1
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Ramirez-Otero MA, Costanzo V. "Bridging the DNA divide": Understanding the interplay between replication- gaps and homologous recombination proteins RAD51 and BRCA1/2. DNA Repair (Amst) 2024; 141:103738. [PMID: 39084178 DOI: 10.1016/j.dnarep.2024.103738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 06/24/2024] [Accepted: 07/25/2024] [Indexed: 08/02/2024]
Abstract
A key but often neglected component of genomic instability is the emergence of single-stranded DNA (ssDNA) gaps during DNA replication in the absence of functional homologous recombination (HR) proteins, such as RAD51 and BRCA1/2. Research in prokaryotes has shed light on the dual role of RAD51's bacterial ortholog, RecA, in HR and the protection of replication forks, emphasizing its essential role in preventing the formation of ssDNA gaps, which is vital for cellular viability. This phenomenon was corroborated in eukaryotic cells deficient in HR, where the formation of ssDNA gaps within newly synthesized DNA and their subsequent processing by the MRE11 nuclease were observed. Without functional HR proteins, cells employ alternative ssDNA gap-filling mechanisms to ensure survival, though this compensatory response can compromise genomic stability. A notable example is the involvement of the translesion synthesis (TLS) polymerase POLζ, along with the repair protein POLθ, in the suppression of replicative ssDNA gaps. Persistent ssDNA gaps may result in replication fork collapse, chromosomal anomalies, and cell death, which contribute to cancer progression and resistance to therapy. Elucidating the processes that avert ssDNA gaps and safeguard replication forks is critical for enhancing cancer treatment approaches by exploiting the vulnerabilities of cancer cells in these pathways.
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Affiliation(s)
| | - Vincenzo Costanzo
- IFOM ETS - The AIRC Institute of Molecular Oncology, Italy; Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy.
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2
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Hanthi YW, Ramirez-Otero MA, Appleby R, De Antoni A, Joudeh L, Sannino V, Waked S, Ardizzoia A, Barra V, Fachinetti D, Pellegrini L, Costanzo V. RAD51 protects abasic sites to prevent replication fork breakage. Mol Cell 2024; 84:3026-3043.e11. [PMID: 39178838 DOI: 10.1016/j.molcel.2024.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 06/03/2024] [Accepted: 07/08/2024] [Indexed: 08/26/2024]
Abstract
Abasic sites are DNA lesions repaired by base excision repair. Cleavage of unrepaired abasic sites in single-stranded DNA (ssDNA) can lead to chromosomal breakage during DNA replication. How rupture of abasic DNA is prevented remains poorly understood. Here, using cryoelectron microscopy (cryo-EM), Xenopus laevis egg extracts, and human cells, we show that RAD51 nucleofilaments specifically recognize and protect abasic sites, which increase RAD51 association rate to DNA. In the absence of BRCA2 or RAD51, abasic sites accumulate as a result of DNA base methylation, oxidation, and deamination, inducing abasic ssDNA gaps that make replicating DNA fibers sensitive to APE1. RAD51 assembled on abasic DNA prevents abasic site cleavage by the MRE11-RAD50 complex, suppressing replication fork breakage triggered by an excess of abasic sites or POLθ polymerase inhibition. Our study highlights the critical role of BRCA2 and RAD51 in safeguarding against unrepaired abasic sites in DNA templates stemming from base alterations, ensuring genomic stability.
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Affiliation(s)
| | | | - Robert Appleby
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Anna De Antoni
- IFOM, The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Luay Joudeh
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | | | - Salli Waked
- IFOM, The AIRC Institute of Molecular Oncology, Milan, Italy
| | | | - Viviana Barra
- Institute Curie, PSL Research University, CNRS, UMR 144, 26 Rue d'Ulm, 75005 Paris, France
| | - Daniele Fachinetti
- Institute Curie, PSL Research University, CNRS, UMR 144, 26 Rue d'Ulm, 75005 Paris, France
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK.
| | - Vincenzo Costanzo
- IFOM, The AIRC Institute of Molecular Oncology, Milan, Italy; Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy.
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3
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Bennett L, Vernon E, Thanendran V, Jones C, Gamble A, Staples C. MRNIP limits ssDNA gaps during replication stress. Nucleic Acids Res 2024; 52:8320-8331. [PMID: 38917325 PMCID: PMC11317133 DOI: 10.1093/nar/gkae546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 06/10/2024] [Accepted: 06/14/2024] [Indexed: 06/27/2024] Open
Abstract
Replication repriming by the specialized primase-polymerase PRIMPOL ensures the continuity of DNA synthesis during replication stress. PRIMPOL activity generates residual post-replicative single-stranded nascent DNA gaps, which are linked with mutagenesis and chemosensitivity in BRCA1/2-deficient models, and which are suppressed by replication fork reversal mediated by the DNA translocases SMARCAL1 and ZRANB3. Here, we report that the MRE11 regulator MRNIP limits the prevalence of PRIMPOL and MRE11-dependent ssDNA gaps in cells in which fork reversal is perturbed either by treatment with the PARP inhibitor Olaparib, or by depletion of SMARCAL1 or ZRANB3. MRNIP-deficient cells are sensitive to PARP inhibition and accumulate PRIMPOL-dependent DNA damage, supportive of a pro-survival role for MRNIP linked to the regulation of gap prevalence. In MRNIP-deficient cells, post-replicative gap filling is driven in S-phase by UBC13-mediated template switching involving REV1 and the TLS polymerase Pol-ζ. Our findings represent the first report of modulation of post-replicative ssDNA gap dynamics by a direct MRE11 regulator.
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Affiliation(s)
- Laura G Bennett
- North West Cancer Research Institute, North Wales Medical School, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Ellen G Vernon
- North West Cancer Research Institute, North Wales Medical School, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Vithursha Thanendran
- North West Cancer Research Institute, North Wales Medical School, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Caryl M Jones
- North West Cancer Research Institute, North Wales Medical School, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Amelia Gamble
- North West Cancer Research Institute, North Wales Medical School, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Christopher J Staples
- North West Cancer Research Institute, North Wales Medical School, Bangor, Gwynedd, Wales LL57 2UW, UK
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4
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Khatib JB, Dhoonmoon A, Moldovan GL, Nicolae CM. PARP10 promotes the repair of nascent strand DNA gaps through RAD18 mediated translesion synthesis. Nat Commun 2024; 15:6197. [PMID: 39043663 PMCID: PMC11266678 DOI: 10.1038/s41467-024-50429-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 07/10/2024] [Indexed: 07/25/2024] Open
Abstract
Replication stress compromises genomic integrity. Fork blocking lesions such as those induced by cisplatin and other chemotherapeutic agents arrest replication forks. Repriming downstream of these lesions represents an important mechanism of replication restart, however the single stranded DNA (ssDNA) gaps left behind, unless efficiently filled, can serve as entry point for nucleases. Nascent strand gaps can be repaired by BRCA-mediated homology repair. Alternatively, gaps can also be filled by translesion synthesis (TLS) polymerases. How these events are regulated is still not clear. Here, we show that PARP10, a poorly-characterized mono-ADP-ribosyltransferase, is recruited to nascent strand gaps to promote their repair. PARP10 interacts with the ubiquitin ligase RAD18 and recruits it to these structures, resulting in the ubiquitination of the replication factor PCNA. PCNA ubiquitination, in turn, recruits the TLS polymerase REV1 for gap filling. We show that PARP10 recruitment to gaps and the subsequent REV1-mediated gap filling requires both the catalytic activity of PARP10, and its ability to interact with PCNA. We moreover show that PARP10 is hyperactive in BRCA-deficient cells, and its inactivation potentiates gap accumulations and cytotoxicity in these cells. Our work uncovers PARP10 as a regulator of ssDNA gap filling, which promotes genomic stability in BRCA-deficient cells.
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Affiliation(s)
- Jude B Khatib
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Ashna Dhoonmoon
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
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5
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Dibitetto D, Widmer CA, Rottenberg S. PARPi, BRCA, and gaps: controversies and future research. Trends Cancer 2024:S2405-8033(24)00134-1. [PMID: 39004561 DOI: 10.1016/j.trecan.2024.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/17/2024] [Accepted: 06/21/2024] [Indexed: 07/16/2024]
Abstract
In recent years, various poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) have been approved for the treatment of several cancers to target the vulnerability of homologous recombination (HR) deficiency (e.g., due to BRCA1/2 dysfunction). In this review we analyze the ongoing debates and recent breakthroughs in the use of PARPis for BRCA1/2-deficient cancers, juxtaposing the 'double-strand break (DSB)' and 'single-stranded DNA (ssDNA) gap' models of synthetic lethality induced by PARPis. We spotlight the complexity of this interaction, highlighting emerging research on the role of DNA polymerase theta (POLθ) and ssDNA gaps in shaping therapy responses. We scrutinize the clinical ramifications of these findings, especially concerning PARPi efficacy and resistance mechanisms, underscoring the heterogeneity of BRCA-mutated tumors and the urgent need for advanced research to bridge the gap between laboratory models and patient outcomes.
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Affiliation(s)
- Diego Dibitetto
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland; Bern Center for Precision Medicine and Cancer Therapy Research Cluster, Department for Biomedical Research, University of Bern, 3012 Bern, Switzerland; Molecular Oncology and DNA Damage Response Laboratory, Department of Experimental Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milan, Italy.
| | - Carmen A Widmer
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland; Bern Center for Precision Medicine and Cancer Therapy Research Cluster, Department for Biomedical Research, University of Bern, 3012 Bern, Switzerland
| | - Sven Rottenberg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland; Bern Center for Precision Medicine and Cancer Therapy Research Cluster, Department for Biomedical Research, University of Bern, 3012 Bern, Switzerland; Division of Molecular Pathology, The Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands.
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6
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Vekariya U, Minakhin L, Chandramouly G, Tyagi M, Kent T, Sullivan-Reed K, Atkins J, Ralph D, Nieborowska-Skorska M, Kukuyan AM, Tang HY, Pomerantz RT, Skorski T. PARG is essential for Polθ-mediated DNA end-joining by removing repressive poly-ADP-ribose marks. Nat Commun 2024; 15:5822. [PMID: 38987289 PMCID: PMC11236980 DOI: 10.1038/s41467-024-50158-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 06/27/2024] [Indexed: 07/12/2024] Open
Abstract
DNA polymerase theta (Polθ)-mediated end-joining (TMEJ) repairs DNA double-strand breaks and confers resistance to genotoxic agents. How Polθ is regulated at the molecular level to exert TMEJ remains poorly characterized. We find that Polθ interacts with and is PARylated by PARP1 in a HPF1-independent manner. PARP1 recruits Polθ to the vicinity of DNA damage via PARylation dependent liquid demixing, however, PARylated Polθ cannot perform TMEJ due to its inability to bind DNA. PARG-mediated de-PARylation of Polθ reactivates its DNA binding and end-joining activities. Consistent with this, PARG is essential for TMEJ and the temporal recruitment of PARG to DNA damage corresponds with TMEJ activation and dissipation of PARP1 and PAR. In conclusion, we show a two-step spatiotemporal mechanism of TMEJ regulation. First, PARP1 PARylates Polθ and facilitates its recruitment to DNA damage sites in an inactivated state. PARG subsequently activates TMEJ by removing repressive PAR marks on Polθ.
