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Ramachandran D, Tyrer JP, Kommoss S, DeFazio A, Riggan MJ, Webb PM, Fasching PA, Lambrechts D, García MJ, Rodríguez-Antona C, Goodman MT, Modugno F, Moysich KB, Karlan BY, Lester J, Kjaer SK, Jensen A, Høgdall E, Goode EL, Cliby WA, Kumar A, Wang C, Cunningham JM, Winham SJ, Monteiro AN, Schildkraut JM, Cramer DW, Terry KL, Titus L, Bjorge L, Thomsen LCV, Pejovic T, Høgdall CK, McNeish IA, May T, Huntsman DG, Pfisterer J, Canzler U, Park-Simon TW, Schröder W, Belau A, Hanker L, Harter P, Sehouli J, Kimmig R, de Gregorio N, Schmalfeldt B, Baumann K, Hilpert F, Burges A, Winterhoff B, Schürmann P, Speith LM, Hillemanns P, Berchuck A, Johnatty SE, Ramus SJ, Chenevix-Trench G, Pharoah PDP, Dörk T, Heitz F. Genome-wide association analyses of ovarian cancer patients undergoing primary debulking surgery identify candidate genes for residual disease. NPJ Genom Med 2024; 9:19. [PMID: 38443389 PMCID: PMC10915171 DOI: 10.1038/s41525-024-00395-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 01/15/2024] [Indexed: 03/07/2024] Open
Abstract
Survival from ovarian cancer depends on the resection status after primary surgery. We performed genome-wide association analyses for resection status of 7705 ovarian cancer patients, including 4954 with high-grade serous carcinoma (HGSOC), to identify variants associated with residual disease. The most significant association with resection status was observed for rs72845444, upstream of MGMT, in HGSOC (p = 3.9 × 10-8). In gene-based analyses, PPP2R5C was the most strongly associated gene in HGSOC after stage adjustment. In an independent set of 378 ovarian tumours from the AGO-OVAR 11 study, variants near MGMT and PPP2R5C correlated with methylation and transcript levels, and PPP2R5C mRNA levels predicted progression-free survival in patients with residual disease. MGMT encodes a DNA repair enzyme, and PPP2R5C encodes the B56γ subunit of the PP2A tumour suppressor. Our results link heritable variation at these two loci with resection status in HGSOC.
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Grants
- K05 CA154337 NCI NIH HHS
- R01 CA058598 NCI NIH HHS
- UL1 TR000124 NCATS NIH HHS
- P50 CA105009 NCI NIH HHS
- K07 CA080668 NCI NIH HHS
- P30 CA076292 NCI NIH HHS
- R01 CA076016 NCI NIH HHS
- R01 CA248288 NCI NIH HHS
- U19 CA148112 NCI NIH HHS
- R01 CA149429 NCI NIH HHS
- Wellcome Trust
- P50 CA136393 NCI NIH HHS
- R21 CA267050 NCI NIH HHS
- M01 RR000056 NCRR NIH HHS
- R01 CA095023 NCI NIH HHS
- R01 CA054419 NCI NIH HHS
- P30 CA015083 NCI NIH HHS
- Deutsche Forschungsgemeinschaft (German Research Foundation)
- The Ovarian Cancer Association Consortium is funded by generous contributions from its research investigators and through anonymous donations. OCAC was funded by a grant from the Ovarian Cancer Research Fund (OCRF). The OCAC OncoArray genotyping project was funded through grants from the U.S. National Institutes of Health (CA1X01HG007491-01 (C.I.A.), U19-CA148112 (T.A.S.), R01-CA149429 (C.M.P.) and R01-CA058598 (M.T.G.); Canadian Institutes of Health Research (MOP-86727 (L.E.K.) and the Ovarian Cancer Research Fund (A.B.). The COGS project was funded through a European Commission’s Seventh Framework Programme grant (agreement number 223175 - HEALTH-F2-2009-223175) and in part by the US National Cancer Institute GAME-ON Post-GWAS Initiative (U19-CA148112). This study made use of data generated by the Wellcome Trust Case Control consortium that was funded by the Wellcome Trust under award 076113. The results published are in part based upon data generated by The Cancer Genome Atlas Pilot Project established by the National Cancer Institute and National Human Genome Research Institute (dbGap accession number phs000178.v8.p7). Funding for individual studies: AUS: The Australian Ovarian Cancer Study (AOCS) was supported by the U.S. Army Medical Research and Materiel Command (DAMD17-01-1-0729), National Health & Medical Research Council of Australia (199600, 400413 and 400281), Cancer Councils of New South Wales, Victoria, Queensland, South Australia and Tasmania and Cancer Foundation of Western Australia (Multi-State Applications 191, 211 and 182). AOCS gratefully acknowledges additional support from Ovarian Cancer Australia and the Peter MacCallum Foundation; BAV: ELAN Funds of the University of Erlangen-Nuremberg; BEL: National Kankerplan; CNI: Instituto de Salud Carlos III (PI 19/01730); Ministerio de Economía y Competitividad (SAF2012); HAW: U.S. National Institutes of Health (R01-CA58598, N01-CN-55424 and N01-PC-67001); HOP: University of Pittsburgh School of Medicine Dean’s Faculty Advancement Award (F. Modugno), Department of Defense (DAMD17-02-1-0669, OC20085) and United States National Cancer Institute (R21-CA267050, K07-CA080668, R01-CA95023, MO1-RR000056); LAX: American Cancer Society Early Detection Professorship (SIOP-06-258-01-COUN) and the National Center for Advancing Translational Sciences (NCATS), Grant UL1TR000124; MAC: National Institutes of Health (R01-CA2482288, P30-CA15083, P50-CA136393); Mayo Foundation; Minnesota Ovarian Cancer Alliance; Fred C. and Katherine B. Andersen Foundation; Fraternal Order of Eagles; MAL: Funding for this study was provided by research grant R01- CA61107 from the National Cancer Institute, Bethesda, MD, research grant 94 222 52 from the Danish Cancer Society, Copenhagen, Denmark, the Mermaid I project; and the Mermaid III project; MAY: National Institutes of Health (R01-CA2482288, P30-CA15083, P50-CA136393); Mayo Foundation; Minnesota Ovarian Cancer Alliance; Fred C. and Katherine B. Andersen Foundation; MOF: Moffitt Cancer Center, Merck Pharmaceuticals, the state of Florida, Hillsborough County, and the city of Tampa; NCO: National Institutes of Health (R01-CA76016) and the Department of Defense (DAMD17-02-1-0666); NEC: National Institutes of Health R01-CA54419 and P50-CA105009 and Department of Defense W81XWH-10-1-02802; NOR: Helse Vest, The Norwegian Cancer Society, The Research Council of Norway; OPL: National Health and Medical Research Council (NHMRC) of Australia (APP1025142, APP1120431) and Brisbane Women’s Club; ORE: Sherie Hildreth Ovarian Cancer (SHOC) Foundation; PVD: Canadian Cancer Society and Cancer Research Society GRePEC Program; SRO: Cancer Research UK (C536/A13086, C536/A6689) and Imperial Experimental Cancer Research Centre (C1312/A15589); UHN: Princess Margaret Cancer Centre Foundation-Bridge for the Cure; VAN: BC Cancer Foundation, VGH & UBC Hospital Foundation; VTL: NIH K05-CA154337; WMH: National Health and Medical Research Council of Australia, Enabling Grants ID 310670 & ID 628903. Cancer Institute NSW Grants 12/RIG/1-17 & 15/RIG/1-16. The AGO-OVAR 11 study was funded by Roche Pharma AG.
- National Health and Medical Research Council (NHMRC) of Australia (APP1025142, APP1120431) and Brisbane Women’s Club
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Affiliation(s)
| | - Jonathan P Tyrer
- Centre for Cancer Genetic Epidemiology, Department of Oncology, University of Cambridge, Cambridge, UK
| | - Stefan Kommoss
- Department of Women's Health, Tuebingen University Hospital, Tuebingen, Germany
| | - Anna DeFazio
- Centre for Cancer Research, The Westmead Institute for Medical Research, University of Sydney, Sydney, NSW, Australia
- Discipline of Obstetrics and Gynaecology, The University of Sydney, Sydney, NSW, Australia
- Department of Gynaecological Oncology, Westmead Hospital, Sydney, NSW, Australia
- The Daffodil Centre, The University of Sydney, a joint venture with Cancer Council NSW, Sydney, NSW, Australia
| | - Marjorie J Riggan
- Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Duke University Medical Center, Durham, NC, USA
| | - Penelope M Webb
- Population Health Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Peter A Fasching
- Department of Gynecology and Obstetrics, Comprehensive Cancer Center Erlangen-EMN, Friedrich-Alexander University Erlangen-Nuremberg, University Hospital Erlangen, Erlangen, Germany
| | - Diether Lambrechts
- Laboratory for Translational Genetics, Department of Human Genetics, KU Leuven, Leuven, Belgium
- VIB Center for Cancer Biology, VIB, Leuven, Belgium
| | - María J García
- Biochemistry and Molecular Biology area, Department of Basic Health Sciences, Faculty of Health Sciences, Rey Juan Carlos University, Madrid, Spain
| | - Cristina Rodríguez-Antona
- Hereditary Endocrine Cancer Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Marc T Goodman
- Cancer Prevention and Control Program, Cedars-Sinai Cancer, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Francesmary Modugno
- Department of Epidemiology, University of Pittsburgh School of Public Health, Pittsburgh, PA, USA
- Division of Gynecologic Oncology, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Women's Cancer Research Center, Magee-Womens Research Institute and Hillman Cancer Center, Pittsburgh, PA, USA
| | - Kirsten B Moysich
- Department of Cancer Prevention and Control, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Beth Y Karlan
- David Geffen School of Medicine, Department of Obstetrics and Gynecology, University of California at Los Angeles, Los Angeles, CA, USA
| | - Jenny Lester
- David Geffen School of Medicine, Department of Obstetrics and Gynecology, University of California at Los Angeles, Los Angeles, CA, USA
| | - Susanne K Kjaer
- Department of Virus, Lifestyle and Genes, Danish Cancer Institute, Copenhagen, Denmark
- Department of Gynaecology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Allan Jensen
- Department of Virus, Lifestyle and Genes, Danish Cancer Institute, Copenhagen, Denmark
| | - Estrid Høgdall
- Department of Pathology, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Ellen L Goode
- Department of Quantitative Health Sciences, Division of Epidemiology, Mayo Clinic, Rochester, MN, USA
| | - William A Cliby
- Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Mayo Clinic, Rochester, MN, USA
| | - Amanika Kumar
- Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Mayo Clinic, Rochester, MN, USA
| | - Chen Wang
- Department of Quantitative Health Sciences, Division of Computational Biology, Mayo Clinic, Rochester, MN, USA
| | - Julie M Cunningham
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Stacey J Winham
- Department of Quantitative Health Sciences, Division of Computational Biology, Mayo Clinic, Rochester, MN, USA
| | - Alvaro N Monteiro
- Department of Cancer Epidemiology, Moffitt Cancer Center, Tampa, FL, USA
| | - Joellen M Schildkraut
- Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Daniel W Cramer
- Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics and Gyneclogy, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Kathryn L Terry
- Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics and Gyneclogy, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Linda Titus
- Norris Cotton Cancer Center, Lebanon, NH, USA
| | - Line Bjorge
- Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway
- Centre for Cancer Biomarkers CCBIO, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Liv Cecilie Vestrheim Thomsen
- Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway
- Centre for Cancer Biomarkers CCBIO, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Tanja Pejovic
- Department of ObGyn, Providence Medical Center, Medford, OR, USA
