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Impact of G-Quadruplexes and Chronic Inflammation on Genome Instability: Additive Effects during Carcinogenesis. Genes (Basel) 2021; 12:genes12111779. [PMID: 34828385 PMCID: PMC8619830 DOI: 10.3390/genes12111779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 02/07/2023] Open
Abstract
Genome instability is an enabling characteristic of cancer, essential for cancer cell evolution. Hotspots of genome instability, from small-scale point mutations to large-scale structural variants, are associated with sequences that potentially form non-B DNA structures. G-quadruplex (G4) forming motifs are enriched at structural variant endpoints in cancer genomes. Chronic inflammation is a physiological state underlying cancer development, and oxidative DNA damage is commonly invoked to explain how inflammation promotes genome instability. We summarize where G4s and oxidative stress overlap, with a focus on DNA replication. Guanine has low ionization potential, making G4s vulnerable to oxidative damage. Impacts to G4 structure are dependent upon lesion type, location, and G4 conformation. Occasionally, G4s pose a challenge to replicative DNA polymerases, requiring specialized DNA polymerases to maintain genome stability. Therefore, chronic inflammation creates a dual challenge for DNA polymerases to maintain genome stability: faithful G4 synthesis and bypassing unrepaired oxidative lesions. Inflammation is also accompanied by global transcriptome changes that may impact mutagenesis. Several studies suggest a regulatory role for G4s within cancer- and inflammatory-related gene promoters. We discuss the extent to which inflammation could influence gene regulation by G4s, thereby impacting genome instability, and highlight key areas for new investigation.
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52
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Zell J, Duskova K, Chouh L, Bossaert M, Chéron N, Granzhan A, Britton S, Monchaud D. Dual targeting of higher-order DNA structures by azacryptands induces DNA junction-mediated DNA damage in cancer cells. Nucleic Acids Res 2021; 49:10275-10288. [PMID: 34551430 PMCID: PMC8501980 DOI: 10.1093/nar/gkab796] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 08/16/2021] [Accepted: 09/01/2021] [Indexed: 12/11/2022] Open
Abstract
DNA is intrinsically dynamic and folds transiently into alternative higher-order structures such as G-quadruplexes (G4s) and three-way DNA junctions (TWJs). G4s and TWJs can be stabilised by small molecules (ligands) that have high chemotherapeutic potential, either as standalone DNA damaging agents or combined in synthetic lethality strategies. While previous approaches have claimed to use ligands that specifically target either G4s or TWJs, we report here on a new approach in which ligands targeting both TWJs and G4s in vitro demonstrate cellular effects distinct from that of G4 ligands, and attributable to TWJ targeting. The DNA binding modes of these new, dual TWJ-/G4-ligands were studied by a panel of in vitro methods and theoretical simulations, and their cellular properties by extensive cell-based assays. We show here that cytotoxic activity of TWJ-/G4-ligands is mitigated by the DNA damage response (DDR) and DNA topoisomerase 2 (TOP2), making them different from typical G4-ligands, and implying a pivotal role of TWJs in cells. We designed and used a clickable ligand, TrisNP-α, to provide unique insights into the TWJ landscape in cells and its modulation upon co-treatments. This wealth of data was exploited to design an efficient synthetic lethality strategy combining dual ligands with clinically relevant DDR inhibitors.
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Affiliation(s)
- Joanna Zell
- Institut de Chimie Moléculaire de l’Université de Bourgogne (ICMUB), CNRS UMR 6302, UBFC Dijon, 21078 Dijon, France
| | - Katerina Duskova
- Institut de Chimie Moléculaire de l’Université de Bourgogne (ICMUB), CNRS UMR 6302, UBFC Dijon, 21078 Dijon, France
| | - Leïla Chouh
- Institut Curie, CNRS UMR 9187, INSERM U1196, PSL Research University, 91405 Orsay, France
- Université Paris Saclay, CNRS UMR 9187, INSERM U1196, 91405 Orsay, France
| | - Madeleine Bossaert
- Institut de Pharmacologie et de Biologie Structurale (IPBS), CNRS UMR 5089, Université de Toulouse, UPS, Équipe labellisée la Ligue Contre le Cancer, 31077 Toulouse, France
| | - Nicolas Chéron
- Pasteur, Département de chimie, École Normale Supérieure (ENS), CNRS UMR8640, PSL Research University, Sorbonne Université, 75005 Paris, France
| | - Anton Granzhan
- Institut Curie, CNRS UMR 9187, INSERM U1196, PSL Research University, 91405 Orsay, France
- Université Paris Saclay, CNRS UMR 9187, INSERM U1196, 91405 Orsay, France
| | - Sébastien Britton
- Institut de Pharmacologie et de Biologie Structurale (IPBS), CNRS UMR 5089, Université de Toulouse, UPS, Équipe labellisée la Ligue Contre le Cancer, 31077 Toulouse, France
| | - David Monchaud
- Institut de Chimie Moléculaire de l’Université de Bourgogne (ICMUB), CNRS UMR 6302, UBFC Dijon, 21078 Dijon, France
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53
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Fleming AM, Burrows CJ. Oxidative stress-mediated epigenetic regulation by G-quadruplexes. NAR Cancer 2021; 3:zcab038. [PMID: 34541539 PMCID: PMC8445369 DOI: 10.1093/narcan/zcab038] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/20/2021] [Accepted: 09/06/2021] [Indexed: 02/06/2023] Open
Abstract
Many cancer-associated genes are regulated by guanine (G)-rich sequences that are capable of refolding from the canonical duplex structure to an intrastrand G-quadruplex. These same sequences are sensitive to oxidative damage that is repaired by the base excision repair glycosylases OGG1 and NEIL1–3. We describe studies indicating that oxidation of a guanosine base in a gene promoter G-quadruplex can lead to up- and downregulation of gene expression that is location dependent and involves the base excision repair pathway in which the first intermediate, an apurinic (AP) site, plays a key role mediated by AP endonuclease 1 (APE1/REF1). The nuclease activity of APE1 is paused at a G-quadruplex, while the REF1 capacity of this protein engages activating transcription factors such as HIF-1α, AP-1 and p53. The mechanism has been probed by in vitro biophysical studies, whole-genome approaches and reporter plasmids in cellulo. Replacement of promoter elements by a G-quadruplex sequence usually led to upregulation, but depending on the strand and precise location, examples of downregulation were also found. The impact of oxidative stress-mediated lesions in the G-rich sequence enhanced the effect, whether it was positive or negative.
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Affiliation(s)
- Aaron M Fleming
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850, USA
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850, USA
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54
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Kim YA, Leiserson MDM, Moorjani P, Sharan R, Wojtowicz D, Przytycka TM. Mutational Signatures: From Methods to Mechanisms. Annu Rev Biomed Data Sci 2021; 4:189-206. [PMID: 34465178 DOI: 10.1146/annurev-biodatasci-122320-120920] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mutations are the driving force of evolution, yet they underlie many diseases, in particular, cancer. They are thought to arise from a combination of stochastic errors in DNA processing, naturally occurring DNA damage (e.g., the spontaneous deamination of methylated CpG sites), replication errors, and dysregulation of DNA repair mechanisms. High-throughput sequencing has made it possible to generate large datasets to study mutational processes in health and disease. Since the emergence of the first mutational process studies in 2012, this field is gaining increasing attention and has already accumulated a host of computational approaches and biomedical applications.