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Affiliation(s)
- Umeshkumar Vekariya
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Leonid Minakhin
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Gurushankar Chandramouly
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Mrityunjay Tyagi
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Tatiana Kent
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Katherine Sullivan-Reed
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Jessica Atkins
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Douglas Ralph
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Margaret Nieborowska-Skorska
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Anna-Mariya Kukuyan
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Hsin-Yao Tang
- Proteomics and Metabolomics Facility, The Wistar Institute, Philadelphia, PA, 19104, USA
| | - Richard T Pomerantz
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA.
| | - Tomasz Skorski
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA.
- Department of Cancer and Cellular Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA.
- Nuclear Dynamics and Cancer Program, Fox Chase Cancer Center, Philadelphia, PA, USA.
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7
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Carvajal-Maldonado D, Li Y, Returan M, Averill AM, Doublié S, Wood RD. Dynamic stem-loop extension by Pol θ and templated insertion during DNA repair. J Biol Chem 2024; 300:107461. [PMID: 38876299 PMCID: PMC11292364 DOI: 10.1016/j.jbc.2024.107461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/26/2024] [Accepted: 05/28/2024] [Indexed: 06/16/2024] Open
Abstract
Theta-mediated end joining (TMEJ) is critical for survival of cancer cells when other DNA double-stranded break repair pathways are impaired. Human DNA polymerase theta (Pol θ) can extend ssDNA oligonucleotides, but little is known about preferred substrates and mechanism. We show that Pol θ can extend both ssDNA and RNA substrates by unimolecular stem-loop synthesis initiated by only two 3' terminal base pairs. Given sufficient time, Pol θ uses alternative pairing configurations that greatly expand the repertoire of sequence outcomes. Further primer-template adjustments yield low-fidelity outcomes when the nucleotide pool is imbalanced. Unimolecular stem-loop synthesis competes with bimolecular end joining, even when a longer terminal microhomology for end joining is available. Both reactions are partially suppressed by the ssDNA-binding protein replication protein A. Protein-primer grasp residues that are specific to Pol θ are needed for rapid stem-loop synthesis. The ability to perform stem-loop synthesis from a minimally paired primer is rare among human DNA polymerases, but we show that human DNA polymerases Pol η and Pol λ can catalyze related reactions. Using purified human Pol θ, we reconstituted in vitro TMEJ incorporating an insertion arising from a stem-loop extension. These activities may help explain TMEJ repair events that include inverted repeat sequences.
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Affiliation(s)
- Denisse Carvajal-Maldonado
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA
| | - Yuzhen Li
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA
| | - Mark Returan
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA
| | - April M Averill
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA.
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8
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Miramova A, Gartner A, Ivanov D. How to sensitize glioblastomas to temozolomide chemotherapy: a gap-centered view. Front Cell Dev Biol 2024; 12:1436563. [PMID: 39011394 PMCID: PMC11246897 DOI: 10.3389/fcell.2024.1436563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Accepted: 06/17/2024] [Indexed: 07/17/2024] Open
Abstract
Temozolomide (TMZ) is a methylating agent used as the first-line drug in the chemotherapy of glioblastomas. However, cancer cells eventually acquire resistance, necessitating the development of TMZ-potentiating therapy agents. TMZ induces several DNA base adducts, including O 6 -meG, 3-meA, and 7-meG. TMZ cytotoxicity stems from the ability of these adducts to directly (3-meA) or indirectly (O 6 -meG) impair DNA replication. Although TMZ toxicity is generally attributed to O 6 -meG, other alkylated bases can be similarly important depending on the status of various DNA repair pathways of the treated cells. In this mini-review we emphasize the necessity to distinguish TMZ-sensitive glioblastomas, which do not express methylguanine-DNA methyltransferase (MGMT) and are killed by the futile cycle of mismatch repair (MMR) of the O 6 -meG/T pairs, vs. TMZ-resistant MGMT-positive or MMR-negative glioblastomas, which are selected in the course of the treatment and are killed only at higher TMZ doses by the replication-blocking 3-meA. These two types of cells can be TMZ-sensitized by inhibiting different DNA repair pathways. However, in both cases, the toxic intermediates appear to be ssDNA gaps, a vulnerability also seen in BRCA-deficient cancers. PARP inhibitors (PARPi), which were initially developed to treat BRCA1/2-deficient cancers by synthetic lethality, were re-purposed in clinical trials to potentiate the effects of TMZ. We discuss how the recent advances in our understanding of the genetic determinants of TMZ toxicity might lead to new approaches for the treatment of glioblastomas by inhibiting PARP1 and other enzymes involved in the repair of alkylation damage (e.g., APE1).
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Affiliation(s)
- Alila Miramova
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Anton Gartner
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
- Graduate School for Health Sciences and Technology, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea
| | - Dmitri Ivanov
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea
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9
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Técher H, Gopaul D, Heuzé J, Bouzalmad N, Leray B, Vernet A, Mettling C, Moreaux J, Pasero P, Lin YL. MRE11 and TREX1 control senescence by coordinating replication stress and interferon signaling. Nat Commun 2024; 15:5423. [PMID: 38926338 PMCID: PMC11208572 DOI: 10.1038/s41467-024-49740-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 06/14/2024] [Indexed: 06/28/2024] Open
Abstract
Oncogene-induced senescence (OIS) arrests cell proliferation in response to replication stress (RS) induced by oncogenes. OIS depends on the DNA damage response (DDR), but also on the cGAS-STING pathway, which detects cytosolic DNA and induces type I interferons (IFNs). Whether and how RS and IFN responses cooperate to promote OIS remains unknown. Here, we show that the induction of OIS by the H-RASV12 oncogene in immortalized human fibroblasts depends on the MRE11 nuclease. Indeed, treatment with the MRE11 inhibitor Mirin prevented RS, micronuclei formation and IFN response induced by RASV12. Overexpression of the cytosolic nuclease TREX1 also prevented OIS. Conversely, overexpression of a dominant negative mutant of TREX1 or treatment with IFN-β was sufficient to induce RS and DNA damage, independent of RASV12 induction. These data suggest that the IFN response acts as a positive feedback loop to amplify DDR in OIS through a process regulated by MRE11 and TREX1.
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Affiliation(s)
- Hervé Técher
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, CNRS UMR7284 - INSERM U1081, Nice, France
| | - Diyavarshini Gopaul
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France
- Biotech Research and Innovation Centre, University of Copenhagen, 2200 N, Copenhagen, Denmark
| | - Jonathan Heuzé
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France
| | - Nail Bouzalmad
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France
| | - Baptiste Leray
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France
| | - Audrey Vernet
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France
| | - Clément Mettling
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
| | - Jérôme Moreaux
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
- Department of Biological Hematology, CHU Montpellier, Montpellier, France
- University of Montpellier, UFR Medicine, Montpellier, France
| | - Philippe Pasero
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France.
| | - Yea-Lih Lin
- Institut de Génétique Humaine, University of Montpellier, CNRS, Equipe Labellisée Ligue contre le Cancer, Montpellier, France.
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10
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García-Rodríguez N, Domínguez-García I, Domínguez-Pérez MD, Huertas P. EXO1 and DNA2-mediated ssDNA gap expansion is essential for ATR activation and to maintain viability in BRCA1-deficient cells. Nucleic Acids Res 2024; 52:6376-6391. [PMID: 38721777 PMCID: PMC11194085 DOI: 10.1093/nar/gkae317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 03/25/2024] [Accepted: 05/02/2024] [Indexed: 06/25/2024] Open
Abstract
DNA replication faces challenges from DNA lesions originated from endogenous or exogenous sources of stress, leading to the accumulation of single-stranded DNA (ssDNA) that triggers the activation of the ATR checkpoint response. To complete genome replication in the presence of damaged DNA, cells employ DNA damage tolerance mechanisms that operate not only at stalled replication forks but also at ssDNA gaps originated by repriming of DNA synthesis downstream of lesions. Here, we demonstrate that human cells accumulate post-replicative ssDNA gaps following replicative stress induction. These gaps, initiated by PrimPol repriming and expanded by the long-range resection factors EXO1 and DNA2, constitute the principal origin of the ssDNA signal responsible for ATR activation upon replication stress, in contrast to stalled forks. Strikingly, the loss of EXO1 or DNA2 results in synthetic lethality when combined with BRCA1 deficiency, but not BRCA2. This phenomenon aligns with the observation that BRCA1 alone contributes to the expansion of ssDNA gaps. Remarkably, BRCA1-deficient cells become addicted to the overexpression of EXO1, DNA2 or BLM. This dependence on long-range resection unveils a new vulnerability of BRCA1-mutant tumors, shedding light on potential therapeutic targets for these cancers.
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Affiliation(s)
- Néstor García-Rodríguez
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
| | - Iria Domínguez-García
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
| | - María del Carmen Domínguez-Pérez
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
| | - Pablo Huertas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
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11
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Saxena S, Nabel CS, Seay TW, Patel PS, Kawale AS, Crosby CR, Tigro H, Oh E, Vander Heiden MG, Hata AN, Suo Z, Zou L. Unprocessed genomic uracil as a source of DNA replication stress in cancer cells. Mol Cell 2024; 84:2036-2052.e7. [PMID: 38688279 PMCID: PMC11162326 DOI: 10.1016/j.molcel.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 03/26/2024] [Accepted: 04/05/2024] [Indexed: 05/02/2024]
Abstract
Alterations of bases in DNA constitute a major source of genomic instability. It is believed that base alterations trigger base excision repair (BER), generating DNA repair intermediates interfering with DNA replication. Here, we show that genomic uracil, a common type of base alteration, induces DNA replication stress (RS) without being processed by BER. In the absence of uracil DNA glycosylase (UNG), genomic uracil accumulates to high levels, DNA replication forks slow down, and PrimPol-mediated repriming is enhanced, generating single-stranded gaps in nascent DNA. ATR inhibition in UNG-deficient cells blocks the repair of uracil-induced gaps, increasing replication fork collapse and cell death. Notably, a subset of cancer cells upregulates UNG2 to suppress genomic uracil and limit RS, and these cancer cells are hypersensitive to co-treatment with ATR inhibitors and drugs increasing genomic uracil. These results reveal unprocessed genomic uracil as an unexpected source of RS and a targetable vulnerability of cancer cells.
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Affiliation(s)
- Sneha Saxena
- Mass General Cancer Center, Harvard Medical School, Charlestown, MA, USA
| | - Christopher S Nabel
- Mass General Cancer Center, Harvard Medical School, Charlestown, MA, USA; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Turner W Seay
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Parasvi S Patel
- Mass General Cancer Center, Harvard Medical School, Charlestown, MA, USA
| | - Ajinkya S Kawale
- Mass General Cancer Center, Harvard Medical School, Charlestown, MA, USA
| | - Caroline R Crosby
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Helene Tigro
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Eugene Oh
- Mass General Cancer Center, Harvard Medical School, Charlestown, MA, USA
| | - Matthew G Vander Heiden
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Medical Oncology, Dana Farber Cancer Institute, Boston, MA, USA
| | - Aaron N Hata
- Mass General Cancer Center, Harvard Medical School, Charlestown, MA, USA; Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Zucai Suo
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Lee Zou
- Mass General Cancer Center, Harvard Medical School, Charlestown, MA, USA; Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA.
