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Osma-Garcia IC, Capitan-Sobrino D, Mouysset M, Aubert Y, Maloudi O, Turner M, Diaz-Muñoz MD. The splicing regulators TIA1 and TIAL1 are required for the expression of the DNA damage repair machinery during B cell lymphopoiesis. Cell Rep 2022; 41:111869. [PMID: 36543128 PMCID: PMC9794549 DOI: 10.1016/j.celrep.2022.111869] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 10/01/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022] Open
Abstract
B cell lymphopoiesis requires dynamic modulation of the B cell transcriptome for timely coordination of somatic mutagenesis and DNA repair in progenitor B (pro-B) cells. Here, we show that, in pro-B cells, the RNA-binding proteins T cell intracellular antigen 1 (TIA1) and TIA1-like protein (TIAL1) act redundantly to enable developmental progression. They are global splicing regulators that control the expression of hundreds of mRNAs, including those involved in DNA damage repair. Mechanistically, TIA1 and TIAL1 bind to 5' splice sites for exon definition, splicing, and expression of DNA damage sensors, such as Chek2 and Rif1. In their absence, pro-B cells show exacerbated DNA damage, altered P53 expression, and increased cell death. Our study uncovers the importance of tight regulation of RNA splicing by TIA1 and TIAL1 for the expression of integrative transcriptional programs that control DNA damage sensing and repair during B cell development.
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Affiliation(s)
- Ines C. Osma-Garcia
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse 31024, France
| | - Dunja Capitan-Sobrino
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse 31024, France
| | - Mailys Mouysset
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse 31024, France
| | - Yann Aubert
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse 31024, France
| | - Orlane Maloudi
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse 31024, France
| | - Martin Turner
- Immunology Program, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Manuel D. Diaz-Muñoz
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITy), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse 31024, France,Corresponding author
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2
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Zhang T, Wang Z, Liu M, Liu L, Yang X, Zhang Y, Bie J, Li Y, Ren M, Song C, Wang W, Tan H, Luo J. Acetylation dependent translocation of EWSR1 regulates CHK2 alternative splicing in response to DNA damage. Oncogene 2022; 41:3694-3704. [PMID: 35732801 DOI: 10.1038/s41388-022-02383-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 06/08/2022] [Accepted: 06/10/2022] [Indexed: 11/09/2022]
Abstract
Ewing sarcoma breakpoint region 1 (EWSR1) is a member of FET (FUS/EWSR1/TAF15) RNA-binding family of proteins. The Ewing sarcoma oncoprotein EWS-FLI1 has been extensively studied, while much less is known about EWSR1 itself, especially the potential role of EWSR1 in response to DNA damage. Here, we found that UV irradiation induces acetylation of EWSR1, which is required for its nucleoli translocation. We identified K423, K432, K438, K640, and K643 as the major acetylation sites, p300/CBP and HDAC3/HDAC10 as the major acetyltransferases and deacetylases, respectively. Mechanically, UV-induced EWSR1 acetylation repressed its interaction with spliceosomal component U1C, which caused abnormal splicing of CHK2, suppressing the activity of CHK2 in response to UV irradiation. Taken together, our findings uncover acetylation as a novel regulatory modification of EWSR1, and is essential for its function in DNA damage response.
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Affiliation(s)
- Tianzhuo Zhang
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China.,Department of Biochemistry and Biophysics, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, China
| | - Zhe Wang
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Minghui Liu
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Lu Liu
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Xin Yang
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Yu Zhang
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Juntao Bie
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Yutong Li
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Mengmeng Ren
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Chen Song
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China
| | - Wengong Wang
- Department of Biochemistry and Biophysics, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, China
| | - Hongyu Tan
- Department of Anesthesiology, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Peking University Cancer Hospital & Institute, Beijing, 100142, China.
| | - Jianyuan Luo
- Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing, 100191, China. .,Department of Biochemistry and Biophysics, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, China.
