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Mainwaring OJ, Weishaupt H, Zhao M, Rosén G, Borgenvik A, Breinschmid L, Verbaan AD, Richardson S, Thompson D, Clifford SC, Hill RM, Annusver K, Sundström A, Holmberg KO, Kasper M, Hutter S, Swartling FJ. ARF suppression by MYC but not MYCN confers increased malignancy of aggressive pediatric brain tumors. Nat Commun 2023; 14:1221. [PMID: 36869047 PMCID: PMC9984535 DOI: 10.1038/s41467-023-36847-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 02/20/2023] [Indexed: 03/05/2023] Open
Abstract
Medulloblastoma, the most common malignant pediatric brain tumor, often harbors MYC amplifications. Compared to high-grade gliomas, MYC-amplified medulloblastomas often show increased photoreceptor activity and arise in the presence of a functional ARF/p53 suppressor pathway. Here, we generate an immunocompetent transgenic mouse model with regulatable MYC that develop clonal tumors that molecularly resemble photoreceptor-positive Group 3 medulloblastoma. Compared to MYCN-expressing brain tumors driven from the same promoter, pronounced ARF silencing is present in our MYC-expressing model and in human medulloblastoma. While partial Arf suppression causes increased malignancy in MYCN-expressing tumors, complete Arf depletion promotes photoreceptor-negative high-grade glioma formation. Computational models and clinical data further identify drugs targeting MYC-driven tumors with a suppressed but functional ARF pathway. We show that the HSP90 inhibitor, Onalespib, significantly targets MYC-driven but not MYCN-driven tumors in an ARF-dependent manner. The treatment increases cell death in synergy with cisplatin and demonstrates potential for targeting MYC-driven medulloblastoma.
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Affiliation(s)
- Oliver J Mainwaring
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Holger Weishaupt
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Miao Zhao
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Gabriela Rosén
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Anna Borgenvik
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Laura Breinschmid
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Annemieke D Verbaan
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Stacey Richardson
- Wolfson Childhood Cancer Research Centre, Translational and Clinical Research Institute, Newcastle University Centre for Cancer, Newcastle upon Tyne, NE1 7RU, UK
| | - Dean Thompson
- Wolfson Childhood Cancer Research Centre, Translational and Clinical Research Institute, Newcastle University Centre for Cancer, Newcastle upon Tyne, NE1 7RU, UK
| | - Steven C Clifford
- Wolfson Childhood Cancer Research Centre, Translational and Clinical Research Institute, Newcastle University Centre for Cancer, Newcastle upon Tyne, NE1 7RU, UK
| | - Rebecca M Hill
- Wolfson Childhood Cancer Research Centre, Translational and Clinical Research Institute, Newcastle University Centre for Cancer, Newcastle upon Tyne, NE1 7RU, UK
| | - Karl Annusver
- Department of Cell and Molecular Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Anders Sundström
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Karl O Holmberg
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Maria Kasper
- Department of Cell and Molecular Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Sonja Hutter
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Fredrik J Swartling
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
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2
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Montano E, Pollice A, Lucci V, Falco G, Affinito O, La Mantia G, Vivo M, Angrisano T. Pancreatic Progenitor Commitment Is Marked by an Increase in Ink4a/Arf Expression. Biomolecules 2021; 11:biom11081124. [PMID: 34439790 PMCID: PMC8392192 DOI: 10.3390/biom11081124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/20/2021] [Accepted: 07/28/2021] [Indexed: 01/06/2023] Open
Abstract
The identification of the molecular mechanisms controlling early cell fate decisions in mammals is of paramount importance as the ability to determine specific lineage differentiation represents a significant opportunity for new therapies. Pancreatic Progenitor Cells (PPCs) constitute a regenerative reserve essential for the maintenance and regeneration of the pancreas. Besides, PPCs represent an excellent model for understanding pathological pancreatic cellular remodeling. Given the lack of valid markers of early endoderm, the identification of new ones is of fundamental importance. Both products of the Ink4a/Arf locus, in addition to being critical cell-cycle regulators, appear to be involved in several disease pathologies. Moreover, the locus' expression is epigenetically regulated in ES reprogramming processes, thus constituting the ideal candidates to modulate PPCs homeostasis. In this study, starting from mouse embryonic stem cells (mESCs), we analyzed the early stages of pancreatic commitment. By inducing mESCs commitment to the pancreatic lineage, we observed that both products of the Cdkn2a locus, Ink4a and Arf, mark a naïve pancreatic cellular state that resembled PPC-like specification. Treatment with epi-drugs suggests a role for chromatin remodeling in the CDKN2a (Cycline Dependent Kinase Inhibitor 2A) locus regulation in line with previous observations in other cellular systems. Our data considerably improve the comprehension of pancreatic cellular ontogeny, which could be critical for implementing pluripotent stem cells programming and reprogramming toward pancreatic lineage commitment.
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Affiliation(s)
- Elena Montano
- Department of Biology, University of Naples “Federico II”, 80147 Naples, Italy; (E.M.); (A.P.); (V.L.); (G.F.); (G.L.M.)
| | - Alessandra Pollice
- Department of Biology, University of Naples “Federico II”, 80147 Naples, Italy; (E.M.); (A.P.); (V.L.); (G.F.); (G.L.M.)
| | - Valeria Lucci
- Department of Biology, University of Naples “Federico II”, 80147 Naples, Italy; (E.M.); (A.P.); (V.L.); (G.F.); (G.L.M.)
- Department of Nuclear Medicine, IRCCS—Referral Cancer Center of Basilicata (CROB), 85028 Rionero in Vulture, Italy
| | - Geppino Falco
- Department of Biology, University of Naples “Federico II”, 80147 Naples, Italy; (E.M.); (A.P.); (V.L.); (G.F.); (G.L.M.)
- Department of Nuclear Medicine, IRCCS—Referral Cancer Center of Basilicata (CROB), 85028 Rionero in Vulture, Italy
- Biogem Scarl, Istituto di Ricerche Genetiche “Gaetano Salvatore”, 83031 Ariano Irpino, Italy
| | | | - Girolama La Mantia
- Department of Biology, University of Naples “Federico II”, 80147 Naples, Italy; (E.M.); (A.P.); (V.L.); (G.F.); (G.L.M.)
| | - Maria Vivo
- Department of Chemistry and Biology, University of Salerno, 84084 Fisciano, Italy
- Correspondence: (M.V.); (T.A.); Tel.: +39-081-679721 (T.A.)
| | - Tiziana Angrisano
- Department of Biology, University of Naples “Federico II”, 80147 Naples, Italy; (E.M.); (A.P.); (V.L.); (G.F.); (G.L.M.)
- Correspondence: (M.V.); (T.A.); Tel.: +39-081-679721 (T.A.)
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3
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Timmerman DM, Remmers TL, Hillenius S, Looijenga LHJ. Mechanisms of TP53 Pathway Inactivation in Embryonic and Somatic Cells-Relevance for Understanding (Germ Cell) Tumorigenesis. Int J Mol Sci 2021; 22:ijms22105377. [PMID: 34065345 PMCID: PMC8161298 DOI: 10.3390/ijms22105377] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/14/2021] [Accepted: 05/15/2021] [Indexed: 01/10/2023] Open
Abstract
The P53 pathway is the most important cellular pathway to maintain genomic and cellular integrity, both in embryonic and non-embryonic cells. Stress signals induce its activation, initiating autophagy or cell cycle arrest to enable DNA repair. The persistence of these signals causes either senescence or apoptosis. Over 50% of all solid tumors harbor mutations in TP53 that inactivate the pathway. The remaining cancers are suggested to harbor mutations in genes that regulate the P53 pathway such as its inhibitors Mouse Double Minute 2 and 4 (MDM2 and MDM4, respectively). Many reviews have already been dedicated to P53, MDM2, and MDM4, while this review additionally focuses on the other factors that can deregulate P53 signaling. We discuss that P14ARF (ARF) functions as a negative regulator of MDM2, explaining the frequent loss of ARF detected in cancers. The long non-coding RNA Antisense Non-coding RNA in the INK4 Locus (ANRIL) is encoded on the same locus as ARF, inhibiting ARF expression, thus contributing to the process of tumorigenesis. Mutations in tripartite motif (TRIM) proteins deregulate P53 signaling through their ubiquitin ligase activity. Several microRNAs (miRNAs) inactivate the P53 pathway through inhibition of translation. CCCTC-binding factor (CTCF) maintains an open chromatin structure at the TP53 locus, explaining its inactivation of CTCF during tumorigenesis. P21, a downstream effector of P53, has been found to be deregulated in different tumor types. This review provides a comprehensive overview of these factors that are known to deregulate the P53 pathway in both somatic and embryonic cells, as well as their malignant counterparts (i.e., somatic and germ cell tumors). It provides insights into which aspects still need to be unraveled to grasp their contribution to tumorigenesis, putatively leading to novel targets for effective cancer therapies.