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12
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Hill BR, Ozgencil M, Buckley-Benbow L, Skingsley SLP, Tomlinson D, Eizmendi CO, Agnarelli A, Bellelli R. Loss of POLE3-POLE4 unleashes replicative gap accumulation upon treatment with PARP inhibitors. Cell Rep 2024; 43:114205. [PMID: 38753485 DOI: 10.1016/j.celrep.2024.114205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 04/06/2024] [Accepted: 04/23/2024] [Indexed: 05/18/2024] Open
Abstract
The advent of PARP inhibitors (PARPis) has profoundly changed the treatment landscape of BRCA1/BRCA2-mutated cancers. Despite this, the development of resistance to these compounds has become a major challenge. Hence, a detailed understanding of the mechanisms underlying PARPi sensitivity is crucially needed. Here, we show that loss of the POLE3-POLE4 subunits of DNA polymerase epsilon (Polε) strongly sensitizes cancer cells to PARPis in a Polε level-independent manner. Loss of POLE3-POLE4 is not associated with defective RAD51 foci formation, excluding a major defect in homologous recombination. On the contrary, treatment with PARPis triggers replicative gap accumulation in POLE3-POLE4 knockout (KO) cells in a PRIMPOL-dependent manner. In addition to this, the loss of POLE3-POLE4 further sensitizes BRCA1-silenced cells to PARPis. Importantly, the knockdown of 53BP1 does not rescue PARPi sensitivity in POLE3-POLE4 KO cells, bypassing a common PARPi resistance mechanism and outlining a potential strategy to sensitize cancer cells to PARPis.
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Affiliation(s)
- Bethany Rebekah Hill
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK
| | - Meryem Ozgencil
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK
| | - Lauryn Buckley-Benbow
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK
| | - Sophie Louise Pamela Skingsley
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK
| | - Danielle Tomlinson
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK
| | - Carmen Ortueta Eizmendi
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK
| | - Alessandro Agnarelli
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK
| | - Roberto Bellelli
- Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK.
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13
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Dibitetto D, Liptay M, Vivalda F, Dogan H, Gogola E, González Fernández M, Duarte A, Schmid JA, Decollogny M, Francica P, Przetocka S, Durant ST, Forment JV, Klebic I, Siffert M, de Bruijn R, Kousholt AN, Marti NA, Dettwiler M, Sørensen CS, Tille JC, Undurraga M, Labidi-Galy I, Lopes M, Sartori AA, Jonkers J, Rottenberg S. H2AX promotes replication fork degradation and chemosensitivity in BRCA-deficient tumours. Nat Commun 2024; 15:4430. [PMID: 38789420 PMCID: PMC11126719 DOI: 10.1038/s41467-024-48715-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Histone H2AX plays a key role in DNA damage signalling in the surrounding regions of DNA double-strand breaks (DSBs). In response to DNA damage, H2AX becomes phosphorylated on serine residue 139 (known as γH2AX), resulting in the recruitment of the DNA repair effectors 53BP1 and BRCA1. Here, by studying resistance to poly(ADP-ribose) polymerase (PARP) inhibitors in BRCA1/2-deficient mammary tumours, we identify a function for γH2AX in orchestrating drug-induced replication fork degradation. Mechanistically, γH2AX-driven replication fork degradation is elicited by suppressing CtIP-mediated fork protection. As a result, H2AX loss restores replication fork stability and increases chemoresistance in BRCA1/2-deficient tumour cells without restoring homology-directed DNA repair, as highlighted by the lack of DNA damage-induced RAD51 foci. Furthermore, in the attempt to discover acquired genetic vulnerabilities, we find that ATM but not ATR inhibition overcomes PARP inhibitor (PARPi) resistance in H2AX-deficient tumours by interfering with CtIP-mediated fork protection. In summary, our results demonstrate a role for H2AX in replication fork biology in BRCA-deficient tumours and establish a function of H2AX separable from its classical role in DNA damage signalling and DSB repair.
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Affiliation(s)
- Diego Dibitetto
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland.
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland.
- Department of Experimental Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, via Mario Negri 2, 20156, Milan, Italy.
| | - Martin Liptay
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland
| | - Francesca Vivalda
- Institute of Molecular Cancer Research, University of Zürich, Zürich, Switzerland
| | - Hülya Dogan
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland
| | - Ewa Gogola
- Division of Molecular Pathology, The Netherlands Cancer Institute, 1066CX, Amsterdam, The Netherlands
- Oncode Institute, Amsterdam, The Netherlands
| | - Martín González Fernández
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland
| | - Alexandra Duarte
- Division of Molecular Pathology, The Netherlands Cancer Institute, 1066CX, Amsterdam, The Netherlands
- Oncode Institute, Amsterdam, The Netherlands
| | - Jonas A Schmid
- Institute of Molecular Cancer Research, University of Zürich, Zürich, Switzerland
| | - Morgane Decollogny
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland
| | - Paola Francica
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland
| | - Sara Przetocka
- Institute of Molecular Cancer Research, University of Zürich, Zürich, Switzerland
| | - Stephen T Durant
- DDR Biology, Bioscience, Oncology R&D, AstraZeneca, Cambridge, CB4 0WG, UK
| | - Josep V Forment
- DDR Biology, Bioscience, Oncology R&D, AstraZeneca, Cambridge, CB4 0WG, UK
| | - Ismar Klebic
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
| | - Myriam Siffert
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
| | - Roebi de Bruijn
- Division of Molecular Pathology, The Netherlands Cancer Institute, 1066CX, Amsterdam, The Netherlands
- Oncode Institute, Amsterdam, The Netherlands
| | - Arne N Kousholt
- Oncode Institute, Amsterdam, The Netherlands
- Biotech Research and Innovation Centre, University of Copenhagen, 2200 N, Copenhagen, Denmark
| | - Nicole A Marti
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland
| | - Martina Dettwiler
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland
| | - Claus S Sørensen
- Biotech Research and Innovation Centre, University of Copenhagen, 2200 N, Copenhagen, Denmark
| | - Jean-Christophe Tille
- Division of Clinical Pathology, Department of Diagnostics, Hôpitaux Universitaires de Genève, Geneva, Switzerland
| | - Manuela Undurraga
- Division of Gynecology, Department of Pediatrics and Gynecology, Hôpitaux Universitaires de Genève, Geneva, Switzerland
| | - Intidhar Labidi-Galy
- Faculty of Medicine, Department of Medicine and Center of Translational Research in Onco-Hematology, University of Geneva, Swiss Cancer Center Leman, Geneva, Switzerland
- Department of Oncology, Hôpitaux Universitaires de Genève, 4, Rue Gabrielle Perret-Gentil, Geneva, 1205, Switzerland
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zürich, Zürich, Switzerland
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zürich, Zürich, Switzerland
| | - Jos Jonkers
- Division of Molecular Pathology, The Netherlands Cancer Institute, 1066CX, Amsterdam, The Netherlands.
- Oncode Institute, Amsterdam, The Netherlands.
| | - Sven Rottenberg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012, Bern, Switzerland.
- Cancer Therapy Resistance Cluster and Bern Center for Precision Medicine, Department for Biomedical Research, University of Bern, 3012, Bern, Switzerland.
- Division of Molecular Pathology, The Netherlands Cancer Institute, 1066CX, Amsterdam, The Netherlands.
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14
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Schreuder A, Wendel TJ, Dorresteijn CGV, Noordermeer SM. (Single-stranded DNA) gaps in understanding BRCAness. Trends Genet 2024:S0168-9525(24)00100-8. [PMID: 38789375 DOI: 10.1016/j.tig.2024.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/26/2024]
Abstract
The tumour-suppressive roles of BRCA1 and 2 have been attributed to three seemingly distinct functions - homologous recombination, replication fork protection, and single-stranded (ss)DNA gap suppression - and their relative importance is under debate. In this review, we examine the origin and resolution of ssDNA gaps and discuss the recent advances in understanding the role of BRCA1/2 in gap suppression. There are ample data showing that gap accumulation in BRCA1/2-deficient cells is linked to genomic instability and chemosensitivity. However, it remains unclear whether there is a causative role and the function of BRCA1/2 in gap suppression cannot unambiguously be dissected from their other functions. We therefore conclude that the three functions of BRCA1 and 2 are closely intertwined and not mutually exclusive.
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Affiliation(s)
- Anne Schreuder
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands
| | - Tiemen J Wendel
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands
| | - Carlo G V Dorresteijn
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands
| | - Sylvie M Noordermeer
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands.
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15
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Wu S, Yao X, Sun W, Jiang K, Hao J. Exploration of poly (ADP-ribose) polymerase inhibitor resistance in the treatment of BRCA1/2-mutated cancer. Genes Chromosomes Cancer 2024; 63:e23243. [PMID: 38747337 DOI: 10.1002/gcc.23243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Accepted: 04/19/2024] [Indexed: 05/21/2024] Open
Abstract
Breast cancer susceptibility 1/2 (BRCA1/2) genes play a crucial role in DNA damage repair, yet mutations in these genes increase the susceptibility to tumorigenesis. Exploiting the synthetic lethality mechanism between BRCA1/2 mutations and poly(ADP-ribose) polymerase (PARP) inhibition has led to the development and clinical approval of PARP inhibitor (PARPi), representing a milestone in targeted therapy for BRCA1/2 mutant tumors. This approach has paved the way for leveraging synthetic lethality in tumor treatment strategies. Despite the initial success of PARPis, resistance to these agents diminishes their efficacy in BRCA1/2-mutant tumors. Investigations into PARPi resistance have identified replication fork stability and homologous recombination repair as key factors sensitive to PARPis. Additionally, studies suggest that replication gaps may also confer sensitivity to PARPis. Moreover, emerging evidence indicates a correlation between PARPi resistance and cisplatin resistance, suggesting a potential overlap in the mechanisms underlying resistance to both agents. Given these findings, it is imperative to explore the interplay between replication gaps and PARPi resistance, particularly in the context of platinum resistance. Understanding the impact of replication gaps on PARPi resistance may offer insights into novel therapeutic strategies to overcome resistance mechanisms and enhance the efficacy of targeted therapies in BRCA1/2-mutant tumors.
