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Liu Z, Xi Q, Hou M, Zou T, Liu H, Zhou X, Jin L, Zhu L, Zhang X. Loss of function variant in CIP2A associated with female infertility with early embryonic arrest and fragmentation. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167228. [PMID: 38734318 DOI: 10.1016/j.bbadis.2024.167228] [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: 10/11/2023] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 05/13/2024]
Abstract
BACKGROUND Early embryonic arrest and fragmentation (EEAF) is a common cause of female infertility, but the genetic causes remain to be largely unknown. CIP2A encodes the cellular inhibitor of PP2A, playing a crucial role in mitosis and mouse oocyte meiosis. METHODS Exome sequencing and Sanger sequencing were performed to identify candidate causative genes in patients with EEAF. The pathogenicity of the CIP2A variant was assessed and confirmed in cultured cell lines and human oocytes through Western blotting, semi-quantitative RT-PCR, TUNEL staining, and fluorescence localization analysis. FINDINGS We identified CIP2A (c.1510C > T, p.L504F) as a novel disease-causing gene in human EEAF from a consanguineous family. L504 is highly conserved throughout evolution. The CIP2A variant (c.1510C > T, p.L504F) reduced the expression level of the mutant CIP2A protein, leading to the abnormal aggregation of mutant CIP2A protein and cell apoptosis. Abnormal aggregation of CIP2A protein and chromosomal dispersion occurred in the patient's oocytes and early embryos. We further replicated the patient phenotype by knockdown CIP2A in human oocytes. Additionally, CIP2A deficiency resulted in decreased levels of phosphorylated ERK1/2. INTERPRETATION We first found that the CIP2A loss-of-function variant associate with female infertility characterized by EEAF. Our findings suggest the uniqueness and importance of CIP2A gene in human oocyte and early embryo development. FUNDING This work was supported by National Key Research and Development Program of China (2023YFC2706302), the National Natural Science Foundation of China (81000079, 81170165, and 81870959), the HUST Academic Frontier Youth Team (2016QYTD02), and the Key Research of Huazhong University of Science and Technology, Tongji Hospital (2022A20).
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Affiliation(s)
- Zhenxing Liu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Qingsong Xi
- Oncology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Meiqi Hou
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Tingting Zou
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Huihui Liu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xiaopei Zhou
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Lei Jin
- Reproductive Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Lixia Zhu
- Reproductive Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Xianqin Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
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Prabhakar AT, James CD, Youssef AH, Hossain RA, Hill RD, Bristol ML, Wang X, Dubey A, Karimi E, Morgan IM. A human papillomavirus 16 E2-TopBP1 dependent SIRT1-p300 acetylation switch regulates mitotic viral and human protein levels and activates the DNA damage response. mBio 2024; 15:e0067624. [PMID: 38722185 PMCID: PMC11237546 DOI: 10.1128/mbio.00676-24] [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: 03/04/2024] [Accepted: 03/27/2024] [Indexed: 05/21/2024] Open
Abstract
An interaction between human papillomavirus 16 (HPV16) E2 and the cellular proteins TopBP1 and BRD4 is required for E2 plasmid segregation function. The E2-TopBP1 interaction promotes increased mitotic E2 protein levels in U2OS and N/Tert-1 cells, as well as in human foreskin keratinocytes immortalized by HPV16 (HFK + HPV16). SIRT1 deacetylation reduces E2 protein stability and here we demonstrate that increased E2 acetylation occurs during mitosis in a TopBP1 interacting-dependent manner, promoting E2 mitotic stabilization. p300 mediates E2 acetylation and acetylation is increased due to E2 switching off SIRT1 function during mitosis in a TopBP1 interacting-dependent manner, confirmed by increased p53 stability and acetylation on lysine 382, a known target for SIRT1 deacetylation. SIRT1 can complex with E2 in growing cells but is unable to do so during mitosis due to the E2-TopBP1 interaction; SIRT1 is also unable to complex with p53 in mitotic E2 wild-type cells but can complex with p53 outside of mitosis. E2 lysines 111 and 112 are highly conserved residues across all E2 proteins and we demonstrate that K111 hyper-acetylation occurs during mitosis, promoting E2 interaction with Topoisomerase 1 (Top1). We demonstrate that K112 ubiquitination promotes E2 proteasomal degradation during mitosis. E2-TopBP1 interaction promotes mitotic acetylation of CHK2, promoting phosphorylation and activation of the DNA damage response (DDR). The results present a new model in which the E2-TopBP1 complex inactivates SIRT1 during mitosis, and activates the DDR. This is a novel mechanism of HPV16 activation of the DDR, a requirement for the viral life cycle. IMPORTANCE Human papillomaviruses (HPVs) are causative agents in around 5% of all human cancers. While there are prophylactic vaccines that will significantly alleviate HPV disease burden on future generations, there are currently no anti-viral strategies available for the treatment of HPV cancers. To generate such reagents, we must understand more about the HPV life cycle, and in particular about viral-host interactions. Here, we describe a novel mitotic complex generated by the HPV16 E2 protein interacting with the host protein TopBP1 that controls the function of the deacetylase SIRT1. The E2-TopBP1 interaction disrupts SIRT1 function during mitosis in order to enhance acetylation and stability of viral and host proteins. We also demonstrate that the E2-TopBP1 interaction activates the DDR. This novel complex is essential for the HPV16 life cycle and represents a novel anti-viral therapeutic target.