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4
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Kon N, Churchill M, Li H, Mukherjee S, Manfredi JJ, Gu W. Robust p53 Stabilization Is Dispensable for Its Activation and Tumor Suppressor Function. Cancer Res 2021; 81:935-944. [PMID: 33323382 PMCID: PMC8026563 DOI: 10.1158/0008-5472.can-20-1804] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 11/06/2020] [Accepted: 12/10/2020] [Indexed: 11/16/2022]
Abstract
p53 is a short-lived protein with low basal levels under normal homeostasis conditions. However, upon DNA damage, levels of p53 dramatically increase for its activation. Although robust stabilization of p53 serves as a "trademark" for DNA damage responses, the requirement for such dramatic protein stabilization in tumor suppression has not been well addressed. Here we generated a mutant p53KQ mouse where all the C-terminal domain lysine residues were mutated to glutamines (K to Q mutations at K367, K369, K370, K378, K379, K383, and K384) to mimic constitutive acetylation of the p53 C-terminus. Because of p53 activation, p53KQ/KQ mice were perinatal lethal, yet this lethality was averted in p53KQ/- mice, which displayed normal postnatal development. Nevertheless, p53KQ/- mice died prematurely due to anemia and hematopoiesis failure. Further analyses indicated that expression of the acetylation-mimicking p53 mutant in vivo induces activation of p53 targets in various tissues without obviously increasing p53 levels. In the well-established pancreatic ductal adenocarcinoma (PDAC) mouse model, expression of the acetylation-mimicking p53-mutant protein effectively suppressed K-Ras-induced PDAC development in the absence of robust p53 stabilization. Together, our results provide proof-of-principle evidence that p53-mediated transcriptional function and tumor suppression can be achieved independently of its robust stabilization and reveal an alternative approach to activate p53 function for therapeutic purposes. SIGNIFICANCE: Although robust p53 stabilization is critical for acute p53 responses such as DNA damage, this study underscores the important role of low basal p53 protein levels in p53 activation and tumor suppression.
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Affiliation(s)
- Ning Kon
- Institute for Cancer Genetics, Department of Pathology and Cell Biology, and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - Michael Churchill
- Department of Medicine and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - Huan Li
- Institute for Cancer Genetics, Department of Pathology and Cell Biology, and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - Siddhartha Mukherjee
- Department of Medicine and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - James J Manfredi
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Wei Gu
- Institute for Cancer Genetics, Department of Pathology and Cell Biology, and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York.
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5
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Non-Canonical Functions of the ARF Tumor Suppressor in Development and Tumorigenesis. Biomolecules 2021; 11:biom11010086. [PMID: 33445626 PMCID: PMC7827855 DOI: 10.3390/biom11010086] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/02/2021] [Accepted: 01/04/2021] [Indexed: 12/12/2022] Open
Abstract
P14ARF (ARF; Alternative Reading Frame) is an extensively characterized tumor suppressor which, in response to oncogenic stimuli, mediates cell cycle arrest and apoptosis via p53-dependent and independent routes. ARF has been shown to be frequently lost through CpG island promoter methylation in a wide spectrum of human malignancies, such as colorectal, prostate, breast, and gastric cancers, while point mutations and deletions in the p14ARF locus have been linked with various forms of melanomas and glioblastomas. Although ARF has been mostly studied in the context of tumorigenesis, it has been also implicated in purely developmental processes, such as spermatogenesis, and mammary gland and ocular development, while it has been additionally involved in the regulation of angiogenesis. Moreover, ARF has been found to hold important roles in stem cell self-renewal and differentiation. As is often the case with tumor suppressors, ARF functions as a pleiotropic protein regulating a number of different mechanisms at the crossroad of development and tumorigenesis. Here, we provide an overview of the non-canonical functions of ARF in cancer and developmental biology, by dissecting the crosstalk of ARF signaling with key oncogenic and developmental pathways.
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6
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Post-Translational Regulation of ARF: Perspective in Cancer. Biomolecules 2020; 10:biom10081143. [PMID: 32759846 PMCID: PMC7465197 DOI: 10.3390/biom10081143] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/25/2020] [Accepted: 07/29/2020] [Indexed: 02/07/2023] Open
Abstract
Tumorigenesis can be induced by various stresses that cause aberrant DNA mutations and unhindered cell proliferation. Under such conditions, normal cells autonomously induce defense mechanisms, thereby stimulating tumor suppressor activation. ARF, encoded by the CDKN2a locus, is one of the most frequently mutated or deleted tumor suppressors in human cancer. The safeguard roles of ARF in tumorigenesis are mainly mediated via the MDM2-p53 axis, which plays a prominent role in tumor suppression. Under normal conditions, low p53 expression is stringently regulated by its target gene, MDM2 E3 ligase, which induces p53 degradation in a ubiquitin-proteasome-dependent manner. Oncogenic signals induced by MYC, RAS, and E2Fs trap MDM2 in the inhibited state by inducing ARF expression as a safeguard measure, thereby activating the tumor-suppressive function of p53. In addition to the MDM2-p53 axis, ARF can also interact with diverse proteins and regulate various cellular functions, such as cellular senescence, apoptosis, and anoikis, in a p53-independent manner. As the evidence indicating ARF as a key tumor suppressor has been accumulated, there is growing evidence that ARF is sophisticatedly fine-tuned by the diverse factors through transcriptional and post-translational regulatory mechanisms. In this review, we mainly focused on how cancer cells employ transcriptional and post-translational regulatory mechanisms to manipulate ARF activities to circumvent the tumor-suppressive function of ARF. We further discussed the clinical implications of ARF in human cancer.
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7
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Rhodes SD, He Y, Smith A, Jiang L, Lu Q, Mund J, Li X, Bessler W, Qian S, Dyer W, Sandusky GE, Horvai AE, Armstrong AE, Clapp DW. Cdkn2a (Arf) loss drives NF1-associated atypical neurofibroma and malignant transformation. Hum Mol Genet 2020; 28:2752-2762. [PMID: 31091306 DOI: 10.1093/hmg/ddz095] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/15/2019] [Accepted: 05/06/2019] [Indexed: 02/06/2023] Open
Abstract
Plexiform neurofibroma (PN) tumors are a hallmark manifestation of neurofibromatosis type 1 (NF1) that arise in the Schwann cell (SC) lineage. NF1 is a common heritable cancer predisposition syndrome caused by germline mutations in the NF1 tumor suppressor, which encodes a GTPase-activating protein called neurofibromin that negatively regulates Ras proteins. Whereas most PN are clinically indolent, a subset progress to atypical neurofibromatous neoplasms of uncertain biologic potential (ANNUBP) and/or to malignant peripheral nerve sheath tumors (MPNSTs). In small clinical series, loss of 9p21.3, which includes the CDKN2A locus, has been associated with the genesis of ANNUBP. Here we show that the Cdkn2a alternate reading frame (Arf) serves as a gatekeeper tumor suppressor in mice that prevents PN progression by inducing senescence-mediated growth arrest in aberrantly proliferating Nf1-/- SC. Conditional ablation of Nf1 and Arf in the neural crest-derived SC lineage allows escape from senescence, resulting in tumors that accurately phenocopy human ANNUBP and progress to MPNST with high penetrance. This animal model will serve as a platform to study the clonal development of ANNUBP and MPNST and to identify new therapies to treat existing tumors and to prevent disease progression.