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Affiliation(s)
- Shuyi Wu
- School of Life Sciences, Zhejiang Chinese Medicine University, HangZhou, China
| | - Xuanjie Yao
- The Fourth Clinical Medical College, Zhejiang Chinese Medicine University, HangZhou, China
| | - Weiwei Sun
- School of Life Sciences, Zhejiang Chinese Medicine University, HangZhou, China
| | - Kaitao Jiang
- School of Life Sciences, Zhejiang Chinese Medicine University, HangZhou, China
| | - Jie Hao
- School of Life Sciences, Zhejiang Chinese Medicine University, HangZhou, China
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16
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Fried W, Tyagi M, Minakhin L, Chandramouly G, Tredinnick T, Ramanjulu M, Auerbacher W, Calbert M, Rusanov T, Hoang T, Borisonnik N, Betsch R, Krais JJ, Wang Y, Vekariya UM, Gordon J, Morton G, Kent T, Skorski T, Johnson N, Childers W, Chen XS, Pomerantz RT. Discovery of a small-molecule inhibitor that traps Polθ on DNA and synergizes with PARP inhibitors. Nat Commun 2024; 15:2862. [PMID: 38580648 PMCID: PMC10997755 DOI: 10.1038/s41467-024-46593-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 03/04/2024] [Indexed: 04/07/2024] Open
Abstract
The DNA damage response (DDR) protein DNA Polymerase θ (Polθ) is synthetic lethal with homologous recombination (HR) factors and is therefore a promising drug target in BRCA1/2 mutant cancers. We discover an allosteric Polθ inhibitor (Polθi) class with 4-6 nM IC50 that selectively kills HR-deficient cells and acts synergistically with PARP inhibitors (PARPi) in multiple genetic backgrounds. X-ray crystallography and biochemistry reveal that Polθi selectively inhibits Polθ polymerase (Polθ-pol) in the closed conformation on B-form DNA/DNA via an induced fit mechanism. In contrast, Polθi fails to inhibit Polθ-pol catalytic activity on A-form DNA/RNA in which the enzyme binds in the open configuration. Remarkably, Polθi binding to the Polθ-pol:DNA/DNA closed complex traps the polymerase on DNA for more than forty minutes which elucidates the inhibitory mechanism of action. These data reveal a unique small-molecule DNA polymerase:DNA trapping mechanism that induces synthetic lethality in HR-deficient cells and potentiates the activity of PARPi.
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Affiliation(s)
- William Fried
- Molecular and Computational Biology, Department of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Mrityunjay Tyagi
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Leonid Minakhin
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Gurushankar Chandramouly
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Taylor Tredinnick
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Mercy Ramanjulu
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
| | - William Auerbacher
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Marissa Calbert
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
| | - Timur Rusanov
- Department of Pharmacology and Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | | | | | - Robert Betsch
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - John J Krais
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Yifan Wang
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Umeshkumar M Vekariya
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
- Department of Cancer and Cellular Biology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, USA
| | - John Gordon
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
| | - George Morton
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Tatiana Kent
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Tomasz Skorski
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
- Department of Cancer and Cellular Biology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, USA
| | - Neil Johnson
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Wayne Childers
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Xiaojiang S Chen
- Molecular and Computational Biology, Department of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
| | - Richard T Pomerantz
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA.
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA.
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17
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Meroni A, Wells SE, Fonseca C, Ray Chaudhuri A, Caldecott KW, Vindigni A. DNA combing versus DNA spreading and the separation of sister chromatids. J Cell Biol 2024; 223:e202305082. [PMID: 38315097 PMCID: PMC10840220 DOI: 10.1083/jcb.202305082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 12/01/2023] [Accepted: 01/22/2024] [Indexed: 02/07/2024] Open
Abstract
DNA combing and DNA spreading are two central approaches for studying DNA replication fork dynamics genome-wide at single-molecule resolution by distributing labeled genomic DNA on coverslips or slides for immunodetection. Perturbations in DNA replication fork dynamics can differentially affect either leading or lagging strand synthesis, for example, in instances where replication is blocked by a lesion or obstacle on only one of the two strands. Thus, we sought to investigate whether the DNA combing and/or spreading approaches are suitable for resolving adjacent sister chromatids during DNA replication, thereby enabling the detection of DNA replication dynamics within individual nascent strands. To this end, we developed a thymidine labeling scheme that discriminates between these two possibilities. Our data suggests that DNA combing resolves sister chromatids, allowing the detection of strand-specific alterations, whereas DNA spreading typically does not. These findings have important implications when interpreting DNA replication dynamics from data obtained by these two commonly used techniques.
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Affiliation(s)
- Alice Meroni
- Division of Oncology, Department of Medicine, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Sophie E. Wells
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer Brighton, UK
| | - Carmen Fonseca
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Arnab Ray Chaudhuri
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Keith W. Caldecott
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer Brighton, UK
| | - Alessandro Vindigni
- Division of Oncology, Department of Medicine, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
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18
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Cong K, MacGilvary N, Lee S, MacLeod SG, Calvo J, Peng M, Nedergaard Kousholt A, Day TA, Cantor SB. FANCJ promotes PARP1 activity during DNA replication that is essential in BRCA1 deficient cells. Nat Commun 2024; 15:2599. [PMID: 38521768 PMCID: PMC10960859 DOI: 10.1038/s41467-024-46824-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 03/07/2024] [Indexed: 03/25/2024] Open
Abstract
The effectiveness of poly (ADP-ribose) polymerase inhibitors (PARPi) in creating single-stranded DNA gaps and inducing sensitivity requires the FANCJ DNA helicase. Yet, how FANCJ relates to PARP1 inhibition or trapping, which contribute to PARPi toxicity, remains unclear. Here, we find PARPi effectiveness hinges on S-phase PARP1 activity, which is reduced in FANCJ deficient cells as G-quadruplexes sequester PARP1 and MSH2. Additionally, loss of the FANCJ-MLH1 interaction diminishes PARP1 activity; however, depleting MSH2 reinstates PARPi sensitivity and gaps. Indicating sequestered and trapped PARP1 are distinct, FANCJ loss increases PARPi resistance in cells susceptible to PARP1 trapping. However, with BRCA1 deficiency, the loss of FANCJ mirrors PARP1 loss or inhibition, with the detrimental commonality being loss of S-phase PARP1 activity. These insights underline the crucial role of PARP1 activity during DNA replication in BRCA1 deficient cells and emphasize the importance of understanding drug mechanisms for enhancing therapeutic response.
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Affiliation(s)
- Ke Cong
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Nathan MacGilvary
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Silviana Lee
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Shannon G MacLeod
- Northeastern University Biology Department 360 Huntington Avenue, Mugar Life Science Building, Rm 220, Boston, MA, 02115-5005, USA
| | - Jennifer Calvo
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Min Peng
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Arne Nedergaard Kousholt
- Division of Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, 1066CX, Amsterdam, the Netherlands
| | - Tovah A Day
- Northeastern University Biology Department 360 Huntington Avenue, Mugar Life Science Building, Rm 220, Boston, MA, 02115-5005, USA
| | - Sharon B Cantor
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA.
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19
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Nusawardhana A, Pale LM, Nicolae CM, Moldovan GL. USP1-dependent nucleolytic expansion of PRIMPOL-generated nascent DNA strand discontinuities during replication stress. Nucleic Acids Res 2024; 52:2340-2354. [PMID: 38180818 PMCID: PMC10954467 DOI: 10.1093/nar/gkad1237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 12/11/2023] [Accepted: 12/15/2023] [Indexed: 01/07/2024] Open
Abstract
DNA replication stress-induced fork arrest represents a significant threat to genomic integrity. One major mechanism of replication restart involves repriming downstream of the arrested fork by PRIMPOL, leaving behind a single-stranded DNA (ssDNA) gap. Accumulation of nascent strand ssDNA gaps has emerged as a possible determinant of the cellular hypersensitivity to genotoxic agents in certain genetic backgrounds such as BRCA deficiency, but how gaps are converted into cytotoxic structures is still unclear. Here, we investigate the processing of PRIMPOL-dependent ssDNA gaps upon replication stress induced by hydroxyurea and cisplatin. We show that gaps generated in PRIMPOL-overexpressing cells are expanded in the 3'-5' direction by the MRE11 exonuclease, and in the 5'-3' direction by the EXO1 exonuclease. This bidirectional exonucleolytic gap expansion ultimately promotes their conversion into DSBs. We moreover identify the de-ubiquitinating enzyme USP1 as a critical regulator of PRIMPOL-generated ssDNA gaps. USP1 promotes gap accumulation during S-phase, and their expansion by the MRE11 and EXO1 nucleases. This activity of USP1 is linked to its role in de-ubiquitinating PCNA, suggesting that PCNA ubiquitination prevents gap accumulation during replication. Finally, we show that USP1 depletion suppresses DSB formation in PRIMPOL-overexpressing cells, highlighting an unexpected role for USP1 in promoting genomic instability under these conditions.
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Affiliation(s)
- Alexandra Nusawardhana
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Lindsey M Pale
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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20
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van de Kooij B, Schreuder A, Pavani R, Garzero V, Uruci S, Wendel TJ, van Hoeck A, San Martin Alonso M, Everts M, Koerse D, Callen E, Boom J, Mei H, Cuppen E, Luijsterburg MS, van Vugt MATM, Nussenzweig A, van Attikum H, Noordermeer SM. EXO1 protects BRCA1-deficient cells against toxic DNA lesions. Mol Cell 2024; 84:659-674.e7. [PMID: 38266640 DOI: 10.1016/j.molcel.2023.12.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 10/14/2023] [Accepted: 12/22/2023] [Indexed: 01/26/2024]
Abstract
Inactivating mutations in the BRCA1 and BRCA2 genes impair DNA double-strand break (DSB) repair by homologous recombination (HR), leading to chromosomal instability and cancer. Importantly, BRCA1/2 deficiency also causes therapeutically targetable vulnerabilities. Here, we identify the dependency on the end resection factor EXO1 as a key vulnerability of BRCA1-deficient cells. EXO1 deficiency generates poly(ADP-ribose)-decorated DNA lesions during S phase that associate with unresolved DSBs and genomic instability in BRCA1-deficient but not in wild-type or BRCA2-deficient cells. Our data indicate that BRCA1/EXO1 double-deficient cells accumulate DSBs due to impaired repair by single-strand annealing (SSA) on top of their HR defect. In contrast, BRCA2-deficient cells retain SSA activity in the absence of EXO1 and hence tolerate EXO1 loss. Consistent with a dependency on EXO1-mediated SSA, we find that BRCA1-mutated tumors show elevated EXO1 expression and increased SSA-associated genomic scars compared with BRCA1-proficient tumors. Overall, our findings uncover EXO1 as a promising therapeutic target for BRCA1-deficient tumors.