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - Claus K Høgdall
- Department of Gynaecology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Iain A McNeish
- Division of Cancer and Ovarian Cancer Action Research Centre, Department Surgery & Cancer, Imperial College London, London, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Taymaa May
- Division of Gynecologic Oncology, University Health Network, Princess Margaret Hospital, Toronto, ON, Canada
| | - David G Huntsman
- Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada
- Department of Molecular Oncology, BC Cancer Research Centre, Vancouver, BC, Canada
| | | | - Ulrich Canzler
- University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany
| | | | - Willibald Schröder
- Klinikum Bremen-Mitte, Bremen, Germany
- Gynaekologicum Bremen, Bremen, Germany
| | - Antje Belau
- University Hospital Greifswald, Greifswald, Germany
- Frauenarztpraxis Belau, Greifswald, Germany
| | - Lars Hanker
- University Hospital Frankfurt, Frankfurt, Germany
- University Hospital Schleswig-Holstein, Campus Lübeck, Lübeck, Germany
| | - Philipp Harter
- Department of Gynecology and Gynecologic Oncology, Evangelische Kliniken Essen-Mitte (KEM), Essen, Germany
| | - Jalid Sehouli
- Charité - Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany
| | - Rainer Kimmig
- University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Nikolaus de Gregorio
- University Hospital Ulm, Ulm, Germany
- SLK-Kliniken Heilbronn, Klinikum am Gesundbrunnen, Heilbronn, Germany
| | | | - Klaus Baumann
- University Hospital Gießen and Marburg, Site Marburg, Marburg, Germany
- Klinikum Ludwigshafen, Ludwigshafen, Germany
| | - Felix Hilpert
- University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
- Krankenhaus Jerusalem, Mammazentrum Hamburg, Hamburg, Germany
| | | | - Boris Winterhoff
- Department of Obstetrics, Gynecology and Women's Health, Division of Gynecologic Oncology, University of Minnesota, Minneapolis, MN, USA
| | - Peter Schürmann
- Gynaecology Research Unit, Hannover Medical School, Hannover, Germany
| | - Lisa-Marie Speith
- Gynaecology Research Unit, Hannover Medical School, Hannover, Germany
| | - Peter Hillemanns
- Gynaecology Research Unit, Hannover Medical School, Hannover, Germany
| | - Andrew Berchuck
- Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Duke University Medical Center, Durham, NC, USA
| | - Sharon E Johnatty
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Susan J Ramus
- School of Clinical Medicine, UNSW Medicine and Health, University of NSW Sydney, Sydney, NSW, Australia
- Adult Cancer Program, Lowy Cancer Research Centre, University of NSW Sydney, Sydney, NSW, Australia
| | | | - Paul D P Pharoah
- Centre for Cancer Genetic Epidemiology, Department of Oncology, University of Cambridge, Cambridge, UK
- Department of Computational Biomedicine, Cedars-Sinai Medical Center, West Hollywood, CA, USA
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
| | - Thilo Dörk
- Gynaecology Research Unit, Hannover Medical School, Hannover, Germany.
| | - Florian Heitz
- Department of Gynecology and Gynecologic Oncology, Evangelische Kliniken Essen-Mitte (KEM), Essen, Germany.
- Charité - Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.
- Department of Gynecology and Gynecological Oncology, HSK, Dr. Horst-Schmidt Klinik, Wiesbaden, Wiesbaden, Germany.
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2
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Wu CG, Balakrishnan VK, Merrill RA, Parihar PS, Konovolov K, Chen YC, Xu Z, Wei H, Sundaresan R, Cui Q, Wadzinski BE, Swingle MR, Musiyenko A, Chung WK, Honkanen RE, Suzuki A, Huang X, Strack S, Xing Y. B56δ long-disordered arms form a dynamic PP2A regulation interface coupled with global allostery and Jordan's syndrome mutations. Proc Natl Acad Sci U S A 2024; 121:e2310727120. [PMID: 38150499 PMCID: PMC10769853 DOI: 10.1073/pnas.2310727120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 11/27/2023] [Indexed: 12/29/2023] Open
Abstract
Intrinsically disordered regions (IDR) and short linear motifs (SLiMs) play pivotal roles in the intricate signaling networks governed by phosphatases and kinases. B56δ (encoded by PPP2R5D) is a regulatory subunit of protein phosphatase 2A (PP2A) with long IDRs that harbor a substrate-mimicking SLiM and multiple phosphorylation sites. De novo missense mutations in PPP2R5D cause intellectual disabilities (ID), macrocephaly, Parkinsonism, and a broad range of neurological symptoms. Our single-particle cryo-EM structures of the PP2A-B56δ holoenzyme reveal that the long, disordered arms at the B56δ termini fold against each other and the holoenzyme core. This architecture suppresses both the phosphatase active site and the substrate-binding protein groove, thereby stabilizing the enzyme in a closed latent form with dual autoinhibition. The resulting interface spans over 190 Å and harbors unfavorable contacts, activation phosphorylation sites, and nearly all residues with ID-associated mutations. Our studies suggest that this dynamic interface is coupled to an allosteric network responsive to phosphorylation and altered globally by mutations. Furthermore, we found that ID mutations increase the holoenzyme activity and perturb the phosphorylation rates, and the severe variants significantly increase the mitotic duration and error rates compared to the normal variant.
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Affiliation(s)
- Cheng-Guo Wu
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
| | - Vijaya K. Balakrishnan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
| | - Ronald A. Merrill
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA52242
| | - Pankaj S. Parihar
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
| | - Kirill Konovolov
- Chemistry Department, University of Wisconsin at Madison, Madison, WI53706
| | - Yu-Chia Chen
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Molecular and Cellular Pharmacology Program, University of Wisconsin at Madison, Madison, WI53706
| | - Zhen Xu
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA52242
| | - Hui Wei
- The Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY10027
| | - Ramya Sundaresan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
| | - Qiang Cui
- Department of Chemistry, Boston University, Boston, MA02215
| | | | - Mark R. Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL36688
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL36688
| | - Wendy K. Chung
- Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, MA02215
| | - Richard E. Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL36688
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
- Molecular and Cellular Pharmacology Program, University of Wisconsin at Madison, Madison, WI53706
| | - Xuhui Huang
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
- Chemistry Department, University of Wisconsin at Madison, Madison, WI53706
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA52242
| | - Yongna Xing
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
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3
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Peris I, Romero-Murillo S, Vicente C, Narla G, Odero MD. Regulation and role of the PP2A-B56 holoenzyme family in cancer. Biochim Biophys Acta Rev Cancer 2023; 1878:188953. [PMID: 37437699 DOI: 10.1016/j.bbcan.2023.188953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/07/2023] [Accepted: 07/08/2023] [Indexed: 07/14/2023]
Abstract
Protein phosphatase 2A (PP2A) inactivation is common in cancer, leading to sustained activation of pro-survival and growth-promoting pathways. PP2A consists of a scaffolding A-subunit, a catalytic C-subunit, and a regulatory B-subunit. The functional complexity of PP2A holoenzymes arises mainly through the vast repertoire of regulatory B-subunits, which determine both their substrate specificity and their subcellular localization. Therefore, a major challenge for developing more effective therapeutic strategies for cancer is to identify the specific PP2A complexes to be targeted. Of note, the development of small molecules specifically directed at PP2A-B56α has opened new therapeutic avenues in both solid and hematological tumors. Here, we focus on the B56/PR61 family of PP2A regulatory subunits, which have a central role in directing PP2A tumor suppressor activity. We provide an overview of the mechanisms controlling the formation and regulation of these complexes, the pathways they control, and the mechanisms underlying their deregulation in cancer.
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Affiliation(s)
- Irene Peris
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.
| | - Silvia Romero-Murillo
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain
| | - Carmen Vicente
- Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, The University of Michigan Medical School, Ann Arbor, MI, USA
| | - Maria D Odero
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain; CIBERONC, Instituto de Salud Carlos III, Madrid, Spain.
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4
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Guo Y, Bao J, Lin D, Hong K, Cen K, Sun J, Wang Z, Wu Z. Novel immune checkpoint-related gene model to predict prognosis and treatment responsiveness in low-grade gliomas. Heliyon 2023; 9:e20178. [PMID: 37809899 PMCID: PMC10559968 DOI: 10.1016/j.heliyon.2023.e20178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 09/05/2023] [Accepted: 09/13/2023] [Indexed: 10/10/2023] Open
Abstract
Recently, studies have shown that immune checkpoint-related genes (ICGs) are instrumental in maintaining immune homeostasis and can be regarded as potential therapeutic targets. However, the prognostic applications of ICGs require further elucidation in low-grade glioma (LGG) cases. In the present study, a unique prognostic gene signature in LGG has been identified and validated as well based on ICGs as a means of facilitating clinical decision-making. The RNA-seq data as well as corresponding clinical data of LGG samples have been retrieved utilizing the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. ICG-defined non-negative matrix factorization (NMF) clustering was performed to categorize patients with LGG into two molecular subtypes with different prognoses, clinical traits, and immune microenvironments. In the TCGA database, a signature integrating 8 genes has been developed utilizing the LASSO Cox method and validated in the GEO database. The signature developed is superior to other well-recognized signatures in terms of predicting the survival probability of patients with LGG. This 8-gene signature was then subsequently applied to categorize patients into high- and low-risk groups, and differences between them in terms of gene alteration frequency were observed. There were remarkable variations in IDH1 (91% and 64%) across low-as well as high-risk groups. Additionally, various analyses like function enrichment, tumor immune microenvironment, and chemotherapy drug sensitivity revealed significant variations across high- and low-risk populations. Overall, this 8-gene signature may function as a useful tool for prognosis and immunotherapy outcome predictions among LGG patients.