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Affiliation(s)
- Steven D Rhodes
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA.,Division of Pediatric Hematology-Oncology, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Yongzheng He
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Abbi Smith
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Li Jiang
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Qingbo Lu
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Julie Mund
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Xiaohong Li
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Waylan Bessler
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Shaomin Qian
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - William Dyer
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - George E Sandusky
- Department of Pathology, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - Andrew E Horvai
- Department of Pathology and Laboratory Medicine, University of California, San Francisco, 94143, USA
| | - Amy E Armstrong
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA.,Division of Pediatric Hematology-Oncology, Indiana University School of Medicine, Indianapolis, 46202, USA
| | - D Wade Clapp
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, 46202, USA
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8
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Palmer N, Talib SZA, Kaldis P. Diverse roles for CDK-associated activity during spermatogenesis. FEBS Lett 2019; 593:2925-2949. [PMID: 31566717 PMCID: PMC6900092 DOI: 10.1002/1873-3468.13627] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/20/2019] [Accepted: 09/26/2019] [Indexed: 12/22/2022]
Abstract
The primary function of cyclin-dependent kinases (CDKs) in complex with their activating cyclin partners is to promote mitotic division in somatic cells. This canonical cell cycle-associated activity is also crucial for fertility as it allows the proliferation and differentiation of stem cells within the reproductive organs to generate meiotically competent cells. Intriguingly, several CDKs exhibit meiosis-specific functions and are essential for the completion of the two reductional meiotic divisions required to generate haploid gametes. These meiosis-specific functions are mediated by both known CDK/cyclin complexes and meiosis-specific CDK-regulators and are important for a variety of processes during meiotic prophase. The majority of meiotic defects observed upon deletion of these proteins occur during the extended prophase I of the first meiotic division. Importantly a lack of redundancy is seen within the meiotic arrest phenotypes described for many of these proteins, suggesting intricate layers of cell cycle control are required for normal meiotic progression. Using the process of male germ cell development (spermatogenesis) as a reference, this review seeks to highlight the diverse roles of selected CDKs their activators, and their regulators during gametogenesis.
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Affiliation(s)
- Nathan Palmer
- Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Singapore, Singapore.,Department of Biochemistry, National University of Singapore (NUS), Singapore, Singapore
| | - S Zakiah A Talib
- Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Philipp Kaldis
- Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Singapore, Singapore.,Department of Biochemistry, National University of Singapore (NUS), Singapore, Singapore.,Department of Clinical Sciences, Clinical Research Centre (CRC), Lund University, Malmö, Sweden
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9
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Fontana R, Ranieri M, La Mantia G, Vivo M. Dual Role of the Alternative Reading Frame ARF Protein in Cancer. Biomolecules 2019; 9:E87. [PMID: 30836703 PMCID: PMC6468759 DOI: 10.3390/biom9030087] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 02/07/2023] Open
Abstract
The CDKN2a/ARF locus expresses two partially overlapping transcripts that encode two distinct proteins, namely p14ARF (p19Arf in mouse) and p16INK4a, which present no sequence identity. Initial data obtained in mice showed that both proteins are potent tumor suppressors. In line with a tumor-suppressive role, ARF-deficient mice develop lymphomas, sarcomas, and adenocarcinomas, with a median survival rate of one year of age. In humans, the importance of ARF inactivation in cancer is less clear whereas a more obvious role has been documented for p16INK4a. Indeed, many alterations in human tumors result in the elimination of the entire locus, while the majority of point mutations affect p16INK4a. Nevertheless, specific mutations of p14ARF have been described in different types of human cancers such as colorectal and gastric carcinomas, melanoma and glioblastoma. The activity of the tumor suppressor ARF has been shown to rely on both p53-dependent and independent functions. However, novel data collected in the last years has challenged the traditional and established role of this protein as a tumor suppressor. In particular, tumors retaining ARF expression evolve to metastatic and invasive phenotypes and in humans are associated with a poor prognosis. In this review, the recent evidence and the molecular mechanisms of a novel role played by ARF will be presented and discussed, both in pathological and physiological contexts.
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Affiliation(s)
- Rosa Fontana
- Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Michela Ranieri
- Division of Hematology and Medical Oncology, Laura and Isaac Perlmutter Cancer Center, NYU Langone Medical Center, New York, NY 10016, USA.
| | - Girolama La Mantia
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy.
| | - Maria Vivo
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy.
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10
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Ezh2 programs T FH differentiation by integrating phosphorylation-dependent activation of Bcl6 and polycomb-dependent repression of p19Arf. Nat Commun 2018; 9:5452. [PMID: 30575739 PMCID: PMC6303346 DOI: 10.1038/s41467-018-07853-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 11/28/2018] [Indexed: 02/02/2023] Open
Abstract
Ezh2 is an histone methyltransferase (HMT) that catalyzes H3K27me3 and functions in TH1, TH2, and Treg cells primarily via HMT activity. Here we show that Ezh2 ablation impairs T follicular helper (TFH) cell differentiation and activation of the TFH transcription program. In TFH cells, most Ezh2-occupied genomic sites, including the Bcl6 promoter, are associated with H3K27ac rather than H3K27me3. Mechanistically, Ezh2 is recruited by Tcf1 to directly activate Bcl6 transcription, with this function requiring Ezh2 phosphorylation at Ser21. Meanwhile, Ezh2 deploys H3K27me3 to repress Cdkn2a expression in TFH cells, where aberrantly upregulated p19Arf, a Cdkn2a protein product, triggers TFH cell apoptosis and antagonizes Bcl6 function via protein-protein interaction. Either forced expression of Bcl6 or genetic ablation of p19Arf in Ezh2-deficient cells improves TFH cell differentiation and helper function. Thus, Ezh2 orchestrates TFH-lineage specification and function maturation by integrating phosphorylation-dependent transcriptional activation and HMT-dependent gene repression. Ezh2 is an histone methyltransferase that catalyzes H3K27me3. Here the authors show that Ezh2 promotes T follicular helper (TFH) differentiation and helper activity, by cooperating with Tcf1 to activate Bcl6 transcription and epigenetically repressing p19Arf, an antagonist of Bcl6 function and TFH cell survival.
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11
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PKC Dependent p14ARF Phosphorylation on Threonine 8 Drives Cell Proliferation. Sci Rep 2018; 8:7056. [PMID: 29728595 PMCID: PMC5935756 DOI: 10.1038/s41598-018-25496-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 04/24/2018] [Indexed: 01/11/2023] Open
Abstract
ARF role as tumor suppressor has been challenged in the last years by several findings of different groups ultimately showing that its functions can be strictly context dependent. We previously showed that ARF loss in HeLa cells induces spreading defects, evident as rounded morphology of depleted cells, accompanied by a decrease of phosphorylated Focal Adhesion Kinase (FAK) protein levels and anoikis. These data, together with previous finding that a PKC dependent signalling pathway can lead to ARF stabilization, led us to the hypothesis that ARF functions in cell proliferation might be regulated by phosphorylation. In line with this, we show here that upon spreading ARF is induced through PKC activation. A constitutive-phosphorylated ARF mutant on the conserved threonine 8 (T8D) is able to mediate both cell spreading and FAK activation. Finally, ARF-T8D expression confers growth advantage to cells thus leading to the intriguing hypothesis that ARF phosphorylation could be a mechanism through which pro-proliferative or anti proliferative signals could be transduced inside the cells in both physiological and pathological conditions.
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12
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Xie V, Tong D, Wallington-Beddoe CT, Bradstock KF, Bendall LJ. Sphingosine kinase 2 supports the development of BCR/ABL-independent acute lymphoblastic leukemia in mice. Biomark Res 2018; 6:6. [PMID: 29441205 PMCID: PMC5800079 DOI: 10.1186/s40364-018-0120-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 01/30/2018] [Indexed: 01/05/2023] Open
Abstract
Background Sphingosine kinase (SphK) 2 has been implicated in the development of a range of cancers and inhibitors of this enzyme are currently in clinical trial. We have previously demonstrated a role for SphK2 in the development of acute lymphoblastic leukemia (ALL). Methods In this and our previous study we use mouse models: in the previous study the disease was driven by the proto-oncogene BCR/ABL1, while in this study cancer risk was elevated by deletion of the tumor suppressor ARF. Results Mice lacking ARF and SphK2 had a significantly reduced incidence of ALL compared mice with wild type SphK2. Conclusions These results show that the role of SphK2 in ALL development is not limited to BCR/ABL1 driven disease extending the potential use of inhibitors of this enzyme to ALL patients whose disease have driver mutations other than BCR/ABL1.
