression program.
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Yang R, Li R, Huang Z, Zuo Y, Yue H, Wu H, Gu F, Wang F, He M, Bian Z. Mycn deficiency underlies the development of orofacial clefts in mice and humans. Hum Mol Genet 2021; 31:803-815. [PMID: 34590686 DOI: 10.1093/hmg/ddab288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 01/09/2023] Open
Abstract
Non-syndromic cleft lip with or without cleft palate (NSCL/P) is the most common subphenotype of non-syndromic orofacial clefts (NSOFCs) arising from genetic and/or environmental perturbations during embryonic development. We previously identified 2p24.2 as a risk locus associated with NSCL/P in the Chinese Han population, and MYCN is a candidate risk gene in this region. To understand the potential function of MYCN in craniofacial development, we generated Wnt1-Cre;Mycnflox/flox mice that exhibited cleft palate, microglossia, and micrognathia, resembling the Pierre Robin sequence (PRS) in humans. Further analyses indicated that the cleft palate was secondary to the delayed elevation of palatal shelves caused by micrognathia. The micrognathia resulted from impaired chondrogenic differentiation in Merkel's cartilage, which limited tongue development, leading to microglossia. In terms of mechanism, Mycn deficiency in cranial neural crest cells (CNCCs) downregulated Sox9 expression by inhibiting Wnt5a in a CNCC-derived chondrogenic lineage in Merkel's cartilage. To investigate whether MYCN deficiency contributed to NSCL/P, we performed direct sequencing targeting all exons and exon-intron boundaries of MYCN in 104 multiplex families with mendelian NSCL/P and identified a novel pathogenic variant in MYCN. Taken together, our data indicate that ablation of Mycn in mouse CNCCs could resemble PRS by suppressing the Wnt5a-Sox9 signaling pathway in Merkel's cartilage and that mutations in MYCN may be novel potential causes of NSCL/P.
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Affiliation(s)
- Ruihuan Yang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Ruyi Li
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Zhuo Huang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Yining Zuo
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Haitang Yue
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Hailin Wu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Fan Gu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Fei Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Miao He
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Zhuan Bian
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
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11
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Liaño-Pons J, Arsenian-Henriksson M, León J. The Multiple Faces of MNT and Its Role as a MYC Modulator. Cancers (Basel) 2021; 13:4682. [PMID: 34572909 PMCID: PMC8465425 DOI: 10.3390/cancers13184682] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/29/2022] Open
Abstract
MNT is a crucial modulator of MYC, controls several cellular functions, and is activated in most human cancers. It is the largest, most divergent, and most ubiquitously expressed protein of the MXD family. MNT was first described as a MYC antagonist and tumor suppressor. Indeed, 10% of human tumors present deletions of one MNT allele. However, some reports show that MNT functions in cooperation with MYC by maintaining cell proliferation, promoting tumor cell survival, and supporting MYC-driven tumorigenesis in cellular and animal models. Although MAX was originally considered MNT's obligate partner, our recent findings demonstrate that MNT also works independently. MNT forms homodimers and interacts with proteins both outside and inside of the proximal MYC network. These complexes are involved in a wide array of cellular processes, from transcriptional repression via SIN3 to the modulation of metabolism through MLX as well as immunity and apoptosis via REL. In this review, we discuss the present knowledge of MNT with a special focus on its interactome, which sheds light on the complex and essential role of MNT in cell biology.
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Affiliation(s)
- Judit Liaño-Pons
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, SE-171 65 Stockholm, Sweden;
| | - Marie Arsenian-Henriksson
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, SE-171 65 Stockholm, Sweden;
| | - Javier León
- Departmento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, 39011 Santander, Spain;
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12
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O'Sullivan MJ, Jang JH, Panariti A, Bedrat A, Ijpma G, Lemos B, Park JA, Lauzon AM, Martin JG. Airway Epithelial Cells Drive Airway Smooth Muscle Cell Phenotype Switching to the Proliferative and Pro-inflammatory Phenotype. Front Physiol 2021; 12:687654. [PMID: 34295265 PMCID: PMC8290262 DOI: 10.3389/fphys.2021.687654] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/03/2021] [Indexed: 12/13/2022] Open
Abstract
The increased mass of airway smooth muscle (ASM) in the airways of asthmatic patients may contribute to the pathology of this disease by increasing the capacity for airway narrowing. Evidence for the airway epithelium as a participant in ASM remodeling is accruing. To investigate mechanisms by which airway epithelial cells induce ASM cell (ASMC) proliferation, we have employed a co-culture model to explore markers of ASMC proliferative phenotype. Co-culture with epithelial cells led to incorporation of bromodeoxyuridine into ASMCs, indicating augmented proliferation and an associated increase in mRNA of the pro-proliferative co-transcription factor Elk1. Although the mitogen heparin-binding epidermal growth factor (HB-EGF) was augmented in the co-culture supernatant, the ASMC epidermal growth factor receptor (EGFR), an effector of HB-EGF induced proliferation, did not mediate epithelial-induced proliferation. The co-culture increased the expression of ASMC mRNA for the pro-inflammatory cytokines IL-6 and IL-8 as well as the pro-proliferative microRNA miR-210. The transcriptional repressor Max-binding protein (Mnt), a putative target of miR-210, was transcriptionally repressed in co-cultured ASMCs. Together, these data indicate that the airway epithelium-induced proliferative phenotype of ASMCs is not driven by EGFR signaling, but rather may be dependent on miR210 targeting of tumor suppressor Mnt.
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Affiliation(s)
- M J O'Sullivan
- Meakins-Christie Laboratories, McGill University Health Centre, Montreal, QC, Canada.,T.H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - J H Jang
- Meakins-Christie Laboratories, McGill University Health Centre, Montreal, QC, Canada
| | - A Panariti
- Meakins-Christie Laboratories, McGill University Health Centre, Montreal, QC, Canada
| | - A Bedrat
- T.H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - G Ijpma
- Meakins-Christie Laboratories, McGill University Health Centre, Montreal, QC, Canada
| | - B Lemos
- T.H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - J A Park
- T.H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - A M Lauzon
- Meakins-Christie Laboratories, McGill University Health Centre, Montreal, QC, Canada
| | - J G Martin
- Meakins-Christie Laboratories, McGill University Health Centre, Montreal, QC, Canada
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13
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Zhu X, Xu T, Zhu J. The regulatory function of tandem repeat VNTR2-1 in hTERT gene involves basic Helix-loop-helix family transcription factors. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2021; 62:338-349. [PMID: 34115413 PMCID: PMC9648534 DOI: 10.1002/em.22447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/06/2021] [Accepted: 06/09/2021] [Indexed: 06/12/2023]
Abstract
Telomerase is a ribonucleoprotein enzyme that synthesizes telomere end sequence. The expression of hTERT gene, encoding the catalytic subunit of human telomerase, is restricted to highly proliferative tissues and is undetectable in most somatic cells. Abnormal activation of hTERT gene is found in 90% of human tumors. Previously, we identified tandem repeat of 42-bp/unit, VNTR2-1, in intron 2 of the hTERT gene, as a novel regulatory element important for hTERT transcription in cancer cells. In the current study, we found that multiple 42-bp repeats of VNTR2-1 activated luciferase gene in reporter plasmids. Mutation of the predicted cis-regulatory elements within the 42-bp repeats, including a E-box motif, resulted in a partial or complete loss of its enhancer activity. Moreover, MYC family proteins, c-MYC, MAX, and MNT, regulated hTERT gene transcription through both VNTR2-1 and E-boxes at the proximal hTERT promoter. Chromatin segmentation analysis of published ChIP-sequencing data from K562 cells indicated that VNTR2-1 was a bivalent enhancer. In telomerase-expressing human melanoma cell line MelJuSo, deletion of VNTR2-1 caused the hTERT promoter chromatin status to change from an active state to a repressed state, accompanied by increases of H3K27me3 and H3K9me3 marks. Therefore, we provided additional evidence for VNTR2-1 as a functional regulatory element that regulated hTERT expression by MYC family transcription factors. These results have improved our knowledge on the functions of repetitive genomic DNAs and the regulatory mechanisms of human telomerase gene.
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Affiliation(s)
| | | | - Jiyue Zhu
- To whom correspondence should be addressed. Tel: 1-509-368-6565; Fax: 1-509-368-6561; ; 412E Spokane Falls Blvd, PBS323, Spokane, WA, 99202, USA
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14
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Shostak A, Schermann G, Diernfellner A, Brunner M. MXD/MIZ1 transcription regulatory complexes activate the expression of MYC-repressed genes. FEBS Lett 2021; 595:1639-1655. [PMID: 33914337 DOI: 10.1002/1873-3468.14097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 12/27/2022]
Abstract
MXDs are transcription repressors that antagonize MYC-mediated gene activation. MYC, when associated with MIZ1, acts also as a repressor of a subset of genes, including p15 and p21. A role for MXDs in regulation of MYC-repressed genes is not known. We report that MXDs activate transcription of p15 and p21 in U2OS cells. This activation required DNA binding by MXDs and their interaction with MIZ1. MXD mutants deficient in MIZ1 binding interacted with the MYC-binding partner MAX and were active as repressors of MYC-activated genes but failed to activate MYC-repressed genes. Mutant MXDs with reduced DNA-binding affinity interacted with MAX and MIZ1 but neither repressed nor activated transcription. Our data show that MXDs and MYC have a reciprocally antagonistic potential to regulate transcription of target genes.