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Affiliation(s)
- Bert van de Kooij
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands; Department of Medical Oncology, University Medical Center Groningen, Groningen 9713 GZ, the Netherlands
| | - Anne Schreuder
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands; Oncode Institute, Utrecht 3521 AL, the Netherlands
| | - Raphael Pavani
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Veronica Garzero
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands; Oncode Institute, Utrecht 3521 AL, the Netherlands
| | - Sidrit Uruci
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands
| | - Tiemen J Wendel
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands; Oncode Institute, Utrecht 3521 AL, the Netherlands
| | - Arne van Hoeck
- Oncode Institute, Utrecht 3521 AL, the Netherlands; Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht 3584 CG, the Netherlands
| | - Marta San Martin Alonso
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands; Oncode Institute, Utrecht 3521 AL, the Netherlands
| | - Marieke Everts
- Department of Medical Oncology, University Medical Center Groningen, Groningen 9713 GZ, the Netherlands
| | - Dana Koerse
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands
| | - Elsa Callen
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jasper Boom
- Sequencing Analysis Support Core, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands
| | - Hailiang Mei
- Sequencing Analysis Support Core, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands
| | - Edwin Cuppen
- Oncode Institute, Utrecht 3521 AL, the Netherlands; Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht 3584 CG, the Netherlands; Hartwig Medical Foundation, Amsterdam 1098 XH, the Netherlands
| | - Martijn S Luijsterburg
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands
| | - Marcel A T M van Vugt
- Department of Medical Oncology, University Medical Center Groningen, Groningen 9713 GZ, the Netherlands
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Haico van Attikum
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands.
| | - Sylvie M Noordermeer
- Department of Human Genetics, Leiden University Medical Centre, Leiden 2333 ZC, the Netherlands; Oncode Institute, Utrecht 3521 AL, the Netherlands.
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21
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Lim PX, Zaman M, Feng W, Jasin M. BRCA2 promotes genomic integrity and therapy resistance primarily through its role in homology-directed repair. Mol Cell 2024; 84:447-462.e10. [PMID: 38244544 PMCID: PMC11188060 DOI: 10.1016/j.molcel.2023.12.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 10/10/2023] [Accepted: 12/15/2023] [Indexed: 01/22/2024]
Abstract
Tumor suppressor BRCA2 functions in homology-directed repair (HDR), the protection of stalled replication forks, and the suppression of replicative gaps, but their relative contributions to genome integrity and chemotherapy response are under scrutiny. Here, we report that mouse and human cells require a RAD51 filament stabilization motif in BRCA2 for fork protection and gap suppression but not HDR. In mice, the loss of fork protection/gap suppression does not compromise genome stability or shorten tumor latency. By contrast, HDR deficiency increases spontaneous and replication stress-induced chromosome aberrations and tumor predisposition. Unlike with HDR, fork protection/gap suppression defects are also observed in Brca2 heterozygous cells, likely due to reduced RAD51 stabilization at stalled forks/gaps. Gaps arise from PRIMPOL activity, which is associated with 5-hydroxymethyl-2'-deoxyuridine sensitivity due to the formation of SMUG1-generated abasic sites and is exacerbated by poly(ADP-ribose) polymerase (PARP) inhibition. However, HDR proficiency has the major role in mitigating sensitivity to chemotherapeutics, including PARP inhibitors.
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Affiliation(s)
- Pei Xin Lim
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Mahdia Zaman
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Weiran Feng
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.
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22
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Cong K, MacGilvary N, Lee S, MacLeod SG, Calvo J, Peng M, Kousholt AN, Day T, Cantor SB. FANCJ promotes PARP1 activity during DNA replication that is essential in BRCA1 deficient cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.04.574095. [PMID: 38260529 PMCID: PMC10802319 DOI: 10.1101/2024.01.04.574095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Single-stranded DNA gaps are postulated to be fundamental to the mechanism of anti-cancer drugs. Gaining insights into their induction could therefore be pivotal for advancing therapeutic strategies. For poly (ADP-ribose) polymerase inhibitors (PARPi) to be effective, the presence of FANCJ helicase is required. However, the relationship between FANCJ dependent gaps and PARP1 catalytic inhibition or trapping-both linked to PARPi toxicity in BRCA deficient cells-is yet to be elucidated. Here, we find that the efficacy of PARPi is contingent on S-phase PARP1 activity, which is compromised in FANCJ deficient cells because PARP1, along with MSH2, is "sequestered" by G-quadruplexes. PARP1's replication activity is also diminished in cells missing a FANCJ-MLH1 interaction, but in such cells, depleting MSH2 can release sequestered PARP1, restoring PARPi-induced gaps and sensitivity. Our observations indicate that sequestered and trapped PARP1 are different chromatin-bound forms, with FANCJ loss increasing PARPi resistance in cells susceptible to canonical PARP1 trapping. However, in BRCA1 null cells, the loss of FANCJ mirrors the effects of PARP1 loss or inhibition, with the common detrimental factor being the loss of PARP1 activity during DNA replication, not trapping. These insights underline the crucial role of PARP1 activity during DNA replication in BRCA deficient cells and emphasize the importance of understanding drug mechanisms for enhancing precision medicine.
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23
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Khatib JB, Nicolae CM, Moldovan GL. Role of Translesion DNA Synthesis in the Metabolism of Replication-associated Nascent Strand Gaps. J Mol Biol 2024; 436:168275. [PMID: 37714300 PMCID: PMC10842951 DOI: 10.1016/j.jmb.2023.168275] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/11/2023] [Accepted: 09/08/2023] [Indexed: 09/17/2023]
Abstract
Translesion DNA synthesis (TLS) is a DNA damage tolerance pathway utilized by cells to overcome lesions encountered throughout DNA replication. During replication stress, cancer cells show increased dependency on TLS proteins for cellular survival and chemoresistance. TLS proteins have been described to be involved in various DNA repair pathways. One of the major emerging roles of TLS is single-stranded DNA (ssDNA) gap-filling, primarily after the repriming activity of PrimPol upon encountering a lesion. Conversely, suppression of ssDNA gap accumulation by TLS is considered to represent a mechanism for cancer cells to evade the toxicity of chemotherapeutic agents, specifically in BRCA-deficient cells. Thus, TLS inhibition is emerging as a potential treatment regimen for DNA repair-deficient tumors.
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Affiliation(s)
- Jude B Khatib
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA. https://twitter.com/JudeBKhatib
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
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24
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Ronson GE, Starowicz K, Anthony EJ, Piberger AL, Clarke LC, Garvin AJ, Beggs AD, Whalley CM, Edmonds MJ, Beesley JFJ, Morris JR. Mechanisms of synthetic lethality between BRCA1/2 and 53BP1 deficiencies and DNA polymerase theta targeting. Nat Commun 2023; 14:7834. [PMID: 38030626 PMCID: PMC10687250 DOI: 10.1038/s41467-023-43677-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 11/16/2023] [Indexed: 12/01/2023] Open
Abstract
A synthetic lethal relationship exists between disruption of polymerase theta (Polθ), and loss of either 53BP1 or homologous recombination (HR) proteins, including BRCA1; however, the mechanistic basis of these observations are unclear. Here we reveal two distinct mechanisms of Polθ synthetic lethality, identifying dual influences of 1) whether Polθ is lost or inhibited, and 2) the underlying susceptible genotype. Firstly, we find that the sensitivity of BRCA1/2- and 53BP1-deficient cells to Polθ loss, and 53BP1-deficient cells to Polθ inhibition (ART558) requires RAD52, and appropriate reduction of RAD52 can ameliorate these phenotypes. We show that in the absence of Polθ, RAD52 accumulations suppress ssDNA gap-filling in G2/M and encourage MRE11 nuclease accumulation. In contrast, the survival of BRCA1-deficient cells treated with Polθ inhibitor are not restored by RAD52 suppression, and ssDNA gap-filling is prevented by the chemically inhibited polymerase itself. These data define an additional role for Polθ, reveal the mechanism underlying synthetic lethality between 53BP1, BRCA1/2 and Polθ loss, and indicate genotype-dependent Polθ inhibitor mechanisms.
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Affiliation(s)
- George E Ronson
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Katarzyna Starowicz
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
- Adthera Bio, Lyndon House, 62 Hagley Road, Birmingham, B16 8PE, UK
| | - Elizabeth J Anthony
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Ann Liza Piberger
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Lucy C Clarke
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
- West Midlands Regional Genetics Laboratory, Birmingham Women's Hospital, Mindelsohn Way, Birmingham, B15 2TG, UK
| | - Alexander J Garvin
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
- University of Leeds, Leeds, UK
| | - Andrew D Beggs
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
- Genomics Birmingham, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Celina M Whalley
- Genomics Birmingham, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Matthew J Edmonds
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
- Certara Insight, Danebrook Court, Oxford Office Village, Kidlington, Oxfordshire, OX5 1LQ, UK
| | - James F J Beesley
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Joanna R Morris
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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25
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Krais JJ, Glass DJ, Chudoba I, Wang Y, Feng W, Simpson D, Patel P, Liu Z, Neumann-Domer R, Betsch RG, Bernhardy AJ, Bradbury AM, Conger J, Yueh WT, Nacson J, Pomerantz RT, Gupta GP, Testa JR, Johnson N. Genetic separation of Brca1 functions reveal mutation-dependent Polθ vulnerabilities. Nat Commun 2023; 14:7714. [PMID: 38001070 PMCID: PMC10673838 DOI: 10.1038/s41467-023-43446-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 11/09/2023] [Indexed: 11/26/2023] Open
Abstract
Homologous recombination (HR)-deficiency induces a dependency on DNA polymerase theta (Polθ/Polq)-mediated end joining, and Polθ inhibitors (Polθi) are in development for cancer therapy. BRCA1 and BRCA2 deficient cells are thought to be synthetic lethal with Polθ, but whether distinct HR gene mutations give rise to equivalent Polθ-dependence, and the events that drive lethality, are unclear. In this study, we utilized mouse models with separate Brca1 functional defects to mechanistically define Brca1-Polθ synthetic lethality. Surprisingly, homozygous Brca1 mutant, Polq-/- cells were viable, but grew slowly and had chromosomal instability. Brca1 mutant cells proficient in DNA end resection were significantly more dependent on Polθ for viability; here, treatment with Polθi elevated RPA foci, which persisted through mitosis. In an isogenic system, BRCA1 null cells were defective, but PALB2 and BRCA2 mutant cells exhibited active resection, and consequently stronger sensitivity to Polθi. Thus, DNA end resection is a critical determinant of Polθi sensitivity in HR-deficient cells, and should be considered when selecting patients for clinical studies.
