1
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Yan X, Mischel P, Chang H. Extrachromosomal DNA in cancer. Nat Rev Cancer 2024; 24:261-273. [PMID: 38409389 DOI: 10.1038/s41568-024-00669-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/18/2024] [Indexed: 02/28/2024]
Abstract
Extrachromosomal DNA (ecDNA) has recently been recognized as a major contributor to cancer pathogenesis that is identified in most cancer types and is associated with poor outcomes. When it was discovered over 60 years ago, ecDNA was considered to be rare, and its impact on tumour biology was not well understood. The application of modern imaging and computational techniques has yielded powerful new insights into the importance of ecDNA in cancer. The non-chromosomal inheritance of ecDNA during cell division results in high oncogene copy number, intra-tumoural genetic heterogeneity and rapid tumour evolution that contributes to treatment resistance and shorter patient survival. In addition, the circular architecture of ecDNA results in altered patterns of gene regulation that drive elevated oncogene expression, potentially enabling the remodelling of tumour genomes. The generation of clusters of ecDNAs, termed ecDNA hubs, results in interactions between enhancers and promoters in trans, yielding a new paradigm in oncogenic transcription. In this Review, we highlight the rapid advancements in ecDNA research, providing new insights into ecDNA biogenesis, maintenance and transcription and its role in promoting tumour heterogeneity. To conclude, we delve into a set of unanswered questions whose answers will pave the way for the development of ecDNA targeted therapeutic approaches.
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Affiliation(s)
- Xiaowei Yan
- Department of Dermatology, Stanford University, Stanford, CA, USA
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
| | - Paul Mischel
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.
- Sarafan ChEM-H, Stanford University, Stanford, CA, USA.
| | - Howard Chang
- Department of Dermatology, Stanford University, Stanford, CA, USA.
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA.
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA.
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2
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Yegorov YE. Olovnikov, Telomeres, and Telomerase. Is It Possible to Prolong a Healthy Life? BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1704-1718. [PMID: 38105192 DOI: 10.1134/s0006297923110032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/29/2023] [Accepted: 08/31/2023] [Indexed: 12/19/2023]
Abstract
The science of telomeres and telomerase has made tremendous progress in recent decades. In this review, we consider it first in a historical context (the Carrel-Hayflick-Olovnikov-Blackburn chain of discoveries) and then review current knowledge on the telomere structure and dynamics in norm and pathology. Central to the review are consequences of the telomere shortening, including telomere position effects, DNA damage signaling, and increased genetic instability. Cell senescence and role of telomere length in its development are discussed separately. Therapeutic aspects and risks of telomere lengthening methods including use of telomerase and other approaches are also discussed.
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Affiliation(s)
- Yegor E Yegorov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
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3
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Sakamoto M, Patil T. MET alterations in advanced non-small cell lung cancer. Lung Cancer 2023; 178:254-268. [PMID: 36924573 DOI: 10.1016/j.lungcan.2023.02.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/23/2023] [Accepted: 02/21/2023] [Indexed: 03/05/2023]
Abstract
Targeting the MET pathway in advanced NSCLC has been of particular interest due to its role as both a primary oncogenic driver and secondary oncogenic driver of acquired resistance. Activation of the MET pathway can occur through several mechanisms, which can complicate the diagnostic and treatment approach. Recently, several MET-directed therapies have been developed with promising results. In this narrative review, we summarize the biology and mechanism of MET as a clinically relevant driver mutation, distinct MET alterations including diagnostic challenges, significance in the setting of acquired resistance, and novel treatment strategies in advanced NSCLC.
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Affiliation(s)
- Mandy Sakamoto
- Department of Medicine, Division of Medical Oncology, United States
| | - Tejas Patil
- Department of Medicine, Division of Medical Oncology, United States.
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4
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Wilson C, Murnane JP. High-throughput screen to identify compounds that prevent or target telomere loss in human cancer cells. NAR Cancer 2022; 4:zcac029. [PMID: 36196242 PMCID: PMC9527662 DOI: 10.1093/narcan/zcac029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/09/2022] [Accepted: 09/29/2022] [Indexed: 11/14/2022] Open
Abstract
Chromosome instability (CIN) is an early step in carcinogenesis that promotes tumor cell progression and resistance to therapy. Using plasmids integrated adjacent to telomeres, we have previously demonstrated that the sensitivity of subtelomeric regions to DNA double-strand breaks (DSBs) contributes to telomere loss and CIN in cancer. A high-throughput screen was created to identify compounds that affect telomere loss due to subtelomeric DSBs introduced by I-SceI endonuclease, as detected by cells expressing green fluorescent protein (GFP). A screen of a library of 1832 biologically-active compounds identified a variety of compounds that increase or decrease the number of GFP-positive cells following activation of I-SceI. A curated screen done in triplicate at various concentrations found that inhibition of classical nonhomologous end joining (C-NHEJ) increased DSB-induced telomere loss, demonstrating that C-NHEJ is functional in subtelomeric regions. Compounds that decreased DSB-induced telomere loss included inhibitors of mTOR, p38 and tankyrase, consistent with our earlier hypothesis that the sensitivity of subtelomeric regions to DSBs is a result of inappropriate resection during repair. Although this assay was also designed to identify compounds that selectively target cells experiencing telomere loss and/or chromosome instability, no compounds of this type were identified in the current screen.
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Affiliation(s)
- Chris Wilson
- Department of Pharmaceutical Chemistry, Small Molecule Discovery Center, University of California, San Francisco, CA 94143, USA
| | - John P Murnane
- To whom correspondence should be addressed. Tel: +1 415 680 4434;
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5
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Ilić M, Zaalberg IC, Raaijmakers JA, Medema RH. Life of double minutes: generation, maintenance, and elimination. Chromosoma 2022; 131:107-125. [PMID: 35487993 PMCID: PMC9470669 DOI: 10.1007/s00412-022-00773-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 03/17/2022] [Accepted: 03/24/2022] [Indexed: 12/20/2022]
Abstract
Advances in genome sequencing have revealed a type of extrachromosomal DNA, historically named double minutes (also referred to as ecDNA), to be common in a wide range of cancer types, but not in healthy tissues. These cancer-associated circular DNA molecules contain one or a few genes that are amplified when double minutes accumulate. Double minutes harbor oncogenes or drug resistance genes that contribute to tumor aggressiveness through copy number amplification in combination with favorable epigenetic properties. Unequal distribution of double minutes over daughter cells contributes to intratumoral heterogeneity, thereby increasing tumor adaptability. In this review, we discuss various models delineating the mechanism of generation of double minutes. Furthermore, we highlight how double minutes are maintained, how they evolve, and discuss possible mechanisms driving their elimination.
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Affiliation(s)
- Mila Ilić
- Division of Cell Biology, Oncode Institute, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Irene C Zaalberg
- Division of Cell Biology, Oncode Institute, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Universiteitsweg, 100, 3584, CG Utrecht, The Netherlands
| | - Jonne A Raaijmakers
- Division of Cell Biology, Oncode Institute, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - René H Medema
- Division of Cell Biology, Oncode Institute, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
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6
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Abstract
In cancer, complex genome rearrangements and other structural alterations, including the amplification of oncogenes on circular extrachromosomal DNA (ecDNA) elements, drive the formation and progression of tumors. ecDNA is a particularly challenging structural alteration. By untethering oncogenes from chromosomal constraints, it elevates oncogene copy number, drives intratumoral genetic heterogeneity, promotes rapid tumor evolution, and results in treatment resistance. The profound changes in DNA shape and nuclear architecture generated by ecDNA alter the transcriptional landscape of tumors by catalyzing new types of regulatory interactions that do not occur on chromosomes. The current suite of tools for interrogating cancer genomes is well suited for deciphering sequence but has limited ability to resolve the complex changes in DNA structure and dynamics that ecDNA generates. Here, we review the challenges of resolving ecDNA form and function and discuss the emerging tool kit for deciphering ecDNA architecture and spatial organization, including what has been learned to date about how this dramatic change in shape alters tumor development, progression, and drug resistance.
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Affiliation(s)
- Vineet Bafna
- Department of Computer Science and Engineering and Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, California, USA;
| | - Paul S Mischel
- Department of Pathology and ChEM-H, Stanford University School of Medicine, Stanford, California, USA;
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7
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Danforth JM, Provencher L, Goodarzi AA. Chromatin and the Cellular Response to Particle Radiation-Induced Oxidative and Clustered DNA Damage. Front Cell Dev Biol 2022; 10:910440. [PMID: 35912116 PMCID: PMC9326100 DOI: 10.3389/fcell.2022.910440] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/21/2022] [Indexed: 12/03/2022] Open
Abstract
Exposure to environmental ionizing radiation is prevalent, with greatest lifetime doses typically from high Linear Energy Transfer (high-LET) alpha particles via the radioactive decay of radon gas in indoor air. Particle radiation is highly genotoxic, inducing DNA damage including oxidative base lesions and DNA double strand breaks. Due to the ionization density of high-LET radiation, the consequent damage is highly clustered wherein ≥2 distinct DNA lesions occur within 1–2 helical turns of one another. These multiply-damaged sites are difficult for eukaryotic cells to resolve either quickly or accurately, resulting in the persistence of DNA damage and/or the accumulation of mutations at a greater rate per absorbed dose, relative to lower LET radiation types. The proximity of the same and different types of DNA lesions to one another is challenging for DNA repair processes, with diverse pathways often confounding or interplaying with one another in complex ways. In this context, understanding the state of the higher order chromatin compaction and arrangements is essential, as it influences the density of damage produced by high-LET radiation and regulates the recruitment and activity of DNA repair factors. This review will summarize the latest research exploring the processes by which clustered DNA damage sites are induced, detected, and repaired in the context of chromatin.
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8
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Steele CD, Abbasi A, Islam SMA, Bowes AL, Khandekar A, Haase K, Hames-Fathi S, Ajayi D, Verfaillie A, Dhami P, McLatchie A, Lechner M, Light N, Shlien A, Malkin D, Feber A, Proszek P, Lesluyes T, Mertens F, Flanagan AM, Tarabichi M, Van Loo P, Alexandrov LB, Pillay N. Signatures of copy number alterations in human cancer. Nature 2022; 606:984-991. [PMID: 35705804 PMCID: PMC9242861 DOI: 10.1038/s41586-022-04738-6] [Citation(s) in RCA: 154] [Impact Index Per Article: 77.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 04/07/2022] [Indexed: 12/15/2022]
Abstract
Gains and losses of DNA are prevalent in cancer and emerge as a consequence of inter-related processes of replication stress, mitotic errors, spindle multipolarity and breakage-fusion-bridge cycles, among others, which may lead to chromosomal instability and aneuploidy1,2. These copy number alterations contribute to cancer initiation, progression and therapeutic resistance3-5. Here we present a conceptual framework to examine the patterns of copy number alterations in human cancer that is widely applicable to diverse data types, including whole-genome sequencing, whole-exome sequencing, reduced representation bisulfite sequencing, single-cell DNA sequencing and SNP6 microarray data. Deploying this framework to 9,873 cancers representing 33 human cancer types from The Cancer Genome Atlas6 revealed a set of 21 copy number signatures that explain the copy number patterns of 97% of samples. Seventeen copy number signatures were attributed to biological phenomena of whole-genome doubling, aneuploidy, loss of heterozygosity, homologous recombination deficiency, chromothripsis and haploidization. The aetiologies of four copy number signatures remain unexplained. Some cancer types harbour amplicon signatures associated with extrachromosomal DNA, disease-specific survival and proto-oncogene gains such as MDM2. In contrast to base-scale mutational signatures, no copy number signature was associated with many known exogenous cancer risk factors. Our results synthesize the global landscape of copy number alterations in human cancer by revealing a diversity of mutational processes that give rise to these alterations.