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Affiliation(s)
- Yoo-Ah Kim
- National Center of Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA;
| | - Mark D M Leiserson
- Department of Computer Science and Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland 20742, USA
| | - Priya Moorjani
- Department of Molecular and Cell Biology and Center for Computational Biology, University of California, Berkeley, California 94720, USA
| | - Roded Sharan
- Blavatnik School of Computer Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - Damian Wojtowicz
- National Center of Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA;
| | - Teresa M Przytycka
- National Center of Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA;
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55
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Radiotherapy is associated with a deletion signature that contributes to poor outcomes in patients with cancer. Nat Genet 2021; 53:1088-1096. [PMID: 34045764 PMCID: PMC8483261 DOI: 10.1038/s41588-021-00874-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 04/21/2021] [Indexed: 02/04/2023]
Abstract
Ionizing radiation causes DNA damage and is a mainstay for cancer treatment, but understanding of its genomic impact is limited. We analyzed mutational spectra following radiotherapy in 190 paired primary and recurrent gliomas from the Glioma Longitudinal Analysis Consortium and 3,693 post-treatment metastatic tumors from the Hartwig Medical Foundation. We identified radiotherapy-associated significant increases in the burden of small deletions (5-15 bp) and large deletions (20+ bp to chromosome-arm length). Small deletions were characterized by a larger span size, lacking breakpoint microhomology and were genomically more dispersed when compared to pre-existing deletions and deletions in non-irradiated tumors. Mutational signature analysis implicated classical non-homologous end-joining-mediated DNA damage repair and APOBEC mutagenesis following radiotherapy. A high radiation-associated deletion burden was associated with worse clinical outcomes, suggesting that effective repair of radiation-induced DNA damage is detrimental to patient survival. These results may be leveraged to predict sensitivity to radiation therapy in recurrent cancer.
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56
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Guiblet WM, DeGiorgio M, Cheng X, Chiaromonte F, Eckert KA, Huang YF, Makova KD. Selection and thermostability suggest G-quadruplexes are novel functional elements of the human genome. Genome Res 2021; 31:1136-1149. [PMID: 34187812 PMCID: PMC8256861 DOI: 10.1101/gr.269589.120] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 05/24/2021] [Indexed: 12/11/2022]
Abstract
Approximately 1% of the human genome has the ability to fold into G-quadruplexes (G4s)-noncanonical strand-specific DNA structures forming at G-rich motifs. G4s regulate several key cellular processes (e.g., transcription) and have been hypothesized to participate in others (e.g., firing of replication origins). Moreover, G4s differ in their thermostability, and this may affect their function. Yet, G4s may also hinder replication, transcription, and translation and may increase genome instability and mutation rates. Therefore, depending on their genomic location, thermostability, and functionality, G4 loci might evolve under different selective pressures, which has never been investigated. Here we conducted the first genome-wide analysis of G4 distribution, thermostability, and selection. We found an overrepresentation, high thermostability, and purifying selection for G4s within genic components in which they are expected to be functional-promoters, CpG islands, and 5' and 3' UTRs. A similar pattern was observed for G4s within replication origins, enhancers, eQTLs, and TAD boundary regions, strongly suggesting their functionality. In contrast, G4s on the nontranscribed strand of exons were underrepresented, were unstable, and evolved neutrally. In general, G4s on the nontranscribed strand of genic components had lower density and were less stable than those on the transcribed strand, suggesting that the former are avoided at the RNA level. Across the genome, purifying selection was stronger at stable G4s. Our results suggest that purifying selection preserves the sequences of functional G4s, whereas nonfunctional G4s are too costly to be tolerated in the genome. Thus, G4s are emerging as fundamental, functional genomic elements.
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Affiliation(s)
- Wilfried M Guiblet
- Bioinformatics and Genomics Graduate Program, Penn State University, University Park, Pennsylvania 16802, USA
| | - Michael DeGiorgio
- Department of Computer and Electrical Engineering and Computer Science, Florida Atlantic University, Boca Raton, Florida 33431, USA
| | - Xiaoheng Cheng
- Department of Biology, Penn State University, University Park, Pennsylvania 16802, USA
| | - Francesca Chiaromonte
- Department of Statistics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for Medical Genomics, Penn State University, University Park and Hershey, Pennsylvania 16802, USA
- Sant'Anna School of Advanced Studies, 56127 Pisa, Italy
| | - Kristin A Eckert
- Center for Medical Genomics, Penn State University, University Park and Hershey, Pennsylvania 16802, USA
- Department of Pathology, Penn State University, College of Medicine, Hershey, Pennsylvania 17033, USA
| | - Yi-Fei Huang
- Department of Biology, Penn State University, University Park, Pennsylvania 16802, USA
- Center for Medical Genomics, Penn State University, University Park and Hershey, Pennsylvania 16802, USA
| | - Kateryna D Makova
- Department of Biology, Penn State University, University Park, Pennsylvania 16802, USA
- Center for Medical Genomics, Penn State University, University Park and Hershey, Pennsylvania 16802, USA
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57
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Lago S, Nadai M, Cernilogar FM, Kazerani M, Domíniguez Moreno H, Schotta G, Richter SN. Promoter G-quadruplexes and transcription factors cooperate to shape the cell type-specific transcriptome. Nat Commun 2021; 12:3885. [PMID: 34162892 PMCID: PMC8222265 DOI: 10.1038/s41467-021-24198-2] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 06/07/2021] [Indexed: 02/07/2023] Open
Abstract
Cell identity is maintained by activation of cell-specific gene programs, regulated by epigenetic marks, transcription factors and chromatin organization. DNA G-quadruplex (G4)-folded regions in cells were reported to be associated with either increased or decreased transcriptional activity. By G4-ChIP-seq/RNA-seq analysis on liposarcoma cells we confirmed that G4s in promoters are invariably associated with high transcription levels in open chromatin. Comparing G4 presence, location and transcript levels in liposarcoma cells to available data on keratinocytes, we showed that the same promoter sequences of the same genes in the two cell lines had different G4-folding state: high transcript levels consistently associated with G4-folding. Transcription factors AP-1 and SP1, whose binding sites were the most significantly represented in G4-folded sequences, coimmunoprecipitated with their G4-folded promoters. Thus, G4s and their associated transcription factors cooperate to determine cell-specific transcriptional programs, making G4s to strongly emerge as new epigenetic regulators of the transcription machinery.
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Affiliation(s)
- Sara Lago
- Department of Molecular Medicine, University of Padua, Padua, Italy.
| | - Matteo Nadai
- Department of Molecular Medicine, University of Padua, Padua, Italy
| | - Filippo M Cernilogar
- Division of Molecular Biology, Biomedical Center, Faculty of Medicine, LMU Munich, Martinsried, Germany
| | - Maryam Kazerani
- Division of Molecular Biology, Biomedical Center, Faculty of Medicine, LMU Munich, Martinsried, Germany
| | - Helena Domíniguez Moreno
- Division of Molecular Biology, Biomedical Center, Faculty of Medicine, LMU Munich, Martinsried, Germany
| | - Gunnar Schotta
- Division of Molecular Biology, Biomedical Center, Faculty of Medicine, LMU Munich, Martinsried, Germany.
| | - Sara N Richter
- Department of Molecular Medicine, University of Padua, Padua, Italy.
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58
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Cheloshkina K, Bzhikhatlov I, Poptsova M. Randomness in Cancer Breakpoint Prediction. J Comput Biol 2021; 28:716-731. [PMID: 34129386 DOI: 10.1089/cmb.2020.0551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cancer genomes are susceptible to multiple rearrangements by deleting, inserting, and translocating genomic regions. Recently, the problem of finding determinants of breakpoint formations was approached with machine learning methods; however, unlike cancer point mutations, breakpoint prediction appeared to be a more difficult task, and various machine learning models did not achieve high prediction power often slightly exceeding the threshold of random guessing. This raised the question of whether the breakpoints are random noise in cancer mutagenesis or there exist determinants in structural mutagenesis. In the present study, we investigated randomness in cancer breakpoint genome distributions through the power of machine learning models to predict breakpoint hot spots. We divided all cancer types into three groups by degree of randomness in their breakpoint formation. We tested different density thresholds and explored the bias in hot spot definition. We also compared prediction of hot spots versus individual breakpoints. We found that hot spots are considerably better predicted than individual breakpoints; however, some individual breakpoints can also be predicted with a satisfactory power, and thus, it is not proper to filter them from analyses. We demonstrated that positive-unlabeled learning can provide insights into insufficiency of cancer data sets, which are not always reflected by data set sizes. Overall, the present results support the view that cancer breakpoint landscape can be represented by predictable dense breakpoint regions and scattered individual breakpoints, which are not all random noise, but some are generated by detectable mechanism.