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3
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Madhavan BK, Han Z, Singh B, Bordt N, Kaymak S, Bandapalli OR, Kihm L, Shahzad K, Isermann B, Herzig S, Nawroth P, Kumar V. Elevated Expression of the RAGE Variant- V in SCLC Mitigates the Effect of Chemotherapeutic Drugs. Cancers (Basel) 2021; 13:cancers13112843. [PMID: 34200336 PMCID: PMC8201239 DOI: 10.3390/cancers13112843] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 02/01/2023] Open
Abstract
Simple Summary Radiomimetic drugs induce extensive genotoxic insults to their target cells. Irreparable DNA damage leaves cells with the choice between a program leading to cell death or senescence, but not DNA repair. Among the challenges of an advanced stage of small cell lung carcinoma (SCLC), the resistance to radiomimetic drugs is the most prominent one. In SCLC, the initial chemotherapeutic treatment primes cell to modify their DNA repair and cell cycle regulatory systems, using alternative but highly efficient forms of DNA repair and auxiliary factors. This modulated system now bypasses several regulatory controls. Thus, at this stage, cells become resistant to any beneficial effects of chemotherapeutic drugs. In the present study, we observed that variant-V of the receptor for advanced glycation end-products (RAGE) is abundantly expressed in advancing and metastasizing SCLC. Therefore, it may serve as a potential target for specific therapeutic interventions directed to SCLC. Abstract Small cell lung carcinoma (SCLC) is a highly aggressive malignancy with a very high mortality rate. A prominent part of this is because these carcinomas are refractory to chemotherapies, such as etoposide or cisplatin, making effective treatment almost impossible. Here, we report that elevated expression of the RAGE variant-V in SCLC promotes homology-directed DNA DSBs repair when challenged with anti-cancer drugs. This variant exclusively localizes to the nucleus, interacts with members of the double-strand break (DSB) repair machinery and thus promotes the recruitment of DSBs repair factors at the site of damage. Increased expression of this variant thus, promotes timely DNA repair. Congruently, the tumor cells expressing high levels of variant-V can tolerate chemotherapeutic drug treatment better than the RAGE depleted cells. Our findings reveal a yet undisclosed role of the RAGE variant-V in the homology-directed DNA repair. This variant thus can be a potential target to be considered for future therapeutic approaches in advanced SSLC.
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Affiliation(s)
- Bindhu K. Madhavan
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
| | - Zhe Han
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
| | - Bishal Singh
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
| | - Nico Bordt
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
| | - Serap Kaymak
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
| | - Obul Reddy Bandapalli
- Hopp Children’s Cancer Center (KiTZ), 69120 Heidelberg, Germany;
- Medical Faculty, Heidelberg University, 69117 Heidelberg, Germany
| | - Lars Kihm
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
| | - Khurrum Shahzad
- Institute for Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig, 04103 Leipzig, Germany; (K.S.); (B.I.)
| | - Berend Isermann
- Institute for Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig, 04103 Leipzig, Germany; (K.S.); (B.I.)
| | - Stephan Herzig
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany;
- Molecular Metabolic Control, Technical University Munich, 80333 Munich, Germany
- Helmholtz Center Munich, Institute for Diabetes and Cancer, D-85764 Neuherberg, Germany
- Joint Heidelberg-IDC Translational Diabetes Programm, Helmholtz-Zentrum, 69120 Heidelberg, Germany
| | - Peter Nawroth
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany;
- Joint Heidelberg-IDC Translational Diabetes Programm, Helmholtz-Zentrum, 69120 Heidelberg, Germany
| | - Varun Kumar
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, INF 410, 69120 Heidelberg, Germany; (B.K.M.); (Z.H.); (B.S.); (N.B.); (S.K.); (L.K.); (P.N.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany;
- European Molecular Biology Laboratory, Advanced Light Microscopy Facility, 69117 Heidelberg, Germany
- Correspondence: ; Tel.: +49-6221-56-6960
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4
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Angarola BL, Anczuków O. Splicing alterations in healthy aging and disease. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021. [PMID: 33565261 DOI: 10.1002/wrna.1643.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alternative RNA splicing is a key step in gene expression that allows generation of numerous messenger RNA transcripts encoding proteins of varied functions from the same gene. It is thus a rich source of proteomic and functional diversity. Alterations in alternative RNA splicing are observed both during healthy aging and in a number of human diseases, several of which display premature aging phenotypes or increased incidence with age. Age-associated splicing alterations include differential splicing of genes associated with hallmarks of aging, as well as changes in the levels of core spliceosomal genes and regulatory splicing factors. Here, we review the current known links between alternative RNA splicing, its regulators, healthy biological aging, and diseases associated with aging or aging-like phenotypes. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA.,Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA.,Institute for Systems Genomics, UConn Health, Farmington, Connecticut, USA
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5
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Angarola BL, Anczuków O. Splicing alterations in healthy aging and disease. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1643. [PMID: 33565261 DOI: 10.1002/wrna.1643] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 12/19/2022]
Abstract
Alternative RNA splicing is a key step in gene expression that allows generation of numerous messenger RNA transcripts encoding proteins of varied functions from the same gene. It is thus a rich source of proteomic and functional diversity. Alterations in alternative RNA splicing are observed both during healthy aging and in a number of human diseases, several of which display premature aging phenotypes or increased incidence with age. Age-associated splicing alterations include differential splicing of genes associated with hallmarks of aging, as well as changes in the levels of core spliceosomal genes and regulatory splicing factors. Here, we review the current known links between alternative RNA splicing, its regulators, healthy biological aging, and diseases associated with aging or aging-like phenotypes. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA.,Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA.,Institute for Systems Genomics, UConn Health, Farmington, Connecticut, USA
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6
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Ta HQ, Dworak N, Ivey ML, Roller DG, Gioeli D. AR phosphorylation and CHK2 kinase activity regulates IR-stabilized AR-CHK2 interaction and prostate cancer survival. eLife 2020; 9:51378. [PMID: 32579110 PMCID: PMC7338052 DOI: 10.7554/elife.51378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 06/22/2020] [Indexed: 12/12/2022] Open
Abstract
We have previously demonstrated that checkpoint kinase 2 (CHK2) is a critical negative regulator of androgen receptor (AR) transcriptional activity, prostate cancer (PCa) cell growth, and androgen sensitivity. We have now uncovered that the AR directly interacts with CHK2 and ionizing radiation (IR) increases this interaction. This IR-induced increase in AR-CHK2 interactions requires AR phosphorylation and CHK2 kinase activity. PCa associated CHK2 mutants with impaired kinase activity reduced IR-induced AR-CHK2 interactions. The destabilization of AR - CHK2 interactions induced by CHK2 variants impairs CHK2 negative regulation of cell growth. CHK2 depletion increases transcription of DNAPK and RAD54, increases clonogenic survival, and increases resolution of DNA double strand breaks. The data support a model where CHK2 sequesters the AR through direct binding decreasing AR transcription and suppressing PCa cell growth. CHK2 mutation or loss of expression thereby leads to increased AR transcriptional activity and survival in response to DNA damage.