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Affiliation(s)
- Christopher D Steele
- Research Department of Pathology, Cancer Institute, University College London, London, UK
| | - Ammal Abbasi
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, USA
- Department of Bioengineering, UC San Diego, La Jolla, CA, USA
- Moores Cancer Center, UC San Diego, La Jolla, CA, USA
| | - S M Ashiqul Islam
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, USA
- Department of Bioengineering, UC San Diego, La Jolla, CA, USA
- Moores Cancer Center, UC San Diego, La Jolla, CA, USA
| | - Amy L Bowes
- Research Department of Pathology, Cancer Institute, University College London, London, UK
- Cancer Genomics Laboratory, The Francis Crick Institute, London, UK
| | - Azhar Khandekar
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, USA
- Department of Bioengineering, UC San Diego, La Jolla, CA, USA
- Moores Cancer Center, UC San Diego, La Jolla, CA, USA
| | - Kerstin Haase
- Cancer Genomics Laboratory, The Francis Crick Institute, London, UK
| | - Shadi Hames-Fathi
- Research Department of Pathology, Cancer Institute, University College London, London, UK
| | - Dolapo Ajayi
- Research Department of Pathology, Cancer Institute, University College London, London, UK
| | | | - Pawan Dhami
- CRUK-UCL Cancer Institute Translational Technology Platform (Genomics), London, UK
| | - Alex McLatchie
- CRUK-UCL Cancer Institute Translational Technology Platform (Genomics), London, UK
| | - Matt Lechner
- Research Department of Oncology, UCL Cancer Institute, London, UK
| | - Nicholas Light
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Adam Shlien
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - David Malkin
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Division of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Feber
- Translational Epigenetics, Division of Molecular Pathology, Institute of Cancer Research, London, UK
- Clinical Genomics, Translational Research Laboratory, Royal Marsden NHS Trust, London, UK
| | - Paula Proszek
- Translational Epigenetics, Division of Molecular Pathology, Institute of Cancer Research, London, UK
- Clinical Genomics, Translational Research Laboratory, Royal Marsden NHS Trust, London, UK
| | - Tom Lesluyes
- Cancer Genomics Laboratory, The Francis Crick Institute, London, UK
| | - Fredrik Mertens
- Division of Clinical Genetics, Department of Laboratory Medicine, Lund University, Lund, Sweden
- Department of Clinical Genetics and Pathology, Division of Laboratory Medicine, Lund, Sweden
| | - Adrienne M Flanagan
- Research Department of Pathology, Cancer Institute, University College London, London, UK
- Department of Cellular and Molecular Pathology, Royal National Orthopaedic Hospital NHS Trust, Stanmore, UK
| | - Maxime Tarabichi
- Cancer Genomics Laboratory, The Francis Crick Institute, London, UK
- Institute for Interdisciplinary Research, Université Libre de Bruxelles, Brussels, Belgium
| | - Peter Van Loo
- Cancer Genomics Laboratory, The Francis Crick Institute, London, UK
| | - Ludmil B Alexandrov
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, USA.
- Department of Bioengineering, UC San Diego, La Jolla, CA, USA.
- Moores Cancer Center, UC San Diego, La Jolla, CA, USA.
| | - Nischalan Pillay
- Research Department of Pathology, Cancer Institute, University College London, London, UK.
- Department of Cellular and Molecular Pathology, Royal National Orthopaedic Hospital NHS Trust, Stanmore, UK.
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9
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Tuna M, Amos CI, Mills GB. Whole-chromosome arm acquired uniparental disomy in cancer development is a consequence of isochromosome formation. Neoplasia 2022; 25:9-17. [PMID: 35065533 PMCID: PMC8788198 DOI: 10.1016/j.neo.2021.12.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/21/2021] [Accepted: 12/22/2021] [Indexed: 01/09/2023]
Abstract
Using SNP-based microarray data from The Cancer Genome Atlas (TCGA), we investigated isochromosomes (deletion of one arm and duplication of the other arm) and related acquired uniparental disomy in 12 tumor types. We observed a high frequency of isochromosomes (25.98%) across all type of tumors except thyroid cancers. The highest frequency of isochromosomes was found in lung squamous cell carcinoma (54.18%). Moreover, whole-chromosome arm acquired uniparental disomy (aUPD) was common in the deleted arms of isochromosomes. These data are consistent with whole-chromosome arm aUPD likely being a consequence of isochromosomes formation. Our findings implicated aUPD as occurring through error-prone DNA repair of a deleted arm or segment of a chromosome that leads to homozygosity for existing alterations. Isochromosomes were significantly more frequent in TP53 mutated samples than wild types in 6 types of tumors with loss of TP53 function potentially contributing to development of isochromosomes. Isochromosomes are common alterations in cancer, and losing one arm of a chromosome could result in duplication of the lost arm. Duplication of the remaining arm leads promulgation of the effects on any defects in the remaining allele, due to subsequent homozygosity.
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Affiliation(s)
- Musaffe Tuna
- Department of Medicine, Baylor College of Medicine, One Baylor Plaza room 100.23D, Houston, TX 77030, USA.
| | - Christopher I Amos
- Department of Medicine, Baylor College of Medicine, One Baylor Plaza room 100.23D, Houston, TX 77030, USA; Institute of Clinical and Translational Medicine, Baylor College of Medicine, USA
| | - Gordon B Mills
- Department of Cell, Developmental & Cancer Biology, School of Medicine, Oregon Health Science University, Portland, OR, USA; Precision Oncology, Knight Cancer Institute, Portland, OR, USA
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10
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Zavacka K, Plevova K. Chromothripsis in Chronic Lymphocytic Leukemia: A Driving Force of Genome Instability. Front Oncol 2021; 11:771664. [PMID: 34900721 PMCID: PMC8661134 DOI: 10.3389/fonc.2021.771664] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 11/01/2021] [Indexed: 11/22/2022] Open
Abstract
Chromothripsis represents a mechanism of massive chromosome shattering and reassembly leading to the formation of derivative chromosomes with abnormal functions and expression. It has been observed in many cancer types, importantly, including chronic lymphocytic leukemia (CLL). Due to the associated chromosomal rearrangements, it has a significant impact on the pathophysiology of the disease. Recent studies have suggested that chromothripsis may be more common than initially inferred, especially in CLL cases with adverse clinical outcome. Here, we review the main features of chromothripsis, the challenges of its assessment, and the potential benefit of its detection. We summarize recent findings of chromothripsis occurrence across hematological malignancies and address its causes and consequences in the context of CLL clinical features, as well as chromothripsis-related molecular abnormalities described in published CLL studies. Furthermore, we discuss the use of the current knowledge about genome functions associated with chromothripsis in the optimization of treatment strategies in CLL.
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Affiliation(s)
- Kristyna Zavacka
- Department of Internal Medicine - Hematology and Oncology, University Hospital Brno & Faculty of Medicine, Masaryk University, Brno, Czechia.,Center of Molecular Medicine, Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Karla Plevova
- Department of Internal Medicine - Hematology and Oncology, University Hospital Brno & Faculty of Medicine, Masaryk University, Brno, Czechia.,Center of Molecular Medicine, Central European Institute of Technology, Masaryk University, Brno, Czechia.,Institute of Medical Genetics and Genomics, University Hospital Brno & Masaryk University, Brno, Czechia
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11
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Tomaszewska P, Kosina R. Cytogenetic events in the endosperm of amphiploid Avena magna × A. longiglumis. JOURNAL OF PLANT RESEARCH 2021; 134:1047-1060. [PMID: 34057611 PMCID: PMC8364899 DOI: 10.1007/s10265-021-01314-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 05/19/2021] [Indexed: 05/13/2023]
Abstract
This study analysed cytogenetic events occurring in the syncytial endosperm of the Avena magna H. C. Murphy & Terrell × Avena longiglumis Durieu amphiploid, which is a product of two wild species having different genomes. Selection through the elimination of chromosomes and their fragments, including those translocated, decreased the level of ploidy in the endosperm below the expected 3n, leading to the modal number close to 2n. During intergenomic translocations, fragments of the heterochromatin-rich C-genome were transferred to the D and Al genomes. Terminal and non-reciprocal exchanges dominated, whereas other types of translocations, including microexchanges, were less common. Using two probes and by counterstaining with DAPI, the A. longiglumis and the rare exchanges between the D and Al genomes were detected by GISH. The large discontinuity in the probe labelling in the C chromosomes demonstrated inequality in the distribution of repetitive sequences along the chromosome and probable intragenomic rearrangements. In the nucleus, the spatial arrangement of genomes was non-random and showed a sectorial-concentric pattern, which can vary during the cell cycle, especially in the less stable tissue like the hybrid endosperm.
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Affiliation(s)
| | - Romuald Kosina
- Institute of Environmental Biology, University of Wrocław, Przybyszewskiego 63, 51-148, Wroclaw, Poland.
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12
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Bull C, Mayrhofer G, Fenech M. Exposure to hypomethylating 5-aza-2'-deoxycytidine (decitabine) causes rapid, severe DNA damage, telomere elongation and mitotic dysfunction in human WIL2-NS cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2021; 868-869:503385. [PMID: 34454691 DOI: 10.1016/j.mrgentox.2021.503385] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/31/2021] [Accepted: 07/13/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND 5-aza-2'-deoxycytidine (5azadC, decitabine) is a DNA hypomethylating agent used in the treatment of myelodysplastic syndromes. Due to cytotoxic side effects dose optimization is essential. The aim of this study was to define and quantify the effects of 5azadC on biomarkers of chromosomal stability, and telomere length, in human lymphoblastoid cell line, WIL2-NS, at clinically relevant dosages. METHODS Human WIL2-NS cells were maintained in complete medium containing 0, 0.2 or 1.0 μM 5azadC for four days, and analysed daily for telomere length (flow cytometry), chromosomal stability (cytokinesis-block micronucleus cytome (CBMN-cyt) assay), and global methylation (%5me-C). RESULTS DNA methylation decreased significantly in 1.0 μM 5azadC, relative to control (p < 0.0001). Exposure to 1.0 μM 5azadC resulted in 1.7-fold increase in telomere length (p < 0.0001), in parallel with rapid increase in biomarkers of DNA damage; (micronuclei (MN, 6-fold increase), nucleoplasmic bridges (NPB, a 12-fold increase), and nuclear buds (NBud, a 13-fold increase) (all p < 0.0001). Fused nuclei (FUS), indicative of mitotic dysfunction, showed a 5- and 13-fold increase in the 0.2 μM and 1.0 μM conditions, respectively (p = 0.001) after 4 days. CONCLUSIONS These data show that (i) clinically relevant concentrations of 5azadC are highly genotoxic; (ii) hypomethylation was associated with increased TL and DNA damage; and (iii) longer TL was associated with chromosomal instability. These findings suggest that lower doses of 5azdC may be effective as a hypomethylating agent, while potentially reducing DNA damage and risk for secondary disease.
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Affiliation(s)
- Caroline Bull
- CSIRO Health & Biosecurity, Gate 13 Kintore Avenue, Adelaide, South Australia, Australia; School of Molecular and Biomedical Sciences, University of Adelaide, North Terrace, Adelaide, South Australia, Australia.
| | - Graham Mayrhofer
- School of Molecular and Biomedical Sciences, University of Adelaide, North Terrace, Adelaide, South Australia, Australia
| | - Michael Fenech
- CSIRO Health & Biosecurity, Gate 13 Kintore Avenue, Adelaide, South Australia, Australia
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13
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Rahnama M, Wang B, Dostart J, Novikova O, Yackzan D, Yackzan A, Bruss H, Baker M, Jacob H, Zhang X, Lamb A, Stewart A, Heist M, Hoover J, Calie P, Chen L, Liu J, Farman ML. Telomere Roles in Fungal Genome Evolution and Adaptation. Front Genet 2021; 12:676751. [PMID: 34434216 PMCID: PMC8381367 DOI: 10.3389/fgene.2021.676751] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 06/28/2021] [Indexed: 11/27/2022] Open
Abstract
Telomeres form the ends of linear chromosomes and usually comprise protein complexes that bind to simple repeated sequence motifs that are added to the 3′ ends of DNA by the telomerase reverse transcriptase (TERT). One of the primary functions attributed to telomeres is to solve the “end-replication problem” which, if left unaddressed, would cause gradual, inexorable attrition of sequences from the chromosome ends and, eventually, loss of viability. Telomere-binding proteins also protect the chromosome from 5′ to 3′ exonuclease action, and disguise the chromosome ends from the double-strand break repair machinery whose illegitimate action potentially generates catastrophic chromosome aberrations. Telomeres are of special interest in the blast fungus, Pyricularia, because the adjacent regions are enriched in genes controlling interactions with host plants, and the chromosome ends show enhanced polymorphism and genetic instability. Previously, we showed that telomere instability in some P. oryzae strains is caused by novel retrotransposons (MoTeRs) that insert in telomere repeats, generating interstitial telomere sequences that drive frequent, break-induced rearrangements. Here, we sought to gain further insight on telomeric involvement in shaping Pyricularia genome architecture by characterizing sequence polymorphisms at chromosome ends, and surrounding internalized MoTeR loci (relics) and interstitial telomere repeats. This provided evidence that telomere dynamics have played historical, and likely ongoing, roles in shaping the Pyricularia genome. We further demonstrate that even telomeres lacking MoTeR insertions are poorly preserved, such that the telomere-adjacent sequences exhibit frequent presence/absence polymorphism, as well as exchanges with the genome interior. Using TERT knockout experiments, we characterized chromosomal responses to failed telomere maintenance which suggested that much of the MoTeR relic-/interstitial telomere-associated polymorphism could be driven by compromised telomere function. Finally, we describe three possible examples of a phenomenon known as “Adaptive Telomere Failure,” where spontaneous losses of telomere maintenance drive rapid accumulation of sequence polymorphism with possible adaptive advantages. Together, our data suggest that telomere maintenance is frequently compromised in Pyricularia but the chromosome alterations resulting from telomere failure are not as catastrophic as prior research would predict, and may, in fact, be potent drivers of adaptive polymorphism.