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Affiliation(s)
- Yangyang Guo
- Department of Neurosurgery, The First Affiliated Hospital of Ningbo University, Haishu District, Ningbo, 315010, Zhejiang, People's Republic of China
| | - Jingxia Bao
- Department of Breast Surgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, People's Republic of China
| | - Danfeng Lin
- Department of Breast Surgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, People's Republic of China
| | - Kai Hong
- Department of Neurosurgery, The First Affiliated Hospital of Ningbo University, Haishu District, Ningbo, 315010, Zhejiang, People's Republic of China
| | - Kenan Cen
- The Affiliated Hospital of Medical School of Ningbo University, Jiangbei District, Ningbo, 315020, Zhejiang, People's Republic of China
| | - Jie Sun
- Department of Neurosurgery, The First Affiliated Hospital of Ningbo University, Haishu District, Ningbo, 315010, Zhejiang, People's Republic of China
| | - Zhepei Wang
- Department of Neurosurgery, The First Affiliated Hospital of Ningbo University, Haishu District, Ningbo, 315010, Zhejiang, People's Republic of China
| | - Zhixuan Wu
- Department of Breast Surgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, People's Republic of China
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5
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Hsiao KC, Ruan SY, Chen SM, Lai TY, Chan RH, Zhang YM, Chu CA, Cheng HC, Tsai HW, Tu YF, Law BK, Chang TT, Chow NH, Chiang CW. The B56γ3-containing protein phosphatase 2A attenuates p70S6K-mediated negative feedback loop to enhance AKT-facilitated epithelial-mesenchymal transition in colorectal cancer. Cell Commun Signal 2023; 21:172. [PMID: 37430297 DOI: 10.1186/s12964-023-01182-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 06/04/2023] [Indexed: 07/12/2023] Open
Abstract
BACKGROUND Protein phosphatase 2A (PP2A) is one of the major protein phosphatases in eukaryotic cells and is essential for cellular homeostasis. PP2A is a heterotrimer comprising the dimeric AC core enzyme and a highly variable regulatory B subunit. Distinct B subunits help the core enzyme gain full activity toward specific substrates and contribute to diverse cellular roles of PP2A. PP2A has been thought to play a tumor suppressor and the B56γ3 regulatory subunit was shown to play a key tumor suppressor regulatory subunit of PP2A. Nevertheless, we uncovered a molecular mechanism of how B56γ3 may act as an oncogene in colorectal cancer (CRC). METHODS Polyclonal pools of CRC cells with stable B56γ3 overexpression or knockdown were generated by retroviral or lentiviral infection and subsequent drug selection. Co-immunoprecipitation(co-IP) and in vitro pull-down analysis were applied to analyze the protein-protein interaction. Transwell migration and invasion assays were applied to investigate the role of B56γ3 in affecting motility and invasive capability of CRC cells. The sensitivity of CRC cells to 5-fluorouracil (5-FU) was analyzed using the PrestoBlue reagent assay for cell viability. Immunohistochemistry (IHC) was applied to investigate the expression levels of phospho-AKT and B56γ3 in paired tumor and normal tissue specimens of CRC. DataSets of TCGA and GEO were analyzed to investigate the correlation of B56γ3 expression with overall survival rates of CRC patients. RESULTS We showed that B56γ3 promoted epithelial-mesenchymal transition (EMT) and reduced the sensitivity of CRC cells to 5-FU through upregulating AKT activity. Mechanistically, B56γ3 upregulates AKT activity by targeting PP2A to attenuate the p70S6K-mediated negative feedback loop regulation on PI3K/AKT activation. B56γ3 was highly expressed and positively correlated with the level of phospho-AKT in tumor tissues of CRC. Moreover, high B56γ3 expression is associated with poor prognosis of a subset of patients with CRC. CONCLUSIONS Our finding reveals that the B56γ3 regulatory subunit-containing PP2A plays an oncogenic role in CRC cells by sustaining AKT activation through suppressing p70S6K activity and suggests that the interaction between B56γ3 and p70S6K may serve as a therapeutic target for CRC. Video Abstract.
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Affiliation(s)
- Kai-Ching Hsiao
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Siou-Ying Ruan
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Shih-Min Chen
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Tai-Yu Lai
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Ren-Hao Chan
- Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Yan-Ming Zhang
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Chien-An Chu
- Department of Pathology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Hung-Chi Cheng
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Hung-Wen Tsai
- Department of Pathology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Yi-Fang Tu
- Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Brian K Law
- Department of Pharmacology and Therapeutics and the UF-Health Cancer Center, University of Florida, Gainesville, FL, 32610, USA
| | - Ting-Tsung Chang
- Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Nan-Haw Chow
- Department of Pathology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Chi-Wu Chiang
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC.
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC.
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Wu CG, Balakrishnan VK, Parihar PS, Konovolov K, Chen YC, Merrill RA, Wei H, Carragher B, Sundaresan R, Cui Q, Wadzinski BE, Swingle MR, Musiyenko A, Honkanen R, Chung WK, Suzuki A, Strack S, Huang X, Xing Y. Extended regulation interface coupled to the allosteric network and disease mutations in the PP2A-B56δ holoenzyme. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.09.530109. [PMID: 37066309 PMCID: PMC10103954 DOI: 10.1101/2023.03.09.530109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
An increasing number of mutations associated with devastating human diseases are diagnosed by whole-genome/exon sequencing. Recurrent de novo missense mutations have been discovered in B56δ (encoded by PPP2R5D), a regulatory subunit of protein phosphatase 2A (PP2A), that cause intellectual disabilities (ID), macrocephaly, Parkinsonism, and a broad range of neurological symptoms. Single-particle cryo-EM structures show that the PP2A-B56δ holoenzyme possesses closed latent and open active forms. In the closed form, the long, disordered arms of B56δ termini fold against each other and the holoenzyme core, establishing dual autoinhibition of the phosphatase active site and the substrate-binding protein groove. The resulting interface spans over 190 Å and harbors unfavorable contacts, activation phosphorylation sites, and nearly all residues with ID-associated mutations. Our studies suggest that this dynamic interface is close to an allosteric network responsive to activation phosphorylation and altered globally by mutations. Furthermore, we found that ID mutations perturb the activation phosphorylation rates, and the severe variants significantly increase the mitotic duration and error rates compared to the wild variant.
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Affiliation(s)
- Cheng-Guo Wu
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Vijaya K. Balakrishnan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
| | - Pankaj S. Parihar
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
| | - Kirill Konovolov
- Chemistry Department, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Yu-Chia Chen
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Molecular and Cellular Pharmacology program, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Hui Wei
- New York Structural biology Center, New York, NY 10027, USA
| | | | - Ramya Sundaresan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
| | - Qiang Cui
- Department of Chemistry, Metcalf Center for Science & Engineering, Boston University, Boston, MA 02215, USA
| | - Brian E. Wadzinski
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Mark R. Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Richard Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Wendy K. Chung
- Departments of Pediatrics and Medicine, Columbia University, New York, NY 10032, USA
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Xuhui Huang
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
- Chemistry Department, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Yongna Xing
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
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The repression of oncoprotein SET by the tumor suppressor p53 reveals a p53-SET-PP2A feedback loop for cancer therapy. SCIENCE CHINA. LIFE SCIENCES 2023; 66:81-93. [PMID: 35881220 DOI: 10.1007/s11427-021-2123-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 04/30/2022] [Indexed: 02/04/2023]
Abstract
The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms, including the hijacking of the tumor suppressors p53 and PP2A. Targeting aberrant SET represents a promising strategy for cancer intervention. However, the mechanism by which endogenous SET is regulated in cancer cells remains largely unknown. Here, we identified the tumor suppressor p53 as a key regulator that transcriptionally repressed the expression of SET in both normal and cancer cells. In addition, p53 stimulated PP2A phosphatase activity via p53-mediated transcriptional repression of SET, whereby SET-mediated inhibition of PP2A was alleviated. Moreover, targeting the interaction between SET and PP2A catalytic subunit (PP2Ac) with FTY720 enhanced stress-induced p53 activation via PP2A-mediated dephosphorylation of p53 on threonine 55 (Thr55). Therefore, our findings uncovered a previously unknown p53-SET-PP2A regulatory feedback loop. To functionally potentiate this feedback loop, we designed a combined therapeutic strategy by simultaneously administrating a p53 activator and SET antagonist in cancer cells and observed a dramatic synergistic effect on tumor suppression. Our study reveals mechanistic insight into the regulation of the oncoprotein SET and raises a potential strategy for cancer therapy by stimulating the p53-SET-PP2A feedback loop.
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Kashani E, Vassella E. Pleiotropy of PP2A Phosphatases in Cancer with a Focus on Glioblastoma IDH Wildtype. Cancers (Basel) 2022; 14:5227. [PMID: 36358647 PMCID: PMC9654311 DOI: 10.3390/cancers14215227] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/13/2022] [Accepted: 10/20/2022] [Indexed: 07/29/2023] Open
Abstract
Serine/Threonine protein phosphatase 2A (PP2A) is a heterotrimeric (or occasionally, heterodimeric) phosphatase with pleiotropic functions and ubiquitous expression. Despite the fact that they all contribute to protein dephosphorylation, multiple PP2A complexes exist which differ considerably by their subcellular localization and their substrate specificity, suggesting diverse PP2A functions. PP2A complex formation is tightly regulated by means of gene expression regulation by transcription factors, microRNAs, and post-translational modifications. Furthermore, a constant competition between PP2A regulatory subunits is taking place dynamically and depending on the spatiotemporal circumstance; many of the integral subunits can outcompete the rest, subjecting them to proteolysis. PP2A modulation is especially important in the context of brain tumors due to its ability to modulate distinct glioma-promoting signal transduction pathways, such as PI3K/Akt, Wnt, Ras, NF-κb, etc. Furthermore, PP2A is also implicated in DNA repair and survival pathways that are activated upon treatment of glioma cells with chemo-radiation. Depending on the cancer cell type, preclinical studies have shown some promise in utilising PP2A activator or PP2A inhibitors to overcome therapy resistance. This review has a special focus on "glioblastoma, IDH wild-type" (GBM) tumors, for which the therapy options have limited efficacy, and tumor relapse is inevitable.
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Affiliation(s)
- Elham Kashani
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Erik Vassella
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
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Sandal P, Jong CJ, Merrill RA, Song J, Strack S. Protein phosphatase 2A - structure, function and role in neurodevelopmental disorders. J Cell Sci 2021; 134:270819. [PMID: 34228795 DOI: 10.1242/jcs.248187] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Neurodevelopmental disorders (NDDs), including intellectual disability (ID), autism and schizophrenia, have high socioeconomic impact, yet poorly understood etiologies. A recent surge of large-scale genome or exome sequencing studies has identified a multitude of mostly de novo mutations in subunits of the protein phosphatase 2A (PP2A) holoenzyme that are strongly associated with NDDs. PP2A is responsible for at least 50% of total Ser/Thr dephosphorylation in most cell types and is predominantly found as trimeric holoenzymes composed of catalytic (C), scaffolding (A) and variable regulatory (B) subunits. PP2A can exist in nearly 100 different subunit combinations in mammalian cells, dictating distinct localizations, substrates and regulatory mechanisms. PP2A is well established as a regulator of cell division, growth, and differentiation, and the roles of PP2A in cancer and various neurodegenerative disorders, such as Alzheimer's disease, have been reviewed in detail. This Review summarizes and discusses recent reports on NDDs associated with mutations of PP2A subunits and PP2A-associated proteins. We also discuss the potential impact of these mutations on the structure and function of the PP2A holoenzymes and the etiology of NDDs.