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Affiliation(s)
- Vicki Xie
- 1Centre for Cancer Research, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia
| | - Daochen Tong
- 1Centre for Cancer Research, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia
| | - Craig T Wallington-Beddoe
- 1Centre for Cancer Research, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia.,3Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia.,4College of Medicine and Public Health, Flinders University, Adelaide, Australia.,5School of Medicine, University of Adelaide, Adelaide, Australia
| | - Ken F Bradstock
- 2Haematology Department, Westmead Hospital, Westmead, NSW Australia
| | - Linda J Bendall
- 1Centre for Cancer Research, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia
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13
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Small mitochondrial Arf (smArf) protein corrects p53-independent developmental defects of Arf tumor suppressor-deficient mice. Proc Natl Acad Sci U S A 2017; 114:7420-7425. [PMID: 28652370 DOI: 10.1073/pnas.1707292114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mouse p19Arf (human p14ARF) tumor suppressor protein, encoded in part from an alternative reading frame of the Ink4a (Cdkn2a) gene, inhibits the Mdm2 E3 ubiquitin ligase to activate p53. Arf is not expressed in most normal tissues of young mice but is induced by high thresholds of aberrant hyperproliferative signals, thereby activating p53 in incipient tumor cells that have experienced oncogene activation. The single Arf mRNA encodes two distinct polypeptides, including full-length p19Arf and N-terminally truncated and unstable p15smArf ("small mitochondrial Arf") initiated from an internal in-frame AUG codon specifying methionine-45. Interactions of p19Arf with Mdm2, or separately with nucleophosmin (NPM, B23) that localizes and stabilizes p19Arf within the nucleolus, require p19Arf N-terminal amino acids that are not present within p15smArf We have generated mice that produce either smARF alone or M45A-mutated (smArf-deficient) full-length p19Arf proteins. BCR-ABL-expressing pro/pre-B cells producing smArf alone are as oncogenic as their Arf-null counterparts in generating acute lymphoblastic leukemia when infused into unconditioned syngeneic mice. In contrast, smArf-deficient cells from mice of the ArfM45A strain are as resistant as wild-type Arf+/+ cells to comparable oncogenic challenge and do not produce tumors. Apart from being prone to tumor development, Arf-null mice are blind, and their male germ cells exhibit defects in meiotic maturation and sperm production. Although ArfM45A mice manifest the latter defects, smArf alone remarkably rescues both of these p53-independent developmental phenotypes.
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14
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p14ARF interacts with the focal adhesion kinase and protects cells from anoikis. Oncogene 2017; 36:4913-4928. [PMID: 28436949 PMCID: PMC5582215 DOI: 10.1038/onc.2017.104] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 03/01/2017] [Accepted: 03/06/2017] [Indexed: 12/13/2022]
Abstract
The ARF protein functions as an important sensor of hyper-proliferative stimuli restricting cell proliferation through both p53-dependent and -independent pathways. Although to date the majority of studies on ARF have focused on its anti-proliferative role, few studies have addressed whether ARF may also have pro-survival functions. Here we show for the first time that during the process of adhesion and spreading ARF re-localizes to sites of active actin polymerization and to focal adhesion points where it interacts with the phosphorylated focal adhesion kinase. In line with its recruitment to focal adhesions, we observe that hampering ARF function in cancer cells leads to gross defects in cytoskeleton organization resulting in apoptosis through a mechanism dependent on the Death-Associated Protein Kinase. Our data uncover a novel function for p14ARF in protecting cells from anoikis that may reflect its role in anchorage independence, a hallmark of malignant tumor cells.
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15
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Owczarek TB, Kobayashi T, Ramirez R, Rong L, Puzio-Kuter AM, Iyer G, Teo MY, Sánchez-Vega F, Wang J, Schultz N, Zheng T, Solit DB, Al-Ahmadie HA, Abate-Shen C. ARF Confers a Context-Dependent Response to Chemotherapy in Muscle-Invasive Bladder Cancer. Cancer Res 2017; 77:1035-1046. [PMID: 28082400 PMCID: PMC5313321 DOI: 10.1158/0008-5472.can-16-2621] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/12/2016] [Accepted: 12/12/2016] [Indexed: 12/14/2022]
Abstract
Muscle-invasive bladder cancer (MIBC) generally responds poorly to treatment and tends to exhibit significant mortality. Here we show that expression of the tumor suppressor p14ARF (ARF) is upregulated in aggressive subtypes of MIBC. Accumulation of ARF in the nucleolus is associated with poor outcome and attenuated response to chemotherapy. In both genetically engineered mouse models and murine xenograft models of human MIBC, we demonstrate that tumors expressing ARF failed to respond to treatment with the platinum-based chemotherapy agent cisplatin. Resistance was mediated in part by the integrin-binding protein ITGB3BP (CENPR) and reflected ARF-dependent impairment of protein translation, which was exaggerated by drug treatment. Overall, our results highlight a context-dependent role for ARF in modulating the drug response of bladder cancer. Cancer Res; 77(4); 1035-46. ©2017 AACR.
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Affiliation(s)
- Tomasz B Owczarek
- Department of Medicine, Columbia University Medical Center, New York, New York
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Takashi Kobayashi
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Ricardo Ramirez
- Department of Human Oncology and Pathogenesis, Memorial Sloan-Kettering Cancer Center, New York, New York
- Weill Cornell Graduate School, Cornell University, New York, New York
| | - Lijie Rong
- Department of Medicine, Columbia University Medical Center, New York, New York
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Anna M Puzio-Kuter
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Gopa Iyer
- Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York
- Weill Medical College, Cornell University, New York, New York
| | - Min Yuen Teo
- Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York
| | - Francisco Sánchez-Vega
- Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York
- Marie-Josée and Henry R. Kravis Center for Molecular Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York
| | - Jingqiang Wang
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Nikolaus Schultz
- Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York
- Marie-Josée and Henry R. Kravis Center for Molecular Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York
| | - Tian Zheng
- Department of Statistics, Columbia University, New York, New York
| | - David B Solit
- Department of Human Oncology and Pathogenesis, Memorial Sloan-Kettering Cancer Center, New York, New York
- Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York
- Marie-Josée and Henry R. Kravis Center for Molecular Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York
- Weill Medical College, Cornell University, New York, New York
| | - Hikmat A Al-Ahmadie
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York
| | - Cory Abate-Shen
- Department of Medicine, Columbia University Medical Center, New York, New York.
- Department of Urology, Columbia University Medical Center, New York, New York
- Department of Systems Biology, Columbia University Medical Center, New York, New York
- Department of Pathology & Cell Biology, Columbia University Medical Center, New York, New York
- Institute of Cancer Genetics, Columbia University Medical Center, New York, New York
- Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York
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16
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Hesse RG, Kouklis GK, Ahituv N, Pomerantz JH. The human ARF tumor suppressor senses blastema activity and suppresses epimorphic tissue regeneration. eLife 2015; 4:e07702. [PMID: 26575287 PMCID: PMC4657621 DOI: 10.7554/elife.07702] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 10/02/2015] [Indexed: 12/29/2022] Open
Abstract
The control of proliferation and differentiation by tumor suppressor genes suggests that evolution of divergent tumor suppressor repertoires could influence species' regenerative capacity. To directly test that premise, we humanized the zebrafish p53 pathway by introducing regulatory and coding sequences of the human tumor suppressor ARF into the zebrafish genome. ARF was dormant during development, in uninjured adult fins, and during wound healing, but was highly expressed in the blastema during epimorphic fin regeneration after amputation. Regenerative, but not developmental signals resulted in binding of zebrafish E2f to the human ARF promoter and activated conserved ARF-dependent Tp53 functions. The context-dependent activation of ARF did not affect growth and development but inhibited regeneration, an unexpected distinct tumor suppressor response to regenerative versus developmental environments. The antagonistic pleiotropic characteristics of ARF as both tumor and regeneration suppressor imply that inducing epimorphic regeneration clinically would require modulation of ARF -p53 axis activation.