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Affiliation(s)
- Mostafa Rahnama
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Baohua Wang
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States.,State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jane Dostart
- Department of Biological Sciences, Eastern Kentucky University, Richmond, KY, United States
| | - Olga Novikova
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Daniel Yackzan
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Andrew Yackzan
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Haley Bruss
- Department of Biological Sciences, Eastern Kentucky University, Richmond, KY, United States
| | - Maray Baker
- Department of Biological Sciences, Eastern Kentucky University, Richmond, KY, United States
| | - Haven Jacob
- Department of Biological Sciences, Eastern Kentucky University, Richmond, KY, United States
| | - Xiaofei Zhang
- Department of Computer Sciences, University of Kentucky, Lexington, KY, United States
| | - April Lamb
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Alex Stewart
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Melanie Heist
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Joey Hoover
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Patrick Calie
- Department of Biological Sciences, Eastern Kentucky University, Richmond, KY, United States
| | - Li Chen
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Jinze Liu
- Department of Computer Sciences, University of Kentucky, Lexington, KY, United States
| | - Mark L Farman
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
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14
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Svetec Miklenić M, Svetec IK. Palindromes in DNA-A Risk for Genome Stability and Implications in Cancer. Int J Mol Sci 2021; 22:2840. [PMID: 33799581 PMCID: PMC7999016 DOI: 10.3390/ijms22062840] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 02/07/2023] Open
Abstract
A palindrome in DNA consists of two closely spaced or adjacent inverted repeats. Certain palindromes have important biological functions as parts of various cis-acting elements and protein binding sites. However, many palindromes are known as fragile sites in the genome, sites prone to chromosome breakage which can lead to various genetic rearrangements or even cell death. The ability of certain palindromes to initiate genetic recombination lies in their ability to form secondary structures in DNA which can cause replication stalling and double-strand breaks. Given their recombinogenic nature, it is not surprising that palindromes in the human genome are involved in genetic rearrangements in cancer cells as well as other known recurrent translocations and deletions associated with certain syndromes in humans. Here, we bring an overview of current understanding and knowledge on molecular mechanisms of palindrome recombinogenicity and discuss possible implications of DNA palindromes in carcinogenesis. Furthermore, we overview the data on known palindromic sequences in the human genome and efforts to estimate their number and distribution, as well as underlying mechanisms of genetic rearrangements specific palindromic sequences cause.
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Affiliation(s)
| | - Ivan Krešimir Svetec
- Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia;
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15
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Hande V, Teo K, Srikanth P, Wong JSM, Sethu S, Martinez-Lopez W, Hande MP. Investigations on the new mechanism of action for acetaldehyde-induced clastogenic effects in human lung fibroblasts. Mutat Res 2020; 861-862:503303. [PMID: 33551104 DOI: 10.1016/j.mrgentox.2020.503303] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/08/2020] [Accepted: 12/14/2020] [Indexed: 12/31/2022]
Abstract
Acetaldehyde (AA) has been classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC, WHO) and by the US Environmental Protection Agency due to its ability to cause tumours following inhalation or alcohol consumption in animals. Humans are constantly exposed to AA through inhalation from the environment through cigarette smoke, vehicle fumes and industrial emissions as well as by persistent alcohol ingestion. Individuals with deficiencies in the enzymes that are involved in the metabolism of AA are more susceptible to its toxicity and constitute a vulnerable human population. Studies have shown that AA induces DNA damage and cytogenetic abnormalities. A study was undertaken to elucidate the clastogenic effects induced by AA and any preceding DNA damage that occurs in normal human lung fibroblasts as this will further validate the detrimental effects of inhalation exposure to AA. AA exposure induced DNA damage, involving DNA double strand breaks, which could possibly occur at the telomeric regions as well, resulting in a clastogenic effect and subsequent genomic instability, which contributed to the cell cycle arrest. The clastogenic effect induced by AA in human lung fibroblasts was evidenced by micronuclei induction and chromosomal aberrations, including those at the telomeric regions. Co-localisation between the DNA double strand breaks and telomeric regions was observed, suggesting possible induction of DNA double strand breaks due to AA exposure at the telomeric regions as a new mechanism beyond the clastogenic effect of AA. From the cell cycle profile following AA exposure, a G2/M phase arrest and a decrease in cell viability were also detected. Therefore, these effects due to AA exposure via inhalation may have implications in the development of carcinogenesis in humans.
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Affiliation(s)
- Varsha Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Keith Teo
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; University of Auckland, New Zealand
| | - Prarthana Srikanth
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Jane See Mei Wong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Swaminathan Sethu
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, India
| | - Wilner Martinez-Lopez
- Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay; Associate Unit on Genomic Stability, Faculty of Medicine, University of the Republic (UdelaR), Montevideo, Uruguay; Vellore Institute of Technology, Vellore, India
| | - Manoor Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Vellore Institute of Technology, Vellore, India; Mangalore University, India; Tembusu College, National University of Singapore, Singapore.
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16
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Toledo F. Mechanisms Generating Cancer Genome Complexity: Back to the Future. Cancers (Basel) 2020; 12:E3783. [PMID: 33334014 PMCID: PMC7765419 DOI: 10.3390/cancers12123783] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/30/2020] [Accepted: 12/11/2020] [Indexed: 11/16/2022] Open
Abstract
Understanding the mechanisms underlying cancer genome evolution has been a major goal for decades. A recent study combining live cell imaging and single-cell genome sequencing suggested that interwoven chromosome breakage-fusion-bridge cycles, micronucleation events and chromothripsis episodes drive cancer genome evolution. Here, I discuss the "interphase breakage model," suggested from prior fluorescent in situ hybridization data that led to a similar conclusion. In this model, the rapid genome evolution observed at early stages of gene amplification was proposed to result from the interweaving of an amplification mechanism (breakage-fusion-bridge cycles) and of a deletion mechanism (micronucleation and stitching of DNA fragments retained in the nucleus).
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Affiliation(s)
- Franck Toledo
- Genetics of Tumor Suppression, Institut Curie, PSL Research University, Sorbonne University, CNRS UMR3244 Dynamics of Genetic Information, 26 rue d'Ulm, CEDEX 05, 75248 Paris, France
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17
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Aberrant Telomere Length in Circulating Cell-Free DNA as Possible Blood Biomarker with High Diagnostic Performance in Endometrial Cancer. Pathol Oncol Res 2020; 26:2281-2289. [PMID: 32462419 DOI: 10.1007/s12253-020-00819-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 05/12/2020] [Indexed: 02/07/2023]
Abstract
To investigate the diagnostic performance of relative telomere length (RTL) in cell-free DNA (cfDNA) for endometrioid endometrial cancer (EC). We measured RTL in cfDNA of 40 EC patients (65 ± 12 years) and 31 healthy controls (HC) (63 ± 13 years), excluding in both groups other oncologic and severe non-oncologic diseases to limit confounders. Circulating cfDNA was extracted from serum using the QIAamp DNA Blood Mini kit (Qiagen, Hilden, Germany). After the quantitative real-time polymerase chain reaction, telomere repeat copy number to single-gene copy number ratio was calculated. RTL in cfDNA was found to be significantly lower in EC patients than in HC (p < 0.0001). The diagnostic performance of cfDNA RTL was estimated with receiver operating characteristics (ROC) curve analysis, which showed a diagnostic accuracy for EC of 0.87 (95% CI: 0.79-0.95, p < 0.0001). The cutoff cfDNA RTL value of 2.505 (T/S copy ratio) reported a sensitivity of 80.0% (95% CI: 64.35-90.95) and a specificity of 80.65% (95% CI: 62.53-92.55). Significant differences of RTL among EC stages or grades (p = 0.85 and p = 0.89, respectively) were not observed. Our results suggest that cfDNA RTL analysis may be a diagnostic tool for EC detection since the early stage, whilst its diagnostic performance seems unsatisfactory for cancer progression, staging, and grading. However, further studies are needed to confirm these preliminary findings. In particular, future investigations should focus on high-risk patients (such as those with atypical endometrial hyperplasia) that may benefit from this tool, because TL shortening is not specific for EC and is influenced by other oncologic and non-oncologic diseases.
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18
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Tuna M, I Amos C, B Mills G. Acquired Uniparental Disomy Regions Are Associated with Disease Outcome in Patients with Oral Cavity and Oropharynx But Not Larynx Cancers. Transl Oncol 2020; 13:100763. [PMID: 32305020 PMCID: PMC7163079 DOI: 10.1016/j.tranon.2020.100763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 03/11/2020] [Accepted: 03/14/2020] [Indexed: 12/24/2022] Open
Abstract
Acquired uniparental disomy (aUPD) regions pinpoint homozygousity and monoallelic expressed genes. We analyzed The Cancer Genome Atlas single-nucleotide polymorphism arrays and expression data from oral cavity, oropharynx, and larynx cancers to identify frequency of aUPD in each tumor type and association of aUPD regions and differentially expressed genes in the regions with survival. Cox proportional hazard models were used for survival function; and Student’s t test, for differentially expressed genes between groups. The frequency of aUPD was highest in larynx cancers (88.35%) followed by oral cavity (81.11%) and oropharynx cancers (73.85%). In univariate analysis, 11 regions at chromosome 9p were associated with overall survival (OS) in oral cavity cancers. Two regions at chromosome 17p were associated with OS in oropharyngeal cancers, but no aUPD region was associated with survival in patients with larynx cancers. Overexpression of SIGMAR1, C9orf23, and HINT2 was associated with reduced OS in patients with oral cavity cancers, and upregulation of MED27 and YWHAE was associated with shorter OS in patients with oropharynx cancers. In multivariate analysis, four aUPD regions at chromosome 9p and overexpression of HINT2 were associated with shorter OS in oral cavity cancers, and overexpression of MED27 was associated with worse OS in patients with oropharynx cancers. aUPD regions and differentially expressed genes in those regions influence the outcome and may play a role in aggressiveness in oral cavity and oropharynx cancers but not in patients with larynx cancers.