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Affiliation(s)
- Priyanka Sandal
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Chian Ju Jong
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Jianing Song
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
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10
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Cell Cycle and DNA Repair Regulation in the Damage Response: Protein Phosphatases Take Over the Reins. Int J Mol Sci 2020; 21:ijms21020446. [PMID: 31936707 PMCID: PMC7014277 DOI: 10.3390/ijms21020446] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/29/2019] [Accepted: 01/02/2020] [Indexed: 12/14/2022] Open
Abstract
Cells are constantly suffering genotoxic stresses that affect the integrity of our genetic material. Genotoxic insults must be repaired to avoid the loss or inappropriate transmission of the genetic information, a situation that could lead to the appearance of developmental abnormalities and tumorigenesis. To combat this threat, eukaryotic cells have evolved a set of sophisticated molecular mechanisms that are collectively known as the DNA damage response (DDR). This surveillance system controls several aspects of the cellular response, including the detection of lesions, a temporary cell cycle arrest, and the repair of the broken DNA. While the regulation of the DDR by numerous kinases has been well documented over the last decade, the complex roles of protein dephosphorylation have only recently begun to be investigated. Here, we review recent progress in the characterization of DDR-related protein phosphatases during the response to a DNA lesion, focusing mainly on their ability to modulate the DNA damage checkpoint and the repair of the damaged DNA. We also discuss their protein composition and structure, target specificity, and biochemical regulation along the different stages encompassed in the DDR. The compilation of this information will allow us to better comprehend the physiological significance of protein dephosphorylation in the maintenance of genome integrity and cell viability in response to genotoxic stress.
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11
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Zhao JL, Zhang LQ, Liu N, Xu SL, Yue ZL, Zhang LL, Deng ZP, Burlingame AL, Sun DY, Wang ZY, Sun Y, Zhang SW. Mutual Regulation of Receptor-Like Kinase SIT1 and B'κ-PP2A Shapes the Early Response of Rice to Salt Stress. THE PLANT CELL 2019; 31:2131-2151. [PMID: 31221736 PMCID: PMC6751134 DOI: 10.1105/tpc.18.00706] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/22/2019] [Accepted: 06/14/2019] [Indexed: 05/03/2023]
Abstract
The receptor-like kinase SIT1 acts as a sensor in rice (Oryza sativa) roots, relaying salt stress signals via elevated kinase activity to enhance salt sensitivity. Here, we demonstrate that Protein Phosphatase 2A (PP2A) regulatory subunit B'κ constrains SIT1 activity under salt stress. B'κ-PP2A deactivates SIT1 directly by dephosphorylating the kinase at Thr515/516, a salt-induced phosphorylation site in the activation loop that is essential for SIT1 activity. B'κ overexpression suppresses the salt sensitivity of rice plants expressing high levels of SIT1, thereby contributing to salt tolerance. B'κ functions in a SIT1 kinase-dependent manner. During early salt stress, activated SIT1 phosphorylates B'κ; this not only enhances its binding with SIT1, it also promotes B'κ protein accumulation via Ser502 phosphorylation. Consequently, by blocking SIT1 phosphorylation, B'κ inhibits and fine-tunes SIT1 activity to balance plant growth and stress adaptation.
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Affiliation(s)
- Ji-Long Zhao
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
| | - Li-Qing Zhang
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
| | - Ning Liu
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
| | - Shou-Ling Xu
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143
| | - Zhi-Liang Yue
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
| | - Lu-Lu Zhang
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
| | - Zhi-Ping Deng
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143
| | - Da-Ye Sun
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
| | - Zhi-Yong Wang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Ying Sun
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
| | - Sheng-Wei Zhang
- College of Life Science, Hebei Normal University, Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China
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12
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El Taweel M, Gawdat RM, Abdelfattah R. Prognostic Impact of PPP2R5C Gene Expression in Adult Acute Myeloid Leukemia Patients with Normal Cytogenetics. Indian J Hematol Blood Transfus 2019; 36:37-46. [PMID: 32158086 DOI: 10.1007/s12288-019-01142-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 05/28/2019] [Indexed: 10/26/2022] Open
Abstract
Protein Phosphatase 2A (PP2A) is a crucial regulator of the cellular signalling pathways, proliferation, cell cycle checkpoints and apoptosis. The PPP2R5C gene encodes PP2A regulatory B56γ subunit. Malignant transformation may occur, if mRNA of PPP2R5C is functionally deregulated, structurally altered, decreased or overexpressed. Therefore, the purpose of the study was to examine PPP2R5C mRNA expression, evaluate its association with the different clinical and haematological parameters and determine its prognostic impact in Egyptian adult acute myeloid leukaemia patients with normal cytogenetics (CN-AML). Peripheral blood samples of 50 de novo CN-AML patients and 20 age- and gender-matched healthy controls were examined for PPP2R5C expression by Quantitative Real Time-Polymerase Chain Reaction. The expression levels of PPP2R5C mRNA were significantly higher in the CN-AML samples than in the control samples (P ≤ 0.001). There was a statistical significant difference between the low and high expression levels of PPP2R5C with regard to age (P = 0.005, r = - 0.447, P = 0.001). The patients with an unfavourable response to induction chemotherapy had significant higher PPP2R5C expression levels than those with a favourable response (P = 0.002). There was a significant influence of high PPP2R5C expression levels on the overall survival and progression free survival (P = 0.03, 0.026), respectively. PPP2R5C overexpression is an adverse prognostic factor which affects leukaemogenesis in the CN-AML, it may predict the disease progression and overall survival during the follow-up of the patients.
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Affiliation(s)
- Maha El Taweel
- 1Clinical Pathology Department, National Cancer Institute, Cairo University, Cairo, Egypt
| | - Rania M Gawdat
- 2Clinical and Chemical Pathology Department, Faculty of Medicine, Beni-Suef Teaching Hospital, Beni-Suef University, Beni- Suef, Egypt
| | - Rafaat Abdelfattah
- 3Department of Medical Oncology, National Cancer Institute, Cairo University, Cairo, Egypt
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13
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Tu W, Dong C, Fu J, Pan Y, Kobayashi A, Furusawa Y, Konishi T, Shao C. Both irradiated and bystander effects link with DNA repair capacity and the linear energy transfer. Life Sci 2019; 222:228-234. [PMID: 30858123 DOI: 10.1016/j.lfs.2019.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 01/21/2023]
Abstract
AIMS In comparison with a low linear energy transfer (LET) radiation, a high-LET radiation induces more complex DNA damage. This study wonders whether radiation-induced bystander effect (RIBE) is dependent of LET. MATERIALS AND METHODS Chinese hamster ovary CHO-9 cells and its subline EM-C11 cells (SSB repair deficient) and XR-C1 cells (DSB repair deficient) were irradiated by γ-rays, α-particles, or carbon ions with different LETs of 13, 30 and 70 keV/μm. Cell proliferation, cell death, DNA damage, cell cycle distribution and some protein expressions were measured with the cell counting kit-8 (CCK-8), colony formation, micronuclei (MN), flow cytometry and western blot, respectively. KEY FINDINGS A series of cell responses were induced by these radiations in a LET-dependent manner, including proliferation inhibition, cell death, MN induction, G2/M phase arrest and the expression of γH2AX protein. These cell injuries were also depended on DNA repair capacity, and XR-C1 cells were the most sensitive to each radiation. Furthermore, when the cells were treated with the conditioned medium (CM) collected from irradiated CHO-9 cells, the MN induction and cell death response in the bystander cells of EM-C11 or XR-C1 increased along with LET of irradiation, and the bystander damage was easier to be induced in EM-C11 and XR-C1 cells than that in CHO-9 cells. SIGNIFICANCE Both cellular DNA repair capacity and the LET value of radiation could deeply influence damage extents of not only the irradiated cells but also the bystander cells.
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Affiliation(s)
- Wenzhi Tu
- Institute of Radiation Medicine, Fudan University, Shanghai 200032, China; The Comprehensive Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Chen Dong
- Institute of Radiation Medicine, Fudan University, Shanghai 200032, China
| | - Jiamei Fu
- Institute of Radiation Medicine, Fudan University, Shanghai 200032, China
| | - Yan Pan
- Institute of Radiation Medicine, Fudan University, Shanghai 200032, China
| | - Alisa Kobayashi
- Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Inage, Chiba 263-8555, Japan
| | - Yoshiya Furusawa
- Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Inage, Chiba 263-8555, Japan
| | - Teruaki Konishi
- Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Inage, Chiba 263-8555, Japan
| | - Chunlin Shao
- Institute of Radiation Medicine, Fudan University, Shanghai 200032, China.
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Sun WG, Song RP, Wang Y, Zhang YH, Wang HX, Ge S, Liu JR, Liu LX. γ-Tocotrienol-Inhibited Cell Proliferation of Human Gastric Cancer by Regulation of Nuclear Factor-κB Activity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 67:441-451. [PMID: 30562020 DOI: 10.1021/acs.jafc.8b05832] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
γ-Tocotrienol (γ-T3) exhibits the activity of anticancer via regulating cell signaling pathways. Nuclear factor-κB (NF-κB), one of the crucial pro-inflammatory factors, is involved in the regulation of cell proliferation, apoptosis, invasion, and migration of tumor. In the present study, NF-κB activity inhibited by γ-T3 was investigated in gastric cancer cells. Cell proliferation, NF-κB activity, active protein phosphatase type 2A (PP2A), and ataxia-telangiectasia mutated (ATM) protein were explored using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT), methylene blue, enzyme-linked immunosorbent assay (ELISA), malachite green, luciferase, and Western blotting assays. The effects of γ-T3 on tumor growth and the expression of NF-κB and PP2A proteins were also further examined by implanting human gastric cancer cells in a BALB/c nude mouse model. The results showed that γ-T3 significantly inhibited the cell proliferation and attenuated the NF-κB activity in vitro and in vivo. γ-T3 dramatically increased PP2A activity and protein expression, which suppressed ATM phosphorylation and its translocation to the cytoplasm in gastric cancer cells. Thus, our findings may provide mechanistic insight into effects of γ-T3 on the regulation of NF-κB activity by a PP2A-dependent mechanism and suggest that PP2A may serve as a molecular target for a potential chemopreventive agent.