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Affiliation(s)
- Robert G Hesse
- Department of Surgery,
Division of Plastic Surgery, Program in Craniofacial Biology,
University of California, San Francisco,
San
Francisco, United States
| | - Gayle K Kouklis
- Department of Surgery,
Division of Plastic Surgery, Program in Craniofacial Biology,
University of California, San Francisco,
San
Francisco, United States
| | - Nadav Ahituv
- Department of
Bioengineering and Therapeutic Sciences and Institute for Human
Genetics, University of California, San
Francisco, San
Francisco, United States
| | - Jason H Pomerantz
- Departments of Surgery
and Orofacial Sciences, Division of Plastic Surgery, Program in Craniofacial
Biology, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell
Research, University of California, San
Francisco, San
Francisco, United States
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17
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Sheshadri N, Catanzaro JM, Bott AJ, Sun Y, Ullman E, Chen EI, Pan JA, Wu S, Crawford HC, Zhang J, Zong WX. SCCA1/SERPINB3 promotes oncogenesis and epithelial-mesenchymal transition via the unfolded protein response and IL6 signaling. Cancer Res 2014; 74:6318-29. [PMID: 25213322 DOI: 10.1158/0008-5472.can-14-0798] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The serine/cysteine protease inhibitor SCCA1 (SERPINB3) is upregulated in many advanced cancers with poor prognosis, but there is limited information about whether it makes functional contributions to malignancy. Here, we show that SCCA1 expression promoted oncogenic transformation and epithelial-mesenchymal transition (EMT) in mammary epithelial cells, and that SCCA1 silencing in breast cancer cells halted their proliferation. SCCA1 overexpression in neu(+) mammary tumors increased the unfolded protein response (UPR), IL6 expression, and inflammatory phenotypes. Mechanistically, SCCA1 induced a prolonged nonlethal increase in the UPR that was sufficient to activate NF-κB and expression of the protumorigenic cytokine IL6. Overall, our findings established that SCCA1 contributes to tumorigenesis by promoting EMT and a UPR-dependent induction of NF-κB and IL6 autocrine signaling that promotes a protumorigenic inflammation.
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Affiliation(s)
- Namratha Sheshadri
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York
| | - Joseph M Catanzaro
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York
| | - Alex J Bott
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York
| | - Yu Sun
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York
| | - Erica Ullman
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York
| | - Emily I Chen
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
| | - Ji-An Pan
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York
| | - Song Wu
- Department of Applied Math and Statistics, Stony Brook University, Stony Brook, New York
| | | | - Jianhua Zhang
- Department of Pathology, University of Alabama, Birmingham VA Medical Center, Birmingham, Alabama
| | - Wei-Xing Zong
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York.
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18
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Kotsinas A, Papanagnou P, Evangelou K, Trigas GC, Kostourou V, Townsend P, Gorgoulis VG. ARF: a versatile DNA damage response ally at the crossroads of development and tumorigenesis. Front Genet 2014; 5:236. [PMID: 25101116 PMCID: PMC4106421 DOI: 10.3389/fgene.2014.00236] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/03/2014] [Indexed: 11/13/2022] Open
Abstract
Alternative reading frame (ARF) is a tumor suppressor protein that senses oncogenic and other stressogenic signals. It can trigger p53-dependent and -independent responses with cell cycle arrest and apoptosis induction being the most prominent ones. Other ARF activities, particularly p53-independent ones, that could help in understanding cancer development and provide potential therapeutic exploitation are underrated. Although ARF is generally not expressed in normal tissues, it is essential for ocular and male germ cells development. The underlying mechanism(s) in these processes, while not clearly defined, point toward a functional link between ARF, DNA damage and angiogenesis. Based on a recent study from our group demonstrating a functional interplay between ataxia-telangiectasia mutated (ATM) and ARF during carcinogenesis, we discuss the role of ARF at the crossroads of cancer and developmental processes.
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Affiliation(s)
- Athanassios Kotsinas
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, University of Athens Athens, Greece
| | - Panagiota Papanagnou
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, University of Athens Athens, Greece
| | - Konstantinos Evangelou
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, University of Athens Athens, Greece
| | - George C Trigas
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, University of Athens Athens, Greece
| | - Vassiliki Kostourou
- Vascular Adhesion Lab, Biomedical Sciences Research Center Alexander Fleming Athens, Greece
| | - Paul Townsend
- Faculty Institute of Cancer Sciences, University of Manchester, Manchester Academic Health Science Centre Manchester, UK ; Manchester Centre for Cellular Metabolism, University of Manchester, Manchester Academic Health Science Centre Manchester, UK
| | - Vassilis G Gorgoulis
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, University of Athens Athens, Greece ; Faculty Institute of Cancer Sciences, University of Manchester, Manchester Academic Health Science Centre Manchester, UK ; Manchester Centre for Cellular Metabolism, University of Manchester, Manchester Academic Health Science Centre Manchester, UK ; Biomedical Research Foundation, Academy of Athens Athens, Greece
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19
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Isolation and characterization of mammalian cells expressing the Arf promoter during eye development. Biotechniques 2014; 56:239-49. [PMID: 24806224 DOI: 10.2144/000114166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 03/12/2014] [Indexed: 12/27/2022] Open
Abstract
Although many researchers have successfully uncovered novel functions of the tumor suppressor p19(Arf) utilizing various types of cultured cancer cells and immortalized fibroblasts, these systems do not accurately reflect the endogenous environment in which Arf is developmentally expressed. We addressed this by isolating perivascular cells (PVCs) from the primary vitreous of the mouse eye. This rare cell type normally expresses the p19(Arf) tumor suppressor in a non-pathological, developmental context. We utilized fluorescence activated cell sorting (FACS) to purify the cells by virtue of a GFP reporter driven by the native Arf promoter and then characterized their morphology and gene expression pattern. We further examined the effects of reintroduction of Arf expression in the Arf(GFP/GFP) PVCs to verify expected downstream effectors of p19(Arf) as well as uncover novel functions of Arf as a regulator of vasculogenesis. This methodology and cell culture model should serve as a useful tool to examine p19(Arf) biology.
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20
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Affiliation(s)
- Sara M Reed
- Department of Pharmacology; The University of Iowa; Carver College of Medicine; Iowa City, IA USA; Medical Scientist Training Program; The University of Iowa; Carver College of Medicine; Iowa City, IA USA
| | - Frederick W Quelle
- Department of Pharmacology; The University of Iowa; Carver College of Medicine; Iowa City, IA USA; Holden Comprehensive Cancer Center; The University of Iowa; Carver College of Medicine; Iowa City, IA USA
| | - Dawn E Quelle
- Department of Pharmacology; The University of Iowa; Carver College of Medicine; Iowa City, IA USA; Medical Scientist Training Program; The University of Iowa; Carver College of Medicine; Iowa City, IA USA; Holden Comprehensive Cancer Center; The University of Iowa; Carver College of Medicine; Iowa City, IA USA; Department of Pathology; The University of Iowa; Carver College of Medicine; Iowa City, IA USA
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21
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Gutierrez A, Feng H, Stevenson K, Neuberg DS, Calzada O, Zhou Y, Langenau DM, Look AT. Loss of function tp53 mutations do not accelerate the onset of myc-induced T-cell acute lymphoblastic leukaemia in the zebrafish. Br J Haematol 2014; 166:84-90. [PMID: 24690081 DOI: 10.1111/bjh.12851] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/05/2014] [Indexed: 02/01/2023]
Abstract
The TP53 tumour suppressor is activated in response to distinct stimuli, including an ARF-dependent response to oncogene stress and an ATM/ATR-dependent response to DNA damage. In human T-cell acute lymphoblastic leukaemia (T-ALL), TP53-dependent tumour suppression is typically disabled via biallelic ARF deletions. In murine models, loss of Arf (Cdkn2a) or Tp53 markedly accelerates the onset of Myc-induced lymphoblastic malignancies. In zebrafish, no ARF ortholog has been identified, but the sequence of ARF is very poorly conserved evolutionarily, making it difficult to exclude the presence of a zebrafish ARF ortholog without functional studies. Here we show that tp53 mutations have no significant influence on the onset of myc-induced T-ALL in zebrafish, consistent with the lack of additional effects of Tp53 loss on lymphomagenesis in Arf-deficient mice. By contrast, irradiation leads to complete T-ALL regression in tp53 wild-type but not homozygous mutant zebrafish, indicating that the tp53-dependent DNA damage response is intact. We conclude that tp53 inactivation has no impact on the onset of myc-induced T-ALL in the zebrafish, consistent with the lack of a functional ARF ortholog linking myc-induced oncogene stress to tp53-dependent tumour suppression. Thus, the zebrafish model is well suited to the study of ARF-independent pathways in T-ALL pathobiology.