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15
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Sheng Y, Ma R, Yu C, Wu Q, Zhang S, Paulsen K, Zhang J, Ni H, Huang Y, Zheng Y, Qian Z. Role of c-Myc haploinsufficiency in the maintenance of HSCs in mice. Blood 2021; 137:610-623. [PMID: 33538795 PMCID: PMC8215193 DOI: 10.1182/blood.2019004688] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 08/10/2020] [Indexed: 12/13/2022] Open
Abstract
This study was conducted to determine the dosage effect of c-Myc on hematopoiesis and its distinct role in mediating the Wnt/β-catenin pathway in hematopoietic stem cell (HSC) and bone marrow niche cells. c-Myc haploinsufficiency led to ineffective hematopoiesis by inhibiting HSC self-renewal and quiescence and by promoting apoptosis. We have identified Nr4a1, Nr4a2, and Jmjd3, which are critical for the maintenance of HSC functions, as previously unrecognized downstream targets of c-Myc in HSCs. c-Myc directly binds to the promoter regions of Nr4a1, Nr4a2, and Jmjd3 and regulates their expression. Our results revealed that Nr4a1 and Nr4a2 mediates the function of c-Myc in regulating HSC quiescence, whereas all 3 genes contribute to the function of c-Myc in the maintenance of HSC survival. Adenomatous polyposis coli (Apc) is a negative regulator of the Wnt/β-catenin pathway. We have provided the first evidence that Apc haploinsufficiency induces a blockage of erythroid lineage differentiation through promoting secretion of IL6 in bone marrow endothelial cells. We found that c-Myc haploinsufficiency failed to rescue defective function of Apc-deficient HSCs in vivo but it was sufficient to prevent the development of severe anemia in Apc-heterozygous mice and to significantly prolong the survival of those mice. Furthermore, we showed that c-Myc-mediated Apc loss induced IL6 secretion in endothelial cells, and c-Myc haploinsufficiency reversed the negative effect of Apc-deficient endothelial cells on erythroid cell differentiation. Our studies indicate that c-Myc has a context-dependent role in mediating the function of Apc in hematopoiesis.
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Affiliation(s)
- Yue Sheng
- Department of Medicine and
- Department of Biochemistry and Molecular Biology, UF Health Cancer Center, University of Florida, Gainesville, FL
- Department of Medicine and
| | - Rui Ma
- Institute for Tuberculosis Research, University of Illinois at Chicago, Chicago, IL
| | - Chunjie Yu
- Department of Medicine and
- Department of Biochemistry and Molecular Biology, UF Health Cancer Center, University of Florida, Gainesville, FL
- Department of Medicine and
- Institute for Tuberculosis Research, University of Illinois at Chicago, Chicago, IL
| | - Qiong Wu
- Department of Medicine and
- Department of Biochemistry and Molecular Biology, UF Health Cancer Center, University of Florida, Gainesville, FL
- Department of Medicine and
- Institute for Tuberculosis Research, University of Illinois at Chicago, Chicago, IL
| | - Steven Zhang
- Department of Radiation Oncology, UF Health Cancer Center, University of Florida, Gainesville, FL
| | - Kimberly Paulsen
- Department of Medicine and
- Department of Biochemistry and Molecular Biology, UF Health Cancer Center, University of Florida, Gainesville, FL
| | - Jiwang Zhang
- Oncology Institute, Cardinal Bernardin Cancer Center, Department of Cancer Biology, Loyola University Medical Center, Maywood, IL
| | - Hongyu Ni
- Department of Pathology, University of Illinois at Chicago, Chicago, IL
| | - Yong Huang
- Department of Medicine, University of Virginia, Charlottesville, VA; and
| | - Yi Zheng
- Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH
| | - Zhijian Qian
- Department of Medicine and
- Department of Biochemistry and Molecular Biology, UF Health Cancer Center, University of Florida, Gainesville, FL
- Department of Medicine and
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16
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Bugge K, Staby L, Salladini E, Falbe-Hansen RG, Kragelund BB, Skriver K. αα-Hub domains and intrinsically disordered proteins: A decisive combo. J Biol Chem 2021; 296:100226. [PMID: 33361159 PMCID: PMC7948954 DOI: 10.1074/jbc.rev120.012928] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/22/2020] [Accepted: 12/22/2020] [Indexed: 01/02/2023] Open
Abstract
Hub proteins are central nodes in protein-protein interaction networks with critical importance to all living organisms. Recently, a new group of folded hub domains, the αα-hubs, was defined based on a shared αα-hairpin supersecondary structural foundation. The members PAH, RST, TAFH, NCBD, and HHD are found in large proteins such as Sin3, RCD1, TAF4, CBP, and harmonin, which organize disordered transcriptional regulators and membrane scaffolds in interactomes of importance to human diseases and plant quality. In this review, studies of structures, functions, and complexes across the αα-hubs are described and compared to provide a unified description of the group. This analysis expands the associated molecular concepts of "one domain-one binding site", motif-based ligand binding, and coupled folding and binding of intrinsically disordered ligands to additional concepts of importance to signal fidelity. These include context, motif reversibility, multivalency, complex heterogeneity, synergistic αα-hub:ligand folding, accessory binding sites, and supramodules. We propose that these multifaceted protein-protein interaction properties are made possible by the characteristics of the αα-hub fold, including supersite properties, dynamics, variable topologies, accessory helices, and malleability and abetted by adaptability of the disordered ligands. Critically, these features provide additional filters for specificity. With the presentations of new concepts, this review opens for new research questions addressing properties across the group, which are driven from concepts discovered in studies of the individual members. Combined, the members of the αα-hubs are ideal models for deconvoluting signal fidelity maintained by folded hubs and their interactions with intrinsically disordered ligands.
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Affiliation(s)
- Katrine Bugge
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lasse Staby
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Edoardo Salladini
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus G Falbe-Hansen
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Birthe B Kragelund
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
| | - Karen Skriver
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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17
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Long J, Galvan DL, Mise K, Kanwar YS, Li L, Poungavrin N, Overbeek PA, Chang BH, Danesh FR. Role for carbohydrate response element-binding protein (ChREBP) in high glucose-mediated repression of long noncoding RNA Tug1. J Biol Chem 2020; 295:15840-15852. [PMID: 32467232 PMCID: PMC7681008 DOI: 10.1074/jbc.ra120.013228] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/25/2020] [Indexed: 12/28/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) have been shown to play key roles in a variety of biological activities of the cell. However, less is known about how lncRNAs respond to environmental cues and what transcriptional mechanisms regulate their expression. Studies from our laboratory have shown that the lncRNA Tug1 (taurine upregulated gene 1) is crucial for the progression of diabetic kidney disease, a major microvascular complication of diabetes. Using a combination of proximity labeling with the engineered soybean ascorbate peroxidase (APEX2), ChIP-qPCR, biotin-labeled oligonucleotide pulldown, and classical promoter luciferase assays in kidney podocytes, we extend our initial observations in the current study and now provide a detailed analysis on a how high-glucose milieu downregulates Tug1 expression in podocytes. Our results revealed an essential role for the transcription factor carbohydrate response element binding protein (ChREBP) in controlling Tug1 transcription in the podocytes in response to increased glucose levels. Along with ChREBP, other coregulators, including MAX dimerization protein (MLX), MAX dimerization protein 1 (MXD1), and histone deacetylase 1 (HDAC1), were enriched at the Tug1 promoter under high-glucose conditions. These observations provide the first characterization of the mouse Tug1 promoter's response to the high-glucose milieu. Our findings illustrate a molecular mechanism by which ChREBP can coordinate glucose homeostasis with the expression of the lncRNA Tug1 and further our understanding of dynamic transcriptional regulation of lncRNAs in a disease state.
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Affiliation(s)
- Jianyin Long
- Section of Nephrology, Division of Internal Medicine, The University of Texas at MD Anderson Cancer Center, Houston, Texas, USA
| | - Daniel L Galvan
- Section of Nephrology, Division of Internal Medicine, The University of Texas at MD Anderson Cancer Center, Houston, Texas, USA
| | - Koki Mise
- Section of Nephrology, Division of Internal Medicine, The University of Texas at MD Anderson Cancer Center, Houston, Texas, USA; Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Yashpal S Kanwar
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Li Li
- Section of Nephrology, Division of Internal Medicine, The University of Texas at MD Anderson Cancer Center, Houston, Texas, USA; Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Naravat Poungavrin
- Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Paul A Overbeek
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Benny H Chang
- Section of Nephrology, Division of Internal Medicine, The University of Texas at MD Anderson Cancer Center, Houston, Texas, USA
| | - Farhad R Danesh
- Section of Nephrology, Division of Internal Medicine, The University of Texas at MD Anderson Cancer Center, Houston, Texas, USA; Department of Pharmacology & Chemical Biology, Baylor College of Medicine, Houston, Texas, USA.