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Affiliation(s)
- Wen-Guang Sun
- International Peace Maternity and Child Health Hospital, School of Medicine , Shanghai JiaoTong University , 910 Hengshan Road , Shanghai 200030 , P. R. China
| | - Rui-Peng Song
- Department of General Surgery , The First Affiliated Hospital of University of Science and Technology , 17 LuJiang Road , LuYang District, HeFei 230031 , P. R. China
| | - Yong Wang
- Harbin Center for Disease Control and Prevention , 30 WeiXing Road , DaoWai District, Harbin 150056 , P. R. China
| | - Ya-Hui Zhang
- International Peace Maternity and Child Health Hospital, School of Medicine , Shanghai JiaoTong University , 910 Hengshan Road , Shanghai 200030 , P. R. China
| | - Hai-Xia Wang
- International Peace Maternity and Child Health Hospital, School of Medicine , Shanghai JiaoTong University , 910 Hengshan Road , Shanghai 200030 , P. R. China
| | - Sheng Ge
- International Peace Maternity and Child Health Hospital, School of Medicine , Shanghai JiaoTong University , 910 Hengshan Road , Shanghai 200030 , P. R. China
| | - Jia-Ren Liu
- Department of Clinical Laboratory , The Fourth Affiliated Hospital of Harbin Medical University , 37 YiYuan Street , NanGang District, Harbin 150001 , P. R. China
| | - Lian-Xin Liu
- Department of General Surgery , The First Affiliated Hospital of University of Science and Technology , 17 LuJiang Road , LuYang District, HeFei 230031 , P. R. China
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15
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ER stress regulating protein phosphatase 2A-B56γ, targeted by hepatitis B virus X protein, induces cell cycle arrest and apoptosis of hepatocytes. Cell Death Dis 2018; 9:762. [PMID: 29988038 PMCID: PMC6037732 DOI: 10.1038/s41419-018-0787-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 06/08/2018] [Accepted: 06/13/2018] [Indexed: 12/13/2022]
Abstract
Hepatitis B virus X (HBx) protein contributes to the progression of hepatitis B virus (HBV)-related hepatic injury and diseases, but the exact mechanism remains unclear. Protein phosphatase 2 A (PP2A) is a major serine/threonine phosphatase involved in regulating many cellular phosphorylation signals that are important for regulation of cell cycle and apoptosis. Does HBx target to PP2A-B56γ and therefore affect HBx-induced hepatotoxicity? In the present study, the expression of B56γ positively correlated with the level of HBx in HBV-infected primary human hepatocytes in human-liver-chimeric mice, HBx-transgenic mice, HBV-infected cells, and HBx-expressing hepatic cells. B56γ promoted p53/p21-dependent cell cycle arrest and apoptosis. Mechanistically, B56γ was transactivated by AP-1, which was under the regulation of endoplasmic reticulum (ER) stress induced CREBH signaling in HBx-expressing hepatic cells. B56γ dephosphorylated p-Thr55-p53 to trigger p53/p21 pathway-dependent cell cycle G1 phase arrest, resulting in apoptosis of hepatic cells. In conclusion, this study provides a novel insight into a mechanism of B56γ mediating cell cycle arrest and apoptosis of HBx-expressing hepatic cells and a basis for B56γ being a potential therapeutic target for HBV-infected hepatic cells.
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16
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Fabbrizi MR, Meyer B, Misri S, Raj S, Zobel CL, Hallahan DE, Sharma GG. Transient PP2A inhibition alleviates normal tissue stem cell susceptibility to cell death during radiotherapy. Cell Death Dis 2018; 9:492. [PMID: 29706648 PMCID: PMC5924762 DOI: 10.1038/s41419-018-0559-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022]
Abstract
Unintended outcomes of cancer therapy include ionizing radiation (IR)-induced stem cell depletion, diminished regenerative capacity, and accelerated aging. Stem cells exhibit attenuated DNA damage response (DDR) and are hypersensitive to IR, as compared to differentiated non-stem cells. We performed genomic discovery research to compare stem cells to differentiated cells, which revealed Phosphoprotein phosphatase 2A (PP2A) as a potential contributor to susceptibility in stem cells. PP2A dephosphorylates pATM, γH2AX, pAkt etc. and is believed to play dual role in regulating DDR and apoptosis. Although studied widely in cancer cells, the role of PP2A in normal stem cell radiosensitivity is unknown. Here we demonstrate that constitutively high expression and radiation induction of PP2A in stem cells plays a role in promoting susceptibility to irradiation. Transient inhibition of PP2A markedly restores DNA repair, inhibits apoptosis, and enhances survival of stem cells, without affecting differentiated non-stem and cancer cells. PP2Ai-mediated stem cell radioprotection was demonstrated in murine embryonic, adult neural, intestinal, and hematopoietic stem cells.
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Affiliation(s)
- Maria Rita Fabbrizi
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, Saint Louis, MO, 63108, USA
| | - Barbara Meyer
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, Saint Louis, MO, 63108, USA
| | - Sandeep Misri
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, Saint Louis, MO, 63108, USA
| | - Suyash Raj
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, Saint Louis, MO, 63108, USA
| | - Cheri L Zobel
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, Saint Louis, MO, 63108, USA
| | - Dennis E Hallahan
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, Saint Louis, MO, 63108, USA.,Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - Girdhar G Sharma
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, Saint Louis, MO, 63108, USA. .,Siteman Cancer Center, Washington University School of Medicine, Saint Louis, MO, 63108, USA.
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17
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Kauko O, Westermarck J. Non-genomic mechanisms of protein phosphatase 2A (PP2A) regulation in cancer. Int J Biochem Cell Biol 2018; 96:157-164. [DOI: 10.1016/j.biocel.2018.01.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 12/03/2017] [Accepted: 01/09/2018] [Indexed: 02/08/2023]
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18
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Liu R, Tang J, Ding C, Liang W, Zhang L, Chen T, Xiong Y, Dai X, Li W, Xu Y, Hu J, Lu L, Liao W, Lu X. The depletion of ATM inhibits colon cancer proliferation and migration via B56γ2-mediated Chk1/p53/CD44 cascades. Cancer Lett 2017; 390:48-57. [PMID: 28093285 DOI: 10.1016/j.canlet.2016.12.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/15/2016] [Accepted: 12/24/2016] [Indexed: 02/07/2023]
Abstract
Ataxia-telangiectasia mutated (ATM) protein kinase is a major guardian of genomic stability, and its well-established function in cancer is tumor suppression. Here, we report an oncogenic role of ATM. Using two isogenic sets of human colon cancer cell lines that differed only in their ATM status, we demonstrated that ATM deficiency significantly inhibits cancer cell proliferation, migration, and invasion. The tumor-suppressive function of ATM depletion is not modulated by the compensatory activation of ATR, but it is associated with B56γ2-mediated Chk1/p53/CD44 signaling pathways. Under normal growth conditions, the depletion of ATM prevents B56γ2 ubiquitination and degradation, which activates PP2A-mediated Chk1/p53/p21 signaling pathways, leading to senescence and cell cycle arrest. CD44 was validated as a novel ATM target based on its ability to rescue cell migration and invasion defects in ATM-depleted cells. The activation of p53 induced by ATM depletion suppresses CD44 transcription, thus resulting in epithelial-mesenchymal transition (EMT) and cell migration suppression. Our study suggests that ATM has tumorigenic potential in post-formed colon neoplasia, and it supports ATM as an appealing target for improving cancer therapy.
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Affiliation(s)
- Rui Liu
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Jiajia Tang
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Chaodong Ding
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Weicheng Liang
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Li Zhang
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Tianke Chen
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Yan Xiong
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Xiaowei Dai
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Wenfeng Li
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Yunsheng Xu
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Jin Hu
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Liting Lu
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Wanqin Liao
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China
| | - Xincheng Lu
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325000, China.
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19
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The broken "Off" switch in cancer signaling: PP2A as a regulator of tumorigenesis, drug resistance, and immune surveillance. BBA CLINICAL 2016; 6:87-99. [PMID: 27556014 PMCID: PMC4986044 DOI: 10.1016/j.bbacli.2016.08.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/01/2016] [Accepted: 08/02/2016] [Indexed: 12/31/2022]
Abstract
Aberrant activation of signal transduction pathways can transform a normal cell to a malignant one and can impart survival properties that render cancer cells resistant to therapy. A diverse set of cascades have been implicated in various cancers including those mediated by serine/threonine kinases such RAS, PI3K/AKT, and PKC. Signal transduction is a dynamic process involving both "On" and "Off" switches. Activating mutations of RAS or PI3K can be viewed as the switch being stuck in the "On" position resulting in continued signaling by a survival and/or proliferation pathway. On the other hand, inactivation of protein phosphatases such as the PP2A family can be seen as the defective "Off" switch that similarly can activate these pathways. A problem for therapeutic targeting of PP2A is that the enzyme is a hetero-trimer and thus drug targeting involves complex structures. More importantly, since PP2A isoforms generally act as tumor suppressors one would want to activate these enzymes rather than suppress them. The elucidation of the role of cellular inhibitors like SET and CIP2A in cancer suggests that targeting these proteins can have therapeutic efficacy by mechanisms involving PP2A activation. Furthermore, drugs such as FTY-720 can activate PP2A isoforms directly. This review will cover the current state of knowledge of PP2A role as a tumor suppressor in cancer cells and as a mediator of processes that can impact drug resistance and immune surveillance.
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20
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Arriazu E, Pippa R, Odero MD. Protein Phosphatase 2A as a Therapeutic Target in Acute Myeloid Leukemia. Front Oncol 2016; 6:78. [PMID: 27092295 PMCID: PMC4822158 DOI: 10.3389/fonc.2016.00078] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/21/2016] [Indexed: 12/31/2022] Open
Abstract
Acute myeloid leukemia (AML) is a heterogeneous malignant disorder of hematopoietic progenitor cells in which several genetic and epigenetic aberrations have been described. Despite progressive advances in our understanding of the molecular biology of this disease, the outcome for most patients is poor. It is, therefore, necessary to develop more effective treatment strategies. Genetic aberrations affecting kinases have been widely studied in AML; however, the role of phosphatases remains underexplored. Inactivation of the tumor-suppressor protein phosphatase 2A (PP2A) is frequent in AML patients, making it a promising target for therapy. There are several PP2A inactivating mechanisms reported in this disease. Deregulation or specific post-translational modifications of PP2A subunits have been identified as a cause of PP2A malfunction, which lead to deregulation of proliferation or apoptosis pathways, depending on the subunit affected. Likewise, overexpression of either SET or cancerous inhibitor of protein phosphatase 2A, endogenous inhibitors of PP2A, is a recurrent event in AML that impairs PP2A activity, contributing to leukemogenesis progression. Interestingly, the anticancer activity of several PP2A-activating drugs (PADs) depends on interaction/sequestration of SET. Preclinical studies show that pharmacological restoration of PP2A activity by PADs effectively antagonizes leukemogenesis, and that these drugs have synergistic cytotoxic effects with conventional chemotherapy and kinase inhibitors, opening new possibilities for personalized treatment in AML patients, especially in cases with SET-dependent inactivation of PP2A. Here, we review the role of PP2A as a druggable tumor suppressor in AML.