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Affiliation(s)
- Huy Q Ta
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, United States
| | - Natalia Dworak
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, United States
| | - Melissa L Ivey
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, United States
| | - Devin G Roller
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, United States
| | - Daniel Gioeli
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, United States.,Cancer Center Member, University of Virginia, Charlottesville, United States
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7
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Botto AEC, Muñoz JC, Giono LE, Nieto-Moreno N, Cuenca C, Kornblihtt AR, Muñoz MJ. Reciprocal regulation between alternative splicing and the DNA damage response. Genet Mol Biol 2020; 43:e20190111. [PMID: 32236390 PMCID: PMC7197977 DOI: 10.1590/1678-4685-gmb-2019-0111] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 12/16/2019] [Indexed: 12/16/2022] Open
Abstract
Splicing, the process that catalyzes intron removal and flanking exon ligation, can occur in different ways (alternative splicing) in immature RNAs transcribed from a single gene. In order to adapt to a particular context, cells modulate not only the quantity but also the quality (alternative isoforms) of their transcriptome. Since 95% of the human coding genome is subjected to alternative splicing regulation, it is expected that many cellular pathways are modulated by alternative splicing, as is the case for the DNA damage response. Moreover, recent evidence demonstrates that upon a genotoxic insult, classical DNA damage response kinases such as ATM, ATR and DNA-PK orchestrate the gene expression response therefore modulating alternative splicing which, in a reciprocal way, shapes the response to a damaging agent.
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Affiliation(s)
- Adrian E Cambindo Botto
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Juan C Muñoz
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Luciana E Giono
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Nicolás Nieto-Moreno
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Carmen Cuenca
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Alberto R Kornblihtt
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina
| | - Manuel J Muñoz
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiologia, Biologia Molecular y Celular, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, Argentina.,Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan, Italy.,Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
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Barnard M, Mostaghel EA, Auchus RJ, Storbeck KH. The role of adrenal derived androgens in castration resistant prostate cancer. J Steroid Biochem Mol Biol 2020; 197:105506. [PMID: 31672619 PMCID: PMC7883395 DOI: 10.1016/j.jsbmb.2019.105506] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 10/17/2019] [Accepted: 10/22/2019] [Indexed: 01/02/2023]
Abstract
Castration resistant prostate cancer (CRPC) remains androgen dependant despite castrate levels of circulating testosterone following androgen deprivation therapy, the first line of treatment for advanced metstatic prostate cancer. CRPC is characterized by alterations in the expression levels of steroidgenic enzymes that enable the tumour to derive potent androgens from circulating adrenal androgen precursors. Intratumoral androgen biosynthesis leads to the localized production of both canonical androgens such as 5α-dihydrotestosterone (DHT) as well as less well characterized 11-oxygenated androgens, which until recently have been overlooked in the context of CRPC. In this review we discuss the contribution of both canonical and 11-oxygenated androgen precursors to the intratumoral androgen pool in CRPC. We present evidence that CRPC remains androgen dependent and discuss the alterations in steroidogenic enzyme expression and how these affect the various pathways to intratumoral androgen biosynthesis. Finally we summarize the current treatment strategies for targeting adrenal derived androgen biosynthesis.
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Affiliation(s)
- Monique Barnard
- Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa
| | - Elahe A Mostaghel
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA; Department of Medicine, University of Washington, Seattle, WA, USA; Geriatric Research, Education and Clinical Center, VA Puget Sound Health Care System, Seattle, WA, USA
| | - Richard J Auchus
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI, USA; Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Karl-Heinz Storbeck
- Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa.