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18
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Development and survival of MYC-driven lymphomas require the MYC antagonist MNT to curb MYC-induced apoptosis. Blood 2020; 135:1019-1031. [PMID: 31978211 DOI: 10.1182/blood.2019003014] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 12/23/2019] [Indexed: 01/06/2023] Open
Abstract
Deregulated overexpression of MYC is implicated in the development and malignant progression of most (∼70%) human tumors. MYC drives cell growth and proliferation, but also, at high levels, promotes apoptosis. Here, we report that the proliferative capacity of MYC-driven normal and neoplastic B lymphoid cells depends on MNT, a MYC-related transcriptional repressor. Our genetic data establish that MNT synergizes with MYC by suppressing MYC-driven apoptosis, and that it does so primarily by reducing the level of pro-apoptotic BIM. In Eμ-Myc mice, which model the MYC/IGH chromosome translocation in Burkitt's lymphoma, homozygous Mnt deletion greatly reduced lymphoma incidence by enhancing apoptosis and markedly decreasing premalignant B lymphoid cell populations. Strikingly, by inducing Mnt deletion within transplanted fully malignant Eμ-Myc lymphoma cells, we significantly extended transplant recipient survival. The dependency of lymphomas on MNT for survival suggests that drugs inhibiting MNT could significantly boost therapy of MYC-driven tumors by enhancing intrinsic MYC-driven apoptosis.
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19
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Augert A, Mathsyaraja H, Ibrahim AH, Freie B, Geuenich MJ, Cheng PF, Alibeckoff SP, Wu N, Hiatt JB, Basom R, Gazdar A, Sullivan LB, Eisenman RN, MacPherson D. MAX Functions as a Tumor Suppressor and Rewires Metabolism in Small Cell Lung Cancer. Cancer Cell 2020; 38:97-114.e7. [PMID: 32470392 PMCID: PMC7363581 DOI: 10.1016/j.ccell.2020.04.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/14/2020] [Accepted: 04/22/2020] [Indexed: 12/14/2022]
Abstract
Small cell lung cancer (SCLC) is a highly aggressive and lethal neoplasm. To identify candidate tumor suppressors we applied CRISPR/Cas9 gene inactivation screens to a cellular model of early-stage SCLC. Among the top hits was MAX, the obligate heterodimerization partner for MYC family proteins that is mutated in human SCLC. Max deletion increases growth and transformation in cells and dramatically accelerates SCLC progression in an Rb1/Trp53-deleted mouse model. In contrast, deletion of Max abrogates tumorigenesis in MYCL-overexpressing SCLC. Max deletion in SCLC resulted in derepression of metabolic genes involved in serine and one-carbon metabolism. By increasing serine biosynthesis, Max-deleted cells exhibit resistance to serine depletion. Thus, Max loss results in metabolic rewiring and context-specific tumor suppression.
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Affiliation(s)
- Arnaud Augert
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
| | - Haritha Mathsyaraja
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Ali H Ibrahim
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
| | - Brian Freie
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Michael J Geuenich
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Quest University Canada, 3200 University Boulevard, Squamish, BC V8B 0N8, Canada
| | - Pei-Feng Cheng
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Sydney P Alibeckoff
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Nan Wu
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
| | - Joseph B Hiatt
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
| | - Ryan Basom
- Genomics and Bioinformatics Shared Resource, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
| | - Adi Gazdar
- University of Texas, Southwestern, USA, 6000 Harry Hines Boulevard, Dallas, TX 75235, USA
| | - Lucas B Sullivan
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Robert N Eisenman
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | - David MacPherson
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
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20
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Hashiguchi T, Bruss N, Best S, Lam V, Danilova O, Paiva CJ, Wolf J, Gilbert EW, Okada CY, Kaur P, Drew L, Cidado J, Hurlin P, Danilov AV. Cyclin-Dependent Kinase-9 Is a Therapeutic Target in MYC-Expressing Diffuse Large B-Cell Lymphoma. Mol Cancer Ther 2019; 18:1520-1532. [DOI: 10.1158/1535-7163.mct-18-1023] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 12/10/2018] [Accepted: 06/20/2019] [Indexed: 11/16/2022]
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21
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The MYC transcription factor network: balancing metabolism, proliferation and oncogenesis. Front Med 2018; 12:412-425. [PMID: 30054853 PMCID: PMC7358075 DOI: 10.1007/s11684-018-0650-z] [Citation(s) in RCA: 179] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/21/2018] [Indexed: 12/28/2022]
Abstract
Transcription factor networks have evolved in order to control, coordinate, and separate, the functions of distinct network modules spatially and temporally. In this review we focus on the MYC network (also known as the MAX-MLX Network), a highly conserved super-family of related basic-helix-loop-helix-zipper (bHLHZ) proteins that functions to integrate extracellular and intracellular signals and modulate global gene expression. Importantly the MYC network has been shown to be deeply involved in a broad spectrum of human and other animal cancers. Here we summarize molecular and biological properties of the network modules with emphasis on functional interactions among network members. We suggest that these network interactions serve to modulate growth and metabolism at the transcriptional level in order to balance nutrient demand with supply, to maintain growth homeostasis, and to influence cell fate. Moreover, oncogenic activation of MYC and/or loss of a MYC antagonist, results in an imbalance in the activity of the network as a whole, leading to tumor initiation, progression and maintenance.
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22
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Walker CJ, Rush CM, Dama P, O’Hern MJ, Cosgrove CM, Gillespie JL, Zingarelli RA, Smith B, Stein ME, Mutch DG, Shakya R, Chang CW, Selvendiran K, Song JW, Cohn DE, Goodfellow PJ. MAX Mutations in Endometrial Cancer: Clinicopathologic Associations and Recurrent MAX p.His28Arg Functional Characterization. J Natl Cancer Inst 2018; 110:517-526. [PMID: 29155953 PMCID: PMC6279289 DOI: 10.1093/jnci/djx238] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/16/2017] [Accepted: 10/10/2017] [Indexed: 12/30/2022] Open
Abstract
Background Genomic studies have revealed that multiple genes are mutated at varying frequency in endometrial cancer (EC); however, the relevance of many of these mutations is poorly understood. An EC-specific recurrent mutation in the MAX transcription factor p.His28Arg was recently discovered. We sought to assess the functional consequences of this hotspot mutation and determine its association with cancer-relevant phenotypes. Methods MAX was sequenced in 509 endometrioid ECs, and associations between mutation status and clinicopathologic features were assessed. EC cell lines stably expressing MAXH28R were established and used for functional experiments. DNA binding was examined using electrophoretic mobility shift assays and chromatin immunoprecipitation. Transcriptional profiling was performed with microarrays. Murine flank (six to 11 mice per group) and intraperitoneal tumor models were used for in vivo studies. Vascularity of xenografts was assessed by MECA-32 immunohistochemistry. The paracrine pro-angiogenic nature of MAXH28R-expressing EC cells was tested using microfluidic HUVEC sprouting assays and VEGFA enzyme-linked immunosorbent assays. All statistical tests were two-sided. Results Twenty-two of 509 tumors harbored mutations in MAX, including 12 tumors with the p.His28Arg mutation. Patients with a MAX mutation had statistically significantly reduced recurrence-free survival (hazard ratio = 4.00, 95% confidence interval = 1.15 to 13.91, P = .03). MAXH28R increased affinity for canonical E-box sequences, and MAXH28R-expressing EC cells dramatically altered transcriptional profiles. MAXH28R-derived xenografts statistically significantly increased vascular area compared with MAXWT and empty vector tumors (P = .003 and P = .008, respectively). MAXH28R-expressing EC cells secreted nearly double the levels of VEGFA compared with MAXWT cells (P = .03, .005, and .005 at 24, 48, and 72 hours, respectively), and conditioned media from MAXH28R cells increased sprouting when applied to HUVECs. Conclusion These data highlight the importance of MAX mutations in EC and point to increased vascularity as one mechanism contributing to clinical aggressiveness of EC.