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Affiliation(s)
- Kseniia Cheloshkina
- Laboratory of Bioinformatics, Faculty of Computer Science, National Research University Higher School of Economics, Moscow, Russia
| | - Islam Bzhikhatlov
- Faculty of Control Systems and Robotics, ITMO University, St. Petersburg, Russia
| | - Maria Poptsova
- Laboratory of Bioinformatics, Faculty of Computer Science, National Research University Higher School of Economics, Moscow, Russia
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59
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G-quadruplex stabilization via small-molecules as a potential anti-cancer strategy. Biomed Pharmacother 2021; 139:111550. [PMID: 33831835 DOI: 10.1016/j.biopha.2021.111550] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 12/16/2022] Open
Abstract
G-quadruplexes (G4) are secondary four-stranded DNA helical structures consisting of guanine-rich nucleic acids, which can be formed in the promoter regions of several genes under proper conditions. Several cancer cells have been shown to emerge from genomic changes in the expression of crucial growth-regulating genes that allow cells to develop and begin to propagate in an undifferentiated state. Recent attempts have focused on producing treatments targeted at particular protein products of genes that are abnormally expressed. Many of the proteins found are hard to target and considered undruggable due to structural challenges, protein overexpression, or mutations that affect treatment resistance. The utilization of small molecules that stabilize secondary DNA structures existing in several possible oncogenes' promoters and modulate their transcription is a new strategy that avoids some of these problems. In this review, we outline the function of G-quadruplex stabilization in cancer by small-molecules with the aim to improve cancer therapy.
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60
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Roy U, Raghavan SC. Deleterious point mutations in T-cell acute lymphoblastic leukemia: Mechanistic insights into leukemogenesis. Int J Cancer 2021; 149:1210-1220. [PMID: 33634864 DOI: 10.1002/ijc.33527] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 12/11/2022]
Abstract
T-cell acute lymphoblastic leukemia (T-ALL) is characterized by the leukemogenic transformation of immature T cells, which accumulate an array of genetic and epigenetic lesions, leading to a sustained proliferation of abnormal T cells. Genetic alterations in the DNA repair genes, protooncogenes, transcription factors, and epigenetic modifiers have been studied in the past decade using next-generation sequencing and high-resolution copy number arrays. While other genomic lesions like chromosomal rearrangements, inversions, insertions, and gene fusions have been well studied at functional level, the mechanism of generation of driver mutations in T-ALL is the subject of current investigation. Novel oncogenic mutations in the TP53, BRCA2, PTEN, IL7R, RAS, NOTCH1, ETV6, BCL11B, WT1, DNMT3A, PRC2, PHF6, USP7, KDM6A and an array of other genes disrupt the genetic and epigenetic homeostasis in T-ALL. In this review, we have summarized the mechanistic role of deleterious driver mutations in T-ALL initiation and progression. We speculate that the formation of non-B DNA structures could be one of the primary reasons for the occurrence of different genomic lesions seen in T-ALL, which warrants further investigation. Understanding the mechanism behind the genesis of oncogenic mutations will pave the way to develop targeted therapies that can improve the overall survival and treatment outcome.
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Affiliation(s)
- Urbi Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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61
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Díaz-Gay M, Alexandrov LB. Unraveling the genomic landscape of colorectal cancer through mutational signatures. Adv Cancer Res 2021; 151:385-424. [PMID: 34148618 DOI: 10.1016/bs.acr.2021.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Colorectal cancer, along with most other cancer types, is driven by somatic mutations. Characteristic patterns of somatic mutations, known as mutational signatures, arise as a result of the activities of different mutational processes. Mutational signatures have diverse origins, including exogenous and endogenous sources. In the case of colorectal cancer, the analysis of mutational signatures has elucidated specific signatures for classically associated DNA repair deficiencies, namely mismatch repair (leading to microsatellite instability), base excision repair (due to MUTYH or NTHL1 mutations), and polymerase proofreading (due to POLE and POLD1 exonuclease domain mutations). Additional signatures also play a role in colorectal cancer, including those related to normal aging and those associated with gut microbiota, as well as a number of signatures with unknown etiologies. This chapter provides an overview of the current knowledge of mutational signatures, with a focus on colorectal cancer and on the recently reported signatures in physiologically normal and inflammatory bowel disease-affected somatic colon tissues.
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Affiliation(s)
- Marcos Díaz-Gay
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, United States; Department of Bioengineering, UC San Diego, La Jolla, CA, United States; Moores Cancer Center, UC San Diego, La Jolla, CA, United States
| | - Ludmil B Alexandrov
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, United States; Department of Bioengineering, UC San Diego, La Jolla, CA, United States; Moores Cancer Center, UC San Diego, La Jolla, CA, United States.
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62
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Langenbucher A, Bowen D, Sakhtemani R, Bournique E, Wise JF, Zou L, Bhagwat AS, Buisson R, Lawrence MS. An extended APOBEC3A mutation signature in cancer. Nat Commun 2021; 12:1602. [PMID: 33707442 PMCID: PMC7952602 DOI: 10.1038/s41467-021-21891-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 02/17/2021] [Indexed: 12/11/2022] Open
Abstract
APOBEC mutagenesis, a major driver of cancer evolution, is known for targeting TpC sites in DNA. Recently, we showed that APOBEC3A (A3A) targets DNA hairpin loops. Here, we show that DNA secondary structure is in fact an orthogonal influence on A3A substrate optimality and, surprisingly, can override the TpC sequence preference. VpC (non-TpC) sites in optimal hairpins can outperform TpC sites as mutational hotspots. This expanded understanding of APOBEC mutagenesis illuminates the genomic Twin Paradox, a puzzling pattern of closely spaced mutation hotspots in cancer genomes, in which one is a canonical TpC site but the other is a VpC site, and double mutants are seen only in trans, suggesting a two-hit driver event. Our results clarify this paradox, revealing that both hotspots in these twins are optimal A3A substrates. Our findings reshape the notion of a mutation signature, highlighting the additive roles played by DNA sequence and DNA structure.
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Affiliation(s)
- Adam Langenbucher
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
| | - Danae Bowen
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Ramin Sakhtemani
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Department of Chemistry, Wayne State University, Detroit, MI, USA
| | - Elodie Bournique
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Jillian F Wise
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Cancer Immunology, Institute for Cancer Research, University of Oslo, Oslo, Norway
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Ashok S Bhagwat
- Department of Chemistry, Wayne State University, Detroit, MI, USA.
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI, USA.
| | - Rémi Buisson
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, CA, USA.
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA.
| | - Michael S Lawrence
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
- Broad Institute of Harvard and MIT, Cambridge, MA, USA.