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Affiliation(s)
- John J Krais
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA.
| | - David J Glass
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
- Temple University, Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Ilse Chudoba
- MetaSystems Probes, GmbH, Industriestr, 68804, Altlussheim, Germany
| | - Yifan Wang
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Wanjuan Feng
- Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Dennis Simpson
- Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Pooja Patel
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Zemin Liu
- Cytogenetics Laboratory, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Ryan Neumann-Domer
- Cytogenetics Laboratory, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Robert G Betsch
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Andrea J Bernhardy
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Alice M Bradbury
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Jason Conger
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Wei-Ting Yueh
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Joseph Nacson
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Richard T Pomerantz
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Gaorav P Gupta
- Cancer Control and Prevention Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Joseph R Testa
- Cytogenetics Laboratory, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
- Cancer Control and Prevention Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Neil Johnson
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
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26
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Stroik S, Carvajal-Garcia J, Gupta D, Edwards A, Luthman A, Wyatt DW, Dannenberg RL, Feng W, Kunkel TA, Gupta GP, Hedglin M, Wood R, Doublié S, Rothenberg E, Ramsden DA. Stepwise requirements for polymerases δ and θ in theta-mediated end joining. Nature 2023; 623:836-841. [PMID: 37968395 PMCID: PMC10959172 DOI: 10.1038/s41586-023-06729-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 10/06/2023] [Indexed: 11/17/2023]
Abstract
Timely repair of chromosomal double-strand breaks is required for genome integrity and cellular viability. The polymerase theta-mediated end joining pathway has an important role in resolving these breaks and is essential in cancers defective in other DNA repair pathways, thus making it an emerging therapeutic target1. It requires annealing of 2-6 nucleotides of complementary sequence, microhomologies, that are adjacent to the broken ends, followed by initiation of end-bridging DNA synthesis by polymerase θ. However, the other pathway steps remain inadequately defined, and the enzymes required for them are unknown. Here we demonstrate requirements for exonucleolytic digestion of unpaired 3' tails before polymerase θ can initiate synthesis, then a switch to a more accurate, processive and strand-displacing polymerase to complete repair. We show the replicative polymerase, polymerase δ, is required for both steps; its 3' to 5' exonuclease activity for flap trimming, then its polymerase activity for extension and completion of repair. The enzymatic steps that are essential and specific to this pathway are mediated by two separate, sequential engagements of the two polymerases. The requisite coupling of these steps together is likely to be facilitated by physical association of the two polymerases. This pairing of polymerase δ with a polymerase capable of end-bridging synthesis, polymerase θ, may help to explain why the normally high-fidelity polymerase δ participates in genome destabilizing processes such as mitotic DNA synthesis2 and microhomology-mediated break-induced replication3.
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Affiliation(s)
- Susanna Stroik
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Dipika Gupta
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Alyssa Edwards
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Adam Luthman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - David W Wyatt
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Wanjuan Feng
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Gaorav P Gupta
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Richard Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center and The University of Texas MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, USA
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Dale A Ramsden
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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27
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Paniagua I, Jacobs JJL. Freedom to err: The expanding cellular functions of translesion DNA polymerases. Mol Cell 2023; 83:3608-3621. [PMID: 37625405 DOI: 10.1016/j.molcel.2023.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/02/2023] [Accepted: 07/07/2023] [Indexed: 08/27/2023]
Abstract
Translesion synthesis (TLS) DNA polymerases were originally described as error-prone enzymes involved in the bypass of DNA lesions. However, extensive research over the past few decades has revealed that these enzymes play pivotal roles not only in lesion bypass, but also in a myriad of other cellular processes. Such processes include DNA replication, DNA repair, epigenetics, immune signaling, and even viral infection. This review discusses the wide range of functions exhibited by TLS polymerases, including their underlying biochemical mechanisms and associated mutagenicity. Given their multitasking ability to alleviate replication stress, TLS polymerases represent a cellular dependency and a critical vulnerability of cancer cells. Hence, this review also highlights current and emerging strategies for targeting TLS polymerases in cancer therapy.
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Affiliation(s)
- Inés Paniagua
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, the Netherlands
| | - Jacqueline J L Jacobs
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, the Netherlands.
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28
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Hale A, Dhoonmoon A, Straka J, Nicolae CM, Moldovan GL. Multi-step processing of replication stress-derived nascent strand DNA gaps by MRE11 and EXO1 nucleases. Nat Commun 2023; 14:6265. [PMID: 37805499 PMCID: PMC10560291 DOI: 10.1038/s41467-023-42011-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 09/27/2023] [Indexed: 10/09/2023] Open
Abstract
Accumulation of single stranded DNA (ssDNA) gaps in the nascent strand during DNA replication has been associated with cytotoxicity and hypersensitivity to genotoxic stress, particularly upon inactivation of the BRCA tumor suppressor pathway. However, how ssDNA gaps contribute to genotoxicity is not well understood. Here, we describe a multi-step nucleolytic processing of replication stress-induced ssDNA gaps which converts them into cytotoxic double stranded DNA breaks (DSBs). We show that ssDNA gaps are extended bidirectionally by MRE11 in the 3'-5' direction and by EXO1 in the 5'-3' direction, in a process which is suppressed by the BRCA pathway. Subsequently, the parental strand at the ssDNA gap is cleaved by the MRE11 endonuclease generating a double strand break. We also show that exposure to bisphenol A (BPA) and diethylhexyl phthalate (DEHP), which are widespread environmental contaminants due to their use in plastics manufacturing, causes nascent strand ssDNA gaps during replication. These gaps are processed through the same mechanism described above to generate DSBs. Our work sheds light on both the relevance of ssDNA gaps as major determinants of genomic instability, as well as the mechanism through which they are processed to generate genomic instability and cytotoxicity.
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Affiliation(s)
- Anastasia Hale
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Ashna Dhoonmoon
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Joshua Straka
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
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Mladenov E, Mladenova V, Stuschke M, Iliakis G. New Facets of DNA Double Strand Break Repair: Radiation Dose as Key Determinant of HR versus c-NHEJ Engagement. Int J Mol Sci 2023; 24:14956. [PMID: 37834403 PMCID: PMC10573367 DOI: 10.3390/ijms241914956] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/01/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Radiation therapy is an essential component of present-day cancer management, utilizing ionizing radiation (IR) of different modalities to mitigate cancer progression. IR functions by generating ionizations in cells that induce a plethora of DNA lesions. The most detrimental among them are the DNA double strand breaks (DSBs). In the course of evolution, cells of higher eukaryotes have evolved four major DSB repair pathways: classical non-homologous end joining (c-NHEJ), homologous recombination (HR), alternative end-joining (alt-EJ), and single strand annealing (SSA). These mechanistically distinct repair pathways have different cell cycle- and homology-dependencies but, surprisingly, they operate with widely different fidelity and kinetics and therefore contribute unequally to cell survival and genome maintenance. It is therefore reasonable to anticipate tight regulation and coordination in the engagement of these DSB repair pathway to achieve the maximum possible genomic stability. Here, we provide a state-of-the-art review of the accumulated knowledge on the molecular mechanisms underpinning these repair pathways, with emphasis on c-NHEJ and HR. We discuss factors and processes that have recently come to the fore. We outline mechanisms steering DSB repair pathway choice throughout the cell cycle, and highlight the critical role of DNA end resection in this process. Most importantly, however, we point out the strong preference for HR at low DSB loads, and thus low IR doses, for cells irradiated in the G2-phase of the cell cycle. We further explore the molecular underpinnings of transitions from high fidelity to low fidelity error-prone repair pathways and analyze the coordination and consequences of this transition on cell viability and genomic stability. Finally, we elaborate on how these advances may help in the development of improved cancer treatment protocols in radiation therapy.
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Affiliation(s)
- Emil Mladenov
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (V.M.); (M.S.)
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany
| | - Veronika Mladenova
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (V.M.); (M.S.)
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (V.M.); (M.S.)
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, 45147 Essen, Germany
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - George Iliakis
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (V.M.); (M.S.)
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany
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30
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Rein HL, Bernstein KA. Finding significance: New perspectives in variant classification of the RAD51 regulators, BRCA2 and beyond. DNA Repair (Amst) 2023; 130:103563. [PMID: 37651978 PMCID: PMC10529980 DOI: 10.1016/j.dnarep.2023.103563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/11/2023] [Accepted: 08/15/2023] [Indexed: 09/02/2023]
Abstract
For many individuals harboring a variant of uncertain functional significance (VUS) in a homologous recombination (HR) gene, their risk of developing breast and ovarian cancer is unknown. Integral to the process of HR are BRCA1 and regulators of the central HR protein, RAD51, including BRCA2, PALB2, RAD51C and RAD51D. Due to advancements in sequencing technology and the continued expansion of cancer screening panels, the number of VUS identified in these genes has risen significantly. Standard practices for variant classification utilize different types of predictive, population, phenotypic, allelic and functional evidence. While variant analysis is improving, there remains a struggle to keep up with demand. Understanding the effects of an HR variant can aid in preventative care and is critical for developing an effective cancer treatment plan. In this review, we discuss current perspectives in the classification of variants in the breast and ovarian cancer genes BRCA1, BRCA2, PALB2, RAD51C and RAD51D.
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Affiliation(s)
- Hayley L Rein
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, USA
| | - Kara A Bernstein
- University of Pennsylvania School of Medicine, Department of Biochemistry and Biophysics, 421 Curie Boulevard, Philadelphia, PA, USA.
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31
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Brambati A, Sacco O, Porcella S, Heyza J, Kareh M, Schmidt JC, Sfeir A. RHINO directs MMEJ to repair DNA breaks in mitosis. Science 2023; 381:653-660. [PMID: 37440612 PMCID: PMC10561558 DOI: 10.1126/science.adh3694] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/30/2023] [Indexed: 07/15/2023]
Abstract
Nonhomologous end-joining (NHEJ) and homologous recombination (HR) are the primary pathways for repairing DNA double-strand breaks (DSBs) during interphase, whereas microhomology-mediated end-joining (MMEJ) has been regarded as a backup mechanism. Through CRISPR-Cas9-based synthetic lethal screens in cancer cells, we identified subunits of the 9-1-1 complex (RAD9A-RAD1-HUS1) and its interacting partner, RHINO, as crucial MMEJ factors. We uncovered an unexpected function for RHINO in restricting MMEJ to mitosis. RHINO accumulates in M phase, undergoes Polo-like kinase 1 (PLK1) phosphorylation, and interacts with polymerase θ (Polθ), enabling its recruitment to DSBs for subsequent repair. Additionally, we provide evidence that MMEJ activity in mitosis repairs persistent DSBs that originate in S phase. Our findings offer insights into the synthetic lethal relationship between the genes POLQ and BRCA1 and BRAC2 and the synergistic effect of Polθ and poly(ADP-ribose) polymerase (PARP) inhibitors.
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Affiliation(s)
- Alessandra Brambati
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Olivia Sacco
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Sarina Porcella
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Joshua Heyza
- Institute for Quantitative Health Sciences and Engineering, Michigan State University; East Lansing, MI, USA
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University; East Lansing, MI, USA
| | - Mike Kareh
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Jens C. Schmidt
- Institute for Quantitative Health Sciences and Engineering, Michigan State University; East Lansing, MI, USA
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University; East Lansing, MI, USA
| | - Agnel Sfeir
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
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32
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Leung W, Simoneau A, Saxena S, Jackson J, Patel PS, Limbu M, Vindigni A, Zou L. ATR protects ongoing and newly assembled DNA replication forks through distinct mechanisms. Cell Rep 2023; 42:112792. [PMID: 37454295 PMCID: PMC10529362 DOI: 10.1016/j.celrep.2023.112792] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 06/06/2023] [Accepted: 06/27/2023] [Indexed: 07/18/2023] Open
Abstract
The ATR kinase safeguards genomic integrity during S phase, but how ATR protects DNA replication forks remains incompletely understood. Here, we combine four distinct assays to analyze ATR functions at ongoing and newly assembled replication forks upon replication inhibition by hydroxyurea. At ongoing forks, ATR inhibitor (ATRi) increases MRE11- and EXO1-mediated nascent DNA degradation from PrimPol-generated, single-stranded DNA (ssDNA) gaps. ATRi also exposes template ssDNA through fork uncoupling and nascent DNA degradation. Electron microscopy reveals that ATRi reduces reversed forks by increasing gap-dependent nascent DNA degradation. At new forks, ATRi triggers MRE11- and CtIP-initiated template DNA degradation by EXO1, exposing nascent ssDNA. Upon PARP inhibition, ATRi preferentially exacerbates gap-dependent nascent DNA degradation at ongoing forks in BRCA1/2-deficient cells and disrupts the restored gap protection in BRCA1-deficient, PARP-inhibitor-resistant cells. Thus, ATR protects ongoing and new forks through distinct mechanisms, providing an extended view of ATR's functions in stabilizing replication forks.