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MESH Headings
- Aged
- Aged, 80 and over
- Amino Acid Substitution/genetics
- Animals
- Animals, Outbred Strains
- Arginine/genetics
- Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics
- Carcinoma, Endometrioid/epidemiology
- Carcinoma, Endometrioid/genetics
- Carcinoma, Endometrioid/pathology
- Cells, Cultured
- Codon, Nonsense
- Endometrial Neoplasms/epidemiology
- Endometrial Neoplasms/genetics
- Endometrial Neoplasms/pathology
- Female
- Genetic Association Studies
- Genetic Predisposition to Disease
- HEK293 Cells
- Histidine/genetics
- Humans
- Mice
- Mice, Nude
- Middle Aged
- Neoplasm Invasiveness
- Neovascularization, Pathologic/genetics
- Neovascularization, Pathologic/pathology
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Affiliation(s)
| | - Craig M Rush
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | - Paola Dama
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | - Matthew J O’Hern
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | - Casey M Cosgrove
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | | | - Roman A Zingarelli
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | - Blair Smith
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | - Maggie E Stein
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | - David G Mutch
- Siteman Cancer Center and the Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO
| | | | | | | | - Jonathan W Song
- James Comprehensive Cancer Center
- Department of Mechanical and Aerospace Engineering The Ohio State University, Columbus, OH
| | - David E Cohn
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
| | - Paul J Goodfellow
- James Comprehensive Cancer Center
- Department of Obstetrics and Gynecology
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23
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Schaub FX, Dhankani V, Berger AC, Trivedi M, Richardson AB, Shaw R, Zhao W, Zhang X, Ventura A, Liu Y, Ayer DE, Hurlin PJ, Cherniack AD, Eisenman RN, Bernard B, Grandori C. Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas. Cell Syst 2018; 6:282-300.e2. [PMID: 29596783 PMCID: PMC5892207 DOI: 10.1016/j.cels.2018.03.003] [Citation(s) in RCA: 233] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 02/06/2018] [Accepted: 03/02/2018] [Indexed: 12/19/2022]
Abstract
Although the MYC oncogene has been implicated in cancer, a systematic assessment of alterations of MYC, related transcription factors, and co-regulatory proteins, forming the proximal MYC network (PMN), across human cancers is lacking. Using computational approaches, we define genomic and proteomic features associated with MYC and the PMN across the 33 cancers of The Cancer Genome Atlas. Pan-cancer, 28% of all samples had at least one of the MYC paralogs amplified. In contrast, the MYC antagonists MGA and MNT were the most frequently mutated or deleted members, proposing a role as tumor suppressors. MYC alterations were mutually exclusive with PIK3CA, PTEN, APC, or BRAF alterations, suggesting that MYC is a distinct oncogenic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such as immune response and growth factor signaling; chromatin, translation, and DNA replication/repair were conserved pan-cancer. This analysis reveals insights into MYC biology and is a reference for biomarkers and therapeutics for cancers with alterations of MYC or the PMN.
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Affiliation(s)
- Franz X Schaub
- Cure First, Seattle, WA, USA; SEngine Precision Medicine, Seattle, WA, USA
| | | | - Ashton C Berger
- The Eli and Edythe L. Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA
| | | | | | - Reid Shaw
- SEngine Precision Medicine, Seattle, WA, USA
| | - Wei Zhao
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xiaoyang Zhang
- Dana-Farber Cancer Institute, the Broad Institute of Harvard and MIT, and Harvard Medical School, Boston, MA, USA
| | - Andrea Ventura
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yuexin Liu
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Donald E Ayer
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Peter J Hurlin
- Shriners Hospitals for Children Research Center, Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - Andrew D Cherniack
- Dana-Farber Cancer Institute, the Broad Institute of Harvard and MIT, and Harvard Medical School, Boston, MA, USA
| | - Robert N Eisenman
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Brady Bernard
- Institute for Systems Biology, Seattle, WA, USA; Providence Health and Services, Portland, OR, USA.
| | - Carla Grandori
- Cure First, Seattle, WA, USA; SEngine Precision Medicine, Seattle, WA, USA.
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24
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Campbell KJ, Vandenberg CJ, Anstee NS, Hurlin PJ, Cory S. Mnt modulates Myc-driven lymphomagenesis. Cell Death Differ 2017; 24:2117-2126. [PMID: 28800127 PMCID: PMC5686348 DOI: 10.1038/cdd.2017.131] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 07/06/2017] [Indexed: 12/27/2022] Open
Abstract
The transcriptional represser Mnt is a functional antagonist of the proto-oncoprotein Myc. Both Mnt and Myc utilise Max as an obligate partner for DNA binding, and Myc/Max and Mnt/Max complexes compete for occupancy at E-box DNA sequences in promoter regions. We have previously shown in transgenic mouse models that the phenotype and kinetics of onset of haemopoietic tumours varies with the level of Myc expression. We reasoned that a decrease in the level of Mnt would increase the functional level of Myc and accelerate Myc-driven tumorigenesis. We tested the impact of reduced Mnt in three models of myc transgenic mice and in p53+/- mice. To our surprise, mnt heterozygosity actually slowed Myc-driven tumorigenesis in vavP-MYC10 and Eμ-myc mice, suggesting that Mnt facilitates Myc-driven oncogenesis. To explore the underlying cause of the delay in tumour development, we enumerated Myc-driven cell populations in healthy young vavP-MYC10 and Eμ-myc mice, expecting that the reduced rate of leukaemogenesis in mnt heterozygous mice would be reflected in a reduced number of preleukaemic cells, due to increased apoptosis or reduced proliferation or both. However, no differences were apparent. Furthermore, when mnt+/+ and mnt+/- pre-B cells from healthy young Eμ-myc mice were compared in vitro, no differences were seen in their sensitivity to apoptosis or in cell size or cell cycling. Moreover, the frequencies of apoptotic, senescent and proliferating cells were comparable in vivo in mnt+/- and mnt+/+ Eμ-myc lymphomas. Thus, although mnt heterozygosity clearly slowed lymphomagenesis in vavP-MYC10 and Eμ-myc mice, the change(s) in cellular properties responsible for this effect remain to be identified.
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Affiliation(s)
- Kirsteen J Campbell
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, VIC 3052, Australia
| | - Cassandra J Vandenberg
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Natasha S Anstee
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | | | - Suzanne Cory
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
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25
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Hacker SM, Backus KM, Lazear MR, Forli S, Correia BE, Cravatt BF. Global profiling of lysine reactivity and ligandability in the human proteome. Nat Chem 2017; 9:1181-1190. [PMID: 29168484 DOI: 10.1038/nchem.2826] [Citation(s) in RCA: 283] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 06/07/2017] [Indexed: 12/28/2022]
Abstract
Nucleophilic amino acids make important contributions to protein function, including performing key roles in catalysis and serving as sites for post-translational modification. Electrophilic groups that target amino-acid nucleophiles have been used to create covalent ligands and drugs, but have, so far, been mainly limited to cysteine and serine. Here, we report a chemical proteomic platform for the global and quantitative analysis of lysine residues in native biological systems. We have quantified, in total, more than 9,000 lysines in human cell proteomes and have identified several hundred residues with heightened reactivity that are enriched at protein functional sites and can frequently be targeted by electrophilic small molecules. We have also discovered lysine-reactive fragment electrophiles that inhibit enzymes by active site and allosteric mechanisms, as well as disrupt protein-protein interactions in transcriptional regulatory complexes, emphasizing the broad potential and diverse functional consequences of liganding lysine residues throughout the human proteome.
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Affiliation(s)
- Stephan M Hacker
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92307, USA
| | - Keriann M Backus
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92307, USA
| | - Michael R Lazear
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92307, USA
| | - Stefano Forli
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92307, USA
| | - Bruno E Correia
- Laboratory of Protein Design & Immunoengineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Benjamin F Cravatt
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92307, USA
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26
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Xu J, Li D, Cai Z, Zhang Y, Huang Y, Su B, Ma R. An integrative analysis of DNA methylation in osteosarcoma. J Bone Oncol 2017; 9:34-40. [PMID: 29234590 PMCID: PMC5715438 DOI: 10.1016/j.jbo.2017.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 05/09/2017] [Accepted: 05/12/2017] [Indexed: 01/17/2023] Open
Abstract
Background The study aimed to analyze aberrantly methylated genes, relevant pathways and transcription factors (TFs) in osteosarcoma (OS) development. Methods Based on the DNA methylation microarray data GSE36002 that were downloaded from GEO database, the differentially methylated genes in promoter regions were identified between OS and normal samples. Pathway and function enrichment analyses of differentially methylated genes was performed. Subsequently, protein-protein interaction (PPI) network was constructed, followed by identification of cancer-associated differentially methylated genes and significant differentially methylated TFs. Results A total of 1379 hyper-methylation regions and 169 hypo-methylation regions in promoter regions were identified in OS samples compared to normal samples. The differentially hyper-methylated genes were significantly enriched in Neuroactive ligand-receptor interaction pathway, and Peroxisome proliferator activated receptor (PPAR) signaling pathway. The differentially hypo-methylated genes were significantly enriched in Toll-like receptor signaling pathway. In PPI network, signal transducers and activators of transcription (STAT3) had high degree (degree=21). MAX interactor 1, dimerization protein (MXI1), STAT3 and T-cell acute lymphocytic leukemia 1 (TAL1) were significant TFs enriched with target genes in OS samples. They were found to be cancer-associated and hyper-methylated in OS samples. Conclusion Neuroactive ligand-receptor interaction, PPAR signaling, Toll-like receptor signaling pathways are implicated in OS. MXI1, STAT3, and TAL1 may be important TFs involved in OS development.
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Affiliation(s)
- Jie Xu
- Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Deng Li
- Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Zhiqing Cai
- Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Yingbin Zhang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Yulin Huang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Baohua Su
- Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Ruofan Ma
- Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
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27
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MNT and Emerging Concepts of MNT-MYC Antagonism. Genes (Basel) 2017; 8:genes8020083. [PMID: 28230739 PMCID: PMC5333072 DOI: 10.3390/genes8020083] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 02/16/2017] [Indexed: 12/25/2022] Open
Abstract
MYC family proteins play fundamental roles in stem and progenitor cell homeostasis, morphogenesis and cancer. As expected for proteins that profoundly affect the fate of cells, the activities of MYC are regulated at a multitude of levels. One mechanism with the potential to broadly affect the activities of MYC is transcriptional antagonism by a group of MYC-related transcriptional repressors. From this group, the protein MNT has emerged as having perhaps the most far-reaching impact on MYC activities. In this review, we discuss the current understanding of MNT, its regulation and how, as a MYC antagonist, it functions both as a tumor suppressor and facilitator of MYC-driven proliferation and oncogenesis.