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63
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Cheloshkina K, Poptsova M. Comprehensive analysis of cancer breakpoints reveals signatures of genetic and epigenetic contribution to cancer genome rearrangements. PLoS Comput Biol 2021; 17:e1008749. [PMID: 33647036 PMCID: PMC7951985 DOI: 10.1371/journal.pcbi.1008749] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 03/11/2021] [Accepted: 01/28/2021] [Indexed: 11/19/2022] Open
Abstract
Understanding mechanisms of cancer breakpoint mutagenesis is a difficult task and predictive models of cancer breakpoint formation have to this time failed to achieve even moderate predictive power. Here we take advantage of a machine learning approach that can gather important features from big data and quantify contribution of different factors. We performed comprehensive analysis of almost 630,000 cancer breakpoints and quantified the contribution of genomic and epigenomic features-non-B DNA structures, chromatin organization, transcription factor binding sites and epigenetic markers. The results showed that transcription and formation of non-B DNA structures are two major processes responsible for cancer genome fragility. Epigenetic factors, such as chromatin organization in TADs, open/closed regions, DNA methylation, histone marks are less informative but do make their contribution. As a general trend, individual features inside the groups show a relatively high contribution of G-quadruplexes and repeats and CTCF, GABPA, RXRA, SP1, MAX and NR2F2 transcription factors. Overall, the cancer breakpoint landscape can be represented by well-predicted hotspots and poorly predicted individual breakpoints scattered across genomes. We demonstrated that hotspot mutagenesis has genomic and epigenomic factors, and not all individual cancer breakpoints are just random noise but have a definite mutation signature. Besides we found a long-range action of some features on breakpoint mutagenesis. Combining omics data, cancer-specific individual feature importance and adding the distant to local features, predictive models for cancer breakpoint formation achieved 70-90% ROC AUC for different cancer types; however precision remained low at 2% and the recall did not exceed 50%. On the one hand, the power of models strongly correlates with the size of available cancer breakpoint and epigenomic data, and on the other hand finding strong determinants of cancer breakpoint formation still remains a challenge. The strength of predictive signals of each group and of each feature inside a group can be converted into cancer-specific breakpoint mutation signatures. Overall our results add to the understanding of cancer genome rearrangement processes.
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Affiliation(s)
- Kseniia Cheloshkina
- Laboratory of Bioinformatics, Faculty of Computer Science, National Research University Higher School of Economics, Moscow, Russia
- Faculty of Digital Transformation, ITMO University, St. Petersburg, Russia
| | - Maria Poptsova
- Laboratory of Bioinformatics, Faculty of Computer Science, National Research University Higher School of Economics, Moscow, Russia
- * E-mail:
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Guiblet WM, Cremona MA, Harris RS, Chen D, Eckert KA, Chiaromonte F, Huang YF, Makova KD. Non-B DNA: a major contributor to small- and large-scale variation in nucleotide substitution frequencies across the genome. Nucleic Acids Res 2021; 49:1497-1516. [PMID: 33450015 PMCID: PMC7897504 DOI: 10.1093/nar/gkaa1269] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 12/14/2020] [Accepted: 01/11/2021] [Indexed: 12/12/2022] Open
Abstract
Approximately 13% of the human genome can fold into non-canonical (non-B) DNA structures (e.g. G-quadruplexes, Z-DNA, etc.), which have been implicated in vital cellular processes. Non-B DNA also hinders replication, increasing errors and facilitating mutagenesis, yet its contribution to genome-wide variation in mutation rates remains unexplored. Here, we conducted a comprehensive analysis of nucleotide substitution frequencies at non-B DNA loci within noncoding, non-repetitive genome regions, their ±2 kb flanking regions, and 1-Megabase windows, using human-orangutan divergence and human single-nucleotide polymorphisms. Functional data analysis at single-base resolution demonstrated that substitution frequencies are usually elevated at non-B DNA, with patterns specific to each non-B DNA type. Mirror, direct and inverted repeats have higher substitution frequencies in spacers than in repeat arms, whereas G-quadruplexes, particularly stable ones, have higher substitution frequencies in loops than in stems. Several non-B DNA types also affect substitution frequencies in their flanking regions. Finally, non-B DNA explains more variation than any other predictor in multiple regression models for diversity or divergence at 1-Megabase scale. Thus, non-B DNA substantially contributes to variation in substitution frequencies at small and large scales. Our results highlight the role of non-B DNA in germline mutagenesis with implications to evolution and genetic diseases.
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Affiliation(s)
- Wilfried M Guiblet
- Bioinformatics and Genomics Graduate Program, Penn State University, UniversityPark, PA 16802, USA
| | - Marzia A Cremona
- Department of Statistics, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Operations and Decision Systems, Université Laval, Canada
- CHU de Québec – Université Laval Research Center, Canada
| | - Robert S Harris
- Department of Biology, Penn State University, University Park, PA 16802, USA
| | - Di Chen
- Intercollege Graduate Degree Program in Genetics, Huck Institutes of the Life Sciences, Penn State University, UniversityPark, PA 16802, USA
| | - Kristin A Eckert
- Department of Pathology, Penn State University, College of Medicine, Hershey, PA 17033, USA
- Center for Medical Genomics, Penn State University, University Park and Hershey, PA, USA
| | - Francesca Chiaromonte
- Department of Statistics, The Pennsylvania State University, University Park, PA 16802, USA
- Center for Medical Genomics, Penn State University, University Park and Hershey, PA, USA
- EMbeDS, Sant’Anna School of Advanced Studies, 56127 Pisa, Italy
| | - Yi-Fei Huang
- Department of Biology, Penn State University, University Park, PA 16802, USA
- Center for Medical Genomics, Penn State University, University Park and Hershey, PA, USA
| | - Kateryna D Makova
- Department of Biology, Penn State University, University Park, PA 16802, USA
- Center for Medical Genomics, Penn State University, University Park and Hershey, PA, USA
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65
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Savva L, Georgiades SN. Recent Developments in Small-Molecule Ligands of Medicinal Relevance for Harnessing the Anticancer Potential of G-Quadruplexes. Molecules 2021; 26:molecules26040841. [PMID: 33562720 PMCID: PMC7914483 DOI: 10.3390/molecules26040841] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022] Open
Abstract
G-quadruplexes, a family of tetraplex helical nucleic acid topologies, have emerged in recent years as novel targets, with untapped potential for anticancer research. Their potential stems from the fact that G-quadruplexes occur in functionally-important regions of the human genome, such as the telomere tandem sequences, several proto-oncogene promoters, other regulatory regions and sequences of DNA (e.g., rDNA), as well as in mRNAs encoding for proteins with roles in tumorigenesis. Modulation of G-quadruplexes, via interaction with high-affinity ligands, leads to their stabilization, with numerous observed anticancer effects. Despite the fact that only a few lead compounds for G-quadruplex modulation have progressed to clinical trials so far, recent advancements in the field now create conditions that foster further development of drug candidates. This review highlights biological processes through which G-quadruplexes can exert their anticancer effects and describes, via selected case studies, progress of the last few years on the development of efficient and drug-like G-quadruplex-targeted ligands, intended to harness the anticancer potential offered by G-quadruplexes. The review finally provides a critical discussion of perceived challenges and limitations that have previously hampered the progression of G-quadruplex-targeted lead compounds to clinical trials, concluding with an optimistic future outlook.
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Pabis K. Triplex and other DNA motifs show motif-specific associations with mitochondrial DNA deletions and species lifespan. Mech Ageing Dev 2021; 194:111429. [PMID: 33422563 DOI: 10.1016/j.mad.2021.111429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 01/02/2021] [Accepted: 01/03/2021] [Indexed: 11/20/2022]
Abstract
The "theory of resistant biomolecules" posits that long-lived species show resistance to molecular damage at the level of their biomolecules. Here, we test this hypothesis in the context of mitochondrial DNA (mtDNA) as it implies that predicted mutagenic DNA motifs should be inversely correlated with species maximum lifespan (MLS). First, we confirmed that guanine-quadruplex and direct repeat (DR) motifs are mutagenic, as they associate with mtDNA deletions in the human major arc of mtDNA, while also adding mirror repeat (MR) and intramolecular triplex motifs to a growing list of potentially mutagenic features. What is more, triplex motifs showed disease-specific associations with deletions and an apparent interaction with guanine-quadruplex motifs. Surprisingly, even though DR, MR and guanine-quadruplex motifs were associated with mtDNA deletions, their correlation with MLS was explained by the biased base composition of mtDNA. Only triplex motifs negatively correlated with MLS even after adjusting for body mass, phylogeny, mtDNA base composition and effective number of codons. Taken together, our work highlights the importance of base composition for the comparative biogerontology of mtDNA and suggests that future research on mitochondrial triplex motifs is warranted.