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Affiliation(s)
- Musaffe Tuna
- Department of Medicine, Baylor College of Medicine, Houston, TX.
| | - Christopher I Amos
- Department of Medicine, Baylor College of Medicine, Houston, TX; Institute of Clinical and Translational Research, Baylor College of Medicine, Houston, TX
| | - Gordon B Mills
- Department of Cell, Developmental & Cancer Biology, School of Medicine, Oregon Health Science University, Portland, OR; Precision Oncology, Knight Cancer Institute, Oregon Health Science University, Portland, OR
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19
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Abstract
BACKGROUND During cancer progression, malignant cells accumulate somatic mutations that can lead to genetic aberrations. In particular, evolutionary events akin to segmental duplications or deletions can alter the copy-number profile (CNP) of a set of genes in a genome. Our aim is to compute the evolutionary distance between two cells for which only CNPs are known. This asks for the minimum number of segmental amplifications and deletions to turn one CNP into another. This was recently formalized into a model where each event is assumed to alter a copy-number by 1 or -1, even though these events can affect large portions of a chromosome. RESULTS We propose a general cost framework where an event can modify the copy-number of a gene by larger amounts. We show that any cost scheme that allows segmental deletions of arbitrary length makes computing the distance strongly NP-hard. We then devise a factor 2 approximation algorithm for the problem when copy-numbers are non-zero and provide an implementation called cnp2cnp. We evaluate our approach experimentally by reconstructing simulated cancer phylogenies from the pairwise distances inferred by cnp2cnp and compare it against two other alternatives, namely the MEDICC distance and the Euclidean distance. CONCLUSIONS The experimental results show that our distance yields more accurate phylogenies on average than these alternatives if the given CNPs are error-free, but that the MEDICC distance is slightly more robust against error in the data. In all cases, our experiments show that either our approach or the MEDICC approach should preferred over the Euclidean distance.
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Affiliation(s)
| | - Manuel Lafond
- Department of Computer Science, Université de Sherbrooke, Sherbrooke, Canada.
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20
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Kim C, Sung S, Kim J, Lee J. Repair and Reconstruction of Telomeric and Subtelomeric Regions and Genesis of New Telomeres: Implications for Chromosome Evolution. Bioessays 2020; 42:e1900177. [PMID: 32236965 DOI: 10.1002/bies.201900177] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 02/20/2020] [Indexed: 12/12/2022]
Abstract
DNA damage repair within telomeres are suppressed to maintain the integrity of linear chromosomes, but the accidental activation of repairs can lead to genome instability. This review develops the concept that mechanisms to repair DNA damage in telomeres contribute to genetic variability and karyotype evolution, rather than catastrophe. Spontaneous breaks in telomeres can be repaired by telomerase, but in some cases DNA repair pathways are activated, and can cause chromosomal rearrangements or fusions. The resultant changes can also affect subtelomeric regions that are adjacent to telomeres. Subtelomeres are actively involved in such chromosomal changes, and are therefore the most variable regions in the genome. The case of Caenorhabditis elegans in the context of changes of subtelomeric structures revealed by long-read sequencing is also discussed. Theoretical and methodological issues covered in this review will help to explore the mechanism of chromosome evolution by reconstruction of chromosomal ends in nature.
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Affiliation(s)
- Chuna Kim
- Department of Biological Sciences, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08827, Korea.,Aging Research Institute, Korea Research Institute of Bioscience and Biotechnology, Gwahak-ro 125, Daejeon, 34141, Korea
| | - Sanghyun Sung
- Department of Biological Sciences, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08827, Korea
| | - Jun Kim
- Department of Biological Sciences, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08827, Korea
| | - Junho Lee
- Department of Biological Sciences, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08827, Korea
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21
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Sieverling L, Hong C, Koser SD, Ginsbach P, Kleinheinz K, Hutter B, Braun DM, Cortés-Ciriano I, Xi R, Kabbe R, Park PJ, Eils R, Schlesner M, Brors B, Rippe K, Jones DTW, Feuerbach L. Genomic footprints of activated telomere maintenance mechanisms in cancer. Nat Commun 2020; 11:733. [PMID: 32024817 PMCID: PMC7002710 DOI: 10.1038/s41467-019-13824-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 11/26/2019] [Indexed: 12/14/2022] Open
Abstract
Cancers require telomere maintenance mechanisms for unlimited replicative potential. They achieve this through TERT activation or alternative telomere lengthening associated with ATRX or DAXX loss. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, we dissect whole-genome sequencing data of over 2500 matched tumor-control samples from 36 different tumor types aggregated within the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium to characterize the genomic footprints of these mechanisms. While the telomere content of tumors with ATRX or DAXX mutations (ATRX/DAXXtrunc) is increased, tumors with TERT modifications show a moderate decrease of telomere content. One quarter of all tumor samples contain somatic integrations of telomeric sequences into non-telomeric DNA. This fraction is increased to 80% prevalence in ATRX/DAXXtrunc tumors, which carry an aberrant telomere variant repeat (TVR) distribution as another genomic marker. The latter feature includes enrichment or depletion of the previously undescribed singleton TVRs TTCGGG and TTTGGG, respectively. Our systematic analysis provides new insight into the recurrent genomic alterations associated with telomere maintenance mechanisms in cancer.
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Affiliation(s)
- Lina Sieverling
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Chen Hong
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Sandra D Koser
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Philip Ginsbach
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Kortine Kleinheinz
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Department for Bioinformatics and Functional Genomics, Institute for Pharmacy and Molecular Biotechnology (IPMB) and BioQuant, 69120, Heidelberg, Germany
| | - Barbara Hutter
- German Cancer Consortium (DKTK), Heidelberg, Germany
- National Center for Tumor Diseases (NCT) Heidelberg, Heidelberg, Germany
- Heidelberg Center for Personalized Oncology (DKFZ-HIPO), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Delia M Braun
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
- Division of Chromatin Networks, German Cancer Research Center (DKFZ) and BioQuant, 69120, Heidelberg, Germany
| | - Isidro Cortés-Ciriano
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Department of Chemistry, Centre for Molecular Science Informatics, University of Cambridge, Cambridge, CB2 1EW, UK
- Ludwig Center at Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Ruibin Xi
- School of Mathematical Sciences and Center for Statistical Science, Peking University, Beijing, 100871, China
| | - Rolf Kabbe
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Peter J Park
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Ludwig Center at Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Roland Eils
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Department for Bioinformatics and Functional Genomics, Institute for Pharmacy and Molecular Biotechnology (IPMB) and BioQuant, 69120, Heidelberg, Germany
| | - Matthias Schlesner
- Bioinformatics and Omics Data Analytics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Benedikt Brors
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- German Cancer Consortium (DKTK), Heidelberg, Germany
- National Center for Tumor Diseases (NCT) Heidelberg, Heidelberg, Germany
| | - Karsten Rippe
- Division of Chromatin Networks, German Cancer Research Center (DKFZ) and BioQuant, 69120, Heidelberg, Germany
| | - David T W Jones
- Hopp Children's Cancer Center (KiTZ), Heidelberg, Germany
- Pediatric Glioma Research Group, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Lars Feuerbach
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany.
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22
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Dewhurst SM. Chromothripsis and telomere crisis: engines of genome instability. Curr Opin Genet Dev 2020; 60:41-47. [PMID: 32151946 PMCID: PMC7230029 DOI: 10.1016/j.gde.2020.02.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 12/14/2022]
Abstract
In the early stages of carcinogenesis cells confront two key suppressive checkpoints; senescence and telomere crisis. Telomere crisis is characterized by massive chromosomal instability and cell death. The genetic instability initiated during crisis leaves detectable scars on cancer genomes, the full scope of which is only just beginning to be appreciated. In particular, the dramatic genome reshuffling phenomenon chromothripsis has been mechanistically linked to the resolution of DNA bridges formed by dicentric chromosomes, and by the shattering of DNA inside micronuclei. Furthermore, an intriguing connection to innate immune signaling has begun to position telomere crisis as a crucial stage not only in the evolution of the cancer genome, but also in the interaction between the genome and the immune system.
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Affiliation(s)
- Sally M Dewhurst
- Laboratory of Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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23
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Meng Y, Liu C, Shen L, Zhou M, Liu W, Kowolik C, Campbell JL, Zheng L, Shen B. TRAF6 mediates human DNA2 polyubiquitination and nuclear localization to maintain nuclear genome integrity. Nucleic Acids Res 2019; 47:7564-7579. [PMID: 31216032 PMCID: PMC6698806 DOI: 10.1093/nar/gkz537] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/29/2019] [Accepted: 06/07/2019] [Indexed: 12/14/2022] Open
Abstract
The multifunctional human DNA2 (hDNA2) nuclease/helicase is required to process DNA ends for homology-directed recombination repair (HDR) and to counteract replication stress. To participate in these processes, hDNA2 must localize to the nucleus and be recruited to the replication or repair sites. However, because hDNA2 lacks the nuclear localization signal that is found in its yeast homolog, it is unclear how its migration into the nucleus is regulated during replication or in response to DNA damage. Here, we report that the E3 ligase TRAF6 binds to and mediates the K63-linked polyubiquitination of hDNA2, increasing the stability of hDNA2 and promoting its nuclear localization. Inhibiting TRAF6-mediated polyubiquitination abolishes the nuclear localization of hDNA2, consequently impairing DNA end resection and HDR. Thus, the current study reveals a mechanism for the regulation of hDNA2 localization and establishes that TRAF6-mediated hDNA2 ubiquitination activates DNA repair pathways to maintain nuclear genome integrity.
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Affiliation(s)
- Yuan Meng
- Colleges of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310027, China.,Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Changwei Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Lei Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Mian Zhou
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Wenpeng Liu
- Colleges of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310027, China.,Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Claudia Kowolik
- Department of Molecular Medicine, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Judith L Campbell
- Division of Chemistry and Chemical Engineering, Braun Laboratories, California Institute of Technology, Pasadena, CA 91125, USA
| | - Li Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Binghui Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
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24
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Hynst J, Plevova K, Radova L, Bystry V, Pal K, Pospisilova S. Bioinformatic pipelines for whole transcriptome sequencing data exploitation in leukemia patients with complex structural variants. PeerJ 2019; 7:e7071. [PMID: 31223530 PMCID: PMC6571010 DOI: 10.7717/peerj.7071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 05/06/2019] [Indexed: 11/21/2022] Open
Abstract
Background Extensive genome rearrangements, known as chromothripsis, have been recently identified in several cancer types. Chromothripsis leads to complex structural variants (cSVs) causing aberrant gene expression and the formation of de novo fusion genes, which can trigger cancer development, or worsen its clinical course. The functional impact of cSVs can be studied at the RNA level using whole transcriptome sequencing (total RNA-Seq). It represents a powerful tool for discovering, profiling, and quantifying changes of gene expression in the overall genomic context. However, bioinformatic analysis of transcriptomic data, especially in cases with cSVs, is a complex and challenging task, and the development of proper bioinformatic tools for transcriptome studies is necessary. Methods We designed a bioinformatic workflow for the analysis of total RNA-Seq data consisting of two separate parts (pipelines): The first pipeline incorporates a statistical solution for differential gene expression analysis in a biologically heterogeneous sample set. We utilized results from transcriptomic arrays which were carried out in parallel to increase the precision of the analysis. The second pipeline is used for the identification of de novo fusion genes. Special attention was given to the filtering of false positives (FPs), which was achieved through consensus fusion calling with several fusion gene callers. We applied the workflow to the data obtained from ten patients with chronic lymphocytic leukemia (CLL) to describe the consequences of their cSVs in detail. The fusion genes identified by our pipeline were correlated with genomic break-points detected by genomic arrays. Results We set up a novel solution for differential gene expression analysis of individual samples and de novo fusion gene detection from total RNA-Seq data. The results of the differential gene expression analysis were concordant with results obtained by transcriptomic arrays, which demonstrates the analytical capabilities of our method. We also showed that the consensus fusion gene detection approach was able to identify true positives (TPs) efficiently. Detected coordinates of fusion gene junctions were in concordance with genomic breakpoints assessed using genomic arrays. Discussion Byapplying our methods to real clinical samples, we proved that our approach for total RNA-Seq data analysis generates results consistent with other genomic analytical techniques. The data obtained by our analyses provided clues for the study of the biological consequences of cSVs with far-reaching implications for clinical outcome and management of cancer patients. The bioinformatic workflow is also widely applicable for addressing other research questions in different contexts, for which transcriptomic data are generated.