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28
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Stefan E, Bister K. MYC and RAF: Key Effectors in Cellular Signaling and Major Drivers in Human Cancer. Curr Top Microbiol Immunol 2017; 407:117-151. [PMID: 28466200 DOI: 10.1007/82_2017_4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The prototypes of the human MYC and RAF gene families are orthologs of animal proto-oncogenes that were originally identified as transduced alleles in the genomes of highly oncogenic retroviruses. MYC and RAF genes are now established as key regulatory elements in normal cellular physiology, but also as major cancer driver genes. Although the predominantly nuclear MYC proteins and the cytoplasmic RAF proteins have different biochemical functions, they are functionally linked in pivotal signaling cascades and circuits. The MYC protein is a transcription factor and together with its dimerization partner MAX holds a central position in a regulatory network of bHLH-LZ proteins. MYC regulates transcription conducted by all RNA polymerases and controls virtually the entire transcriptome. Fundamental cellular processes including distinct catabolic and anabolic branches of metabolism, cell cycle regulation, cell growth and proliferation, differentiation, stem cell regulation, and apoptosis are under MYC control. Deregulation of MYC expression by rearrangement or amplification of the MYC locus or by defects in kinase-mediated upstream signaling, accompanied by loss of apoptotic checkpoints, leads to tumorigenesis and is a hallmark of most human cancers. The critically controlled serine/threonine RAF kinases are central nodes of the cytoplasmic MAPK signaling cascade transducing converted extracellular signals to the nucleus for reshaping transcription factor controlled gene expression profiles. Specific mutations of RAF kinases, such as the prevalent BRAF(V600E) mutation in melanoma, or defects in upstream signaling or feedback loops cause decoupled kinase activities which lead to tumorigenesis. Different strategies for pharmacological interference with MYC- or RAF-induced tumorigenesis are being developed and several RAF kinase inhibitors are already in clinical use.
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Affiliation(s)
- Eduard Stefan
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | - Klaus Bister
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
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29
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Kapoor I, Kanaujiya J, Kumar Y, Thota JR, Bhatt MLB, Chattopadhyay N, Sanyal S, Trivedi AK. Proteomic discovery of MNT as a novel interacting partner of E3 ubiquitin ligase E6AP and a key mediator of myeloid differentiation. Oncotarget 2016; 7:7640-56. [PMID: 26506232 PMCID: PMC4884944 DOI: 10.18632/oncotarget.6156] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 09/30/2015] [Indexed: 12/31/2022] Open
Abstract
Perturbed stability of regulatory proteins is a major cause of transformations leading to cancer, including several leukemia subtypes. Here, for the first time we demonstrate that E6-associated protein (E6AP), an E3 ubiquitin ligase negatively targets MAX binding protein MNT for ubiquitin-mediated proteasome degradation and impedes ATRA mediated myeloid cell differentiation. MNT is a member of the Myc/Max/Mad network of transcription factor that regulates cell proliferation, differentiation, cellular transformation and tumorigenesis. Wild-type E6AP promoted proteasome dependent degradation of MNT, while catalytically inactive E6AP having cysteine replaced with alanine at amino-acid 843 position (E6APC843A) rather stabilized it. Further, these proteins physically associated with each other both in non-myeloid (HEK293T) and myeloid cells. MNT overexpression induced G0-G1 growth arrest and promoted myeloid differentiation while its knockdown mitigated even ATRA induced differentiation suggesting MNT to be crucial for myeloid differentiation. We further showed that ATRA inhibited E6AP and stabilized MNT expression by protecting it from E6AP mediated ubiquitin-proteasome degradation. Notably, E6AP knockdown in HL60 cells restored MNT expression and promoted myeloid differentiation. Taken together, our data demonstrated that E6AP negatively regulates granulocytic differentiation by targeting MNT for degradation which is required for growth arrest and subsequent myeloid differentiation by various differentiation inducing agents.
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Affiliation(s)
- Isha Kapoor
- Biochemistry Division, CSIR-Central Drug Research Institute, Lucknow, UP, India
| | - Jitendra Kanaujiya
- Biochemistry Division, CSIR-Central Drug Research Institute, Lucknow, UP, India
| | - Yogesh Kumar
- Biochemistry Division, CSIR-Central Drug Research Institute, Lucknow, UP, India
| | | | - Madan L B Bhatt
- Department of Radiotherapy, King George's Medical University, Lucknow, UP, India
| | - Naibedya Chattopadhyay
- Division of Endocrinology and Center for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute (CSIR-CDRI), Lucknow, UP, India
| | - Sabyasachi Sanyal
- Biochemistry Division, CSIR-Central Drug Research Institute, Lucknow, UP, India
| | - Arun Kumar Trivedi
- Biochemistry Division, CSIR-Central Drug Research Institute, Lucknow, UP, India
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30
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Shostak A, Ruppert B, Ha N, Bruns P, Toprak UH, Eils R, Schlesner M, Diernfellner A, Brunner M. MYC/MIZ1-dependent gene repression inversely coordinates the circadian clock with cell cycle and proliferation. Nat Commun 2016; 7:11807. [PMID: 27339797 PMCID: PMC4931031 DOI: 10.1038/ncomms11807] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 04/29/2016] [Indexed: 11/24/2022] Open
Abstract
The circadian clock and the cell cycle are major cellular systems that organize global physiology in temporal fashion. It seems conceivable that the potentially conflicting programs are coordinated. We show here that overexpression of MYC in U2OS cells attenuates the clock and conversely promotes cell proliferation while downregulation of MYC strengthens the clock and reduces proliferation. Inhibition of the circadian clock is crucially dependent on the formation of repressive complexes of MYC with MIZ1 and subsequent downregulation of the core clock genes BMAL1 (ARNTL), CLOCK and NPAS2. We show furthermore that BMAL1 expression levels correlate inversely with MYC levels in 102 human lymphomas. Our data suggest that MYC acts as a master coordinator that inversely modulates the impact of cell cycle and circadian clock on gene expression. The circadian clock and the cell cycle systems coordinate global physiology. Here the authors show that MYC represses the clock genes, together with MIZ1, and induces proliferation, suggesting that MYC inversely modulates cell cycle and circadian clock genes.
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Affiliation(s)
- Anton Shostak
- Heidelberg University, Biochemistry Center, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Bianca Ruppert
- Heidelberg University, Biochemistry Center, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Nati Ha
- Heidelberg University, Biochemistry Center, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Philipp Bruns
- Division Theoretical Bioinformatics (B080), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
| | - Umut H Toprak
- Division Theoretical Bioinformatics (B080), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
| | | | - Roland Eils
- Division Theoretical Bioinformatics (B080), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany.,Department for Bioinformatics and Functional Genomics, Institute for Pharmacy and Molecular Biotechnology (IPMB) and BioQuant, Heidelberg University, Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany
| | - Matthias Schlesner
- Division Theoretical Bioinformatics (B080), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
| | - Axel Diernfellner
- Heidelberg University, Biochemistry Center, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Michael Brunner
- Heidelberg University, Biochemistry Center, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
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31
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Bansal N, David G, Farias E, Waxman S. Emerging Roles of Epigenetic Regulator Sin3 in Cancer. Adv Cancer Res 2016; 130:113-35. [PMID: 27037752 DOI: 10.1016/bs.acr.2016.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Revolutionizing treatment strategies is an urgent clinical need in the fight against cancer. Recently the scientific community has recognized chromatin-associated proteins as promising therapeutic candidates. However, there is a need to develop more targeted epigenetic inhibitors with less toxicity. Sin3 family is one such target which consists of evolutionary conserved proteins with two paralogues Sin3A and Sin3B. Sin3A/B are global transcription regulators that provide a versatile platform for diverse chromatin-modifying activities. Sin3 proteins regulate key cellular functions that include cell cycle, proliferation, and differentiation, and have recently been implicated in cancer pathogenesis. In this chapter, we summarize the key concepts of Sin3 biology and elaborate the recent advancements in the role of Sin3 proteins in cancer with specific examples in multiple endocrine neoplasia type 2, pancreatic ductal adenocarcinoma, and triple negative breast cancer. Finally, a program to create an integrative approach for screening antitumor agents that target chromatin-associated factors like Sin3 is presented.