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Affiliation(s)
- Kamil Pabis
- Georg August University of Göttingen, Göttingen, Germany.
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67
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Martínez-Jiménez F, Muiños F, Sentís I, Deu-Pons J, Reyes-Salazar I, Arnedo-Pac C, Mularoni L, Pich O, Bonet J, Kranas H, Gonzalez-Perez A, Lopez-Bigas N. A compendium of mutational cancer driver genes. Nat Rev Cancer 2020; 20:555-572. [PMID: 32778778 DOI: 10.1038/s41568-020-0290-x] [Citation(s) in RCA: 534] [Impact Index Per Article: 133.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/02/2020] [Indexed: 12/11/2022]
Abstract
A fundamental goal in cancer research is to understand the mechanisms of cell transformation. This is key to developing more efficient cancer detection methods and therapeutic approaches. One milestone towards this objective is the identification of all the genes with mutations capable of driving tumours. Since the 1970s, the list of cancer genes has been growing steadily. Because cancer driver genes are under positive selection in tumorigenesis, their observed patterns of somatic mutations across tumours in a cohort deviate from those expected from neutral mutagenesis. These deviations, which constitute signals of positive selection, may be detected by carefully designed bioinformatics methods, which have become the state of the art in the identification of driver genes. A systematic approach combining several of these signals could lead to a compendium of mutational cancer genes. In this Review, we present the Integrative OncoGenomics (IntOGen) pipeline, an implementation of such an approach to obtain the compendium of mutational cancer drivers. Its application to somatic mutations of more than 28,000 tumours of 66 cancer types reveals 568 cancer genes and points towards their mechanisms of tumorigenesis. The application of this approach to the ever-growing datasets of somatic tumour mutations will support the continuous refinement of our knowledge of the genetic basis of cancer.
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Affiliation(s)
- Francisco Martínez-Jiménez
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Ferran Muiños
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Inés Sentís
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Jordi Deu-Pons
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Iker Reyes-Salazar
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Claudia Arnedo-Pac
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Loris Mularoni
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Oriol Pich
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Jose Bonet
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Hanna Kranas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Abel Gonzalez-Perez
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain.
- Research Program on Biomedical Informatics, Universitat Pompeu Fabra, Barcelona, Spain.
| | - Nuria Lopez-Bigas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain.
- Research Program on Biomedical Informatics, Universitat Pompeu Fabra, Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
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68
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Xu Y, Manghrani A, Liu B, Shi H, Pham U, Liu A, Al-Hashimi HM. Hoogsteen base pairs increase the susceptibility of double-stranded DNA to cytotoxic damage. J Biol Chem 2020; 295:15933-15947. [PMID: 32913127 DOI: 10.1074/jbc.ra120.014530] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 08/24/2020] [Indexed: 11/06/2022] Open
Abstract
As the Watson-Crick faces of nucleobases are protected in dsDNA, it is commonly assumed that deleterious alkylation damage to the Watson-Crick faces of nucleobases predominantly occurs when DNA becomes single-stranded during replication and transcription. However, damage to the Watson-Crick faces of nucleobases has been reported in dsDNA in vitro through mechanisms that are not understood. In addition, the extent of protection from methylation damage conferred by dsDNA relative to ssDNA has not been quantified. Watson-Crick base pairs in dsDNA exist in dynamic equilibrium with Hoogsteen base pairs that expose the Watson-Crick faces of purine nucleobases to solvent. Whether this can influence the damage susceptibility of dsDNA remains unknown. Using dot-blot and primer extension assays, we measured the susceptibility of adenine-N1 to methylation by dimethyl sulfate (DMS) when in an A-T Watson-Crick versus Hoogsteen conformation. Relative to unpaired adenines in a bulge, Watson-Crick A-T base pairs in dsDNA only conferred ∼130-fold protection against adenine-N1 methylation, and this protection was reduced to ∼40-fold for A(syn)-T Hoogsteen base pairs embedded in a DNA-drug complex. Our results indicate that Watson-Crick faces of nucleobases are accessible to alkylating agents in canonical dsDNA and that Hoogsteen base pairs increase this accessibility. Given the higher abundance of dsDNA relative to ssDNA, these results suggest that dsDNA could be a substantial source of cytotoxic damage. The work establishes DMS probing as a method for characterizing A(syn)-T Hoogsteen base pairs in vitro and also lays the foundation for a sequencing approach to map A(syn)-T Hoogsteen and unpaired adenines genome-wide in vivo.
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Affiliation(s)
- Yu Xu
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Akanksha Manghrani
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina, USA
| | - Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Uyen Pham
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina, USA
| | - Amy Liu
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Hashim M Al-Hashimi
- Department of Chemistry, Duke University, Durham, North Carolina, USA; Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina, USA.
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69
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Hänsel-Hertsch R, Simeone A, Shea A, Hui WWI, Zyner KG, Marsico G, Rueda OM, Bruna A, Martin A, Zhang X, Adhikari S, Tannahill D, Caldas C, Balasubramanian S. Landscape of G-quadruplex DNA structural regions in breast cancer. Nat Genet 2020; 52:878-883. [PMID: 32747825 DOI: 10.1038/s41588-020-0672-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 06/25/2020] [Indexed: 12/25/2022]
Abstract
Response and resistance to anticancer therapies vary due to intertumor and intratumor heterogeneity1. Here, we map differentially enriched G-quadruplex (G4) DNA structure-forming regions (∆G4Rs) in 22 breast cancer patient-derived tumor xenograft (PDTX) models. ∆G4Rs are associated with the promoters of highly amplified genes showing high expression, and with somatic single-nucleotide variants. Differences in ΔG4R landscapes reveal seven transcription factor programs across PDTXs. ∆G4R abundance and locations stratify PDTXs into at least three G4-based subtypes. ∆G4Rs in most PDTXs (14 of 22) were found to associate with more than one breast cancer subtype, which we also call an integrative cluster (IC)2. This suggests the frequent coexistence of multiple breast cancer states within a PDTX model, the majority of which display aggressive triple-negative IC10 gene activity. Short-term cultures of PDTX models with increased ∆G4R levels are more sensitive to small molecules targeting G4 DNA. Thus, G4 landscapes reveal additional IC-related intratumor heterogeneity in PDTX biopsies, improving breast cancer stratification and potentially identifying new treatment strategies.
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Affiliation(s)
- Robert Hänsel-Hertsch
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne and University Hospital Cologne, Cologne, Germany
- Institute of Human Genetics, University Hospital Cologne, Cologne, Germany
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Angela Simeone
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Abigail Shea
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Winnie W I Hui
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Katherine G Zyner
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Giovanni Marsico
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
- Inivata, Babraham Research Campus, Cambridge, UK
| | - Oscar M Rueda
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Alejandra Bruna
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
- The Institute of Cancer Research, London, UK
| | - Alistair Martin
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Xiaoyun Zhang
- Department of Chemistry, University of Cambridge, Cambridge, UK
| | | | - David Tannahill
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Carlos Caldas
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
- Cambridge Breast Cancer Research Unit, Cambridge University Hospital NHS Foundation Trust, Cambridge, UK
- Cancer Research UK Cambridge Centre, NIHR Cambridge Biomedical Research Centre and Cambridge Experimental Cancer Medicine Centre, Cambridge University Hospital NHS Foundation Trust, Cambridge, UK
| | - Shankar Balasubramanian
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK.
- Department of Chemistry, University of Cambridge, Cambridge, UK.
- School of Clinical Medicine, University of Cambridge, Cambridge, UK.