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Affiliation(s)
- Jakub Hynst
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic.,Department of Internal Medicine-Hematology and Oncology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Karla Plevova
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic.,Department of Internal Medicine-Hematology and Oncology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Internal Medicine-Hematology and Oncology, University Hospital Brno, Brno, Czech Republic
| | - Lenka Radova
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Vojtech Bystry
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Karol Pal
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic.,Department of Internal Medicine-Hematology and Oncology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Sarka Pospisilova
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic.,Department of Internal Medicine-Hematology and Oncology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Internal Medicine-Hematology and Oncology, University Hospital Brno, Brno, Czech Republic
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25
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Beh TT, Kalitsis P. The Role of Centromere Defects in Cancer. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2019; 56:541-554. [PMID: 28840252 DOI: 10.1007/978-3-319-58592-5_22] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The accurate segregation of chromosomes to daughter cells is essential for healthy development to occur. Imbalances in chromosome number have long been associated with cancers amongst other medical disorders. Little is known whether abnormal chromosome numbers are an early contributor to the cancer progression pathway. Centromere DNA and protein defects are known to impact on the fidelity of chromosome segregation in cell and model systems. In this chapter we discuss recent developments in understanding the contribution of centromere abnormalities at the protein and DNA level and their role in cancer in human and mouse systems.
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Affiliation(s)
- Thian Thian Beh
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Melbourne, 3052, Australia.,Department of Paediatrics, University of Melbourne, Parkville, Melbourne, 3052, Australia
| | - Paul Kalitsis
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Melbourne, 3052, Australia. .,Department of Paediatrics, University of Melbourne, Parkville, Melbourne, 3052, Australia.
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Aygun N, Altungoz O. MYCN is amplified during S phase, and c‑myb is involved in controlling MYCN expression and amplification in MYCN‑amplified neuroblastoma cell lines. Mol Med Rep 2018; 19:345-361. [PMID: 30483774 PMCID: PMC6297758 DOI: 10.3892/mmr.2018.9686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 10/03/2018] [Indexed: 01/08/2023] Open
Abstract
Neuroblastoma derived from primitive sympathetic neural precursors is a common type of solid tumor in infants. MYCN proto-oncogene bHLH transcription factor (MYCN) amplification and 1p36 deletion are important factors associated with the poor prognosis of neuroblastoma. Expression levels of MYCN and c-MYB proto-oncogene transcription factor (c-myb) decline during the differentiation of neuroblastoma cells; E2F transcription factor 1 (E2F1) activates the MYCN promoter. However, the underlying mechanism of MYCN overexpression and amplification requires further investigation. In the present study, potential c-Myb target genes, and the effect of c-myb RNA interference (RNAi) on MYCN expression and amplification were investigated in MYCN-amplified neuroblastoma cell lines. The mRNA expression levels and MYCN gene copy number in five neuroblastoma cell lines were determined by quantitative polymerase chain reaction. In addition, variations in potential target gene expression and MYCN gene copy number between pre- and post-c-myb RNAi treatment groups in MYCN-amplified Kelly, IMR32, SIMA and MHH-NB-11 cell lines, normalized to those of non-MYCN-amplified SH-SY5Y, were examined. To determine the associations between gene expression levels and chromosomal aberrations, MYCN amplification and 1p36 alterations in interphases/metaphases were analyzed using fluorescence in situ hybridization. Statistical analyses revealed correlations between 1p36 alterations and the expression of c-myb, MYB proto-oncogene like 2 (B-myb) and cyclin dependent kinase inhibitor 1A (p21). Additionally, the results of the present study also demonstrated that c-myb may be associated with E2F1 and L3MBTL1 histone methyl-lysine binding protein (L3MBTL1) expression, and that E2F1 may contribute to MYCN, B-myb, p21 and chromatin licensing and DNA replication factor 1 (hCdt1) expression, but to the repression of geminin (GMNN). On c-myb RNAi treatment, L3MBTL1 expression was silenced, while GMNN was upregulated, indicating G2/M arrest. In addition, MYCN gene copy number increased following treatment with c-myb RNAi. Notably, the present study also reported a 43.545% sequence identity between upstream of MYCN and Drosophila melanogaster amplification control element 3, suggesting that expression and/or amplification mechanisms of developmentally-regulated genes may be evolutionarily conserved. In conclusion, c-myb may be associated with regulating MYCN expression and amplification. c-myb, B-myb and p21 may also serve a role against chromosome 1p aberrations. Together, it was concluded that MYCN gene is amplified during S phase, potentially via a replication-based mechanism.
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Affiliation(s)
- Nevim Aygun
- Department of Medical Biology, Faculty of Medicine, Dokuz Eylul University, Izmir 35340, Turkey
| | - Oguz Altungoz
- Department of Medical Biology, Faculty of Medicine, Dokuz Eylul University, Izmir 35340, Turkey
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Gadji M, Pozzo AR. From cellular morphology to molecular and epigenetic anomalies of myelodysplastic syndromes. Genes Chromosomes Cancer 2018; 58:474-483. [PMID: 30303583 DOI: 10.1002/gcc.22689] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 09/27/2018] [Accepted: 09/29/2018] [Indexed: 12/22/2022] Open
Abstract
Myelodysplastic syndromes (MDSs) are a myeloid neoplasm with a propensity for natural evolution or transformation to acute leukemias (AL) over time. Mechanisms for MDS transformation to AL remain poorly understood but are related to genomic instability, which affects the production of the different cell lineages. Genomic instability is also generated by dysfunctional telomeres. Indeed telomeres, the protective ends of chromosomes are the backbone of genome stability. Nuclear telomere remodeling is an early indicator of nuclear remodeling preceding the onset of genomic instability and MDS. This review aims to revisit the pathogenesis and pathophysiology of MDS from morphology and cytogenetics to molecular and epigenetic mechanisms. Furthermore, this review will highlight and discuss recent breakthroughs in dysfunctional telomeres and nuclear telomere architecture roles in the pathogenesis and physiopathology of MDS in the global context of genomic instability.
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Affiliation(s)
- Macoura Gadji
- Department of Physiology and Pathophysiology, University of Manitoba (UfM), Research Institute in Oncology and Hematology (RIOH), CancerCare Manitoba (CCMB), Winnipeg, Manitoba, Canada.,Faculty of Medicine, Pharmacy, and Odontology (FMPO), Service of Hematology, National Centre of Blood Transfusion (CNTS), University Cheikh Anta Diop of Dakar (UCAD), Dakar, Senegal
| | - Aline Rangel Pozzo
- Department of Physiology and Pathophysiology, University of Manitoba (UfM), Research Institute in Oncology and Hematology (RIOH), CancerCare Manitoba (CCMB), Winnipeg, Manitoba, Canada
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28
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Luijten MNH, Lee JXT, Crasta KC. Mutational game changer: Chromothripsis and its emerging relevance to cancer. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 777:29-51. [PMID: 30115429 DOI: 10.1016/j.mrrev.2018.06.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/22/2018] [Accepted: 06/28/2018] [Indexed: 12/14/2022]
Abstract
In recent years, the paradigm that genomic abnormalities in cancer cells arise through progressive accumulation of mutational events has been challenged by the discovery of single catastrophic events. One such phenomenon termed chromothripsis, involving massive chromosomal rearrangements arising all at once, has emerged as a major mutational game changer. The strong interest in this process stems from its widespread association with a range of cancer types and its potential as a mutational driver. In this review, we first describe chromothripsis detection and incidence in cancers. We then explore recently proposed underlying mechanistic origins, which explain the curious observations of the highly localised nature of the rearrangements on chromothriptic chromosomes. Detection of chromothriptic patterns following incorporation of single chromosomes into micronuclei or following telomere attrition have greatly contributed to our understanding of the reasons behind this chromosomal restriction. These underlying cellular events have been found to be participants in the tumourigenic process, strongly suggesting a potential role for chromothripsis in cancer development. Thus, we discuss potential implications of chromothripsis for cancer progression and therapy.
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Affiliation(s)
| | - Jeannie Xue Ting Lee
- Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore.
| | - Karen Carmelina Crasta
- Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore; School of Biological Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore; Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, 61 Biopolis Drive, 138673, Singapore; Department of Medicine, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
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Abstract
The terminal regions of eukaryotic chromosomes, composed of telomere repeat sequences and sub-telomeric sequences, represent some of the most variable and rapidly evolving regions of the genome. The sub-telomeric regions are characterized by segmentally duplicated repetitive DNA elements, interstitial telomere repeat sequences and families of variable genes. Sub-telomeric repeat sequence families are shared among multiple chromosome ends, often rendering detailed sequence characterization difficult. These regions are composed of constitutive heterochromatin and are subjected to high levels of meiotic recombination. Dysfunction within telomere repeat arrays, either due to disruption in the chromatin structure or because of telomere shortening, can lead to chromosomal fusion and the generation of large-scale genomic rearrangements across the genome. The dynamic nature of telomeric regions, therefore, provides functionally useful variation to create genetic diversity, but also provides a mechanism for rapid genomic evolution that can lead to reproductive isolation and speciation. This article is part of the theme issue 'Understanding diversity in telomere dynamics'.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.
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Affiliation(s)
- Duncan M Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
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30
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Telomeres: Implications for Cancer Development. Int J Mol Sci 2018; 19:ijms19010294. [PMID: 29351238 PMCID: PMC5796239 DOI: 10.3390/ijms19010294] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/12/2018] [Accepted: 01/16/2018] [Indexed: 12/31/2022] Open
Abstract
Telomeres facilitate the protection of natural ends of chromosomes from constitutive exposure to the DNA damage response (DDR). This is most likely achieved by a lariat structure that hides the linear telomeric DNA through protein-protein and protein-DNA interactions. The telomere shortening associated with DNA replication in the absence of a compensatory mechanism culminates in unmasked telomeres. Then, the subsequent activation of the DDR will define the fate of cells according to the functionality of cell cycle checkpoints. Dysfunctional telomeres can suppress cancer development by engaging replicative senescence or apoptotic pathways, but they can also promote tumour initiation. Studies in telomere dynamics and karyotype analysis underpin telomere crisis as a key event driving genomic instability. Significant attainment of telomerase or alternative lengthening of telomeres (ALT)-pathway to maintain telomere length may be permissive and required for clonal evolution of genomically-unstable cells during progression to malignancy. We summarise current knowledge of the role of telomeres in the maintenance of chromosomal stability and carcinogenesis.
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Muraki K, Murnane JP. The DNA damage response at dysfunctional telomeres, and at interstitial and subtelomeric DNA double-strand breaks. Genes Genet Syst 2017; 92:135-152. [PMID: 29162774 DOI: 10.1266/ggs.17-00014] [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] [Indexed: 11/23/2022] Open
Abstract
In mammals, DNA double-strand breaks (DSBs) are primarily repaired by classical non-homologous end joining (C-NHEJ), although homologous recombination repair and alternative NHEJ (A-NHEJ), which involve DSB processing, can also occur. These pathways are tightly regulated to maintain chromosome integrity. The ends of chromosomes, called telomeres, contain telomeric DNA that forms a cap structure in cooperation with telomeric proteins to prevent the activation of the DNA damage response and chromosome fusion at chromosome termini. Telomeres and subtelomeric regions are poor substrates for DNA replication; therefore, regions near telomeres are prone to replication fork stalling and chromosome breakage. Moreover, DSBs near telomeres are poorly repaired. As a result, when DSBs occur near telomeres in normal cells, the cells stop proliferating, while in cancer cells, subtelomeric DSBs induce rearrangements due to the absence of cell cycle checkpoints. The sensitivity of subtelomeric regions to DSBs is due to the improper regulation of processing, because although C-NHEJ is functional at subtelomeric DSBs, excessive processing results in an increased frequency of large deletions and chromosome rearrangements involving A-NHEJ.