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9
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A novel FADS2 isoform identified in human milk fat globule suppresses FADS2 mediated Δ6-desaturation of omega-3 fatty acids. Prostaglandins Leukot Essent Fatty Acids 2018; 138:52-59. [PMID: 30041907 DOI: 10.1016/j.plefa.2018.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/19/2018] [Accepted: 06/19/2018] [Indexed: 12/30/2022]
Abstract
INTRODUCTION The only known non-pharmacological means to alter long chain polyunsaturated fatty acid (LCPUFA) abundance in mammalian tissue is by altering substrate fatty acid ratios. Alternative mRNA splicing is increasingly recognized as a modulator of protein structure and function. Here we report identification of a novel alternative transcript (AT) of fatty acid desaturase 2 (FADS2) that inhibits production of omega-3 but not omega-6 LCPUFA, discovered during study of ATs in human milk fat globules (MFG). METHODS Human breastmilk collected from a single donor was used to isolate MFG. An mRNA-sequencing library was constructed from the total RNA isolated from the MFG. The constructed library was sequenced using an Illumina HiSeq instrument operating in high output mode. Expression levels of evolutionary conserved FADSAT were measured using cDNA from MFG by semi-quantitative RT-PCR assay. RESULTS RNA sequencing revealed >15,000 transcripts, including moderate expression of the FADS2 classical transcript (CS). A novel FADS2 alternative transcript (FADS2AT2) with 386 amino acids was discovered. When FADS2AT2 was transiently transfected into MCF7 cells stably expressing FADS2, delta-6 desaturation (D6D) of alpha-linolenic acid 18:3n-3 → 18:4n-3 was suppressed as were downstream products 20:4n-3 and 20:5n-3. In contrast, no significant effect on D6D of linoleic acid 18:2n-6 → 18:3n-6 or downstream products was observed. FADS2, FADS2AT1 and 5 out of 8 known FADS3AT were expressed in MFG. FADS1, FADS3AT3, and FADS3AT5 are undetectable. CONCLUSION The novel, noncatalytic FADS2AT2 regulates FADS2CS-mediated Δ6-desaturation of omega-3 but not omega-6 PUFA biosynthesis. This spliced isoform mediated interaction is the first molecular mechanism by which desaturation of one PUFA family but not the other is modulated.
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10
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Ko HK, Berk M, Chung YM, Willard B, Bareja R, Rubin M, Sboner A, Sharifi N. Loss of an Androgen-Inactivating and Isoform-Specific HSD17B4 Splice Form Enables Emergence of Castration-Resistant Prostate Cancer. Cell Rep 2018; 22:809-819. [PMID: 29346776 PMCID: PMC5798464 DOI: 10.1016/j.celrep.2017.12.081] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 11/21/2017] [Accepted: 12/22/2017] [Indexed: 01/21/2023] Open
Abstract
Castration-resistant prostate cancer (CRPC) requires tumors to engage metabolic mechanisms that allow sustained testosterone and/or dihydrotestosterone to stimulate progression. 17β-Hydroxysteroid dehydrogenase type 4 (17βHSD4), encoded by HSD17B4, is thought to inactivate testosterone and dihydrotestosterone by converting them to their respective inert 17-keto steroids. Counterintuitively, HSD17B4 expression increases in CRPC and predicts poor prognosis. Here, we show that, of five alternative splice forms, only isoform 2 encodes an enzyme capable of testosterone and dihydrotestosterone inactivation. In contrast with other transcripts, functional expression of isoform 2 is specifically suppressed in development of CRPC in patients. Genetically silencing isoform 2 shifts the metabolic balance toward 17β-OH androgens (testosterone and dihydrotestosterone), stimulating androgen receptor (AR) and CRPC development. Our studies specifically implicate HSD17B4 isoform 2 loss in lethal prostate cancer.
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Affiliation(s)
- Hyun-Kyung Ko
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Michael Berk
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Yoon-Mi Chung
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Belinda Willard
- Research Core Services, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Rohan Bareja
- Institute for Precision Medicine, Weill-Cornell Medical Center, New York, NY 10065, USA
| | - Mark Rubin
- Institute for Precision Medicine, Weill-Cornell Medical Center, New York, NY 10065, USA
| | - Andrea Sboner
- Institute for Precision Medicine, Weill-Cornell Medical Center, New York, NY 10065, USA
| | - Nima Sharifi
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Department of Urology, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Department of Hematology and Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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11
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Lehmann J, Schubert S, Seebode C, Apel A, Ohlenbusch A, Emmert S. Splice variants of the endonucleases XPF and XPG contain residual DNA repair capabilities and could be a valuable tool for personalized medicine. Oncotarget 2018; 9:1012-1027. [PMID: 29416673 PMCID: PMC5787415 DOI: 10.18632/oncotarget.23105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/15/2017] [Indexed: 11/25/2022] Open
Abstract
The two endonucleases XPF and XPG are essentially involved in nucleotide excision repair (NER) and interstrand crosslink (ICL) repair. Defects in these two proteins result in severe diseases like xeroderma pigmentosum (XP). We applied our newly CRISPR/Cas9 generated human XPF knockout cell line with complete loss of XPF and primary fibroblasts from an XP-G patient (XP20BE) to analyze until now uncharacterized spontaneous mRNA splice variants of these two endonucleases. Functional analyses of these variants were performed using luciferase-based reporter gene assays. Two XPF and XPG splice variants with residual repair capabilities in NER, as well as ICL repair could be identified. Almost all variants are severely C-terminally truncated and lack important protein-protein interaction domains. Interestingly, XPF-202, differing to XPF-003 in the first 12 amino acids only, had no repair capability at all, suggesting an important role of this region during DNA repair, potentially concerning protein-protein interaction. We also identified splice variants of XPF and XPG exerting inhibitory effects on NER. Moreover, we showed that the XPF and XPG splice variants presented with different inter-individual expression patterns in healthy donors, as well as in various tissues. With regard to their residual repair capability and dominant-negative effects, functionally relevant spontaneous XPF and XPG splice variants present promising prognostic marker candidates for individual cancer risk, disease outcome, or therapeutic success. This merits further investigations, large association studies, and translational research within clinical trials in the future.