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Affiliation(s)
- N Bansal
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - G David
- New York University School of Medicine, New York, NY, United States
| | - E Farias
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - S Waxman
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
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32
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Boudjadi S, Carrier JC, Groulx JF, Beaulieu JF. Integrin α1β1 expression is controlled by c-MYC in colorectal cancer cells. Oncogene 2015; 35:1671-8. [PMID: 26096932 PMCID: PMC4820680 DOI: 10.1038/onc.2015.231] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 04/15/2015] [Accepted: 05/10/2015] [Indexed: 12/13/2022]
Abstract
The α1β1 collagen receptor is only present in a few epithelial cell types. In the intestine, it is specifically expressed in proliferating crypt cells. This integrin has been reported to be involved in various cancers where it mediates the downstream activation of the Ras/ERK proliferative pathway. We have recently shown that integrin α1β1 is present in two-thirds of colon adenocarcinomas, but the mechanism by which ITGA1 expression is regulated is not known. DNA methylation, involved in ITGA1 repression during megakaryocyte differentiation, is not the mechanism of ITGA1 regulation in colorectal cancer cells. Our in silico analysis of the ITGA1 promoter revealed two response elements for MYC, an oncogenic factor known to regulate cancer cell proliferation, invasion and migration. In situ, the expressions of both MYC and ITGA1 are localized in the lower crypt of the normal colon and correlate in 72% of the 65 analyzed colorectal cancers. MYC pharmacological inhibition or downregulation of expression with short hairpin RNA in HT29, T84 and SW480 cells resulted in reduced ITGA1 expression at both the transcript and protein levels. Chromatin immunoprecipitation assays revealed that MYC was bound to the chromatin region of the ITGA1 proximal promoter, whereas MYC overexpression enhanced ITGA1 promoter activity that was reduced with MAD co-transfection or by the disruption of the response elements. We concluded that MYC is a key regulating factor for the control of ITGA1 expression.
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Affiliation(s)
- S Boudjadi
- Laboratory of Intestinal Physiopathology, Department of Anatomy and Cell Biology, Université de Sherbrooke, Sherbrooke, QC, Canada.,Department of Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - J C Carrier
- Laboratory of Intestinal Physiopathology, Department of Anatomy and Cell Biology, Université de Sherbrooke, Sherbrooke, QC, Canada.,Department of Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - J-F Groulx
- Laboratory of Intestinal Physiopathology, Department of Anatomy and Cell Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - J-F Beaulieu
- Laboratory of Intestinal Physiopathology, Department of Anatomy and Cell Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
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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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Abstract
SIGNIFICANCE Hypoxia is a hallmark of the tumor microenvironment and represents a major source of failure in cancer therapy. RECENT ADVANCES Recent work has generated extensive evidence that microRNAs (miRNAs) are significant components of the adaptive response to low oxygen in tumors. Induction of specific miRNAs, collectively termed hypoxamiRs, has become an accepted feature of the hypoxic response in normal and transformed cells. CRITICAL ISSUES Overexpression of miR-210, the prototypical hypoxamiR, is detected in most solid tumors, and it has been linked to adverse prognosis in many tumor types. Several miR-210 target genes, including iron-sulfur (Fe-S) cluster scaffold protein (ISCU) and glycerol-3-phosphate dehydrogenase 1-like (GPD1L), have been correlated with prognosis in an inverse fashion to miR-210, suggesting that their down- regulation by miR-210 occurs in vivo and contributes to tumor growth. Additional miRNAs are modulated by decreased oxygen tension in a more tissue-specific fashion, adding another level of complexity over the classic hypoxia-regulated gene network. FUTURE DIRECTIONS From a biological standpoint, hypoxamiRs are emerging modifiers of cancer cell response to the adaptive challenges of the microenvironment. From a clinical perspective, assessing the status of these miRNAs may contribute to a detailed understanding of hypoxia-induced mechanisms of resistance and/or to the fine-tuning of future hypoxia-modifying therapies.
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Affiliation(s)
- Harriet E Gee
- 1 Department of Radiation Oncology, Sydney Cancer Centre, Royal Prince Alfred Hospital , Camperdown, Australia
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N-Myc differentially regulates expression of MXI1 isoforms in neuroblastoma. Neoplasia 2014; 15:1363-70. [PMID: 24403858 DOI: 10.1593/neo.11606] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 12/15/2022] Open
Abstract
Amplification of the MYCN proto-oncogene is associated with a poor prognosis in patients with metastatic neuroblastoma (NB). MYCN encodes the N-Myc protein, a transcriptional regulator that dimerizes with the Max transcription factor, binds to E-box DNA sequences, and regulates genes involved in cell growth and apoptosis. Overexpression of N-Myc leads to transcriptional activation and an increase in NB cell proliferation. Mxi1, a member of the Myc family of transcriptional regulators, also binds to Max. However, Mxi1 is a transcriptional repressor and inhibits proliferation of NB cells, suggesting that Mxi1 functions as an N-Myc antagonist. Our laboratory previously identified Mxi1-0, an alternatively transcribed Mxi1 isoform. Mxi1-0 has properties distinct from those of Mxi1; in contrast to Mxi1, Mxi1-0 is unable to suppress c-Myc-dependent transcription. We now show that Mxi1-0 expression increases in response to MYCN overexpression in NB cells, with a positive correlation between MYCN and MXI1-0 RNA levels. We also show that N-Myc expression differentially regulates the MXI1 and MXI1-0 promoters: Increased MYCN expression suppresses MXI1 promoter activity while enhancing transcription through the MXI1-0 promoter. Finally, induction of Mxi1-0 leads to increased proliferation, whereas expression of Mxi1 inhibits cell growth, indicating differential roles for these two proteins. These data suggest that N-Myc differentially regulates the expression of MXI1 and MXI1-0 and can alter the balance between the two transcription factors. Furthermore, MXI1-0 appears to be a downstream target of MYCN-dependent signaling pathways and may contribute to N-Myc-dependent cell growth and proliferation.
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Sewastianik T, Prochorec-Sobieszek M, Chapuy B, Juszczyński P. MYC deregulation in lymphoid tumors: molecular mechanisms, clinical consequences and therapeutic implications. Biochim Biophys Acta Rev Cancer 2014; 1846:457-67. [PMID: 25199984 DOI: 10.1016/j.bbcan.2014.08.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 08/28/2014] [Accepted: 08/28/2014] [Indexed: 12/24/2022]
Abstract
MYC is one of the most frequently deregulated oncogenes in human malignancies. It encodes a leucine zipper transcription factor that modulates a broad spectrum of cellular genes responsible for enhancing cell proliferation, cellular metabolism, growth, angiogenesis, metastasis, genomic instability, stem cell self-renewal and reduced differentiation. MYC functions predominantly as an amplifier of expression of already active genes, potentiating the pre-existing transcriptional program, although it can also repress certain transcriptional targets. In mouse models, MYC induces lymphomas, but requires cooperation with other lesions, including inactivation of the p53 pathway, structural alterations of BCL2 family members, or increased PI3K activity. In human B-cell tumors, MYC rearrangements involving the 8q24 region and immunoglobulin heavy or light genes are a hallmark of Burkitt lymphoma (BL), but can also occur in other lymphoid malignancies, that include diffuse large B-cell lymphoma (DLBCL), B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma (BCLU), plasma cell myeloma (PCM), mantle cell lymphoma (MCL) and plasmablastic lymphoma. For non-BL lymphoid malignancies, MYC fusions represent secondary genetic events and exist in the context of complex karyotypes. Regardless of the mechanism deregulating MYC, lymphomas over-expressing MYC are addicted to this oncogene, highlighting the potential clinical utility of MYC targeting strategies. Several promising approaches for pharmaceutical intervention have been suggested which are now in preclinical or clinical development. Herein, we therefore review the molecular pathogenetic mechanisms associated with MYC deregulation in human B-cell lymphomas and their implications for therapies targeting MYC.
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Affiliation(s)
- Tomasz Sewastianik
- Institute of Hematology and Transfusion Medicine, Department of Diagnostic Hematology, Indiry Gandhi Str. 14, 02-776 Warsaw, Poland
| | - Monika Prochorec-Sobieszek
- Institute of Hematology and Transfusion Medicine, Department of Diagnostic Hematology, Indiry Gandhi Str. 14, 02-776 Warsaw, Poland
| | - Bjoern Chapuy
- Dana-Farber Cancer Institute, Harvard Medical School, Department of Medical Oncology, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Przemysław Juszczyński
- Institute of Hematology and Transfusion Medicine, Department of Diagnostic Hematology, Indiry Gandhi Str. 14, 02-776 Warsaw, Poland.
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Yang W, Wei J, Guo T, Shen Y, Liu F. Knockdown of miR-210 decreases hypoxic glioma stem cells stemness and radioresistance. Exp Cell Res 2014; 326:22-35. [PMID: 24930954 DOI: 10.1016/j.yexcr.2014.05.022] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 05/16/2014] [Accepted: 05/26/2014] [Indexed: 02/06/2023]
Abstract
Glioma contains abundant hypoxic regions which provide niches to promote the maintenance and expansion of glioma stem cells (GSCs), which are resistant to conventional therapies and responsible for recurrence. Given the fact that miR-210 plays a vital role in cellular adaption to hypoxia and in stem cell survival and stemness maintenance, strategies correcting the aberrantly expressed miR-210 might open up a new therapeutic avenue to hypoxia GSCs. In the present study, to explore the possibility of miR-210 as an effective therapeutic target to hypoxic GSCs, we employed a lentiviral-mediated anti-sense miR-210 gene transfer technique to knockdown miR-210 expression and analyze phenotypic changes in hypoxic U87s and SHG44s cells. We found that hypoxia led to an increased HIF-2α mRNA expression and miR-210 expression in GSCs. Knockdown of miR-210 decreased neurosphere formation capacity, stem cell marker expression and cell viability, and induced differentiation and G0/G1 arrest in hypoxic GSCs by partially rescued Myc antagonist (MNT) protein expression. Knockdown of MNT could reverse the gene expression changes and the growth inhibition resulting from knockdown of miR-210 in hypoxic GSCs. Moreover, knockdown of miR-210 led to increased apoptotic rate and Caspase-3/7 activity and decreased invasive capacity, reactive oxygen species (ROS) and lactate production and radioresistance in hypoxic GSCs. These findings suggest that miR-210 might be a potential therapeutic target to eliminate GSCs located in hypoxic niches.