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Affiliation(s)
- Elena Arriazu
- Hematology/Oncology Program, Center for Applied Medical Research (CIMA), University of Navarra , Pamplona , Spain
| | - Raffaella Pippa
- Centre for Gene Regulation and Expression, University of Dundee , Dundee , UK
| | - María D Odero
- Hematology/Oncology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain; Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
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21
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Kozlov SV, Waardenberg AJ, Engholm-Keller K, Arthur JW, Graham ME, Lavin M. Reactive Oxygen Species (ROS)-Activated ATM-Dependent Phosphorylation of Cytoplasmic Substrates Identified by Large-Scale Phosphoproteomics Screen. Mol Cell Proteomics 2016; 15:1032-47. [PMID: 26699800 PMCID: PMC4813686 DOI: 10.1074/mcp.m115.055723] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/08/2015] [Indexed: 01/06/2023] Open
Abstract
Ataxia-telangiectasia, mutated (ATM) protein plays a central role in phosphorylating a network of proteins in response to DNA damage. These proteins function in signaling pathways designed to maintain the stability of the genome and minimize the risk of disease by controlling cell cycle checkpoints, initiating DNA repair, and regulating gene expression. ATM kinase can be activated by a variety of stimuli, including oxidative stress. Here, we confirmed activation of cytoplasmic ATM by autophosphorylation at multiple sites. Then we employed a global quantitative phosphoproteomics approach to identify cytoplasmic proteins altered in their phosphorylation state in control and ataxia-telangiectasia (A-T) cells in response to oxidative damage. We demonstrated that ATM was activated by oxidative damage in the cytoplasm as well as in the nucleus and identified a total of 9,833 phosphorylation sites, including 6,686 high-confidence sites mapping to 2,536 unique proteins. A total of 62 differentially phosphorylated peptides were identified; of these, 43 were phosphorylated in control but not in A-T cells, and 19 varied in their level of phosphorylation. Motif enrichment analysis of phosphopeptides revealed that consensus ATM serine glutamine sites were overrepresented. When considering phosphorylation events, only observed in control cells (not observed in A-T cells), with predicted ATM sites phosphoSerine/phosphoThreonine glutamine, we narrowed this list to 11 candidate ATM-dependent cytoplasmic proteins. Two of these 11 were previously described as ATM substrates (HMGA1 and UIMCI/RAP80), another five were identified in a whole cell extract phosphoproteomic screens, and the remaining four proteins had not been identified previously in DNA damage response screens. We validated the phosphorylation of three of these proteins (oxidative stress responsive 1 (OSR1), HDGF, and ccdc82) as ATM dependent after H2O2 exposure, and another protein (S100A11) demonstrated ATM-dependence for translocation from the cytoplasm to the nucleus. These data provide new insights into the activation of ATM by oxidative stress through identification of novel substrates for ATM in the cytoplasm.
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Affiliation(s)
- Sergei V Kozlov
- From the ‡University of Queensland Centre for Clinical Research, University of Queensland, Royal Brisbane & Women's Hospital Campus, Herston, Brisbane, QLD 4029 Australia
| | - Ashley J Waardenberg
- §Bioinformatics Unit, Children's Medical Research Institute, University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia
| | - Kasper Engholm-Keller
- ¶Synapse Proteomics Group, Children's Medical Research Institute, University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia; ‖Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Jonathan W Arthur
- §Bioinformatics Unit, Children's Medical Research Institute, University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia
| | - Mark E Graham
- ¶Synapse Proteomics Group, Children's Medical Research Institute, University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia
| | - Martin Lavin
- From the ‡University of Queensland Centre for Clinical Research, University of Queensland, Royal Brisbane & Women's Hospital Campus, Herston, Brisbane, QLD 4029 Australia;
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22
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Maertens GN. B'-protein phosphatase 2A is a functional binding partner of delta-retroviral integrase. Nucleic Acids Res 2015; 44:364-76. [PMID: 26657642 PMCID: PMC4705670 DOI: 10.1093/nar/gkv1347] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 11/19/2015] [Indexed: 12/31/2022] Open
Abstract
To establish infection, a retrovirus must insert a DNA copy of its RNA genome into host chromatin. This reaction is catalysed by the virally encoded enzyme integrase (IN) and is facilitated by viral genus-specific host factors. Herein, cellular serine/threonine protein phosphatase 2A (PP2A) is identified as a functional IN binding partner exclusive to δ-retroviruses, including human T cell lymphotropic virus type 1 and 2 (HTLV-1 and HTLV-2) and bovine leukaemia virus (BLV). PP2A is a heterotrimer composed of a scaffold, catalytic and one of any of four families of regulatory subunits, and the interaction is specific to the B' family of the regulatory subunits. B'-PP2A and HTLV-1 IN display nuclear co-localization, and the B' subunit stimulates concerted strand transfer activity of δ-retroviral INs in vitro. The protein-protein interaction interface maps to a patch of highly conserved residues on B', which when mutated render B' incapable of binding to and stimulating HTLV-1 and -2 IN strand transfer activity.
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Affiliation(s)
- Goedele N Maertens
- Division of Infectious Diseases, St. Mary's campus, Imperial College London, Norfolk Place, London, W2 1PG, UK
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23
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Cheng YS, Seibert O, Klöting N, Dietrich A, Straßburger K, Fernández-Veledo S, Vendrell JJ, Zorzano A, Blüher M, Herzig S, Berriel Diaz M, Teleman AA. PPP2R5C Couples Hepatic Glucose and Lipid Homeostasis. PLoS Genet 2015; 11:e1005561. [PMID: 26440364 PMCID: PMC4595073 DOI: 10.1371/journal.pgen.1005561] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 09/10/2015] [Indexed: 01/12/2023] Open
Abstract
In mammals, the liver plays a central role in maintaining carbohydrate and lipid homeostasis by acting both as a major source and a major sink of glucose and lipids. In particular, when dietary carbohydrates are in excess, the liver converts them to lipids via de novo lipogenesis. The molecular checkpoints regulating the balance between carbohydrate and lipid homeostasis, however, are not fully understood. Here we identify PPP2R5C, a regulatory subunit of PP2A, as a novel modulator of liver metabolism in postprandial physiology. Inactivation of PPP2R5C in isolated hepatocytes leads to increased glucose uptake and increased de novo lipogenesis. These phenotypes are reiterated in vivo, where hepatocyte specific PPP2R5C knockdown yields mice with improved systemic glucose tolerance and insulin sensitivity, but elevated circulating triglyceride levels. We show that modulation of PPP2R5C levels leads to alterations in AMPK and SREBP-1 activity. We find that hepatic levels of PPP2R5C are elevated in human diabetic patients, and correlate with obesity and insulin resistance in these subjects. In sum, our data suggest that hepatic PPP2R5C represents an important factor in the functional wiring of energy metabolism and the maintenance of a metabolically healthy state. After a meal, dietary glucose travels through the hepatic portal vein to the liver. A substantial part of this glucose is taken up by liver, which converts it to glycogen which is stored, and lipids which are in part stored and in part secreted as VLDL particles. The rest of the organs receive whatever glucose the liver leaves in circulation, plus the secreted lipids. Hence the liver plays a crucial role in determining the balance of sugar versus lipids in the body after a meal. This balance is very important, because too much glucose in circulation leads to diabetic complications whereas too much VLDL increases risk of atherosclerosis. Little is known about how the liver strikes this balance. We identify here a phosphatase—the PP2A holoenzyme containing the PPP2R5C regulatory subunit—as a regulator of this process. We find that knockdown of PPP2R5C in mouse liver specifically causes it to uptake elevated levels of glucose, and secrete elevated levels of VLDL into circulation. This leads to a phenotype of improved glucose tolerance and insulin sensitivity. The prediction from these functional studies in mice is that elevated levels of PPP2R5C expression should lead to insulin resistance. Indeed, we find that PPP2R5C expression levels are elevated in diabetic patients, or healthy controls with visceral obesity, raising the possibility that dysregulation of PPP2R5C expression in humans may contribute towards metabolic dysfunction.
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Affiliation(s)
| | - Oksana Seibert
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Nora Klöting
- Department of Medicine, University of Leipzig, Leipzig, Germany
| | - Arne Dietrich
- Department of Medicine, University of Leipzig, Leipzig, Germany
| | | | - Sonia Fernández-Veledo
- Hospital Universitari de Tarragona Joan XXIII, Institut d´Investigació Sanitària Pere Virgili. Universitat, Rovira i Virgili, CIBERDEM, Tarragona, Spain
| | - Joan J. Vendrell
- Hospital Universitari de Tarragona Joan XXIII. Institut d´Investigació Sanitària Pere Virgili Universitat Rovira i Virgili, CIBERDEM, Tarragona, Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona), Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, and CIBERDEM, Barcelona, , Spain
| | - Matthias Blüher
- Department of Medicine, University of Leipzig, Leipzig, Germany
| | - Stephan Herzig
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany, and Joint Heidelberg-IDC Translational Diabetes Program, University Hospital Heidelberg, Heidelberg, Germany
- Chair Molecular Metabolic Control, Medical Faculty, Technical University Munich, Germany
| | - Mauricio Berriel Diaz
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany, and Joint Heidelberg-IDC Translational Diabetes Program, University Hospital Heidelberg, Heidelberg, Germany
- * E-mail: (MBD); (AAT)
| | - Aurelio A. Teleman
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- * E-mail: (MBD); (AAT)
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24
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Hong CS, Ho W, Zhang C, Yang C, Elder JB, Zhuang Z. LB100, a small molecule inhibitor of PP2A with potent chemo- and radio-sensitizing potential. Cancer Biol Ther 2015; 16:821-33. [PMID: 25897893 DOI: 10.1080/15384047.2015.1040961] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase that plays a significant role in mitotic progression and cellular responses to DNA damage. While traditionally viewed as a tumor suppressor, inhibition of PP2A has recently come to attention as a novel therapeutic means of driving senescent cancer cells into mitosis and promoting cell death via mitotic catastrophe. These findings have been corroborated in numerous studies utilizing naturally produced compounds that selectively inhibit PP2A. To overcome the known human toxicities associated with these compounds, a water-soluble small molecule inhibitor, LB100, was recently developed to competitively inhibit the PP2A protein. This review summarizes the pre-clinical studies to date that have demonstrated the anti-cancer activity of LB100 via its chemo- and radio-sensitizing properties. These studies demonstrate the tremendous therapeutic potential of LB100 in a variety of cancer types. The results of an ongoing phase 1 trial are eagerly anticipated.
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Key Words
- ABC, ATP-binding cassette.