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Affiliation(s)
- Janin Lehmann
- Clinic and Policlinic for Dermatology and Venereology, University Medical Center Rostock, Rostock, Germany
| | - Steffen Schubert
- Information Network of Departments of Dermatology (IVDK), University Medical Center Goettingen, Goettingen, Germany
| | - Christina Seebode
- Clinic and Policlinic for Dermatology and Venereology, University Medical Center Rostock, Rostock, Germany
| | - Antje Apel
- Department of Dermatology, Venereology and Allergology, University Medical Center Goettingen, Goettingen, Germany
| | - Andreas Ohlenbusch
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Neurology, University Medical Center Goettingen, Goettingen, Germany
| | - Steffen Emmert
- Clinic and Policlinic for Dermatology and Venereology, University Medical Center Rostock, Rostock, Germany
- Department of Dermatology, Venereology and Allergology, University Medical Center Goettingen, Goettingen, Germany
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12
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Ta HQ, Ivey ML, Frierson HF, Conaway MR, Dziegielewski J, Larner JM, Gioeli D. Checkpoint Kinase 2 Negatively Regulates Androgen Sensitivity and Prostate Cancer Cell Growth. Cancer Res 2015; 75:5093-105. [PMID: 26573794 DOI: 10.1158/0008-5472.can-15-0224] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 09/12/2015] [Indexed: 12/18/2022]
Abstract
Prostate cancer is the second leading cause of cancer death in American men, and curing metastatic disease remains a significant challenge. Nearly all patients with disseminated prostate cancer initially respond to androgen deprivation therapy (ADT), but virtually all patients will relapse and develop incurable castration-resistant prostate cancer (CRPC). A high-throughput RNAi screen to identify signaling pathways regulating prostate cancer cell growth led to our discovery that checkpoint kinase 2 (CHK2) knockdown dramatically increased prostate cancer growth and hypersensitized cells to low androgen levels. Mechanistic investigations revealed that the effects of CHK2 were dependent on the downstream signaling proteins CDC25C and CDK1. Moreover, CHK2 depletion increased androgen receptor (AR) transcriptional activity on androgen-regulated genes, substantiating the finding that CHK2 affects prostate cancer proliferation, partly, through the AR. Remarkably, we further show that CHK2 is a novel AR-repressed gene, suggestive of a negative feedback loop between CHK2 and AR. In addition, we provide evidence that CHK2 physically associates with the AR and that cell-cycle inhibition increased this association. Finally, IHC analysis of CHK2 in prostate cancer patient samples demonstrated a decrease in CHK2 expression in high-grade tumors. In conclusion, we propose that CHK2 is a negative regulator of androgen sensitivity and prostate cancer growth, and that CHK2 signaling is lost during prostate cancer progression to castration resistance. Thus, perturbing CHK2 signaling may offer a new therapeutic approach for sensitizing CRPC to ADT and radiation.
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Affiliation(s)
- Huy Q Ta
- Departments of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia
| | - Melissa L Ivey
- Departments of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia
| | - Henry F Frierson
- Department of Pathology, University of Virginia Health System, Charlottesville, Virginia. Cancer Center Member, University of Virginia, Charlottesville, Virginia
| | - Mark R Conaway
- Cancer Center Member, University of Virginia, Charlottesville, Virginia. Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia
| | - Jaroslaw Dziegielewski
- Cancer Center Member, University of Virginia, Charlottesville, Virginia. Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia
| | - James M Larner
- Cancer Center Member, University of Virginia, Charlottesville, Virginia. Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia
| | - Daniel Gioeli
- Departments of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia. Cancer Center Member, University of Virginia, Charlottesville, Virginia.