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Affiliation(s)
- Keiko Muraki
- Institute for Protein Research, Osaka University.,Department of Radiation Oncology, University of California, San Francisco
| | - John P Murnane
- Department of Radiation Oncology, University of California, San Francisco
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32
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Shamim HM, Minami Y, Tanaka D, Ukimori S, Murray JM, Ueno M. Fission yeast strains with circular chromosomes require the 9-1-1 checkpoint complex for the viability in response to the anti-cancer drug 5-fluorodeoxyuridine. PLoS One 2017; 12:e0187775. [PMID: 29121084 PMCID: PMC5679574 DOI: 10.1371/journal.pone.0187775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 10/25/2017] [Indexed: 11/18/2022] Open
Abstract
Thymidine kinase converts 5-fluorodeoxyuridine to 5-fluorodeoxyuridine monophosphate, which causes disruption of deoxynucleotide triphosphate ratios. The fission yeast Schizosaccharomyces pombe does not express endogenous thymidine kinase but 5-fluorodeoxyuridine inhibits growth when exogenous thymidine kinase is expressed. Unexpectedly, we found that 5-fluorodeoxyuridine causes S phase arrest even without thymidine kinase expression. DNA damage checkpoint proteins such as the 9-1-1 complex were required for viability in the presence of 5-fluorodeoxyuridine. We also found that strains with circular chromosomes, due to loss of pot1+, which have higher levels of replication stress, were more sensitive to loss of the 9-1-1 complex in the presence of 5-fluorodeoxyuridine. Thus, our results suggest that strains carrying circular chromosomes exhibit a greater dependence on DNA damage checkpoints to ensure viability in the presence of 5-fluorodeoxyuridine compared to stains that have linear chromosomes.
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Affiliation(s)
- Hossain Mohammad Shamim
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yukako Minami
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Daiki Tanaka
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Shinobu Ukimori
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Johanne M. Murray
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Masaru Ueno
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
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33
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Molecular genetics and cellular events of K-Ras-driven tumorigenesis. Oncogene 2017; 37:839-846. [PMID: 29059163 PMCID: PMC5817384 DOI: 10.1038/onc.2017.377] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 08/11/2017] [Accepted: 09/08/2017] [Indexed: 02/06/2023]
Abstract
Cellular transformation and the accumulation of genomic instability are the two key events required for tumorigenesis. K-Ras (Kirsten-rat sarcoma viral oncogene homolog) is a prominent oncogene that has been proven to drive tumorigenesis. K-Ras also modulates numerous genetic regulatory mechanisms and forms a large tumorigenesis network. In this review, we track the genetic aspects of K-Ras signaling networks and assemble the sequence of cellular events that constitute the tumorigenesis process, such as regulation of K-Ras expression (which is influenced by miRNA, small nucleolar RNA and lncRNA), activation of K-Ras (mutations), generation of reactive oxygen species (ROS), induction of DNA damage and apoptosis, induction of DNA damage repair pathways and ROS detoxification systems, cellular transformation after apoptosis by the blebbishield emergency program and the accumulation of genomic/chromosomal instability that leads to tumorigenesis.
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34
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Maciejowski J, de Lange T. Telomeres in cancer: tumour suppression and genome instability. Nat Rev Mol Cell Biol 2017; 18:175-186. [PMID: 28096526 PMCID: PMC5589191 DOI: 10.1038/nrm.2016.171] [Citation(s) in RCA: 437] [Impact Index Per Article: 62.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The shortening of human telomeres has two opposing effects during cancer development. On the one hand, telomere shortening can exert a tumour-suppressive effect through the proliferation arrest induced by activating the kinases ATM and ATR at unprotected chromosome ends. On the other hand, loss of telomere protection can lead to telomere crisis, which is a state of extensive genome instability that can promote cancer progression. Recent data, reviewed here, provide new evidence for the telomere tumour suppressor pathway and has revealed that telomere crisis can induce numerous cancer-relevant changes, including chromothripsis, kataegis and tetraploidization.
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Affiliation(s)
- John Maciejowski
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
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35
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Janson C, Nyhan K, Murnane JP. Replication Stress and Telomere Dysfunction Are Present in Cultured Human Embryonic Stem Cells. Cytogenet Genome Res 2015; 146:251-60. [PMID: 26517359 DOI: 10.1159/000441245] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Indexed: 11/19/2022] Open
Abstract
Replication stress causes DNA damage at fragile sites in the genome. DNA damage at telomeres can initiate breakage-fusion-bridge cycles and chromosome instability, which can result in replicative senescence or tumor formation. Little is known about the extent of replication stress or telomere dysfunction in human embryonic stem cells (hESCs). hESCs are grown in culture with the expectation of being used therapeutically in humans, making it important to minimize the levels of replication stress and telomere dysfunction. Here, the hESC line UCSF4 was cultured in a defined medium with growth factor Activin A, exogenous nucleosides, or DNA polymerase inhibitor aphidicolin. We used quantitative fluorescence in situ hybridization to analyze individual telomeres for dysfunction and observed that it can be increased by aphidicolin or Activin A. In contrast, adding exogenous nucleosides relieved dysfunction, suggesting that telomere dysfunction results from replication stress. Whether these findings can be applied to other hESC lines remains to be determined. However, because the loss of telomeres can lead to chromosome instability and cancer, we conclude that hESCs grown in culture for future therapeutic purposes should be routinely checked for replication stress and telomere dysfunction.
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Affiliation(s)
- Christine Janson
- Department of Radiation Oncology, University of California San Francisco, San Francisco, Calif., USA
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36
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Russo A, Pacchierotti F, Cimini D, Ganem NJ, Genescà A, Natarajan AT, Pavanello S, Valle G, Degrassi F. Genomic instability: Crossing pathways at the origin of structural and numerical chromosome changes. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:563-580. [PMID: 25784636 DOI: 10.1002/em.21945] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 02/02/2015] [Accepted: 02/19/2015] [Indexed: 06/04/2023]
Abstract
Genomic instability leads to a wide spectrum of genetic changes, including single nucleotide mutations, structural chromosome alterations, and numerical chromosome changes. The accepted view on how these events are generated predicts that separate cellular mechanisms and genetic events explain the occurrence of these types of genetic variation. Recently, new findings have shed light on the complexity of the mechanisms leading to structural and numerical chromosome aberrations, their intertwining pathways, and their dynamic evolution, in somatic as well as in germ cells. In this review, we present a critical analysis of these recent discoveries in this area, with the aim to contribute to a deeper knowledge of the molecular networks leading to adverse outcomes in humans following exposure to environmental factors. The review illustrates how several technological advances, including DNA sequencing methods, bioinformatics, and live-cell imaging approaches, have contributed to produce a renewed concept of the mechanisms causing genomic instability. Special attention is also given to the specific pathways causing genomic instability in mammalian germ cells. Remarkably, the same scenario emerged from some pioneering studies published in the 1980s to 1990s, when the evolution of polyploidy, the chromosomal effects of spindle poisons, the fate of micronuclei, were intuitively proposed to share mechanisms and pathways. Thus, an old working hypothesis has eventually found proper validation.
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Affiliation(s)
| | - Francesca Pacchierotti
- Laboratory of Toxicology, Unit of Radiation Biology and Human Health, ENEA CR Casaccia, Rome, Italy
| | - Daniela Cimini
- Department of Biological Sciences and Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia
| | - Neil J Ganem
- Department of Pharmacology, Division of Hematology and Oncology, Boston University School of Medicine, Boston, Massachusetts
| | - Anna Genescà
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | | | - Sofia Pavanello
- Department of Cardiac, Thoracic and Vascular Sciences, Unit of Occupational Medicine, University of Padova, Italy
| | - Giorgio Valle
- Department of Biology, University of Padova, Padova, Italy
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Lee SL, Thomas P, Fenech M. Genome instability biomarkers and blood micronutrient risk profiles associated with mild cognitive impairment and Alzheimer's disease. Mutat Res 2015; 776:54-83. [PMID: 26364206 DOI: 10.1016/j.mrfmmm.2014.12.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 12/06/2014] [Accepted: 12/30/2014] [Indexed: 12/13/2022]
Abstract
Successful maintenance of metabolic systems relating to accurate DNA replication and repair is critical for optimal lifelong human health. Should this homeostatic balance become impaired, genomic instability events can arise, compromising the integrity of the genome, which may result in gene expression and human disease. Both genome instability and micronutrient imbalance have been identified and implicated in diseases associated with accelerated ageing which potentially leads to an increased risk for the future development of clinically defined neurodegenerative disorders. Cognitive decline leading to the clinical diagnosis of mild cognitive impairment (MCI) has been shown to predict an increased risk in later life of developing Alzheimer's disease (AD). Knowledge on the impact of dietary factors in relation to MCI and AD risk is improving but incomplete; in particular the role of nutrient combinations (i.e. nutriomes) has not been thoroughly investigated. Currently, there is a need for preventative strategies as well as the identification of robust and reproducible diagnostic biomarkers that will allow identification of those individuals with increased risk for neurodegenerative diseases. Growing evidence suggests cells originating from different somatic tissues derived from individuals that have been clinically diagnosed with neurodegenerative disorders exhibit elevated frequencies of DNA damage compared to tissues of cognitively normal individuals which could be due to malnutrition. The objective of this review is to discuss current evidence and identify knowledge gaps relating to genome instability biomarkers and blood micronutrient profiles from human studies of MCI and AD that may be specific to and contribute to the increased risk of these diseases. This is a vital step in order to create research strategies for the future development of diagnostics that are indicative of dementia risk and to inform preventative therapies.
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Affiliation(s)
- Sau Lai Lee
- Commonwealth Scientific and Industrial Research Organisation, Animal, Food, and Health Sciences, PO Box 10041, Adelaide BC, Adelaide, SA 5000, Australia; Discipline of Physiology, School of Medical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia.
| | - Philip Thomas
- Commonwealth Scientific and Industrial Research Organisation, Animal, Food, and Health Sciences, PO Box 10041, Adelaide BC, Adelaide, SA 5000, Australia
| | - Michael Fenech
- Commonwealth Scientific and Industrial Research Organisation, Animal, Food, and Health Sciences, PO Box 10041, Adelaide BC, Adelaide, SA 5000, Australia.
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38
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Meng X, Qi X, Guo H, Cai M, Li C, Zhu J, Chen F, Guo H, Li J, Zhao Y, Liu P, Jia X, Yu J, Zhang C, Sun W, Yu Y, Jin Y, Bai J, Wang M, Rosales J, Lee KY, Fu S. Novel role for non-homologous end joining in the formation of double minutes in methotrexate-resistant colon cancer cells. J Med Genet 2014; 52:135-44. [PMID: 25537274 PMCID: PMC4316941 DOI: 10.1136/jmedgenet-2014-102703] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Background Gene amplification is a frequent manifestation of genomic instability that plays a role in tumour progression and development of drug resistance. It is manifested cytogenetically as extrachromosomal double minutes (DMs) or intrachromosomal homogeneously staining regions (HSRs). To better understand the molecular mechanism by which HSRs and DMs are formed and how they relate to the development of methotrexate (MTX) resistance, we used two model systems of MTX-resistant HT-29 colon cancer cell lines harbouring amplified DHFR primarily in (i) HSRs and (ii) DMs. Results In DM-containing cells, we found increased expression of non-homologous end joining (NHEJ) proteins. Depletion or inhibition of DNA-PKcs, a key NHEJ protein, caused decreased DHFR amplification, disappearance of DMs, increased formation of micronuclei or nuclear buds, which correlated with the elimination of DHFR, and increased sensitivity to MTX. These findings indicate for the first time that NHEJ plays a specific role in DM formation, and that increased MTX sensitivity of DM-containing cells depleted of DNA-PKcs results from DHFR elimination. Conversely, in HSR-containing cells, we found no significant change in the expression of NHEJ proteins. Depletion of DNA-PKcs had no effect on DHFR amplification and resulted in only a modest increase in sensitivity to MTX. Interestingly, both DM-containing and HSR-containing cells exhibited decreased proliferation upon DNA-PKcs depletion. Conclusions We demonstrate a novel specific role for NHEJ in the formation of DMs, but not HSRs, in MTX-resistant cells, and that NHEJ may be targeted for the treatment of MTX-resistant colon cancer.