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70
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Murat P, Guilbaud G, Sale JE. DNA polymerase stalling at structured DNA constrains the expansion of short tandem repeats. Genome Biol 2020; 21:209. [PMID: 32819438 PMCID: PMC7441554 DOI: 10.1186/s13059-020-02124-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/28/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Short tandem repeats (STRs) contribute significantly to de novo mutagenesis, driving phenotypic diversity and genetic disease. Although highly diverse, their repetitive sequences induce DNA polymerase slippage and stalling, leading to length and sequence variation. However, current studies of DNA synthesis through STRs are restricted to a handful of selected sequences, limiting our broader understanding of their evolutionary behaviour and hampering the characterisation of the determinants of their abundance and stability in eukaryotic genomes. RESULTS We perform a comprehensive analysis of DNA synthesis at all STR permutations and interrogate the impact of STR sequence and secondary structure on their genomic representation and mutability. To do this, we developed a high-throughput primer extension assay that allows monitoring of the kinetics and fidelity of DNA synthesis through 20,000 sequences comprising all STR permutations in different lengths. By combining these measurements with population-scale genomic data, we show that the response of a model replicative DNA polymerase to variously structured DNA is sufficient to predict the complex genomic behaviour of STRs, including abundance and mutational constraints. We demonstrate that DNA polymerase stalling at DNA structures induces error-prone DNA synthesis, which constrains STR expansion. CONCLUSIONS Our data support a model in which STR length in eukaryotic genomes results from a balance between expansion due to polymerase slippage at repeated DNA sequences and point mutations caused by error-prone DNA synthesis at DNA structures.
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Affiliation(s)
- Pierre Murat
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Guillaume Guilbaud
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Julian E Sale
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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71
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Varshney D, Spiegel J, Zyner K, Tannahill D, Balasubramanian S. The regulation and functions of DNA and RNA G-quadruplexes. Nat Rev Mol Cell Biol 2020; 21:459-474. [PMID: 32313204 PMCID: PMC7115845 DOI: 10.1038/s41580-020-0236-x] [Citation(s) in RCA: 619] [Impact Index Per Article: 154.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2020] [Indexed: 02/06/2023]
Abstract
DNA and RNA can adopt various secondary structures. Four-stranded G-quadruplex (G4) structures form through self-recognition of guanines into stacked tetrads, and considerable biophysical and structural evidence exists for G4 formation in vitro. Computational studies and sequencing methods have revealed the prevalence of G4 sequence motifs at gene regulatory regions in various genomes, including in humans. Experiments using chemical, molecular and cell biology methods have demonstrated that G4s exist in chromatin DNA and in RNA, and have linked G4 formation with key biological processes ranging from transcription and translation to genome instability and cancer. In this Review, we first discuss the identification of G4s and evidence for their formation in cells using chemical biology, imaging and genomic technologies. We then discuss possible functions of DNA G4s and their interacting proteins, particularly in transcription, telomere biology and genome instability. Roles of RNA G4s in RNA biology, especially in translation, are also discussed. Furthermore, we consider the emerging relationships of G4s with chromatin and with RNA modifications. Finally, we discuss the connection between G4 formation and synthetic lethality in cancer cells, and recent progress towards considering G4s as therapeutic targets in human diseases.
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Affiliation(s)
- Dhaval Varshney
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Jochen Spiegel
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Katherine Zyner
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - David Tannahill
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Shankar Balasubramanian
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK.
- Department of Chemistry, University of Cambridge, Cambridge, UK.
- School of Clinical Medicine, University of Cambridge, Cambridge, UK.
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Bartas M, Brázda V, Bohálová N, Cantara A, Volná A, Stachurová T, Malachová K, Jagelská EB, Porubiaková O, Červeň J, Pečinka P. In-Depth Bioinformatic Analyses of Nidovirales Including Human SARS-CoV-2, SARS-CoV, MERS-CoV Viruses Suggest Important Roles of Non-canonical Nucleic Acid Structures in Their Lifecycles. Front Microbiol 2020; 11:1583. [PMID: 32719673 PMCID: PMC7347907 DOI: 10.3389/fmicb.2020.01583] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/17/2020] [Indexed: 12/15/2022] Open
Abstract
Non-canonical nucleic acid structures play important roles in the regulation of molecular processes. Considering the importance of the ongoing coronavirus crisis, we decided to evaluate genomes of all coronaviruses sequenced to date (stated more broadly, the order Nidovirales) to determine if they contain non-canonical nucleic acid structures. We discovered much evidence of putative G-quadruplex sites and even much more of inverted repeats (IRs) loci, which in fact are ubiquitous along the whole genomic sequence and indicate a possible mechanism for genomic RNA packaging. The most notable enrichment of IRs was found inside 5'UTR for IRs of size 12+ nucleotides, and the most notable enrichment of putative quadruplex sites (PQSs) was located before 3'UTR, inside 5'UTR, and before mRNA. This indicates crucial regulatory roles for both IRs and PQSs. Moreover, we found multiple G-quadruplex binding motifs in human proteins having potential for binding of SARS-CoV-2 RNA. Non-canonical nucleic acids structures in Nidovirales and in novel SARS-CoV-2 are therefore promising druggable structures that can be targeted and utilized in the future.
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Affiliation(s)
- Martin Bartas
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czechia
| | - Václav Brázda
- Department of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
- Faculty of Chemistry, Brno University of Technology, Brno, Czechia
| | - Natália Bohálová
- Department of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Alessio Cantara
- Department of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Adriana Volná
- Department of Physics, Faculty of Science, University of Ostrava, Ostrava, Czechia
| | - Tereza Stachurová
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czechia
| | - Kateřina Malachová
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czechia
| | - Eva B. Jagelská
- Department of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
| | - Otília Porubiaková
- Department of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
- Faculty of Chemistry, Brno University of Technology, Brno, Czechia
| | - Jiří Červeň
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czechia
| | - Petr Pečinka
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czechia
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Gonzalez-Perez A, Sabarinathan R, Lopez-Bigas N. Local Determinants of the Mutational Landscape of the Human Genome. Cell 2020; 177:101-114. [PMID: 30901533 DOI: 10.1016/j.cell.2019.02.051] [Citation(s) in RCA: 105] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 02/13/2019] [Accepted: 02/26/2019] [Indexed: 12/19/2022]
Abstract
Large-scale chromatin features, such as replication time and accessibility influence the rate of somatic and germline mutations at the megabase scale. This article reviews how local chromatin structures -e.g., DNA wrapped around nucleosomes, transcription factors bound to DNA- affect the mutation rate at a local scale. It dissects how the interaction of some mutagenic agents and/or DNA repair systems with these local structures influence the generation of mutations. We discuss how this local mutation rate variability affects our understanding of the evolution of the genomic sequence, and the study of the evolution of organisms and tumors.
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Affiliation(s)
- Abel Gonzalez-Perez
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; Research Program on Biomedical Informatics, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain.
| | - Radhakrishnan Sabarinathan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India.
| | - Nuria Lopez-Bigas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; Research Program on Biomedical Informatics, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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74
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Janel-Bintz R, Kuhn L, Frit P, Chicher J, Wagner J, Haracska L, Hammann P, Cordonnier AM. Proteomic Analysis of DNA Synthesis on a Structured DNA Template in Human Cellular Extracts: Interplay Between NHEJ and Replication-Associated Proteins. Proteomics 2020; 20:e1900184. [PMID: 31999075 DOI: 10.1002/pmic.201900184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 12/19/2019] [Indexed: 01/01/2023]
Abstract
It is established that short inverted repeats trigger base substitution mutagenesis in human cells. However, how the replication machinery deals with structured DNA is unknown. It has been previously reported that in human cell-free extracts, DNA primer extension using a structured single-stranded template is transiently blocked at DNA hairpins. Here, the proteomic analysis of proteins bound to the DNA template is reported and evidence that the DNA-PK complex (DNA-PKcs and the Ku heterodimer) recognizes, and is activated by, structured single-stranded DNA is provided. Hijacking the DNA-PK complex by double-stranded oligonucleotides results in a large removal of the pausing sites and an elevated DNA extension efficiency. Conversely, DNA-PKcs inhibition results in its stabilization on the template, along with other proteins acting downstream in the Non-Homologous End-Joining (NHEJ) pathway, especially the XRCC4-DNA ligase 4 complex and the cofactor PAXX. Retention of NHEJ factors to the DNA in the absence of DNA-PKcs activity correlates with additional halts of primer extension, suggesting that these proteins hinder the progression of the DNA synthesis at these sites. Overall these results raise the possibility that, upon binding to hairpins formed onto ssDNA during fork progression, the DNA-PK complex interferes with replication fork dynamics in vivo.