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13
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Shkreta L, Chabot B. The RNA Splicing Response to DNA Damage. Biomolecules 2015; 5:2935-77. [PMID: 26529031 PMCID: PMC4693264 DOI: 10.3390/biom5042935] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 09/20/2015] [Accepted: 10/16/2015] [Indexed: 12/29/2022] Open
Abstract
The number of factors known to participate in the DNA damage response (DDR) has expanded considerably in recent years to include splicing and alternative splicing factors. While the binding of splicing proteins and ribonucleoprotein complexes to nascent transcripts prevents genomic instability by deterring the formation of RNA/DNA duplexes, splicing factors are also recruited to, or removed from, sites of DNA damage. The first steps of the DDR promote the post-translational modification of splicing factors to affect their localization and activity, while more downstream DDR events alter their expression. Although descriptions of molecular mechanisms remain limited, an emerging trend is that DNA damage disrupts the coupling of constitutive and alternative splicing with the transcription of genes involved in DNA repair, cell-cycle control and apoptosis. A better understanding of how changes in splice site selection are integrated into the DDR may provide new avenues to combat cancer and delay aging.
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Affiliation(s)
- Lulzim Shkreta
- Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
| | - Benoit Chabot
- Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
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14
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Pavlovic Z, Singh RK, Bakovic M. A novel murine CTP:phosphoethanolamine cytidylyltransferase splice variant is a post-translational repressor and an indicator that both cytidylyltransferase domains are required for activity. Gene 2014; 543:58-68. [PMID: 24703999 DOI: 10.1016/j.gene.2014.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/20/2014] [Accepted: 04/01/2014] [Indexed: 11/27/2022]
Abstract
CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) has an important regulatory function in biosynthesis of the membrane phospholipid phosphatidylethanolamine. We previously determined that the full-length Pcyt2α and its splice variant Pcyt2β are the main active isoforms of this enzyme. Here we report that mouse Pcyt2 could be spliced at Introns 7 and 8 to produce a unique third isoform, Pcyt2γ, in which the second cytidylyltransferase domain at the C-terminus becomes deleted. Pcyt2γ is ubiquitously expressed in embryonic and adult mouse tissues, and is the most abundant in the kidney, skeletal muscle and testis. Pcyt2γ splicing mechanism dominates over Pcyt2β exon-skipping mechanism in most examined tissues. Although Pcyt2γ maintains the N-terminal cytidylyltransferase domain as most cytidylyltransferases, the lack of the C-terminal cytidylyltransferase domain causes a complete loss of catalytic activity. However, Pcyt2γ interacts with the active isoform, Pcyt2α, and significantly reduces Pcyt2α homodimerization and activity. The inactive N-domain (H35Y, H35A) and C-domain (H244Y, H244A) mutants of Pcyt2α also reduce Pcyt2α homodimerization and activity. This study revealed the importance of both cytidylyltransferase (35)HYGH and (244)HIGH motifs for the activity of murine Pcyt2α and established that the naturally occurring splice variant Pcyt2γ has a function to restrain the enzyme activity through the formation of unproductive enzyme complexes.
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Affiliation(s)
- Zvezdan Pavlovic
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G2W1, Canada.
| | - Ratnesh Kumar Singh
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G2W1, Canada
| | - Marica Bakovic
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G2W1, Canada
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15
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 504] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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16
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Vetter D, Cohen-Naftaly M, Villaneuva A, Lee YA, Kocabayoglu P, Hannivoort R, Narla G, Llovet JM, Thung SN, Friedman SL. Enhanced hepatocarcinogenesis in mouse models and human hepatocellular carcinoma by coordinate KLF6 depletion and increased messenger RNA splicing. Hepatology 2012; 56:1361-70. [PMID: 22535637 PMCID: PMC3412196 DOI: 10.1002/hep.25810] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 04/11/2012] [Indexed: 12/23/2022]
Abstract
UNLABELLED KLF6-SV1 (SV1), the major splice variant of KLF6, antagonizes the KLF6 tumor suppressor by an unknown mechanism. Decreased KLF6 expression in human hepatocellular carcinoma (HCC) correlates with increased mortality, but the contribution of increased SV1 is unknown. We sought to define the impact of SV1 on human outcomes and experimental murine hepatocarcinogenesis and to elucidate its mechanism of action. In hepatitis C virus (HCV)-related HCC, an increased ratio of SV1/KLF6 within the tumor was associated with features of more advanced disease. Six months after a single injection of diethylnitrosamine (DEN), SV1 hepatocyte transgenic mice developed more histologically advanced tumors, whereas Klf6-depleted mice developed bigger tumors compared to the Klf6fl(+/+) control mice. Nine months after DEN, SV1 transgenic mice with Klf6 depletion had the greatest tumor burden. Primary mouse hepatocytes from both the SV1 transgenic animals and those with hepatocyte-specific Klf6 depletion displayed increased DNA synthesis, with an additive effect in hepatocytes harboring both SV1 overexpression and Klf6 depletion. Parallel results were obtained by viral SV1 transduction and depletion of Klf6 through adenovirus-Cre infection of primary Klf6fl(+/+) hepatocytes. Increased DNA synthesis was due to both enhanced cell proliferation and increased ploidy. Coimmunoprecipitation studies in 293T cells uncovered a direct interaction of transfected SV1 with KLF6. Accelerated KLF6 degradation in the presence of SV1 was abrogated by the proteasome inhibitor MG132. CONCLUSION An increased SV1/KLF6 ratio correlates with more aggressive HCC. In mice, an increased SV1/KLF6 ratio, generated either by increasing SV1, decreasing KLF6, or both, accelerates hepatic carcinogenesis. Moreover, SV1 binds directly to KLF6 and accelerates its degradation. These findings represent a novel mechanism underlying the antagonism of tumor suppressor gene function by a splice variant of the same gene.