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Affiliation(s)
- Xiangning Meng
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Xiuying Qi
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Huanhuan Guo
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Mengdi Cai
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Chunxiang Li
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Jing Zhu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Feng Chen
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Huan Guo
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Jie Li
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Yuzhen Zhao
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Peng Liu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Xueyuan Jia
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Jingcui Yu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Chunyu Zhang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Wenjing Sun
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Yang Yu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Yan Jin
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China Key Laboratory of Medical Genetics (Harbin Medical University), Heilongjiang Higher Education Institutions, Harbin, China
| | - Jing Bai
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Mingrong Wang
- State Key Laboratory of Molecular Oncology, Cancer Institute (Hospital), Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Jesusa Rosales
- Departments of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
| | - Ki-Young Lee
- Cell Biology & Anatomy, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Songbin Fu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China Key Laboratory of Medical Genetics (Harbin Medical University), Heilongjiang Higher Education Institutions, Harbin, China
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Garsed DW, Marshall OJ, Corbin VDA, Hsu A, Di Stefano L, Schröder J, Li J, Feng ZP, Kim BW, Kowarsky M, Lansdell B, Brookwell R, Myklebost O, Meza-Zepeda L, Holloway AJ, Pedeutour F, Choo KHA, Damore MA, Deans AJ, Papenfuss AT, Thomas DM. The architecture and evolution of cancer neochromosomes. Cancer Cell 2014; 26:653-67. [PMID: 25517748 DOI: 10.1016/j.ccell.2014.09.010] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 05/15/2014] [Accepted: 09/19/2014] [Indexed: 01/21/2023]
Abstract
We isolated and analyzed, at single-nucleotide resolution, cancer-associated neochromosomes from well- and/or dedifferentiated liposarcomas. Neochromosomes, which can exceed 600 Mb in size, initially arise as circular structures following chromothripsis involving chromosome 12. The core of the neochromosome is amplified, rearranged, and corroded through hundreds of breakage-fusion-bridge cycles. Under selective pressure, amplified oncogenes are overexpressed, while coamplified passenger genes may be silenced epigenetically. New material may be captured during punctuated chromothriptic events. Centromeric corrosion leads to crisis, which is resolved through neocentromere formation or native centromere capture. Finally, amplification terminates, and the neochromosome core is stabilized in linear form by telomere capture. This study investigates the dynamic mutational processes underlying the life history of a special form of cancer mutation.
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Affiliation(s)
- Dale W Garsed
- Cancer Genomics, Peter MacCallum Cancer Centre, East Melbourne, VIC 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, VIC 3010, Australia; Department of Pathology, University of Melbourne, VIC 3010, Australia
| | - Owen J Marshall
- Chromosome Research, Murdoch Childrens Research Institute, and Department of Paediatrics, Royal Children's Hospital, University of Melbourne, Parkville, VIC 3052, Australia
| | - Vincent D A Corbin
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, VIC 3010, Australia; Bioinformatics and Cancer Genomics, Peter MacCallum Cancer Centre, East Melbourne, VIC, 3002, Australia
| | - Arthur Hsu
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Leon Di Stefano
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Jan Schröder
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, VIC 3010, Australia
| | - Jason Li
- Cancer Genomics, Peter MacCallum Cancer Centre, East Melbourne, VIC 3002, Australia
| | - Zhi-Ping Feng
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, VIC 3010, Australia
| | - Bo W Kim
- Chromosome Research, Murdoch Childrens Research Institute, and Department of Paediatrics, Royal Children's Hospital, University of Melbourne, Parkville, VIC 3052, Australia
| | - Mark Kowarsky
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Ben Lansdell
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Ross Brookwell
- Sullivan Nicolaides Pathology, Indooroopilly, QLD 4068, Australia
| | - Ola Myklebost
- Department of Tumor Biology, Oslo University Hospital, Norwegian Radium Hospital, Oslo 0424, Norway
| | - Leonardo Meza-Zepeda
- Department of Tumor Biology, Oslo University Hospital, Norwegian Radium Hospital, Oslo 0424, Norway
| | - Andrew J Holloway
- Cancer Genomics, Peter MacCallum Cancer Centre, East Melbourne, VIC 3002, Australia
| | - Florence Pedeutour
- Laboratory of Solid Tumors Genetics, Nice University Hospital, Nice 06107, France
| | - K H Andy Choo
- Chromosome Research, Murdoch Childrens Research Institute, and Department of Paediatrics, Royal Children's Hospital, University of Melbourne, Parkville, VIC 3052, Australia
| | | | | | - Anthony T Papenfuss
- Bioinformatics Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, VIC 3010, Australia; Department of Mathematics and Statistics, University of Melbourne, VIC, 3010, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, VIC 3010, Australia; Bioinformatics and Cancer Genomics, Peter MacCallum Cancer Centre, East Melbourne, VIC, 3002, Australia.
| | - David M Thomas
- Cancer Genomics, Peter MacCallum Cancer Centre, East Melbourne, VIC 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, VIC 3010, Australia; The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia.
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Jones RE, Oh S, Grimstead JW, Zimbric J, Roger L, Heppel NH, Ashelford KE, Liddiard K, Hendrickson EA, Baird DM. Escape from telomere-driven crisis is DNA ligase III dependent. Cell Rep 2014; 8:1063-76. [PMID: 25127141 DOI: 10.1016/j.celrep.2014.07.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/28/2014] [Accepted: 07/10/2014] [Indexed: 12/27/2022] Open
Abstract
Short dysfunctional telomeres are capable of fusion, generating dicentric chromosomes and initiating breakage-fusion-bridge cycles. Cells that escape the ensuing cellular crisis exhibit large-scale genomic rearrangements that drive clonal evolution and malignant progression. We demonstrate that there is an absolute requirement for fully functional DNA ligase III (LIG3), but not ligase IV (LIG4), to facilitate the escape from a telomere-driven crisis. LIG3- and LIG4-dependent alternative (A) and classical (C) nonhomologous end-joining (NHEJ) pathways were capable of mediating the fusion of short dysfunctional telomeres, both displaying characteristic patterns of microhomology and deletion. Cells that failed to escape crisis exhibited increased proportions of C-NHEJ-mediated interchromosomal fusions, whereas those that escaped displayed increased proportions of intrachromosomal fusions. We propose that the balance between inter- and intrachromosomal telomere fusions dictates the ability of human cells to escape crisis and is influenced by the relative activities of A- and C-NHEJ at short dysfunctional telomeres.
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Affiliation(s)
- Rhiannon E Jones
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Sehyun Oh
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Julia W Grimstead
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Jacob Zimbric
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Laureline Roger
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Nicole H Heppel
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kevin E Ashelford
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kate Liddiard
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Duncan M Baird
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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Friis-Ottessen M, De Angelis PM, Schjølberg AR, Andersen SN, Clausen OPF. Reduced hTERT protein levels are associated with DNA aneuploidy in the colonic mucosa of patients suffering from longstanding ulcerative colitis. Int J Mol Med 2014; 33:1477-83. [PMID: 24676865 PMCID: PMC4055619 DOI: 10.3892/ijmm.2014.1708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 02/24/2014] [Indexed: 12/24/2022] Open
Abstract
Longstanding ulcerative colitis (UC) is a disease of chronic inflammation of the colon. It is associated with the development of colorectal cancer through a multistep process including increasing degrees of dysplasia and DNA-ploidy changes. However, not all UC patients will develop these characteristics even during lifelong disease, and patients may therefore be divided into progressors who develop dysplasia or cancer, and non-progressors who do not exhibit such changes. In the present study, the amount of hTERT, the catalytic subunit of the enzyme telomerase, was estimated by using peroxidase immunohistochemistry (IHC) in a set of progressor and non-progressor UC colectomies. The protein levels in the colonic mucosa of the progressors and non-progressors were compared, and further comparisons between different categories of dysplastic development and to DNA-ploidy status within the progressors were made. Levels of hTERT were elevated in the colonic mucosa of the progressors and non-progressors when compared to non-UC control samples, but no difference was observed between the hTERT levels in the mucosa of progressors and non-progressors. The levels of hTERT associated with levels of Ki67 to a significant degree within the non-progressors. hTERT expression in lesions with DNA-aneuploidy were decreased as compared to diploid lesions, when stratified for different classes of colonic morphology. Our results indicate an association between hTERT protein expression and aneuploidy in UC-progressor colons, and also a possible protective mechanism in the association between hTERT and Ki67, against development of malignant features within the mucosa of a UC-colon.
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Affiliation(s)
- Mariann Friis-Ottessen
- Division of Diagnostics and Intervention, Department of Pathology, Oslo University Hospital, Rikshospitalet, 0424 Oslo, Norway
| | - Paula M De Angelis
- Division of Diagnostics and Intervention, Department of Pathology, Oslo University Hospital, Rikshospitalet, 0424 Oslo, Norway
| | | | - Solveig N Andersen
- Department of Pathology, Akershus University Hospital, Division of Medicine and Laboratory Sciences, University of Oslo, 1474 Nordbyhagen, Norway
| | - Ole Petter F Clausen
- Division of Diagnostics and Intervention, Department of Pathology, Oslo University Hospital, Rikshospitalet, 0424 Oslo, Norway
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Chung L, Onyango D, Guo Z, Jia P, Dai H, Liu S, Zhou M, Lin W, Pang I, Li H, Yuan YC, Huang Q, Zheng L, Lopes J, Nicolas A, Chai W, Raz D, Reckamp KL, Shen B. The FEN1 E359K germline mutation disrupts the FEN1-WRN interaction and FEN1 GEN activity, causing aneuploidy-associated cancers. Oncogene 2014; 34:902-11. [PMID: 24608430 PMCID: PMC4160428 DOI: 10.1038/onc.2014.19] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/18/2013] [Accepted: 12/20/2013] [Indexed: 02/02/2023]
Abstract
Polymorphisms and somatic mutations in Flap Endonuclease 1 (FEN1), an essential enzyme involved in DNA replication and repair, can lead to functional deficiencies of the FEN1 protein and a predisposition to cancer. We identified a FEN1 germline mutation which changed residue E359 to K in a patient whose family had a history of breast cancer. We determined that the E359K mutation, which is in the protein-protein domain of FEN1, abolished the interaction of FEN1 with Werner Syndrome protein (WRN), an interaction which is critical for resolving stalled DNA replication forks. Furthermore, although the flap endonuclease activity of FEN1 E359K was unaffected, it failed to resolve bubble structures, which requires the FEN1 gap dependent endonuclease (GEN) activity. To determine the etiological significance of E359K, we established a mouse model containing this mutation. E359K mouse embryonic fibroblasts (MEF) were more sensitive to DNA cross-linking agents that cause replication forks to stall. Cytological analysis suggested that the FEN1-WRN interaction was also required to for telomere stability; mutant cell lines had fragile telomeres, increased numbers of spontaneous chromosomal anomalies and higher frequencies of transformation. Moreover, the incidence of cancer was significantly higher in mice homozygous for FEN1 E359K than in wild-type mice, suggesting that the FEN1 E359K mutation is oncogenic.
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Affiliation(s)
- L Chung
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - D Onyango
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - Z Guo
- 1] Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA [2] Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - P Jia
- WWAMI Medical Education Program, School of Molecular Biosciences, Washington State University, Spokane, WA, USA
| | - H Dai
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - S Liu
- 1] Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA [2] College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - M Zhou
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - W Lin
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - I Pang
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - H Li
- Department of Molecular Medicine, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - Y-C Yuan
- Department of Molecular Medicine, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - Q Huang
- Department of Pathology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - L Zheng
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - J Lopes
- 1] Section de Recherche, Institut Curie, CNRS UMR3244, Paris, France [2] Muséum National d'Histoire Naturelle, USM 503, INSERM U565, UMR7196, Paris, France
| | - A Nicolas
- Section de Recherche, Institut Curie, CNRS UMR3244, Paris, France
| | - W Chai
- WWAMI Medical Education Program, School of Molecular Biosciences, Washington State University, Spokane, WA, USA
| | - D Raz
- Department of Surgery, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - K L Reckamp
- Department of Medical Oncology and Therapeutics Research, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - B Shen
- Department of Radiation Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
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Abstract
Genomic instability is a characteristic of most cancer cells. It is an increased tendency of genome alteration during cell division. Cancer frequently results from damage to multiple genes controlling cell division and tumor suppressors. It is known that genomic integrity is closely monitored by several surveillance mechanisms, DNA damage checkpoint, DNA repair machinery and mitotic checkpoint. A defect in the regulation of any of these mechanisms often results in genomic instability, which predisposes the cell to malignant transformation. Posttranslational modifications of the histone tails are closely associated with regulation of the cell cycle as well as chromatin structure. Nevertheless, DNA methylation status is also related to genomic integrity. We attempt to summarize recent developments in this field and discuss the debate of driving force of tumor initiation and progression.