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Affiliation(s)
- Wendy Leung
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Antoine Simoneau
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Sneha Saxena
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Jessica Jackson
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Parasvi S Patel
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Mangsi Limbu
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alessandro Vindigni
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA; Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115, USA; Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27708, USA.
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33
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Lavudi K, Banerjee A, Li N, Yang Y, Cai S, Bai X, Zhang X, Li A, Wani E, Yang SM, Zhang J, Rai G, Backes F, Patnaik S, Guo P, Wang QE. ALDH1A1 promotes PARP inhibitor resistance by enhancing retinoic acid receptor-mediated DNA polymerase θ expression. NPJ Precis Oncol 2023; 7:66. [PMID: 37429899 DOI: 10.1038/s41698-023-00411-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 05/30/2023] [Indexed: 07/12/2023] Open
Abstract
Poly (ADP-ribose) Polymerase (PARP) inhibitors (PARPi) have been approved for both frontline and recurrent setting in ovarian cancer with homologous recombination (HR) repair deficiency. However, more than 40% of BRCA1/2-mutated ovarian cancer lack the initial response to PARPi treatment, and the majority of those that initially respond eventually develop resistance. Our previous study has demonstrated that increased expression of aldehyde dehydrogenase 1A1 (ALDH1A1) contributes to PARPi resistance in BRCA2-mutated ovarian cancer cells by enhancing microhomology-mediated end joining (MMEJ) but the mechanism remains unknown. Here, we find that ALDH1A1 enhances the expression of DNA polymerase θ (Polθ, encoded by the POLQ gene) in ovarian cancer cells. Furthermore, we demonstrate that the retinoic acid (RA) pathway is involved in the transcription activation of the POLQ gene. The RA receptor (RAR) can bind to the retinoic acid response element (RARE) located in the promoter of the POLQ gene, promoting transcription activation-related histone modification in the presence of RA. Given that ALDH1A1 catalyzes the biosynthesis of RA, we conclude that ALDH1A1 promotes POLQ expression via the activation of the RA signaling pathway. Finally, using a clinically-relevant patient-derived organoid (PDO) model, we find that ALDH1A1 inhibition by the pharmacological inhibitor NCT-505 in combination with the PARP inhibitor olaparib synergistically reduce the cell viability of PDOs carrying BRCA1/2 mutation and positive ALDH1A1 expression. In summary, our study elucidates a new mechanism contributing to PARPi resistance in HR-deficient ovarian cancer and shows the therapeutic potential of combining PARPi and ALDH1A1 inhibition in treating these patients.
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Affiliation(s)
- Kousalya Lavudi
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA
| | - Ananya Banerjee
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA
| | - Na Li
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA
| | - Yajing Yang
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA
| | - Shurui Cai
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA
| | - Xuetao Bai
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA
| | - Xiaoli Zhang
- Department of Biomedical Informatics, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Aidan Li
- Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Elsa Wani
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Shyh-Ming Yang
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, USA
| | - Junran Zhang
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA
| | - Ganesha Rai
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, USA
| | - Floor Backes
- Department of Obstetrics & Gynecology, Division of Gynecologic Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Srinivas Patnaik
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, 751024, India
| | - Peixuan Guo
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
- Center for RNA Nanobiotechnology and Nanomedicine, Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH, 43210, USA
| | - Qi-En Wang
- Department of Radiation Oncology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA.
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.
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34
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Casimir L, Zimmer S, Racine-Brassard F, Goudreau F, Jacques PÉ, Maréchal A. Chronic treatment with ATR and CHK1 inhibitors does not substantially increase the mutational burden of human cells. Mutat Res 2023; 827:111834. [PMID: 37531716 DOI: 10.1016/j.mrfmmm.2023.111834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/13/2023] [Accepted: 07/19/2023] [Indexed: 08/04/2023]
Abstract
DNA replication stress (RS) entails the frequent slow down and arrest of replication forks by a variety of conditions that hinder accurate and processive genome duplication. Elevated RS leads to genome instability, replication catastrophe and eventually cell death. RS is particularly prevalent in cancer cells and its exacerbation to unsustainable levels by chemotherapeutic agents remains a cornerstone of cancer treatments. The adverse consequences of RS are normally prevented by the ATR and CHK1 checkpoint kinases that stabilize stressed forks, suppress origin firing and promote cell cycle arrest when replication is perturbed. Specific inhibitors of these kinases have been developed and shown to potentiate RS and cell death in multiple in vitro cancer settings. Ongoing clinical trials are now probing their efficacy against various cancer types, either as single agents or in combination with mainstay chemotherapeutics. Despite their promise as valuable additions to the anti-cancer pharmacopoeia, we still lack a genome-wide view of the potential mutagenicity of these new drugs. To investigate this question, we performed chronic long-term treatments of TP53-depleted human cancer cells with ATR and CHK1 inhibitors (ATRi, AZD6738/ceralasertib and CHK1i, MK8776/SCH-900776). ATR or CHK1 inhibition did not significantly increase the mutational burden of cells, nor generate specific mutational signatures. Indeed, no notable changes in the numbers of base substitutions, short insertions/deletions and larger scale rearrangements were observed despite induction of replication-associated DNA breaks during treatments. Interestingly, ATR inhibition did induce a slight increase in closely-spaced mutations, a feature previously attributed to translesion synthesis DNA polymerases. The results suggest that ATRi and CHK1i do not have substantial mutagenic effects in vitro when used as standalone agents.
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Affiliation(s)
- Lisa Casimir
- Département de Biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, QC, Canada; Institut de Recherche sur le Cancer de l'Université de Sherbrooke (IRCUS), Sherbrooke J1K 2R1, QC, Canada
| | - Samuel Zimmer
- Département de Biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, QC, Canada; Institut de Recherche sur le Cancer de l'Université de Sherbrooke (IRCUS), Sherbrooke J1K 2R1, QC, Canada
| | - Félix Racine-Brassard
- Département de Biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, QC, Canada; Institut de Recherche sur le Cancer de l'Université de Sherbrooke (IRCUS), Sherbrooke J1K 2R1, QC, Canada
| | - Félix Goudreau
- Département de Biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, QC, Canada; Institut de Recherche sur le Cancer de l'Université de Sherbrooke (IRCUS), Sherbrooke J1K 2R1, QC, Canada
| | - Pierre-Étienne Jacques
- Département de Biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, QC, Canada; Institut de Recherche sur le Cancer de l'Université de Sherbrooke (IRCUS), Sherbrooke J1K 2R1, QC, Canada; Centre de recherche du Centre hospitalier universitaire de Sherbrooke (CRCHUS), Sherbrooke J1H 5N3, QC, Canada.
| | - Alexandre Maréchal
- Département de Biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, QC, Canada; Institut de Recherche sur le Cancer de l'Université de Sherbrooke (IRCUS), Sherbrooke J1K 2R1, QC, Canada; Centre de recherche du Centre hospitalier universitaire de Sherbrooke (CRCHUS), Sherbrooke J1H 5N3, QC, Canada.
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35
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Fleury H, MacEachern MK, Stiefel CM, Anand R, Sempeck C, Nebenfuehr B, Maurer-Alcalá K, Ball K, Proctor B, Belan O, Taylor E, Ortega R, Dodd B, Weatherly L, Dansoko D, Leung JW, Boulton SJ, Arnoult N. The APE2 nuclease is essential for DNA double-strand break repair by microhomology-mediated end joining. Mol Cell 2023; 83:1429-1445.e8. [PMID: 37044098 PMCID: PMC10164096 DOI: 10.1016/j.molcel.2023.03.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 01/18/2023] [Accepted: 03/16/2023] [Indexed: 04/14/2023]
Abstract
Microhomology-mediated end joining (MMEJ) is an intrinsically mutagenic pathway of DNA double-strand break (DSB) repair essential for proliferation of homologous recombination (HR)-deficient tumors. Although targeting MMEJ has emerged as a powerful strategy to eliminate HR-deficient (HRD) cancers, this is limited by an incomplete understanding of the mechanism and factors required for MMEJ repair. Here, we identify the APE2 nuclease as an MMEJ effector. We show that loss of APE2 inhibits MMEJ at deprotected telomeres and at intra-chromosomal DSBs and is epistatic with Pol Theta for MMEJ activity. Mechanistically, we demonstrate that APE2 possesses intrinsic flap-cleaving activity, that its MMEJ function in cells depends on its nuclease activity, and further identify an uncharacterized domain required for its recruitment to DSBs. We conclude that this previously unappreciated role of APE2 in MMEJ contributes to the addiction of HRD cells to APE2, which could be exploited in the treatment of cancer.
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Affiliation(s)
- Hubert Fleury
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Myles K MacEachern
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Clara M Stiefel
- Department of Radiation Oncology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Roopesh Anand
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK
| | - Colin Sempeck
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Benjamin Nebenfuehr
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Kelper Maurer-Alcalá
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Kerri Ball
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Bruce Proctor
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Ondrej Belan
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK
| | - Erin Taylor
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Raquel Ortega
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Benjamin Dodd
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Laila Weatherly
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Djelika Dansoko
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Justin W Leung
- Department of Radiation Oncology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Simon J Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK; Artios Pharma Ltd, Babraham Research Campus, Cambridge CB22 3FH, UK
| | - Nausica Arnoult
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO, USA.
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36
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Pismataro MC, Astolfi A, Barreca ML, Pacetti M, Schenone S, Bandiera T, Carbone A, Massari S. Small Molecules Targeting DNA Polymerase Theta (POLθ) as Promising Synthetic Lethal Agents for Precision Cancer Therapy. J Med Chem 2023; 66:6498-6522. [PMID: 37134182 DOI: 10.1021/acs.jmedchem.2c02101] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Synthetic lethality (SL) is an innovative strategy in targeted anticancer therapy that exploits tumor genetic vulnerabilities. This topic has come to the forefront in recent years, as witnessed by the increased number of publications since 2007. The first proof of concept for the effectiveness of SL was provided by the approval of poly(ADP-ribose)polymerase inhibitors, which exploit a SL interaction in BRCA-deficient cells, although their use is limited by resistance. Searching for additional SL interactions involving BRCA mutations, the DNA polymerase theta (POLθ) emerged as an exciting target. This review summarizes, for the first time, the POLθ polymerase and helicase inhibitors reported to date. Compounds are described focusing on chemical structure and biological activity. With the aim to enable further drug discovery efforts in interrogating POLθ as a target, we propose a plausible pharmacophore model for POLθ-pol inhibitors and provide a structural analysis of the known POLθ ligand binding sites.