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Affiliation(s)
- Alejandro Gutierrez
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA; Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
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22
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Simultaneous gene editing by injection of mRNAs encoding transcription activator-like effector nucleases into mouse zygotes. Mol Cell Biol 2014; 34:1649-58. [PMID: 24567370 DOI: 10.1128/mcb.00023-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Injection of transcription activator-like effector nucleases (TALEN) mRNAs into mouse zygotes transferred into foster mothers efficiently generated founder mice with heritable mutations in targeted genes. Immunofluorescence visualization of phosphorylated histone 2A (γH2AX) combined with fluorescence in situ hybridization revealed that TALEN pairs targeting the Agouti locus induced site-directed DNA breaks in zygotes within 6 h of injection, an activity that continued at reduced efficiency in two-cell embryos. TALEN-Agouti mRNAs injected into zygotes of brown FvB × C57BL/6 hybrid mice generated completely black pups, confirming that mutations were induced prior to, and/or early after, cell division. Founder mice, many of which were mosaic, transmitted altered Agouti alleles to F1 pups to yield an allelic series of mutant strains. Although mutations were targeted to "spacer" sequences flanked by TALEN binding sites, larger deletions that extended beyond the TALEN-binding sequences were also detected and were similarly inherited through the germ line. Zygotic coinjection of TALEN mRNAs directed to the Agouti, miR-205, and the Arf tumor suppressor loci yielded pups containing frequent and heritable mutations of two or three genes. Simultaneous gene editing in zygotes affords an efficient approach for producing mice with compound mutant phenotypes, bypassing constraints of conventional mouse knockout technology in embryonic stem cells.
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23
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Maggi LB, Winkeler CL, Miceli AP, Apicelli AJ, Brady SN, Kuchenreuther MJ, Weber JD. ARF tumor suppression in the nucleolus. Biochim Biophys Acta Mol Basis Dis 2014; 1842:831-9. [PMID: 24525025 DOI: 10.1016/j.bbadis.2014.01.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 01/27/2014] [Accepted: 01/28/2014] [Indexed: 02/06/2023]
Abstract
Since its discovery close to twenty years ago, the ARF tumor suppressor has played a pivotal role in the field of cancer biology. Elucidating ARF's basal physiological function in the cell has been the focal interest of numerous laboratories throughout the world for many years. Our current understanding of ARF is constantly evolving to include novel frameworks for conceptualizing the regulation of this critical tumor suppressor. As a result of this complexity, there is great need to broaden our understanding of the intricacies governing the biology of the ARF tumor suppressor. The ARF tumor suppressor is a key sensor of signals that instruct a cell to grow and proliferate and is appropriately localized in nucleoli to limit these processes. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Leonard B Maggi
- BRIGHT Institute, Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, USA
| | - Crystal L Winkeler
- BRIGHT Institute, Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, USA
| | - Alexander P Miceli
- BRIGHT Institute, Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, USA
| | - Anthony J Apicelli
- BRIGHT Institute, Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, USA
| | - Suzanne N Brady
- BRIGHT Institute, Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, USA
| | - Michael J Kuchenreuther
- BRIGHT Institute, Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, USA
| | - Jason D Weber
- BRIGHT Institute, Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, USA.
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24
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Iqbal N, Mei J, Liu J, Skapek SX. miR-34a is essential for p19(Arf)-driven cell cycle arrest. Cell Cycle 2014; 13:792-800. [PMID: 24401748 DOI: 10.4161/cc.27725] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The Arf tumor suppressor gene product, p19(Arf), regulates cell proliferation in incipient cancer cells and during embryo development. Beyond its commonly accepted p53-dependent actions, p19(Arf) also acts independently of p53 in both contexts. One such p53-independent effect with in vivo relevance includes its repression of Pdgfrβ, a process that is essential for vision in the mouse. We have utilized cell culture-based and mouse models to define a new role for miR-34a in this process. Ectopic expression of Arf in cultured cells enhanced the expression of several microRNAs predicted to target Pdgfrß synthesis, including the miR-34 family. Because miR-34a has been implicated as a p53-dependent effector, we investigated whether it also contributed to p53-independent effects of p19(Arf). Indeed, in mouse embryo fibroblasts (MEFs) lacking p53, Arf-driven repression of Pdgfrβ and its blockade of Pdgf-B stimulated DNA synthesis were both completely interrupted by anti-microRNA against miR-34a. Ectopic miR-34a directly targeted Pdgfrβ and a plasmid reporter containing wild-type Pdgfrβ 3'UTR sequence, but not one in which the miR-34a target sequence was mutated. Although miR-34a expression has been linked to p53-a well-known effector of p19(Arf)-Arf expression and its knockdown correlated with miR-34a level in MEFs lacking p53. Finally, analysis of the mouse embryonic eye demonstrated that Arf controlled expression of miR-34a, and the related miR-34b and c, in vivo during normal mouse development. Our findings indicate that miR-34a provides an essential link between p19(Arf) and its p53-independent capacity to block cell proliferation driven by Pdgfrβ. This has ramifications for developmental and tumor suppressor roles of Arf.
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Affiliation(s)
- Nida Iqbal
- Division of Hematology/Oncology; Department of Pediatrics; University of Texas Southwestern Medical Center; Dallas, TX USA
| | - Jie Mei
- Division of Hematology/Oncology; Department of Pediatrics; University of Texas Southwestern Medical Center; Dallas, TX USA; College of Fisheries; Key Laboratory of Freshwater Animal Breeding; Ministry of Agriculture; Huazhong Agricultural University; Wuhan, China
| | - Jing Liu
- Division of Hematology/Oncology; Department of Pediatrics; University of Texas Southwestern Medical Center; Dallas, TX USA
| | - Stephen X Skapek
- Division of Hematology/Oncology; Department of Pediatrics; University of Texas Southwestern Medical Center; Dallas, TX USA; Center for Cancer and Blood Disorders; Children's Medical Center; Dallas, TX USA
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25
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Arf tumor suppressor and miR-205 regulate cell adhesion and formation of extraembryonic endoderm from pluripotent stem cells. Proc Natl Acad Sci U S A 2013; 110:E1112-21. [PMID: 23487795 DOI: 10.1073/pnas.1302184110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Induction of the Arf tumor suppressor (encoded by the alternate reading frame of the Cdkn2a locus) following oncogene activation engages a p53-dependent transcriptional program that limits the expansion of incipient cancer cells. Although the p19(Arf) protein is not detected in most tissues of fetal or young adult mice, it is physiologically expressed in the fetal yolk sac, a tissue derived from the extraembryonic endoderm (ExEn). Expression of the mouse p19(Arf) protein marks late stages of ExEn differentiation in cultured embryoid bodies (EBs) derived from either embryonic stem cells or induced pluripotent stem cells. Arf inactivation delays differentiation of the ExEn lineage within EBs, but not the formation of other germ cell lineages from pluripotent progenitors. Arf is required for the timely induction of ExEn cells in response to Ras/Erk signaling and, in turn, acts through p53 to ensure the development, but not maintenance, of the ExEn lineage. Remarkably, a significant temporal delay in ExEn differentiation detected during the maturation of Arf-null EBs is rescued by enforced expression of mouse microRNA-205 (miR-205), a microRNA up-regulated by p19(Arf) and p53 that controls ExEn cell migration and adhesion. The noncanonical and canonical roles of Arf in ExEn development and tumor suppression, respectively, may be conceptually linked through mechanisms that govern cell attachment and migration.