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Affiliation(s)
- Wei Yang
- Department of Radiobiology, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, No.199 Renai Road, Suzhou 215123, China.
| | - Jing Wei
- Department of Radiobiology, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, No.199 Renai Road, Suzhou 215123, China
| | - Tiantian Guo
- Department of Radiobiology, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, No.199 Renai Road, Suzhou 215123, China
| | - Yueming Shen
- Department of Radiobiology, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, No.199 Renai Road, Suzhou 215123, China
| | - Fenju Liu
- Department of Radiobiology, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, No.199 Renai Road, Suzhou 215123, China
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Link JM, Hurlin PJ. The activities of MYC, MNT and the MAX-interactome in lymphocyte proliferation and oncogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:554-62. [PMID: 24731854 DOI: 10.1016/j.bbagrm.2014.04.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/25/2014] [Accepted: 04/04/2014] [Indexed: 12/29/2022]
Abstract
The MYC family of proteins plays essential roles in embryonic development and in oncogenesis. Efforts over the past 30 years to define the transcriptional activities of MYC and how MYC functions to promote proliferation have produced evolving models of MYC function. One picture that has emerged of MYC and its partner protein MAX is of a transcription factor complex with a seemingly unique ability to stimulate the transcription of genes that are epigenetically poised for transcription and to amplify the transcription of actively transcribed genes. During lymphocyte activation, MYC is upregulated and stimulates a pro-proliferative program in part through the upregulation of a wide variety of metabolic effector genes that facilitate cell growth and cell cycle progression. MYC upregulation simultaneously sensitizes cells to apoptosis and activated lymphocytes and lymphoma cells have pro-survival attributes that allow MYC-driven proliferation to prevail. For example, the MAX-interacting protein MNT is upregulated in activated lymphocytes and was found to protect lymphocytes from MYC-dependent apoptosis. Here we review the activities of MYC, MNT and other MAX interacting proteins in the setting of T and B cell activation and oncogenesis. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.
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Affiliation(s)
- Jason M Link
- Shriners Hospitals for Children Portland, 3101 SW Sam Jackson Park Road, Portland, OR 97239, USA; Knight Cancer Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
| | - Peter J Hurlin
- Shriners Hospitals for Children Portland, 3101 SW Sam Jackson Park Road, Portland, OR 97239, USA; Department of Cell and Developmental Biology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Knight Cancer Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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Huang X, Zuo J. Emerging roles of miR-210 and other non-coding RNAs in the hypoxic response. Acta Biochim Biophys Sin (Shanghai) 2014; 46:220-32. [PMID: 24395300 DOI: 10.1093/abbs/gmt141] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Hypoxia is a key component of the tumor microenvironment and represents a well-documented source of therapeutic failure in clinical oncology. Recent work has provided support for the idea that non-coding RNAs, and in particular, microRNAs, may play important roles in the adaptive response to low oxygen in tumors. Specifically, all published studies agree that the induction of microRNA-210 (miR-210) is a consistent feature of the hypoxic response in both normal and malignant cells. miR-210 is a robust target of hypoxia-inducible factors, and its overexpression has been detected in a variety of diseases with a hypoxic component, including most solid tumors. High levels of miR-210 have been linked to an in vivo hypoxic signature and to adverse prognosis in breast and pancreatic cancer patients. A wide variety of miR-210 targets have been identified, pointing to roles in mitochondrial metabolism, angiogenesis, DNA damage response, apoptosis, and cell survival. Such targets are suspected to affect the development of tumors in multiple ways; therefore, an increased knowledge about miR-210's functions may lead to novel diagnostic and therapeutic approaches in cancer.
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Affiliation(s)
- Xin Huang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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Abstract
MYC dimerizes with MAX to bind DNA, with a preference for the E-box consensus CACGTG and several variant motifs. In cells, MYC binds DNA preferentially within transcriptionally active promoter regions. Although several thousand promoters are bound under physiological (low MYC) conditions, these represent only a fraction of all accessible, active promoters. MYC overexpression-as commonly observed in cancer cells-leads to invasion of virtually all active promoters, as well as of distal enhancer elements. We summarize here what is currently known about the mechanisms that may guide this process. We propose that binding site recognition is determined by low-affinity protein-protein interactions between MYC/MAX dimers and components of the basal transcriptional machinery, other chromatin-associated protein complexes, and/or DNA-bound transcription factors. DNA binding occurs subsequently, without an obligate requirement for sequence recognition. Local DNA scanning then leads to preferential stabilization of the MYC/MAX dimer on high-affinity DNA elements. This model is consistent with the invasion of all active promoters that occurs at elevated MYC levels, but posits that important differences in affinity persist between physiological target sites and the newly invaded elements, which may not all be bound in a productive regulatory mode. The implications of this model for transcriptional control by MYC in normal and cancer cells are discussed in the light of the latest literature.
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Affiliation(s)
- Arianna Sabò
- Center for Genomic Science of IIT@SEMM, Istituto Italiano di Tecnologia, 20139 Milan, Italy
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Conacci-Sorrell M, McFerrin L, Eisenman RN. An overview of MYC and its interactome. Cold Spring Harb Perspect Med 2014; 4:a014357. [PMID: 24384812 DOI: 10.1101/cshperspect.a014357] [Citation(s) in RCA: 304] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This review is intended to provide a broad outline of the biological and molecular functions of MYC as well as of the larger protein network within which MYC operates. We present a view of MYC as a sensor that integrates multiple cellular signals to mediate a broad transcriptional response controlling many aspects of cell behavior. We also describe the larger transcriptional network linked to MYC with emphasis on the MXD family of MYC antagonists. Last, we discuss evidence that the network has evolved for millions of years, dating back to the emergence of animals.
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Ivan M, Huang X. miR-210: fine-tuning the hypoxic response. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 772:205-27. [PMID: 24272361 DOI: 10.1007/978-1-4614-5915-6_10] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hypoxia is a central component of the tumor microenvironment and represents a major source of therapeutic failure in cancer therapy. Recent work has provided a wealth of evidence that noncoding RNAs and, in particular, microRNAs, are significant members of the adaptive response to low oxygen in tumors. All published studies agree that miR-210 specifically is a robust target of hypoxia-inducible factors, and the induction of miR-210 is a consistent characteristic of the hypoxic response in normal and transformed cells. Overexpression of miR-210 is detected in most solid tumors and has been linked to adverse prognosis in patients with soft-tissue sarcoma, breast, head and neck, and pancreatic cancer. A wide variety of miR-210 targets have been identified, pointing to roles in the cell cycle, mitochondrial oxidative metabolism, angiogenesis, DNA damage response, and cell survival. Additional microRNAs seem to be modulated by low oxygen in a more tissue-specific fashion, adding another layer of complexity to the vast array of protein-coding genes regulated by hypoxia.
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Affiliation(s)
- Mircea Ivan
- Department of Medicine, Indiana University, 980 W. Walnut Street Walther Hall, Room C225, Indianapolis, IN, 46202, USA,
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Abstract
Most transcription factors specify the subset of genes that will be actively transcribed in the cell by stimulating transcription initiation at these genes, but MYC has a fundamentally different role. MYC binds E-box sites in the promoters of active genes and stimulates recruitment of the elongation factor P-TEFb and thus transcription elongation. Consequently, rather than specifying the set of genes that will be transcribed in any particular cell, MYC's predominant role is to increase the production of transcripts from active genes. This increase in the transcriptional output of the cell's existing gene expression program, called transcriptional amplification, has a profound effect on proliferation and other behaviors of a broad range of cells. Transcriptional amplification may reduce rate-limiting constraints for tumor cell proliferation and explain MYC's broad oncogenic activity among diverse tissues.
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Affiliation(s)
- Peter B Rahl
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
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Reverse engineering the neuroblastoma regulatory network uncovers MAX as one of the master regulators of tumor progression. PLoS One 2013; 8:e82457. [PMID: 24349289 PMCID: PMC3857773 DOI: 10.1371/journal.pone.0082457] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 10/23/2013] [Indexed: 12/17/2022] Open
Abstract
Neuroblastoma is the most common extracranial tumor and a major cause of infant cancer mortality worldwide. Despite its importance, little is known about its molecular mechanisms. A striking feature of this tumor is its clinical heterogeneity. Possible outcomes range from aggressive invasion to other tissues, causing patient death, to spontaneous disease regression or differentiation into benign ganglioneuromas. Several efforts have been made in order to find tumor progression markers. In this work, we have reconstructed the neuroblastoma regulatory network using an information-theoretic approach in order to find genes involved in tumor progression and that could be used as outcome predictors or as therapeutic targets. We have queried the reconstructed neuroblastoma regulatory network using an aggressive neuroblastoma metastasis gene signature in order to find its master regulators (MRs). MRs expression profiles were then investigated in other neuroblastoma datasets so as to detect possible clinical significance. Our analysis pointed MAX as one of the MRs of neuroblastoma progression. We have found that higher MAX expression correlated with favorable patient outcomes. We have also found that MAX expression and protein levels were increased during neuroblastoma SH-SY5Y cells differentiation. We propose that MAX is involved in neuroblastoma progression, possibly increasing cell differentiation by means of regulating the availability of MYC:MAX heterodimers. This mechanism is consistent with the results found in our SH-SY5Y differentiation protocol, suggesting that MAX has a more central role in these cells differentiation than previously reported. Overexpression of MAX has been identified as anti-tumorigenic in other works, but, to our knowledge, this is the first time that the link between the expression of this gene and malignancy was verified under physiological conditions.