- APC, adenomatous polyposis coli
- ARPP19, cyclic AMP-regulated phosphoprotein 19
- ATM, ataxia-telangiectasia mutated
- CIP2A, cancerous inhibitor of PP2A
- CNTF, ciliary neurotrophic factor
- DISC, death-inducing signaling complex
- DVL, dishevelled
- ENSA, α-endosulphine
- GBM, glioblastoma
- GFAP, glial fibrillary acidic protein
- HCC, hepatocellular carcinoma
- HDACs, histone deacetylase complexes
- HIF-1a, hypoxia-inducible factor-1a
- HRR, homologous recombination repair
- MDM2, mouse double minute 2 homolog
- MRI, magnetic resonance imaging
- NPC, nasopharyngeal carcinoma
- PP2A, protein phosphatase 2A
- Plk1, polo-like kinase 1
- TCTP, translationally-controlled tumor protein
- TMZ, temozolomide
- TRAIL, TNF-related apoptosis-inducing ligand
- VEGF, vascular endothelial growth factor
- cell cycle
- chemosensitization
- mitotic catastrophe
- protein phosphatase 2A
- radiosensitizationreview
- small molecule inhibitor
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Affiliation(s)
- Christopher S Hong
- a The Ohio State University Wexner Medical Center ; Department of Neurological Surgery ; Columbus , OH USA
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25
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Leucine-rich repeat-containing protein 59 mediates nuclear import of cancerous inhibitor of PP2A in prostate cancer cells. Tumour Biol 2015; 36:6383-90. [PMID: 25833693 DOI: 10.1007/s13277-015-3326-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 03/12/2015] [Indexed: 10/23/2022] Open
Abstract
Using yeast two-hybrid analysis, we identified several novel protein interactions for the oncoprotein Cancerous Inhibitor of PP2A (CIP2A) and confirmed a subset of these interactions in human cancer cell lines. Analysis of the interaction in prostate carcinoma cells between CIP2A and leucine-rich repeat-containing protein 59 (LRRC59) suggests that CIP2A is translocated into the nucleus at G2/M through its association with LRRC59. Recent work by others has demonstrated that nuclear CIP2A disrupts mitotic checkpoints, which promotes deregulation of the cell cycle and increases cancerous phenotypes. Thus, we provide a novel therapeutic mechanism for inhibiting CIP2A function in cancerous cells via targeting the CIP2A-LRRC59 interaction.
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26
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Shaltiel IA, Krenning L, Bruinsma W, Medema RH. The same, only different - DNA damage checkpoints and their reversal throughout the cell cycle. J Cell Sci 2015; 128:607-20. [PMID: 25609713 DOI: 10.1242/jcs.163766] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cell cycle checkpoints activated by DNA double-strand breaks (DSBs) are essential for the maintenance of the genomic integrity of proliferating cells. Following DNA damage, cells must detect the break and either transiently block cell cycle progression, to allow time for repair, or exit the cell cycle. Reversal of a DNA-damage-induced checkpoint not only requires the repair of these lesions, but a cell must also prevent permanent exit from the cell cycle and actively terminate checkpoint signalling to allow cell cycle progression to resume. It is becoming increasingly clear that despite the shared mechanisms of DNA damage detection throughout the cell cycle, the checkpoint and its reversal are precisely tuned to each cell cycle phase. Furthermore, recent findings challenge the dogmatic view that complete repair is a precondition for cell cycle resumption. In this Commentary, we highlight cell-cycle-dependent differences in checkpoint signalling and recovery after a DNA DSB, and summarise the molecular mechanisms that underlie the reversal of DNA damage checkpoints, before discussing when and how cell fate decisions after a DSB are made.
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Affiliation(s)
- Indra A Shaltiel
- The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Lenno Krenning
- The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Wytse Bruinsma
- The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - René H Medema
- The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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27
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Shimura T, Kobayashi J, Komatsu K, Kunugita N. DNA damage signaling guards against perturbation of cyclin D1 expression triggered by low-dose long-term fractionated radiation. Oncogenesis 2014; 3:e132. [PMID: 25486524 PMCID: PMC4275562 DOI: 10.1038/oncsis.2014.48] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/24/2014] [Accepted: 11/02/2014] [Indexed: 12/20/2022] Open
Abstract
Cyclin D1 expression is precisely controlled during cell-cycle progression. However, repeated exposure to low-dose fractionated radiation (FR) abrogates cell cycle-dependent cyclin D1 degradation by constitutive activation of AKT survival signaling in normal human fibroblasts. The resulting abnormal nuclear cyclin D1 accumulation induces defects in DNA replication and resulting DNA double-strand breaks, and is associated with induction of genomic instability in low-dose irradiated cells. Here, we investigated the role of DNA damage signaling against such perturbed cell-cycle control of cyclin D1 expression. Nuclear cyclin D1 accumulation was induced within 7 days after low-dose FR (0.01 Gy or 0.05 Gy per fraction) in ATM-deficient cells (AT5BIVA), but appeared later in AT5BIVA cells harboring human ATM cDNA. Thus, ATM prevents abnormal nuclear cyclin D1 accumulation at early time points after low-dose FR. We further demonstrated that ATM-mediated downregulation of protein phosphatase 2A activity caused activation of the AKT/cyclin D1 pathway after long-term FR. Perturbation of cyclin D1 expression induced Rad51 foci that indicate homologous recombination repair (HRR) in control cells, while ATM- and NBS1-deficient cells (GM7166) failed to induce Rad51 foci after long-term low-dose FR. After 21 days of FR, NBS1- and ATM-deficient cells showed a decrease in nuclear cyclin D1-positive cells, and an increase in apoptotic cells. Similarly, inhibition of ATM with KU55933 abrogated nuclear cyclin D1 accumulation by induction of apoptosis in ATM-complemented cells exposed to low-dose FR. In conclusion, we here demonstrate that ATM is involved in controlling cyclin D1 levels after low-dose FR. DNA damage signaling mitigates the harmful effects of low-dose long-term FR by suppression of cell death induced by perturbation of cyclin D1 expression.
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Affiliation(s)
- T Shimura
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
| | - J Kobayashi
- Department of Genome Dynamics, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - K Komatsu
- Department of Genome Dynamics, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - N Kunugita
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
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Wandzioch E, Pusey M, Werda A, Bail S, Bhaskar A, Nestor M, Yang JJ, Rice LM. PME-1 Modulates Protein Phosphatase 2A Activity to Promote the Malignant Phenotype of Endometrial Cancer Cells. Cancer Res 2014; 74:4295-305. [DOI: 10.1158/0008-5472.can-13-3130] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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29
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Varadkar P, Despres D, Kraman M, Lozier J, Phadke A, Nagaraju K, Mccright B. The protein phosphatase 2A B56γ regulatory subunit is required for heart development. Dev Dyn 2014; 243:778-90. [PMID: 24425002 DOI: 10.1002/dvdy.24111] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 12/16/2013] [Accepted: 12/19/2013] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Protein Phosphatase 2A (PP2A) function is controlled by regulatory subunits that modulate the activity of the catalytic subunit and direct the PP2A complex to specific intracellular locations. To study PP2A's role in signal transduction pathways that control growth and differentiation in vivo, a transgenic mouse lacking the B56γ regulatory subunit of PP2A was made. RESULTS Lack of PP2A activity specific to the PP2A-B56γ holoenzyme, resulted in the formation of an incomplete ventricular septum and a decrease in the number of ventricular cardiomyocytes. During cardiac development, B56γ is expressed in the nucleus of α-actinin-positive cardiomyocytes that contain Z-bands. The pattern of B56γ expression correlated with the cardiomyocyte apoptosis we observed in B56γ-deficient mice during mid to late gestation. In addition to the cardiac phenotypes, mice lacking B56γ have a decrease in locomotive coordination and gripping strength, indicating that B56γ has a role in controlling PP2A activity required for efficient neuromuscular function. CONCLUSIONS PP2A-B56γ activity is required for efficient cardiomyocyte maturation and survival. The PP2A B56γ regulatory subunit controls PP2A substrate specificity in vivo in a manner that cannot be fully compensated for by other B56 subunits.
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Affiliation(s)
- Prajakta Varadkar
- Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, FDA, Bethesda, Maryland
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30
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Fåhraeus R, Olivares-Illana V. MDM2's social network. Oncogene 2013; 33:4365-76. [PMID: 24096477 DOI: 10.1038/onc.2013.410] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/17/2013] [Accepted: 08/17/2013] [Indexed: 12/22/2022]
Abstract
MDM2 is considered a hub protein due to its capacity to interact with a large number of different partners of which p53 is most well described. MDM2 is an E3 ubiquitin ligase, and many, but not all, of its interactions relate directly to this activity, such as substrates, adaptors or bridges, promoters, inhibitors or complementary factors. Some interactions serve regulatory functions that in response to cellular stresses control the localisation and functions of MDM2 including protein kinases, ribosomal proteins and proteases. Moreover, interactions with nucleotides serve other functions such as mRNA to regulate protein synthesis and DNA to control transcription. To perform such a pleiotropic panorama of different functions, MDM2 is subjected to a multitude of post-translational modifications and is expressed in different isoforms. The large and diverse interactome is made possible due to the plasticity of MDM2 and in this review we have listed the MDM2 interactions until now and we will discuss how this multifaceted protein can interact with such a variety of substrates to provide a key intermediary role in different signalling pathways.
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Affiliation(s)
- R Fåhraeus
- Cibles Therapeutiques, Equipe Labellisée Ligue Contre le Cancer, INSERM Unité 940, Institut de Génétique Moléculaire, Université Paris 7, Hôpital St Louis, 27 rue Juliette Dodu, Paris, France
| | - V Olivares-Illana
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava, Zona Universitaria, San Luis Potosí, México
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31
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Tu WZ, Li B, Huang B, Wang Y, Liu XD, Guan H, Zhang SM, Tang Y, Rang WQ, Zhou PK. γH2AX foci formation in the absence of DNA damage: mitotic H2AX phosphorylation is mediated by the DNA-PKcs/CHK2 pathway. FEBS Lett 2013; 587:3437-43. [PMID: 24021642 DOI: 10.1016/j.febslet.2013.08.028] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/06/2013] [Accepted: 08/21/2013] [Indexed: 12/15/2022]
Abstract
Phosphorylated H2AX is considered to be a biomarker for DNA double-strand breaks (DSB), but recent evidence suggests that γH2AX does not always indicate the presence of DSB. Here we demonstrate the bimodal dynamic of H2AX phosphorylation induced by ionizing radiation, with the second peak appearing when G2/M arrest is induced. An increased level of γH2AX occurred in mitotic cells, and this increase was attenuated by DNA-PKcs inactivation or Chk2 depletion, but not by ATM inhibition. The phosphorylation-mimic CHK2-T68D abrogated the attenuation of mitotic γH2AX induced by DNA-PKcs inactivation. Thus, the DNA-PKcs/CHK2 pathway mediates the mitotic phosphorylation of H2AX in the absence of DNA damage.