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Macrophages, inflammation, and tumor suppressors: ARF, a new player in the game. Mediators Inflamm 2012; 2012:568783. [PMID: 23316105 PMCID: PMC3538382 DOI: 10.1155/2012/568783] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 11/07/2012] [Indexed: 01/10/2023] Open
Abstract
The interaction between tumor progression and innate immune system has been well established in the last years. Indeed, several lines of clinical evidence indicate that immune cells such as tumor-associated macrophages (TAMs) interact with tumor cells, favoring growth, angiogenesis, and metastasis of a variety of cancers. In most tumors, TAMs show properties of an alternative polarization phenotype (M2) characterized by the expression of a series of chemokines, cytokines, and proteases that promote immunosuppression, tumor proliferation, and spreading of the cancer cells.
Tumor suppressor genes have been traditionally linked to the regulation of cancer progression; however, a growing body of evidence indicates that these genes also play essential roles in the regulation of innate immunity pathways through molecular mechanisms that are still poorly understood. In this paper, we provide an overview of the immunobiology of TAMs as well as what is known about tumor suppressors in the context of immune responses. Recent advances regarding the role of the tumor suppressor ARF as a regulator of inflammation and macrophage polarization are also reviewed.
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p19Arf represses platelet-derived growth factor receptor β by transcriptional and posttranscriptional mechanisms. Mol Cell Biol 2012; 32:4270-82. [PMID: 22907756 DOI: 10.1128/mcb.06424-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In addition to cancer surveillance, p19(Arf) plays an essential role in blocking signals stemming from platelet-derived growth factor receptor β (Pdgfrβ) during eye development, but the underlying mechanisms have not been clear. We now show that without Arf, pericyte hyperplasia in the eye results from enhanced Pdgfrβ-dependent proliferation from embryonic day 13.5 (E13.5) of mouse development. Loss of Arf in the eye increases Pdgfrβ expression. In cultured fibroblasts and pericyte-like cells, ectopic p19(Arf) represses and Arf knockdown enhances the expression of Pdgfrβ mRNA and protein. Ectopic Arf also represses primary Pdgfrβ transcripts and a plasmid driven by a minimal promoter, including one missing the CCAAT element required for high-level expression. p19(Arf) uses both p53-dependent and -independent mechanisms to control Pdgfrβ. In vivo, without p53, Pdgfrβ mRNA is elevated and eye development abnormalities resemble the Arf (-/-) phenotype. However, effects of p53 on Pdgfrβ mRNA do not appear to be due to direct p53 or RNA polymerase II recruitment to the promoter. Although p19(Arf) controls Pdgfrβ mRNA in a p53-dependent manner, it also blunts Pdgfrβ protein expression by blocking new protein synthesis in the absence of p53. Thus, our findings demonstrate a novel capacity for p19(Arf) to control Pdgfrβ expression by p53-dependent and -independent mechanisms involving RNA transcription and protein synthesis, respectively, to promote the vascular remodeling needed for normal vision.
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Winkeler CL, Kladney RD, Maggi LB, Weber JD. Cathepsin K-Cre causes unexpected germline deletion of genes in mice. PLoS One 2012; 7:e42005. [PMID: 22860046 PMCID: PMC3409209 DOI: 10.1371/journal.pone.0042005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 06/28/2012] [Indexed: 11/18/2022] Open
Abstract
Osteoclasts are terminally differentiated cells that attach to bone and secrete proteases to degrade the bone matrix. The primary protease responsible for the degradation of the organic component of the bone matrix is Cathepsin K, which was largely thought to be unique to osteoclasts. Given its apparent selective expression in osteoclasts, the Cathepsin K promoter has been engineered to drive the expression of Cre recombinase in mice and has been the most relevant tool for generating osteoclast-specific gene loss. In an effort to understand the role of the ARF tumor suppressor in osteoclasts, we crossed Arf fl/fl mice to CtskCre/+ mice, which unexpectedly resulted in the germline loss of Arf. We subsequently confirmed Cre activity in gametes by generating CtskCre/+; Rosa+ mice. These results raise significant concerns regarding in vivo bone phenotypes created using CtskCre/+ mice and warrant further investigation into the role of Cathepsin K in gametes as well as alternative tools for studying osteoclast-specific gene loss in vivo.
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Affiliation(s)
- Crystal L. Winkeler
- From the BRIGHT Institute and Department of Internal Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Raleigh D. Kladney
- From the BRIGHT Institute and Department of Internal Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Leonard B. Maggi
- From the BRIGHT Institute and Department of Internal Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Jason D. Weber
- From the BRIGHT Institute and Department of Internal Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
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Busch SE, Gurley KE, Moser RD, Kemp CJ. ARF suppresses hepatic vascular neoplasia in a carcinogen-exposed murine model. J Pathol 2012; 227:298-305. [PMID: 22430984 DOI: 10.1002/path.4024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 02/04/2012] [Accepted: 03/09/2012] [Indexed: 01/01/2023]
Abstract
Hepatic haemangiosarcoma is a deadly malignancy whose aetiology remains poorly understood. Inactivation of the CDKN2A locus, which houses the ARF and p16(INK4a) tumour suppressor genes, is a common event in haemangiosarcoma patients, but the precise role of ARF in vascular tumourigenesis is unknown. To determine the extent to which ARF suppresses vascular neoplasia, we examined the incidence of hepatic vascular lesions in Arf-deficient mice exposed to the carcinogen urethane [intraperitoneal (i.p.), 1 mg/g]. Loss of Arf resulted in elevated morbidity and increased the incidence of both haemangiomas and incipient haemangiosarcomas. Suppression of vascular lesion development by ARF was heavily dependent on both Arf gene-dosage and the genetic strain of the mouse. Trp53-deficient mice also developed hepatic vascular lesions after exposure to urethane, suggesting that ARF signals through a p53-dependent pathway to inhibit the development of hepatic haemangiosarcoma. Our findings provide strong evidence that inactivation of Arf is a causative event in vascular neoplasia and suggest that the ARF pathway may be a novel molecular target for therapeutic intervention in haemangiosarcoma patients.
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Affiliation(s)
- Stephanie E Busch
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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Churchman ML, Roig I, Jasin M, Keeney S, Sherr CJ. Expression of arf tumor suppressor in spermatogonia facilitates meiotic progression in male germ cells. PLoS Genet 2011; 7:e1002157. [PMID: 21811412 PMCID: PMC3141002 DOI: 10.1371/journal.pgen.1002157] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 05/11/2011] [Indexed: 11/18/2022] Open
Abstract
The mammalian Cdkn2a (Ink4a-Arf) locus encodes two tumor suppressor proteins (p16Ink4a and p19Arf) that respectively enforce the anti-proliferative functions of the retinoblastoma protein (Rb) and the p53 transcription factor in response to oncogenic stress. Although p19Arf is not normally detected in tissues of young adult mice, a notable exception occurs in the male germ line, where Arf is expressed in spermatogonia, but not in meiotic spermatocytes arising from them. Unlike other contexts in which the induction of Arf potently inhibits cell proliferation, expression of p19Arf in spermatogonia does not interfere with mitotic cell division. Instead, inactivation of Arf triggers germ cell–autonomous, p53-dependent apoptosis of primary spermatocytes in late meiotic prophase, resulting in reduced sperm production. Arf deficiency also causes premature, elevated, and persistent accumulation of the phosphorylated histone variant H2AX, reduces numbers of chromosome-associated complexes of Rad51 and Dmc1 recombinases during meiotic prophase, and yields incompletely synapsed autosomes during pachynema. Inactivation of Ink4a increases the fraction of spermatogonia in S-phase and restores sperm numbers in Ink4a-Arf doubly deficient mice but does not abrogate γ-H2AX accumulation in spermatocytes or p53-dependent apoptosis resulting from Arf inactivation. Thus, as opposed to its canonical role as a tumor suppressor in inducing p53-dependent senescence or apoptosis, Arf expression in spermatogonia instead initiates a salutary feed-forward program that prevents p53-dependent apoptosis, contributing to the survival of meiotic male germ cells. The intimately linked Arf and Ink4a genes, encoded in part by overlapping reading frames within the Cdkn2a locus, are induced by oncogenic stress, activating the p53 and Rb tumor suppressors, respectively, to inhibit proliferation of incipient cancer cells. As such, expression of the p19Arf and p16Ink4a proteins is undetected in most normal mouse tissues. However, p19Arf is physiologically expressed in mitotically dividing spermatogonia, the progenitor cells that differentiate to form meiotic spermatocytes in which Arf expression is extinguished. We show that, instead of provoking cell cycle arrest or death, Arf expression in spermatogonia facilitates survival of their meiotic progeny, ensuring production of normal numbers of mature sperm. When Arf is ablated, meiotic defects ensue, along with p53-dependent cell death of spermatocytes, indicating an unexpected role of p53 in monitoring meiotic progression. Surprisingly, it is the absence of p19Arf rather than its induction that enforces p53 expression in this setting. Co-inactivation of Ink4a compensates for Arf loss by fueling proliferation of spermatogonial progenitors, but does not correct meiotic defects triggered by Arf loss. Although the Arf and Ink4a tumor suppressors are expected to restrain cellular self-renewal, Arf plays an unexpected role in male germ cells by facilitating their proper meiotic progression.