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Affiliation(s)
- Diana Vetter
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
- Department of Abdominal Surgery, University Hospital of Zurich, Zurich, Switzerland
| | - Michal Cohen-Naftaly
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
| | - Augusto Villaneuva
- HCC Translational Research Laboratory, Barcelona-Clinic Liver Cancer Group, Liver Unit. Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS); Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Hospital Clinic, Barcelona, Spain
| | - Youngmin A. Lee
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
| | - Peri Kocabayoglu
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
| | - Rebekka Hannivoort
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Goutham Narla
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
- Departments of Genetics & Genomic Sciences, Mount Sinai School of Medicine, New York, NY
| | - Josep Maria Llovet
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
- HCC Translational Research Laboratory, Barcelona-Clinic Liver Cancer Group, Liver Unit. Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS); Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Hospital Clinic, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats, Mount Sinai School of Medicine, New York, NY
| | - Swan N. Thung
- Department of Pathology, Mount Sinai School of Medicine, New York, NY
| | - Scott L. Friedman
- Department of Medicine/Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY
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17
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Höglund A, Strömvall K, Li Y, Forshell LP, Nilsson JA. Chk2 deficiency in Myc overexpressing lymphoma cells elicits a synergistic lethal response in combination with PARP inhibition. Cell Cycle 2011; 10:3598-607. [PMID: 22030621 DOI: 10.4161/cc.10.20.17887] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Myc is a transcription factor frequently found deregulated in human cancer. The Myc-mediated cellular transformation process is associated with fast proliferative cells and inherent genomic instability, giving rise to malignant, invasive neoplasms with poor prognosis for survival. Transcription-independent functions of Myc include stimulation of replication. Excessive Myc expression stimulates a replication-associated DNA damage response that signals via the phosphoinositide-3-kinase (PI3K)-related protein kinases (PIKKs) ATM and ATR. These, in turn, activate the DNA damage transducers Chk1 and Chk2. Here, we show that Myc can stimulate Chek2 transcript indirectly in vitro as well as in B cells of λ-Myc transgenic mice or in the intestine of Apc (Min) mice. However, Chk2 is dispensable for Myc's ability to transform cells in vitro and for the survival of established lymphoma cells from λ-Myc transgenic mice. Chk2 deficiency induces polyploidy and slow growth, but the cells are viable and protected against DNA damage. Furthermore, inhibition of both Chk1/Chk2 with AZD7762 induces cell death and significantly delays disease progression of transplanted lymphoma cells in vivo. DNA damage recruits PARP family members to sites of DNA breaks that, in turn, facilitate the induction of DNA repair. Strikingly, combining Chk2 and PARP inhibition elicits a synergistic lethal response in the context of Myc overexpression. Our data indicates that only certain types of chemotherapy would give rise to a synergistic lethal response in combination with specific Chk2 inhibitors, which will be important if Chk2 inhibitors enter the clinic.
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Affiliation(s)
- Andreas Höglund
- Department of Molecular Biology, Umeå University, Umeå, Sweden
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18
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Paronetto M, Miñana B, Valcárcel J. The Ewing Sarcoma Protein Regulates DNA Damage-Induced Alternative Splicing. Mol Cell 2011; 43:353-68. [DOI: 10.1016/j.molcel.2011.05.035] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 04/14/2011] [Accepted: 05/25/2011] [Indexed: 01/20/2023]
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CHEK2 genomic and proteomic analyses reveal genetic inactivation or endogenous activation across the 60 cell lines of the US National Cancer Institute. Oncogene 2011; 31:403-18. [PMID: 21765476 DOI: 10.1038/onc.2011.283] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
CHEK2 encodes a serine/threonine kinase (Chk2) activated by ATM in response to DNA double-strand breaks. On the one hand, CHEK2 has been described as a tumor suppressor with proapoptotic, cell-cycle checkpoint and mitotic functions. On the other hand, Chk2 is also commonly activated (phosphorylated at T68) in cancers and precancerous lesions. Here, we report an extensive characterization of CHEK2 across the panel of 60 established cancer cell lines from the NCI Anticancer Screen (the NCI-60) using genomic and proteomic analyses, including exon-specific mRNA expression, DNA copy-number variation (CNV) by aCGH, exome sequencing, as well as western blot analyses for total and activated (pT68-Chk2) Chk2. We show that the high heterogeneity of Chk2 levels in cancer cells is primarily due to its inactivation (owing to low gene expression, alternative splicing, point mutations, copy-number alterations and premature truncation) or reduction of protein levels. Moreover, we observe that a significant percentage of cancer cells (12% of the NCI-60 and HeLa cells) show high endogenous Chk2 activation, which is always associated with p53 inactivation, and which is accompanied by downregulation of the Fanconi anemia and homologous recombination pathways. We also report the presence of activated Chk2 (pT68-Chk2) along with histone γ-H2AX in centrosomes.