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Affiliation(s)
- Maria Chiara Pismataro
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Andrea Astolfi
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Maria Letizia Barreca
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Martina Pacetti
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Silvia Schenone
- Department of Pharmacy, University of Genoa, Viale Benedetto XV 3, 16132 Genoa, Italy
| | - Tiziano Bandiera
- D3 PharmaChemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Anna Carbone
- Department of Pharmacy, University of Genoa, Viale Benedetto XV 3, 16132 Genoa, Italy
| | - Serena Massari
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
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37
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Meroni A, Wells SE, Fonseca C, Ray Chaudhuri A, Caldecott KW, Vindigni A. DNA Combing versus DNA Spreading and the Separation of Sister Chromatids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.02.539129. [PMID: 37205507 PMCID: PMC10187196 DOI: 10.1101/2023.05.02.539129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
DNA combing and DNA spreading are two central approaches for studying DNA replication fork dynamics genome-wide at single-molecule resolution by distributing labeled genomic DNA on coverslips or slides for immunodetection. Perturbations in DNA replication fork dynamics can differentially affect either leading or lagging strand synthesis, for example in instances where replication is blocked by a lesion or obstacle on only one of the two strands. Thus, we sought to investigate whether the DNA combing and/or spreading approaches are suitable for resolving adjacent sister chromatids during DNA replication, thereby enabling the detection of DNA replication dynamics within individual nascent strands. To this end, we developed a thymidine labeling scheme that discriminates between these two possibilities. Our data suggests that DNA combing resolves single chromatids, allowing the detection of strand-specific alterations, whereas DNA spreading does not. These findings have important implications when interpreting DNA replication dynamics from data obtained by these two commonly used techniques.
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38
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Di Biagi L, Malacaria E, Aiello FA, Valenzisi P, Marozzi G, Franchitto A, Pichierri P. RAD52 prevents accumulation of Polα-dependent replication gaps at perturbed replication forks in human cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.12.536536. [PMID: 37090680 PMCID: PMC10120653 DOI: 10.1101/2023.04.12.536536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Replication gaps can arise as a consequence of perturbed DNA replication and their accumulation might undermine the stability of the genome. Loss of RAD52, a protein involved in the regulation of fork reversal, promotes accumulation of parental ssDNA gaps during replication perturbation. Here, we demonstrate that this is due to the engagement of Polα downstream of the extensive degradation of perturbed replication forks after their reversal, and is not dependent on PrimPol. Polα is hyper-recruited at parental ssDNA in the absence of RAD52, and this recruitment is dependent on fork reversal enzymes and RAD51. Of note, we report that the interaction between Polα and RAD51 is stimulated by RAD52 inhibition, and Polα-dependent gap accumulation requires nucleation of RAD51 suggesting that it occurs downstream strand invasion. Altogether, our data indicate that RAD51-Polα-dependent repriming is essential to promote fork restart and limit DNA damage accumulation when RAD52 function is disabled.
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Affiliation(s)
- Ludovica Di Biagi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d’Oro 305, 00136 Rome (Italy)
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Francesca Antonella Aiello
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d’Oro 305, 00136 Rome (Italy)
| | - Pasquale Valenzisi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Giorgia Marozzi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Annapaola Franchitto
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d’Oro 305, 00136 Rome (Italy)
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Brambati A, Sacco O, Porcella S, Heyza J, Kareh M, Schmidt JC, Sfeir A. RHINO restricts MMEJ activity to mitosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.16.532763. [PMID: 36993461 PMCID: PMC10055031 DOI: 10.1101/2023.03.16.532763] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
DNA double-strand breaks (DSBs) are toxic lesions that can lead to genome instability if not properly repaired. Breaks incurred in G1 phase of the cell cycle are predominantly fixed by non-homologous end-joining (NHEJ), while homologous recombination (HR) is the primary repair pathway in S and G2. Microhomology-mediated end-joining (MMEJ) is intrinsically error-prone and considered a backup DSB repair pathway that becomes essential when HR and NHEJ are compromised. In this study, we uncover MMEJ as the major DSB repair pathway in M phase. Using CRISPR/Cas9-based synthetic lethal screens, we identify subunits of the 9-1-1 complex (RAD9A-HUS1-RAD1) and its interacting partner, RHINO, as critical MMEJ factors. Mechanistically, we show that the function of 9-1-1 and RHINO in MMEJ is inconsistent with their well-established role in ATR signaling. Instead, RHINO plays an unexpected and essential role in directing mutagenic repair to M phase by directly binding to Polymerase theta (Polθ) and promoting its recruitment to DSBs in mitosis. In addition, we provide evidence that mitotic MMEJ repairs persistent DNA damage that originates in S phase but is not repaired by HR. The latter findings could explain the synthetic lethal relationship between POLQ and BRCA1/2 and the synergistic effect of Polθ and PARP inhibitors. In summary, our study identifies MMEJ as the primary pathway for repairing DSBs during mitosis and highlights an unanticipated role for RHINO in directing mutagenic repair to M phase.
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van de Kooij B, Schreuder A, Pavani RS, Garzero V, Van Hoeck A, San Martin Alonso M, Koerse D, Wendel TJ, Callen E, Boom J, Mei H, Cuppen E, Nussenzweig A, van Attikum H, Noordermeer SM. EXO1-mediated DNA repair by single-strand annealing is essential for BRCA1-deficient cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.24.529205. [PMID: 37720033 PMCID: PMC10503826 DOI: 10.1101/2023.02.24.529205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Deficiency for the repair of DNA double-strand breaks (DSBs) via homologous recombination (HR) leads to chromosomal instability and diseases such as cancer. Yet, defective HR also results in vulnerabilities that can be exploited for targeted therapy. Here, we identify such a vulnerability and show that BRCA1-deficient cells are dependent on the long-range end-resection factor EXO1 for survival. EXO1 loss results in DNA replication-induced lesions decorated by poly(ADP-ribose)-chains. In cells that lack both BRCA1 and EXO1, this is accompanied by unresolved DSBs due to impaired single-strand annealing (SSA), a DSB repair process that requires the activity of both proteins. In contrast, BRCA2-deficient cells have increased SSA, also in the absence of EXO1, and hence are not dependent on EXO1 for survival. In agreement with our mechanistic data, BRCA1-mutated tumours have elevated EXO1 expression and contain more genomic signatures of SSA compared to BRCA1-proficient tumours. Collectively, our data indicate that EXO1 is a promising novel target for treatment of BRCA1-deficient tumours.
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41
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Multifaceted Nature of DNA Polymerase θ. Int J Mol Sci 2023; 24:ijms24043619. [PMID: 36835031 PMCID: PMC9962433 DOI: 10.3390/ijms24043619] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/26/2023] [Accepted: 02/02/2023] [Indexed: 02/15/2023] Open
Abstract
DNA polymerase θ belongs to the A family of DNA polymerases and plays a key role in DNA repair and damage tolerance, including double-strand break repair and DNA translesion synthesis. Pol θ is often overexpressed in cancer cells and promotes their resistance to chemotherapeutic agents. In this review, we discuss unique biochemical properties and structural features of Pol θ, its multiple roles in protection of genome stability and the potential of Pol θ as a target for cancer treatment.
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Jackson LM, Moldovan GL. Mechanisms of PARP1 inhibitor resistance and their implications for cancer treatment. NAR Cancer 2022; 4:zcac042. [PMID: 36568963 PMCID: PMC9773381 DOI: 10.1093/narcan/zcac042] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/28/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
The discovery of synthetic lethality as a result of the combined loss of PARP1 and BRCA has revolutionized the treatment of DNA repair-deficient cancers. With the development of PARP inhibitors, patients displaying germline or somatic mutations in BRCA1 or BRCA2 were presented with a novel therapeutic strategy. However, a large subset of patients do not respond to PARP inhibitors. Furthermore, many of those who do respond eventually acquire resistance. As such, combating de novo and acquired resistance to PARP inhibitors remains an obstacle in achieving durable responses in patients. In this review, we touch on some of the key mechanisms of PARP inhibitor resistance, including restoration of homologous recombination, replication fork stabilization and suppression of single-stranded DNA gap accumulation, as well as address novel approaches for overcoming PARP inhibitor resistance.
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Affiliation(s)
- Lindsey M Jackson
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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Schrempf A, Bernardo S, Arasa Verge EA, Ramirez Otero MA, Wilson J, Kirchhofer D, Timelthaler G, Ambros AM, Kaya A, Wieder M, Ecker GF, Winter GE, Costanzo V, Loizou JI. POLθ processes ssDNA gaps and promotes replication fork progression in BRCA1-deficient cells. Cell Rep 2022; 41:111716. [PMID: 36400033 DOI: 10.1016/j.celrep.2022.111716] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 08/21/2022] [Accepted: 11/02/2022] [Indexed: 11/19/2022] Open
Abstract
Polymerase theta (POLθ) is an error-prone DNA polymerase whose loss is synthetically lethal in cancer cells bearing breast cancer susceptibility proteins 1 and 2 (BRCA1/2) mutations. To investigate the basis of this genetic interaction, we utilized a small-molecule inhibitor targeting the POLθ polymerase domain. We found that POLθ processes single-stranded DNA (ssDNA) gaps that emerge in the absence of BRCA1, thus promoting unperturbed replication fork progression and survival of BRCA1 mutant cells. A genome-scale CRISPR-Cas9 knockout screen uncovered suppressors of the functional interaction between POLθ and BRCA1, including NBN, a component of the MRN complex, and cell-cycle regulators such as CDK6. While the MRN complex nucleolytically processes ssDNA gaps, CDK6 promotes cell-cycle progression, thereby exacerbating replication stress, a feature of BRCA1-deficient cells that lack POLθ activity. Thus, ssDNA gap formation, modulated by cell-cycle regulators and MRN complex activity, underlies the synthetic lethality between POLθ and BRCA1, an important insight for clinical trials with POLθ inhibitors.
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Affiliation(s)
- Anna Schrempf
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria; CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Sara Bernardo
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria
| | - Emili A Arasa Verge
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria
| | - Miguel A Ramirez Otero
- DNA Metabolism Laboratory, IFOM ETS, The AIRC Institute for Molecular Oncology, 20139 Milan, Italy
| | - Jordan Wilson
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria; CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Dominik Kirchhofer
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria
| | - Gerald Timelthaler
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria
| | - Anna M Ambros
- Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria
| | - Atilla Kaya
- Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria
| | - Marcus Wieder
- Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria
| | - Gerhard F Ecker
- Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria
| | - Georg E Winter
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria
| | - Vincenzo Costanzo
- DNA Metabolism Laboratory, IFOM ETS, The AIRC Institute for Molecular Oncology, 20139 Milan, Italy
| | - Joanna I Loizou
- Center for Cancer Research, Comprehensive Cancer Centre, Medical University of Vienna, 1090 Vienna, Austria; CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria.
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