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Abstract
The study of MYC has led to pivotal discoveries in cancer biology, induced pluripotency, and transcriptional regulation. In this review, continuing advances in our understanding of the function of MYC as a transcription factor and how its transcriptional activity controls normal vertebrate development and contributes to developmental disorders is discussed.
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Affiliation(s)
- Peter J Hurlin
- Shriners Hospitals for Children Portland, Portland, Oregon 97239
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46
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Yang W, Wei J, Sun T, Liu F. Effects of knockdown of miR-210 in combination with ionizing radiation on human hepatoma xenograft in nude mice. Radiat Oncol 2013; 8:102. [PMID: 23618526 PMCID: PMC3661404 DOI: 10.1186/1748-717x-8-102] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 04/23/2013] [Indexed: 12/17/2022] Open
Abstract
Background Solid tumors usually develop local hypoxia, which renders them resilient to radiotherapy. MiR-210 is the most consistently and robustly induced miRNA under hypoxia and functions as a micro-controller of a wide range of cellular responses to hypoxia. Hence, it is important to investigate the effect of knockdown of miR-210 in tumorigenesis and evaluate the efficacy of knockdown of miR-210 in combination with radiotherapy on human tumor xenograft in nude mice. Materials and methods SMMC-7721 Cells with stable integration of the anti-sense miR-210 were generated through lentiviral-mediated gene transfer and were subcutaneously implanted into nude mice. Mice were monitored for tumor growth and survival after radiotherapy. MiR-210 expression in tumor tissues was assessed by real-time Reverse transcription-Polymerase Chain Reaction (RT-PCR). Protein expression of HIF-1α and miR-210 targeted genes in human hepatoma xenograft was assessed by Western blot. Tumors were analyzed for proliferation, apoptosis, and angiogenesis biomarkers by immunohistochemistry staining. Results Tumor growth was delayed in miR-210 downregulated xenograft. Knockdown of miR-210 increased protein expression of miR-210 targeted genes, but decreased HIF-1α protein in hepatoma xenograft. Knockdown of miR-210 in combination with radiotherapy is more effective than radiotherapy alone or miR-210 knockdown therapy alone in suppressing tumor growth and extending survival duration. Combined therapy decreased Ki-67-positive cells and CD31-positive cells and increased TUNEL-positive cells in tumor xenograft. Conclusions Knockdown of miR-210 in combination with radiotherapy showed an enhanced anti-tumor effect on human hepatoma xenograft. Our experiments demonstrated specific inhibition of miR-210 expression might be a means to enhance the effectiveness of radiotherapy to human hepatoma.
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Affiliation(s)
- Wei Yang
- Department of Radiobiology, School of Radiological Medicine and Protection, Soochow University, No, 199 Renai Road, Suzhou 215123, China.
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A repressor protein, Mnt, is a novel negative regulator of vascular smooth muscle cell hypertrophy by angiotensin II and neointimal hyperplasia by arterial injury. Atherosclerosis 2013; 228:90-3. [PMID: 23535568 DOI: 10.1016/j.atherosclerosis.2013.02.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 02/08/2013] [Accepted: 02/25/2013] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The Max-interacting protein Mnt is a transcriptional repressor that can antagonize the transcriptional and proliferation-related activities of Myc. Here, we tested the hypothesis that Mnt is a negative regulator of pathological vascular remodeling. METHODS Adenovirus encoding Mnt or control GFP was infected to cultured rat vascular smooth muscle cells (VSMC) and carotid arteries after a balloon angioplasty. RESULTS In VSMC, adenoviral gene transfer of Mnt suppressed angiotensin II-induced protein expression of early growth response protein-1 (Egr1) and its promoter activation. Mnt adenovirus did not interfere with upstream signaling of angiotensin II. Angiotensin II-induced protein accumulation in VSMC was inhibited by Mnt adenovirus. Mnt adenovirus also inhibited platelet-derived growth factor-induced VSMC proliferation. Moreover, Mnt adenovirus prevented neointima formation in response to arterial injury. The adenoviral Mnt gene transfer also prevented Egr1 induction in neointima. CONCLUSION These data identify Mnt as a previously unrecognized negative regulator of pathological vascular remodeling.
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High-resolution genomic profiling of chronic lymphocytic leukemia reveals new recurrent genomic alterations. Blood 2012; 120:4783-94. [DOI: 10.1182/blood-2012-04-423517] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Abstract
To identify genomic alterations in chronic lymphocytic leukemia (CLL), we performed single-nucleotide polymorphism–array analysis using Affymetrix Version 6.0 on 353 samples from untreated patients entered in the CLL8 treatment trial. Based on paired-sample analysis (n = 144), a mean of 1.8 copy number alterations per patient were identified; approximately 60% of patients carried no copy number alterations other than those detected by fluorescence in situ hybridization analysis. Copy-neutral loss-of-heterozygosity was detected in 6% of CLL patients and was found most frequently on 13q, 17p, and 11q. Minimally deleted regions were refined on 13q14 (deleted in 61% of patients) to the DLEU1 and DLEU2 genes, on 11q22.3 (27% of patients) to ATM, on 2p16.1-2p15 (gained in 7% of patients) to a 1.9-Mb fragment containing 9 genes, and on 8q24.21 (5% of patients) to a segment 486 kb proximal to the MYC locus. 13q deletions exhibited proximal and distal breakpoint cluster regions. Among the most common novel lesions were deletions at 15q15.1 (4% of patients), with the smallest deletion (70.48 kb) found in the MGA locus. Sequence analysis of MGA in 59 samples revealed a truncating mutation in one CLL patient lacking a 15q deletion. MNT at 17p13.3, which in addition to MGA and MYC encodes for the network of MAX-interacting proteins, was also deleted recurrently.
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A critical role for Mnt in Myc-driven T-cell proliferation and oncogenesis. Proc Natl Acad Sci U S A 2012; 109:19685-90. [PMID: 23150551 DOI: 10.1073/pnas.1206406109] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mnt (Max's next tango) is a Max-interacting transcriptional repressor that can antagonize both the proproliferative and proapoptotic functions of Myc in vitro. To ascertain the physiologically relevant functions of Mnt and to help define the relationship between Mnt and Myc in vivo, we generated a series of mouse strains in which Mnt was deleted in T cells in the absence of endogenous c-Myc or in the presence of ectopic c-Myc. We found that apoptosis caused by loss of Mnt did not require Myc but that ectopic Myc expression dramatically decreased the survival of both Mnt-deficient T cells in vivo and Mnt-deficient MEFs in vitro. Consequently, Myc-driven proliferative expansion of T cells in vitro and thymoma formation in vivo were prevented by the absence of Mnt. Consistent with T-cell models, mouse embryo fibroblasts (MEFs) lacking Mnt were refractory to oncogenic transformation by Myc. Tumor suppression caused by loss of Mnt was linked to increased apoptosis mediated by reactive oxygen species (ROS). Thus, although theoretically and experimentally a Myc antagonist, the dominant physiological role of Mnt appears to be suppression of apoptosis. Our results redefine the physiological relationship between Mnt and Myc and requirements for Myc-driven oncogenesis.
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Regulatory switch enforced by basic helix-loop-helix and ACT-domain mediated dimerizations of the maize transcription factor R. Proc Natl Acad Sci U S A 2012; 109:E2091-7. [PMID: 22778424 DOI: 10.1073/pnas.1205513109] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The maize R2R3-MYB regulator C1 cooperates with the basic helix-loop-helix (bHLH) factor R to activate the expression of anthocyanin biosynthetic genes coordinately. As is the case for other bHLH factors, R harbors several protein-protein interaction domains. Here we show that not the classical but rather a briefly extended R bHLH region forms homodimers that bind canonical G-box DNA motifs. This bHLH DNA-binding activity is abolished if the C-terminal ACT (aspartokinase, chorismate, and TyrA) domain is licensed to homodimerize. Then the bHLH remains in the monomeric form, allowing it to interact with R-interacting factor 1 (RIF1). In this configuration, the R-RIF1 complex is recruited to the promoters of a subset of anthocyanin biosynthetic genes, such as A1, through the interaction with its MYB partner C1. If, however, the ACT domain remains monomeric, the bHLH region dimerizes and binds to G-boxes present in several anthocyanin genes, such as Bz1. Our results provide a mechanism by which a dimerization domain in a bHLH factor behaves as a switch that permits distinct configurations of a regulatory complex to be tethered to different promoters. Such a combinatorial gene regulatory framework provides one mechanism by which genes lacking obviously conserved cis-regulatory elements are regulated coordinately.
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