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Affiliation(s)
- Yixin Yao
- Department of Environmental Medicine, New York University Langone Medical Center, Tuxedo, New York, 10987, USA
| | - Wei Dai
- Department of Environmental Medicine, New York University Langone Medical Center, Tuxedo, New York, 10987, USA. ; Department of Biochemistry and Molecular Pharmacology, New York University Langone Medical Center, Tuxedo, New York, 10987, USA
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44
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Pottier G, Viau M, Ricoul M, Shim G, Bellamy M, Cuceu C, Hempel WM, Sabatier L. Lead Exposure Induces Telomere Instability in Human Cells. PLoS One 2013; 8:e67501. [PMID: 23840724 PMCID: PMC3694068 DOI: 10.1371/journal.pone.0067501] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 05/20/2013] [Indexed: 12/31/2022] Open
Abstract
Lead (Pb) is an important environmental contaminant due to its widespread use over many centuries. While it affects primarily every organ system of the body, the most pernicious effects of Pb are on the central nervous system leading to cognitive and behavioral modification. Despite decades of research, the mechanisms responsible for Pb toxicity remain poorly understood. Recent work has suggested that Pb exposure may have consequences on chromosomal integrity as it was shown that Pb exposure leads to the generation of γH2Ax foci, a well-established biomarker for DNA double stranded break (DSB formation). As the chromosomal localization of γH2Ax foci plays an important role in determining the molecular mechanism responsible for their formation, we examined the localization of Pb-induced foci with respect to telomeres. Indeed, short or dysfunctional telomeres (uncapped or damaged telomeres) may be recognized as DSB by the DNA repair machinery, leading to “telomere-Induced Foci” (TIFs). In the current study, we show that while Pb exposure did not increase intra-chromosomal foci, it significantly induced TIFs, leading in some cases, to chromosomal abnormalities including telomere loss. The evidence suggests that these chromosomal abnormalities are likely due to perturbation of telomere replication, in particular on the lagging DNA strand. We propose a mechanism by which Pb exposure leads to the loss of telomere maintenance. As numerous studies have demonstrated a role for telomere maintenance in brain development and tissue homeostasis, our results suggest a possible mechanism for lead-induced neurotoxicity.
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Affiliation(s)
- Géraldine Pottier
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
| | - Muriel Viau
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
| | - Michelle Ricoul
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
| | - Grace Shim
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
| | - Marion Bellamy
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
| | - Corina Cuceu
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
| | - William M. Hempel
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
| | - Laure Sabatier
- Commissariat à l’Energie Atomique (CEA), Laboratoire de Radiobiologie et Oncologie (LRO), Fontenay-aux-Roses, France
- * E-mail:
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Sorzano COS, Pascual-Montano A, Sánchez de Diego A, Martínez-A C, van Wely KHM. Chromothripsis: breakage-fusion-bridge over and over again. Cell Cycle 2013; 12:2016-23. [PMID: 23759584 DOI: 10.4161/cc.25266] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The acquisition of massive but localized chromosome translocations, a phenomenon termed chromothripsis, has received widespread attention since its discovery over a year ago. Until recently, chromothripsis was believed to originate from a single catastrophic event, but the molecular mechanisms leading to this event are yet to be uncovered. Because a thorough interpretation of the data are missing, the phenomenon itself has wrongly acquired the status of a mechanism used to justify many kinds of complex rearrangements. Although the assumption that all translocations in chromothripsis originate from a single event has met with criticism, satisfactory explanations for the intense but localized nature of this phenomenon are still missing. Here, we show why the data used to describe massive catastrophic rearrangements are incompatible with a model comprising a single event only and propose a molecular mechanism in which a combination of known cellular pathways accounts for chromothripsis. Instead of a single traumatic event, the protection of undamaged chromosomes by telomeres can limit repetitive breakage-fusion-bridge events to a single chromosome arm. Ultimately, common properties of chromosomal instability, such as aneuploidy and centromere fission, might establish the complex genetic pattern observed in this genomic state.
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46
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Nieri D, Berardinelli F, Sgura A, Cherubini R, De Nadal V, Gerardi S, Tanzarella C, Antoccia A. Cyogenetics effects in AG01522 human primary fibroblasts exposed to low doses of radiations with different quality. Int J Radiat Biol 2013; 89:698-707. [DOI: 10.3109/09553002.2013.797126] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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The role of ATM in the deficiency in nonhomologous end-joining near telomeres in a human cancer cell line. PLoS Genet 2013; 9:e1003386. [PMID: 23555296 PMCID: PMC3610639 DOI: 10.1371/journal.pgen.1003386] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 01/28/2013] [Indexed: 11/19/2022] Open
Abstract
Telomeres distinguish chromosome ends from double-strand breaks (DSBs) and prevent chromosome fusion. However, telomeres can also interfere with DNA repair, as shown by a deficiency in nonhomologous end joining (NHEJ) and an increase in large deletions at telomeric DSBs. The sensitivity of telomeric regions to DSBs is important in the cellular response to ionizing radiation and oncogene-induced replication stress, either by preventing cell division in normal cells, or by promoting chromosome instability in cancer cells. We have previously proposed that the telomeric protein TRF2 causes the sensitivity of telomeric regions to DSBs, either through its inhibition of ATM, or by promoting the processing of DSBs as though they are telomeres, which is independent of ATM. Our current study addresses the mechanism responsible for the deficiency in repair of DSBs near telomeres by combining assays for large deletions, NHEJ, small deletions, and gross chromosome rearrangements (GCRs) to compare the types of events resulting from DSBs at interstitial and telomeric DSBs. Our results confirm the sensitivity of telomeric regions to DSBs by demonstrating that the frequency of GCRs is greatly increased at DSBs near telomeres and that the role of ATM in DSB repair is very different at interstitial and telomeric DSBs. Unlike at interstitial DSBs, a deficiency in ATM decreases NHEJ and small deletions at telomeric DSBs, while it increases large deletions. These results strongly suggest that ATM is functional near telomeres and is involved in end protection at telomeric DSBs, but is not required for the extensive resection at telomeric DSBs. The results support our model in which the deficiency in DSB repair near telomeres is a result of ATM-independent processing of DSBs as though they are telomeres, leading to extensive resection, telomere loss, and GCRs involving alternative NHEJ.
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Marotta M, Chen X, Inoshita A, Stephens R, Budd GT, Crowe JP, Lyons J, Kondratova A, Tubbs R, Tanaka H. A common copy-number breakpoint of ERBB2 amplification in breast cancer colocalizes with a complex block of segmental duplications. Breast Cancer Res 2012. [PMID: 23181561 PMCID: PMC4053137 DOI: 10.1186/bcr3362] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Introduction Segmental duplications (low-copy repeats) are the recently duplicated genomic segments in the human genome that display nearly identical (> 90%) sequences and account for about 5% of euchromatic regions. In germline, duplicated segments mediate nonallelic homologous recombination and thus cause both non-disease-causing copy-number variants and genomic disorders. To what extent duplicated segments play a role in somatic DNA rearrangements in cancer remains elusive. Duplicated segments often cluster and form genomic blocks enriched with both direct and inverted repeats (complex genomic regions). Such complex regions could be fragile and play a mechanistic role in the amplification of the ERBB2 gene in breast tumors, because repeated sequences are known to initiate gene amplification in model systems. Methods We conducted polymerase chain reaction (PCR)-based assays for primary breast tumors and analyzed publically available array-comparative genomic hybridization data to map a common copy-number breakpoint in ERBB2-amplified primary breast tumors. We further used molecular, bioinformatics, and population-genetics approaches to define duplication contents, structural variants, and haplotypes within the common breakpoint. Results We found a large (> 300-kb) block of duplicated segments that was colocalized with a common-copy number breakpoint for ERBB2 amplification. The breakpoint that potentially initiated ERBB2 amplification localized in a region 1.5 megabases (Mb) on the telomeric side of ERBB2. The region is very complex, with extensive duplications of KRTAP genes, structural variants, and, as a result, a paucity of single-nucleotide polymorphism (SNP) markers. Duplicated segments are varied in size and degree of sequence homology, indicating that duplications have occurred recurrently during genome evolution. Conclusions Amplification of the ERBB2 gene in breast tumors is potentially initiated by a complex region that has unusual genomic features and thus requires rigorous, labor-intensive investigation. The haplotypes we provide could be useful to identify the potential association between the complex region and ERBB2 amplification.
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Muraki K, Nyhan K, Han L, Murnane JP. Mechanisms of telomere loss and their consequences for chromosome instability. Front Oncol 2012; 2:135. [PMID: 23061048 PMCID: PMC3463808 DOI: 10.3389/fonc.2012.00135] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 09/19/2012] [Indexed: 12/17/2022] Open
Abstract
The ends of chromosomes in mammals, called telomeres, are composed of a 6-bp repeat sequence, TTAGGG, which is added on by the enzyme telomerase. In combination with a protein complex called shelterin, these telomeric repeat sequences form a cap that protects the ends of chromosomes. Due to insufficient telomerase expression, telomeres shorten gradually with each cell division in human somatic cells, which limits the number of times they can divide. The extensive cell division involved in cancer cell progression therefore requires that cancer cells must acquire the ability to maintain telomeres, either through expression of telomerase, or through an alternative mechanism involving recombination. It is commonly thought that the source of many chromosome rearrangements in cancer cells is a result of the extensive telomere shortening that occurs prior to the expression of telomerase. However, despite the expression of telomerase, tumor cells can continue to show chromosome instability due to telomere loss. Dysfunctional telomeres in cancer cells can result from oncogene-induced replication stress, which results in double-strand breaks (DSBs) at fragile sites, including telomeres. DSBs near telomeres are especially prone to chromosome rearrangements, because telomeric regions are deficient in DSB repair. The deficiency in DSB repair near telomeres is also an important mechanism for ionizing radiation-induced replicative senescence in normal human cells. In addition, DSBs near telomeres can result in chromosome instability in mouse embryonic stem cells, suggesting that telomere loss can contribute to heritable chromosome rearrangements. Consistent with this possibility, telomeric regions in humans are highly heterogeneous, and chromosome rearrangements near telomeres are commonly involved in human genetic disease. Understanding the mechanisms of telomere loss will therefore provide important insights into both human cancer and genetic disease.
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Affiliation(s)
- Keiko Muraki
- Department of Radiation Oncology, University of California at San Francisco San Francisco, CA, USA
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50
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Zahnreich S, Krunic D, Melnikova L, Szejka A, Drossel B, Sabatier L, Durante M, Ritter S, Fournier C. Duplicated chromosomal fragments stabilize shortened telomeres in normal human IMR-90 cells before transition to senescence. J Cell Physiol 2012; 227:1932-40. [PMID: 21732364 DOI: 10.1002/jcp.22921] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To assess why during in vitro aging of fibroblasts the maintenance of chromosomal stability is effective or occasionally fails, a detailed cytogenetic analysis was performed in normal human IMR-90 fetal lung fibroblasts. The onset of senescence was inferred from proliferation activity, expression pattern of cell cycle regulating proteins, activity of β-galactosidase, and morphological features. Over the period of proliferation, a moderate increase of non-transmissible structural chromosomal aberrations was observed. In addition, using fluorescence in situ hybridization (mFISH and mBAND) techniques, we detected clonally expanding translocations in up to 70% of the analyzed metaphases, all involving one homolog of chromosome 9 as an acceptor. Notably, chromosomes are randomly involved as donor-chromosomes of the translocated terminal acentric fragments. These fragments result from duplication because the donor chromosomes are apparently unchanged. Interstitial telomeric signals were detectable at fusion sites, most likely belonging to chromosome 9. Quantitative fluorescence in situ hybridization (QFISH) detecting telomere sequences, followed by mFISH technique revealed that already in young cells the respective telomeres of one chromosome 9 were particularly short. For the first time, we have observed dysfunctional telomeres of one specific chromosome in normal human cells that have been stabilized by duplicated terminal sequences.
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Affiliation(s)
- Sebastian Zahnreich
- Biophysics Department, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
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