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20
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Li Y, Hu X, Song Y, Lu Z, Ning T, Cai H, Ke Y. Identification of novel alternative splicing variants of interferon regulatory factor 3. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:166-75. [PMID: 21281747 DOI: 10.1016/j.bbagrm.2011.01.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 01/05/2011] [Accepted: 01/21/2011] [Indexed: 10/18/2022]
Abstract
Interferon regulatory factor 3 (IRF-3) plays a crucial role in host defense against viral and microbial infection as well as in cell growth regulation. IRF-3a is the only structurally and functionally characterized IRF-3 splicing variant and has been established to antagonize IRF-3 activity. Here, five novel splicing variants of IRF-3, referred to as IRF-3b, -3c, -3d, -3e, and -3f, were identified and shown to be generated by deletion of exons 2, 3, or 6 or some combination thereof. RT-PCR examination revealed that these novel splicing variants were more frequently expressed in human liver, esophagus, and cervical tumor tissues than in their normal counterparts. Additionally, electrophoretic mobility shift assay and subcellular localization showed only IRF-3 and IRF-3e were capable of binding the PRDI/III element of interferon-beta (IFNβ) promoter in vitro and underwent cytoplasm-to-nucleus translocation following Poly(I:C) stimulation. Coimmunoprecipitation assay revealed that only IRF-3c (3f) of novel splicing variants associated with IRF-3 in vivo. Further luciferase assay showed IRF-3c (3f) and IRF-3e failed to transactivate PRDI/III-containing promoter but appeared to inhibit transactivation potential of IRF-3 to varying degrees. Taken together, our findings suggest novel splicing variants may function as negative modulators of IRF-3 and may be correlated with pathogenesis of human tumors.
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Affiliation(s)
- Yong Li
- Key laboratory of Carcinogenesis and Translational Research, Department of Genesis, Peking University School of Oncology , Beijing Cancer Hospital & Institute, Beijing, PR China
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21
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Berge EO, Knappskog S, Geisler S, Staalesen V, Pacal M, Børresen-Dale AL, Puntervoll P, Lillehaug JR, Lønning PE. Identification and characterization of retinoblastoma gene mutations disturbing apoptosis in human breast cancers. Mol Cancer 2010; 9:173. [PMID: 20594292 PMCID: PMC2908580 DOI: 10.1186/1476-4598-9-173] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 07/01/2010] [Indexed: 12/29/2022] Open
Abstract
Background The tumor suppressor pRb plays a key role regulating cell cycle arrest, and disturbances in the RB1 gene have been reported in different cancer forms. However, the literature reports contradictory findings with respect to a pro - versus anti - apoptotic role of pRb, and the consequence of alterations in RB1 to chemotherapy sensitivity remains unclear. This study is part of a project investigating alterations in pivotal genes as predictive factors to chemotherapy sensitivity in breast cancer. Results Analyzing 73 locally advanced (stage III) breast cancers, we identified two somatic and one germline single nucleotide changes, each leading to amino acid substitution in the pRb protein (Leu607Ile, Arg698Trp, and Arg621Cys, respectively). This is the first study reporting point mutations affecting RB1 in breast cancer tissue. In addition, MLPA analysis revealed two large multiexon deletions (exons 13 to 27 and exons 21 to 23) with the exons 21-23 deletion occurring in the tumor also harboring the Leu607Ile mutation. Interestingly, Leu607Ile and Arg621Cys point mutations both localize to the spacer region of the pRb protein, a region previously shown to harbor somatic and germline mutations. Multiple sequence alignment across species indicates the spacer to be evolutionary conserved. All three RB1 point mutations encoded nuclear proteins with impaired ability to induce apoptosis compared to wild-type pRb in vitro. Notably, three out of four tumors harboring RB1 mutations displayed primary resistance to treatment with either 5-FU/mitomycin or doxorubicin while only 14 out of 64 tumors without mutations were resistant (p = 0.046). Conclusions Although rare, our findings suggest RB1 mutations to be of pathological importance potentially affecting sensitivity to mitomycin/anthracycline treatment in breast cancer.
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