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Affiliation(s)
- Régine Janel-Bintz
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, CNRS, Illkirch, 67412, France
| | - Lauriane Kuhn
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Plateforme Protéomique Strasbourg - Esplanade, FR1589, 67084, Strasbourg, France
| | - Philippe Frit
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Johana Chicher
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Plateforme Protéomique Strasbourg - Esplanade, FR1589, 67084, Strasbourg, France
| | - Jérôme Wagner
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, CNRS, Illkirch, 67412, France
| | - Lajos Haracska
- Institute of Genetics, Biological Research Center, HU-6726, Szeged, Hungary
| | - Philippe Hammann
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Plateforme Protéomique Strasbourg - Esplanade, FR1589, 67084, Strasbourg, France
| | - Agnès M Cordonnier
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, CNRS, Illkirch, 67412, France
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75
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Del Mundo IMA, Cho EJ, Dalby KN, Vasquez KM. A 'light-up' intercalator displacement assay for detection of triplex DNA stabilizers. Chem Commun (Camb) 2020; 56:1996-1999. [PMID: 31960843 PMCID: PMC7323859 DOI: 10.1039/c9cc08817b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here, we developed a coralyne-based, 'light-up' intercalator displacement assay to identify molecular stabilizers of triplex DNA using a sequence from a chromosomal breakpoint hotspot in the human c-MYC oncogene. Its potential to identify triplex DNA ligands was demonstrated using BePI and doxorubicin. Identification of triplex-interacting ligands may allow the regulation of genetic instability in human genomes.
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Affiliation(s)
- Imee M A Del Mundo
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd., Austin, TX, USA.
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76
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Poetsch AR. The genomics of oxidative DNA damage, repair, and resulting mutagenesis. Comput Struct Biotechnol J 2020; 18:207-219. [PMID: 31993111 PMCID: PMC6974700 DOI: 10.1016/j.csbj.2019.12.013] [Citation(s) in RCA: 184] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/13/2019] [Accepted: 12/21/2019] [Indexed: 12/22/2022] Open
Abstract
Reactive oxygen species are a constant threat to DNA as they modify bases with the risk of disrupting genome function, inducing genome instability and mutation. Such risks are due to primary oxidative DNA damage and also mediated by the repair process. This leads to a delicate decision process for the cell as to whether to repair a damaged base at a specific genomic location or better leave it unrepaired. Persistent DNA damage can disrupt genome function, but on the other hand it can also contribute to gene regulation by serving as an epigenetic mark. When such processes are out of balance, pathophysiological conditions could get accelerated, because oxidative DNA damage and resulting mutagenic processes are tightly linked to ageing, inflammation, and the development of multiple age-related diseases, such as cancer and neurodegenerative disorders. Recent technological advancements and novel data analysis strategies have revealed that oxidative DNA damage, its repair, and related mutations distribute heterogeneously over the genome at multiple levels of resolution. The involved mechanisms act in the context of genome sequence, in interaction with genome function and chromatin. This review addresses what we currently know about the genome distribution of oxidative DNA damage, repair intermediates, and mutations. It will specifically focus on the various methodologies to measure oxidative DNA damage distribution and discuss the mechanistic conclusions derived from the different approaches. It will also address the consequences of oxidative DNA damage, specifically how it gives rise to mutations, genome instability, and how it can act as an epigenetic mark.
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77
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Ali M, Afshan N, Jiang C, Zheng H, Xiao SJ. 2D DNA lattice arrays assembled from DNA dumbbell tiles using poly(A-T)-rich stems. NANOSCALE 2019; 11:22216-22221. [PMID: 31728476 DOI: 10.1039/c9nr07911d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Poly(A-T)-rich sequences have been applied as stems of DNA dumbbell tiles for construction of single crystalline 2D DNA lattice arrays in slightly acidic solutions. These arrays show much higher stability and better organised crystalline lattice structures than those assembled from DNA dumbbell tiles with randomly sequenced stems in slightly alkaline environments. DNA nanotechnology probably provides a useful platform to study the mechanical properties of DNA duplexes with specific sequences.
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Affiliation(s)
- Mashooq Ali
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, Jiangsu, China.
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78
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Bacolla A, Ye Z, Ahmed Z, Tainer JA. Cancer mutational burden is shaped by G4 DNA, replication stress and mitochondrial dysfunction. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 147:47-61. [PMID: 30880007 PMCID: PMC6745008 DOI: 10.1016/j.pbiomolbio.2019.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 03/08/2019] [Accepted: 03/12/2019] [Indexed: 02/01/2023]
Abstract
A hallmark of cancer is genomic instability, which can enable cancer cells to evade therapeutic strategies. Here we employed a computational approach to uncover mechanisms underlying cancer mutational burden by focusing upon relationships between 1) translocation breakpoints and the thousands of G4 DNA-forming sequences within retrotransposons impacting transcription and exemplifying probable non-B DNA structures and 2) transcriptome profiling and cancer mutations. We determined the location and number of G4 DNA-forming sequences in the Genome Reference Consortium Human Build 38 and found a total of 358,605 covering ∼13.4 million bases. By analyzing >97,000 unique translocation breakpoints from the Catalogue Of Somatic Mutations In Cancer (COSMIC), we found that breakpoints are overrepresented at G4 DNA-forming sequences within hominid-specific SVA retrotransposons, and generally occur in tumors with mutations in tumor suppressor genes, such as TP53. Furthermore, correlation analyses between mRNA levels and exome mutational loads from The Cancer Genome Atlas (TCGA) encompassing >450,000 gene-mutation regressions revealed strong positive and negative associations, which depended upon tissue of origin. The strongest positive correlations originated from genes not listed as cancer genes in COSMIC; yet, these show strong predictive power for survival in most tumor types by Kaplan-Meier estimation. Thus, correlation analyses of DNA structure and gene expression with mutation loads complement and extend more traditional approaches to elucidate processes shaping genomic instability in cancer. The combined results point to G4 DNA, activation of cell cycle/DNA repair pathways, and mitochondrial dysfunction as three major factors driving the accumulation of somatic mutations in cancer cells.
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Affiliation(s)
- Albino Bacolla
- Departments of Cancer Biology and of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, 6767 Bertner Avenue, Houston, TX, 77030, USA.
| | - Zu Ye
- Departments of Cancer Biology and of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, 6767 Bertner Avenue, Houston, TX, 77030, USA.
| | - Zamal Ahmed
- Departments of Cancer Biology and of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, 6767 Bertner Avenue, Houston, TX, 77030, USA.
| | - John A Tainer
- Departments of Cancer Biology and of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, 6767 Bertner Avenue, Houston, TX, 77030, USA.