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Affiliation(s)
- Wen-Zhi Tu
- Institute for Environmental Medicine and Radiation Hygiene, The College of Public Health, University of South China, Hengyang, Hunan Province 421000, PR China; Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China
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32
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Chen Y, Liu S, Shen Q, Zha X, Zheng H, Yang L, Chen S, Wu X, Li B, Li Y. Differential gene expression profiles of PPP2R5C-siRNA-treated malignant T cells. DNA Cell Biol 2013; 32:573-81. [PMID: 23941244 DOI: 10.1089/dna.2013.2138] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Recently, alterations in the expression pattern of PPP2R5C associated with malignant transformation have been characterized, and PPP2R5C overexpression was demonstrated in leukemias. To confirm the role of PPP2R5C in proliferation and its molecular mechanism, three PPP2R5C-siRNAs and a scrambled nonsilencing siRNA control were used to treat Molt-4 and Jurkat T cells. After nucleofection, PPP2R5C expression and biological consequences based on a highly efficient and specific PPP2R5C-siRNA were demonstrated by qRT-PCR, CCK-8 assay, Annexin V/PI, and flow cytometry. The global gene expression profile of PPP2R5C-siRNA-treated Jurkat T cells was established. A significant reduction in the PPP2R5C mRNA level was observed at 24 to 72 h in Molt-4 and Jurkat T cells with all of the PPP2R5C-siRNAs. The proliferation rate of Molt-4 and Jurkat T cells transfected with different PPP2R5C-siRNAs was significantly decreased at 72 h compared with the control (p<0.05). However, the transfected cells did not show a significant increase in Annexin V/PI-positive cells (apoptosis). The highly efficient PPP2R5C-siRNA2 was used to treat Jurkat T cells for gene expression profile analysis. In total, 439 genes were upregulated, and 524 genes were downregulated at least twofold in PPP2R5C-siRNA-treated Jurkat T cells. Changes in signaling pathway genes closely related to the TCR, Wnt, calcium, MAPK, and p53 signaling pathways were observed. In conclusion, the suppression of PPP2R5C by RNA interference could effectively inhibit the proliferation of leukemic T cells, the PPP2R5C-siRNA treatment altered gene expression profiles, and the differential expression of the glycogen synthase kinase 3 beta (GSK-3β), ataxia telangiectasia mutated (ATM), and Mdm2 p53 binding protein homolog (MDM2) genes may play an important role in the effects of PPP2R5C knockdown in Jurkat T cells.
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Affiliation(s)
- Yu Chen
- 1 Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University , Guangzhou, China
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33
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Abstract
Protein phosphatase 2A (PP2A), one of the main serine-threonine phosphatases in mammalian cells, maintains cell homoeostasis by counteracting most of the kinase-driven intracellular signalling pathways. Unrestrained activation of oncogenic kinases together with inhibition of tumour suppressors is often required for development of cancer. PP2A has been shown to be genetically altered or functionally inactivated in many solid cancers and leukaemias, and is therefore a tumour suppressor. For example, the phosphatase activity of PP2A is suppressed in chronic myeloid leukaemia and other malignancies characterised by aberrant activity of oncogenic kinases. Preclinical studies show that pharmacological restoration of PP2A tumour-suppressor activity by PP2A-activating drugs (eg, FTY720) effectively antagonises cancer development and progression. Here, we discuss PP2A as a druggable tumour suppressor in view of the possible introduction of PP2A-activating drugs into anticancer therapeutic protocols.
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Affiliation(s)
- Danilo Perrotti
- Human Cancer Genetics Program, Department of Molecular Virology, Immunology, and Medical Genetics, and Comprehensive Cancer Center, Ohio State University, Columbus, OH 43210-2207, USA.
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34
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Che J, Lu YW, Sun KK, Feng C, Dong AJ, Jiao Y. Overexpression of TOB1 confers radioprotection to bronchial epithelial cells through the MAPK/ERK pathway. Oncol Rep 2013; 30:637-42. [PMID: 23756562 DOI: 10.3892/or.2013.2536] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 03/06/2013] [Indexed: 11/06/2022] Open
Abstract
The aim of this study was to investigate the effects and mechanisms of antiproliferative transducer of erbB2, 1 (TOB1) on the radiosensitivity of the normal human bronchial epithelial cell line HBE. After exposure to different doses of irradiation or a certain dose for different time intervals, the expression of TOB1 mRNA and protein in HBE cells was determined by semi-quantitative RT-PCR and western blot analysis. Liposome-induced recombinant plasmid transfection and G418 selection were performed to establish a stably transfected TOB1-overexpressing HBE cell line. A clonogenic assay was used to determine the radiosensitivity of the HBE cells with different TOB1 expression statuses. The cell cycle distribution was detected by flow cytometry. The ionizing radiation (IR)-induced γ-H2AX foci formation was detected by immunofluorescence assay. The related mechanism was explored by western blot analysis. TOB1 expression in the HBE cells was not induced by IR, neither dose-dependently nor time-dependently. Compared to the parental or 'mock' transfected HBE cells, the radiosensitivity of HBE cells overexpressing TOB1 was significantly decreased (P<0.05). Exogenous TOB1 prevented HBE cells from apoptosis after IR, in contrast to the control cells (P<0.05), and significantly decreased the IR-induced γ-H2AX foci formation. After IR, the expression of DNA damage repair proteins such as XRCC1, MRE11, FEN1 and ATM was increased in the TOB1‑overexpressing HBE cells when compared with the expression levels in the control cells. HBE/TOB1 cells presented a much higher phosphorylated ERK1/2 and phosphorylated p53 when compared with the levels in the control cell lines when receiving 6 Gy of X-rays. Notably, the increased expression of phosphorylated p53 in HBE/TOB1 cells after IR was sufficiently blocked by U0126, a specific inhibitor of MEK1/2. Different from its functions in several lung cancer cell lines, TOB1 demonstrated a radioprotective function in the immortalized normal human bronchial epithelial cell line HBE via the MAPK/ERK signaling pathway.
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Affiliation(s)
- Jun Che
- Department of Head and Neck Radiotherapy, the Fourth People's Hospital of Wuxi, Wuxi 214062, PR China
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35
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Abstract
Protein phosphatases of the type 2A family (PP2A) represent a major fraction of cellular Ser/Thr phosphatase activity in any given human tissue. In this review, we describe how the holoenzymic nature of PP2A and the existence of several distinct PP2A composing subunits allow for the generation of multiple structurally and functionally different PP2A complexes, explaining why PP2A is involved in the regulation of so many diverse cell biological and physiological processes. Moreover, in human disease, most notably in several cancers and Alzheimer's Disease, PP2A expression and/or activity have been found significantly decreased, underscoring its important functions as a major tumor suppressor and tau phosphatase. Hence, several recent preclinical studies have demonstrated that pharmacological restoration of PP2A activity, as well as pharmacological PP2A inhibition, under certain conditions, may be of significant future therapeutic value.
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36
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Abstract
Mdm2 is an essential regulator of the p53 tumor suppressor. Mdm2 is modified at transcriptional, post-transcriptional, and post-translational levels to control p53 activity in normal versus stressed cells. Importantly, errors in these regulatory mechanisms can result in aberrant Mdm2 expression and failure to initiate programmed cell death in response to DNA damage. Such errors can have severe consequences as evidenced by tumor phenotypes resulting from amplification at the Mdm2 locus and changes in post-transcriptional and post-translational regulation of Mdm2. Although Mdm2 mediated inhibition of p53 is well characterized, Mdm2 interacts with many additional proteins and also targets many of these for proteosomal degradation. Mdm2 also has E3-ligase independent functions and p53-independent functions that have important implications for genome stability and cancer.
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Affiliation(s)
- Maurisa F Riley
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
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37
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Amlin-Van Schaick JC, Kim S, DiFabio C, Lee MH, Broman KW, Reilly KM. Arlm1 is a male-specific modifier of astrocytoma resistance on mouse Chr 12. Neuro Oncol 2012; 14:160-74. [PMID: 22234937 DOI: 10.1093/neuonc/nor206] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
While many cancers show a sex bias, the genetic basis and molecular mechanisms underlying sex bias are not always clear. Astrocytoma and glioblastoma show male predominance in humans. We have shown previously that glial tumors forming in the Nf1-/+; Trp53-/+cis (NPcis) mouse model also show a sex bias in some genetic contexts. Using cross-species comparisons we have identified candidate male-specific modifiers of astrocytoma/glioblastoma. Linkage analysis of B6X(B6X129)-NPcis mice identifies a modifier of astrocytoma resistance specific to males, named Arlm1, on distal mouse Chr 12. Arlm1 is syntenic to human Chr 7p15, 7p21, 7q36, and 14q32 regions that are altered in human glioblastoma. A subset of these genes shows male-specific correlations to glioblastoma patient survival time and represents strong candidates for the Arlm1 modifier gene. Identification of male-specific modifier genes will lead to a better understanding of the molecular basis of male predominance in astrocytoma and glioblastoma.
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Affiliation(s)
- Jessica C Amlin-Van Schaick
- Mouse Cancer Genetics Program, National Cancer Institute, West 7th St at Fort Detrick, Frederick, MD 21702, USA
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38
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Abstract
DNA-damaging therapies represent the most frequently used non-surgical anticancer strategies in the treatment of human tumors. These therapies can kill tumor cells, but at the same time they can be particularly damaging and mutagenic to healthy tissues. The efficacy of DNA-damaging treatments can be improved if tumor cell death is selectively enhanced, and the recent application of poly-(ADP-ribose) polymerase inhibitors in BRCA1/2-deficient tumors is a successful example of this. DNA damage is known to trigger cell-cycle arrest through activation of DNA-damage checkpoints. This arrest can be reversed once the damage has been repaired, but irreparable damage can promote apoptosis or senescence. Alternatively, cells can reenter the cell cycle before repair has been completed, giving rise to mutations. In this review we discuss the mechanisms involved in the activation and inactivation of DNA-damage checkpoints, and how the transition from arrest and cell-cycle re-entry is controlled. In addition, we discuss recent attempts to target the checkpoint in anticancer strategies.
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39
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Lee DH, Chowdhury D. What goes on must come off: phosphatases gate-crash the DNA damage response. Trends Biochem Sci 2011; 36:569-77. [PMID: 21930385 DOI: 10.1016/j.tibs.2011.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/18/2011] [Accepted: 08/19/2011] [Indexed: 12/24/2022]
Abstract
DNA-damage-induced phospho-signaling has been studied for decades, with a focus mainly on initiation of the signaling cascade, and the kinases activated by DNA lesions. It is widely accepted that the balance of phosphorylation needs to be restored and/or maintained by phosphatases, yet there have only been sporadic efforts to investigate the impact of phosphatases on DNA repair. Recent advances in phosphoproteomic strategies and implementation of large genetic screens indicate that these enzymes play pivotal roles in these signaling networks. Dephosphorylation of repair proteins is crucial for efficient DNA repair, and the recommencement of cell division post-repair. Here, we focus on serine/threonine phosphatases implicated in dephosphorylation of DNA repair factors, summarizing recent findings and speculating on untested roles of phosphatases in the DNA damage response.
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Affiliation(s)
- Dong-Hyun Lee
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
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