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Affiliation(s)
- Michelle L. Churchman
- Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
- Department of Genetics and Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Ignasi Roig
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
- Cytology and Histology Unit, Department of Cell Biology, Physiology, and Immunology, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Scott Keeney
- Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Charles J. Sherr
- Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
- Department of Genetics and Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
- * E-mail:
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Functional interactions between Lmo2, the Arf tumor suppressor, and Notch1 in murine T-cell malignancies. Blood 2011; 117:5453-62. [PMID: 21427293 DOI: 10.1182/blood-2010-09-309831] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
LMO2 is a target of chromosomal translocations in T-cell tumors and was activated by retroviral vector insertions in T-cell tumors from X-SCID patients in gene therapy trials. To better understand the cooperating genetic events in LMO2-associated T-cell acute lymphoblastic leukemia (T-ALL), we investigated the roles of Arf tumor suppressor loss and Notch activation in murine models of transplantation. Lmo2 overexpression enhanced the expansion of primitive DN2 thymocytes, eventually facilitating the stochastic induction of clonal CD4(+)/CD8(+) malignancies. Inactivation of the Arf tumor suppressor further increased the self-renewal capacity of the primitive, preleukemic thymocyte pool and accelerated the development of aggressive, Lmo2-induced T-cell lympholeukemias. Notch mutations were frequently detected in these Lmo2-induced tumors. The Arf promoter was not directly engaged by Lmo2 or mutant Notch, and use of a mouse model in which activation of a mutant Notch allele depends on previous engagement of the Arf promoter revealed that Notch activation could occur as a subsequent event in T-cell tumorigenesis. Therefore, Lmo2 cooperates with Arf loss to enhance self-renewal in primitive thymocytes. Notch mutation and Arf inactivation appear to independently cooperate in no requisite order with Lmo2 overexpression in inducing T-ALL, and all 3 events remained insufficient to guarantee immediate tumor development.
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Targeted disruption of Ing2 results in defective spermatogenesis and development of soft-tissue sarcomas. PLoS One 2010; 5:e15541. [PMID: 21124965 PMCID: PMC2988811 DOI: 10.1371/journal.pone.0015541] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 10/06/2010] [Indexed: 12/23/2022] Open
Abstract
ING2 (inhibitor of growth family, member 2) is a member of the plant homeodomain (PHD)-containing ING family of putative tumor suppressors. As part of mSin3A-HDAC corepressor complexes, ING2 binds to tri-methylated lysine 4 of histone H3 (H3K4me3) to regulate chromatin modification and gene expression. ING2 also functionally interacts with the tumor suppressor protein p53 to regulate cellular senescence, apoptosis and DNA damage response in vitro, and is thus expected to modulate carcinogenesis and aging. Here we investigate the developmental and physiological functions of Ing2 through targeted germline disruption. Consistent with its abundant expression in mouse and human testes, male mice deficient for Ing2 showed abnormal spermatogenesis and were infertile. Numbers of mature sperm and sperm motility were significantly reduced in Ing2−/− mice (∼2% of wild type, P<0.0001 and ∼10% of wild type, P<0.0001, respectively). Their testes showed degeneration of seminiferous tubules, meiotic arrest before pachytene stage with incomplete meiotic recombination, induction of p53, and enhanced apoptosis. This phenotype was only partially abrogated by concomitant loss of p53 in the germline. The arrested spermatocytes in Ing2−/− testes were characterized by lack of specific HDAC1 accumulation and deregulated chromatin acetylation. The role of Ing2 in germ cell maturation may extend to human ING2 as well. Using publicly available gene expression datasets, low expression of ING2 was found in teratozoospermic sperm (>3-fold reduction) and in testes from patients with defective spermatogenesis (>7-fold reduction in Sertoli-cell only Syndrome). This study establishes ING2 as a novel regulator of spermatogenesis functioning through both p53- and chromatin-mediated mechanisms, suggests that an HDAC1/ING2/H3K4me3-regulated, stage-specific coordination of chromatin modifications is essential to normal spermatogenesis, and provides an animal model to study idiopathic and iatrogenic infertility in men. In addition, a bona fide tumor suppressive role of Ing2 is demonstrated by increased incidence of soft-tissue sarcomas in Ing2−/− mice.
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Zheng Y, Zhao YD, Gibbons M, Abramova T, Chu PY, Ash JD, Cunningham JM, Skapek SX. Tgfbeta signaling directly induces Arf promoter remodeling by a mechanism involving Smads 2/3 and p38 MAPK. J Biol Chem 2010; 285:35654-64. [PMID: 20826783 DOI: 10.1074/jbc.m110.128959] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have investigated how the Arf gene product, p19(Arf), is activated by Tgfβ during mouse embryo development to better understand how this important tumor suppressor is controlled. Taking advantage of new mouse models, we provide genetic evidence that Arf lies downstream of Tgfβ signaling in cells arising from the Wnt1-expressing neural crest and that the anti-proliferative effects of Tgfβ depend on Arf in vivo. Tgfβ1, -2, and -3 (but not BMP-2, another member of the Tgfβ superfamily) induce p19(Arf) expression in wild type mouse embryo fibroblasts (MEFs), and they enhance Arf promoter activity in Arf(lacZ/lacZ) MEFs. Application of chemical inhibitors of Smad-dependent and -independent pathways show that SB431542, a Tgfβ type I receptor (TβrI) inhibitor, and SB203580, a p38 MAPK inhibitor, impede Tgfβ2 induction of Arf. Genetic studies confirm the findings; transient knockdown of Smad2, Smad3, or p38 MAPK blunt Tgfβ2 effects, as does Cre recombinase treatment of Tgfbr2(fl/fl) MEFs to delete Tgfβ receptor II. Chromatin immunoprecipitation reveals that Tgfβ rapidly induces Smads 2/3 binding and histone H3 acetylation at genomic DNA proximal to Arf exon 1β. This is followed by increased RNA polymerase II binding and progressively increased Arf primary and mature transcripts from 24 through 72 h, indicating that increased transcription contributes to p19(Arf) increase. Last, Arf induction by oncogenic Ras depends on p38 MAPK but is independent of TβrI activation of Smad 2. These findings add to our understanding of how developmental and tumorigenic signals control Arf expression in vivo and in cultured MEFs.
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Affiliation(s)
- Yanbin Zheng
- Department of Pediatrics, Section of Hematology/Oncology and Stem Cell Transplantation, The University of Chicago, Chicago, Illinois 60637, USA
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Abstract
Cancers are rare because their evolution is actively restrained by a range of tumour suppressors. Of these p53 seems unusually crucial as either it or its attendant upstream or downstream pathways are inactivated in virtually all cancers. p53 is an evolutionarily ancient coordinator of metazoan stress responses. Its role in tumour suppression is likely to be a relatively recent adaptation, which is only necessary when large, long-lived organisms acquired the sufficient size and somatic regenerative capacity to necessitate specific mechanisms to reign in rogue proliferating cells. However, such evolutionary reappropriation of this venerable transcription factor entails compromises that restrict its efficacy as a tumour suppressor.
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Affiliation(s)
- Melissa R Junttila
- Department of Pathology and Helen Diller Family Comprehensive Cancer Centre, University of California San Francisco, 513 Parnassus Avenue, Room HSW-450A, UCSF Box 0502, San Francisco, California 94143-0502, USA
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