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79
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Hess JM, Bernards A, Kim J, Miller M, Taylor-Weiner A, Haradhvala NJ, Lawrence MS, Getz G. Passenger Hotspot Mutations in Cancer. Cancer Cell 2019; 36:288-301.e14. [PMID: 31526759 PMCID: PMC7371346 DOI: 10.1016/j.ccell.2019.08.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 05/15/2019] [Accepted: 08/06/2019] [Indexed: 01/04/2023]
Abstract
Current statistical models for assessing hotspot significance do not properly account for variation in site-specific mutability, thereby yielding many false-positives. We thus (i) detail a Log-normal-Poisson (LNP) background model that accounts for this variability in a manner consistent with models of mutagenesis; (ii) use it to show that passenger hotspots arise from all common mutational processes; and (iii) apply it to a ∼10,000-patient cohort to nominate driver hotspots with far fewer false-positives compared with conventional methods. Overall, we show that many cancer hotspot mutations recurring at the same genomic site across multiple tumors are actually passenger events, recurring at inherently mutable genomic sites under no positive selection.
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Affiliation(s)
- Julian M Hess
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Andre Bernards
- Center for Cancer Research, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, 250 Longwood Avenue, Boston, MA 02115, USA
| | - Jaegil Kim
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Mendy Miller
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Nicholas J Haradhvala
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for Cancer Research, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Michael S Lawrence
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for Cancer Research, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, 250 Longwood Avenue, Boston, MA 02115, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA.
| | - Gad Getz
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for Cancer Research, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, 250 Longwood Avenue, Boston, MA 02115, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA.
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80
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Supek F, Lehner B. Scales and mechanisms of somatic mutation rate variation across the human genome. DNA Repair (Amst) 2019; 81:102647. [PMID: 31307927 DOI: 10.1016/j.dnarep.2019.102647] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cancer genome sequencing has revealed that somatic mutation rates vary substantially across the human genome and at scales from megabase-sized domains to individual nucleotides. Here we review recent work that has both revealed the major mutation biases that operate across the genome and the molecular mechanisms that cause them. The default mutation rate landscape in mammalian genomes results in active genes having low mutation rates because of a combination of factors that increase DNA repair: early DNA replication, transcription, active chromatin modifications and accessible chromatin. Therefore, either an increase in the global mutation rate or a redistribution of mutations from inactive to active DNA can increase the rate at which consequential mutations are acquired in active genes. Several environmental carcinogens and intrinsic mechanisms operating in tumor cells likely cause cancer by this second mechanism: by specifically increasing the mutation rate in active regions of the genome.
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Affiliation(s)
- Fran Supek
- Genome Data Science, Institut de Recerca Biomedica (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028, Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain.
| | - Ben Lehner
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain; Systems Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Doctor Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
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81
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Buisson R, Langenbucher A, Bowen D, Kwan EE, Benes CH, Zou L, Lawrence MS. Passenger hotspot mutations in cancer driven by APOBEC3A and mesoscale genomic features. Science 2019; 364:eaaw2872. [PMID: 31249028 PMCID: PMC6731024 DOI: 10.1126/science.aaw2872] [Citation(s) in RCA: 186] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 05/23/2019] [Indexed: 12/12/2022]
Abstract
Cancer drivers require statistical modeling to distinguish them from passenger events, which accumulate during tumorigenesis but provide no fitness advantage to cancer cells. The discovery of driver genes and mutations relies on the assumption that exact positional recurrence is unlikely by chance; thus, the precise sharing of mutations across patients identifies drivers. Examining the mutation landscape in cancer genomes, we found that many recurrent cancer mutations previously designated as drivers are likely passengers. Our integrated bioinformatic and biochemical analyses revealed that these passenger hotspot mutations arise from the preference of APOBEC3A, a cytidine deaminase, for DNA stem-loops. Conversely, recurrent APOBEC-signature mutations not in stem-loops are enriched in well-characterized driver genes and may predict new drivers. This demonstrates that mesoscale genomic features need to be integrated into computational models aimed at identifying mutations linked to diseases.
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Affiliation(s)
- Rémi Buisson
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California, Irvine, CA, USA
| | - Adam Langenbucher
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
| | - Danae Bowen
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California, Irvine, CA, USA
| | - Eugene E Kwan
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
| | - Cyril H Benes
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Michael S Lawrence
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
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82
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Cheloshkina K, Poptsova M. Tissue-specific impact of stem-loops and quadruplexes on cancer breakpoints formation. BMC Cancer 2019; 19:434. [PMID: 31077166 PMCID: PMC6511154 DOI: 10.1186/s12885-019-5653-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/29/2019] [Indexed: 12/30/2022] Open
Abstract
Background Chromosomal rearrangements are the typical phenomena in cancer genomes causing gene disruptions and fusions, corruption of regulatory elements, damage to chromosome integrity. Among the factors contributing to genomic instability are non-B DNA structures with stem-loops and quadruplexes being the most prevalent. We aimed at investigating the impact of specifically these two classes of non-B DNA structures on cancer breakpoint hotspots using machine learning approach. Methods We developed procedure for machine learning model building and evaluation as the considered data are extremely imbalanced and it was required to get a reliable estimate of the prediction power. We built logistic regression models predicting cancer breakpoint hotspots based on the densities of stem-loops and quadruplexes, jointly and separately. We also tested Random Forest models varying different resampling schemes (leave-one-out cross validation, train-test split, 3-fold cross-validation) and class balancing techniques (oversampling, stratification, synthetic minority oversampling). Results We performed analysis of 487,425 breakpoints from 2234 samples covering 10 cancer types available from the International Cancer Genome Consortium. We showed that distribution of breakpoint hotspots in different types of cancer are not correlated, confirming the heterogeneous nature of cancer. It appeared that stem-loop-based model best explains the blood, brain, liver, and prostate cancer breakpoint hotspot profiles while quadruplex-based model has higher performance for the bone, breast, ovary, pancreatic, and skin cancer. For the overall cancer profile and uterus cancer the joint model shows the highest performance. For particular datasets the constructed models reach high predictive power using just one predictor, and in the majority of the cases, the model built on both predictors does not increase the model performance. Conclusion Despite the heterogeneity in breakpoint hotspots’ distribution across different cancer types, our results demonstrate an association between cancer breakpoint hotspots and stem-loops and quadruplexes. Approximately for half of the cancer types stem-loops are the most influential factors while for the others these are quadruplexes. This fact reflects the differences in regulatory potential of stem-loops and quadruplexes at the tissue-specific level, which yet to be discovered at the genome-wide scale. The performed analysis demonstrates that influence of stem-loops and quadruplexes on breakpoint hotspots formation is tissue-specific. Electronic supplementary material The online version of this article (10.1186/s12885-019-5653-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kseniia Cheloshkina
- Faculty of Computer Science, National Research University Higher School of Economics, 125319, Moscow, 3 Kochnovsky Proezd, Russia
| | - Maria Poptsova
- Faculty of Computer Science, National Research University Higher School of Economics, 125319, Moscow, 3 Kochnovsky Proezd, Russia.
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83
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Lerner LK, Sale JE. Replication of G Quadruplex DNA. Genes (Basel) 2019; 10:genes10020095. [PMID: 30700033 PMCID: PMC6409989 DOI: 10.3390/genes10020095] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 01/03/2023] Open
Abstract
A cursory look at any textbook image of DNA replication might suggest that the complex machine that is the replisome runs smoothly along the chromosomal DNA. However, many DNA sequences can adopt non-B form secondary structures and these have the potential to impede progression of the replisome. A picture is emerging in which the maintenance of processive DNA replication requires the action of a significant number of additional proteins beyond the core replisome to resolve secondary structures in the DNA template. By ensuring that DNA synthesis remains closely coupled to DNA unwinding by the replicative helicase, these factors prevent impediments to the replisome from causing genetic and epigenetic instability. This review considers the circumstances in which DNA forms secondary structures, the potential responses of the eukaryotic replisome to these impediments in the light of recent advances in our understanding of its structure and operation and the mechanisms cells deploy to remove secondary structure from the DNA. To illustrate the principles involved, we focus on one of the best understood DNA secondary structures, G quadruplexes (G4s), and on the helicases that promote their resolution.
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Affiliation(s)
- Leticia Koch Lerner
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Julian E Sale
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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