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Affiliation(s)
- Apurva T. Prabhakar
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Claire D. James
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Aya H. Youssef
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Reafa A. Hossain
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Ronald D. Hill
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Molly L. Bristol
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
- VCU Massey Cancer Center, Richmond, Viginia, USA
| | - Xu Wang
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Aanchal Dubey
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Elmira Karimi
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Iain M. Morgan
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
- VCU Massey Cancer Center, Richmond, Viginia, USA
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Cho T, Hoeg L, Setiaputra D, Durocher D. NFATC2IP is a mediator of SUMO-dependent genome integrity. Genes Dev 2024; 38:233-252. [PMID: 38503515 PMCID: PMC11065178 DOI: 10.1101/gad.350914.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 03/04/2024] [Indexed: 03/21/2024]
Abstract
The post-translational modification of proteins by SUMO is crucial for cellular viability and mammalian development in part due to the contribution of SUMOylation to genome duplication and repair. To investigate the mechanisms underpinning the essential function of SUMO, we undertook a genome-scale CRISPR/Cas9 screen probing the response to SUMOylation inhibition. This effort identified 130 genes whose disruption reduces or enhances the toxicity of TAK-981, a clinical-stage inhibitor of the SUMO E1-activating enzyme. Among the strongest hits, we validated and characterized NFATC2IP, an evolutionarily conserved protein related to the fungal Esc2 and Rad60 proteins that harbors tandem SUMO-like domains. Cells lacking NFATC2IP are viable but are hypersensitive to SUMO E1 inhibition, likely due to the accumulation of mitotic chromosome bridges and micronuclei. NFATC2IP primarily acts in interphase and associates with nascent DNA, suggesting a role in the postreplicative resolution of replication or recombination intermediates. Mechanistically, NFATC2IP interacts with the SMC5/6 complex and UBC9, the SUMO E2, via its first and second SUMO-like domains, respectively. AlphaFold-Multimer modeling suggests that NFATC2IP positions and activates the UBC9-NSMCE2 complex, the SUMO E3 ligase associated with SMC5/SMC6. We conclude that NFATC2IP is a key mediator of SUMO-dependent genomic integrity that collaborates with the SMC5/6 complex.
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Affiliation(s)
- Tiffany Cho
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Lisa Hoeg
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Dheva Setiaputra
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada;
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Messer CL, Fox DT. Broken chromosomes heading into mitosis: More than one way to patch a flat tire. J Cell Biol 2024; 223:e202401085. [PMID: 38477879 PMCID: PMC10937182 DOI: 10.1083/jcb.202401085] [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: 01/17/2024] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
A cell dealing with a broken chromosome in mitosis is like a driver dealing with a flat tire on the highway: damage repair must occur under non-ideal circumstances. Mitotic chromosome breaks encounter problems related to structures called micronuclei. These aberrant nuclei are linked to cell death, mutagenesis, and cancer. In the last few years, a flurry of studies illuminated two mechanisms that prevent mitotic problems related to micronuclei. One mechanism prevents micronuclei from forming during mitosis and involves DNA Polymerase Theta, a DNA repair regulator that patches up broken mitotic chromosomes. A second mechanism is activated after micronuclei form and then rupture, and involves CIP2A and TOPBP1 proteins, which patch micronuclear fragments to promote their subsequent mitotic segregation. Here, we review recent progress in this field of mitotic DNA damage and discuss why multiple mechanisms exist. Future studies in this exciting area will reveal new DNA break responses and inform therapeutic strategies.
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Affiliation(s)
- C. Luke Messer
- Department of Biology, St. Bonaventure University, St. Bonaventure, NY, USA
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Donald T. Fox
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
- Duke Regeneration Center, Duke University Medical Center, Durham, NC, USA
- Duke Cancer Institute, Duke University Medical Center, Durham, NC, USA
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Herz M, Zarowiecki M, Wessels L, Pätzel K, Herrmann R, Braun C, Holroyd N, Huckvale T, Bergmann M, Spiliotis M, Koziol U, Berriman M, Brehm K. Genome-wide transcriptome analysis of Echinococcus multilocularis larvae and germinative cell cultures reveals genes involved in parasite stem cell function. Front Cell Infect Microbiol 2024; 14:1335946. [PMID: 38333034 PMCID: PMC10850878 DOI: 10.3389/fcimb.2024.1335946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 01/12/2024] [Indexed: 02/10/2024] Open
Abstract
The lethal zoonosis alveolar echinococcosis is caused by tumour-like growth of the metacestode stage of the tapeworm Echinococcus multilocularis within host organs. We previously demonstrated that metacestode proliferation is exclusively driven by somatic stem cells (germinative cells), which are the only mitotically active parasite cells that give rise to all differentiated cell types. The Echinococcus gene repertoire required for germinative cell maintenance and differentiation has not been characterised so far. We herein carried out Illumina sequencing on cDNA from Echinococcus metacestode vesicles, from metacestode tissue depleted of germinative cells, and from Echinococcus primary cell cultures. We identified a set of ~1,180 genes associated with germinative cells, which contained numerous known stem cell markers alongside genes involved in replication, cell cycle regulation, mitosis, meiosis, epigenetic modification, and nucleotide metabolism. Interestingly, we also identified 44 stem cell associated transcription factors that are likely involved in regulating germinative cell differentiation and/or pluripotency. By in situ hybridization and pulse-chase experiments, we also found a new general Echinococcus stem cell marker, EmCIP2Ah, and we provide evidence implying the presence of a slow cycling stem cell sub-population expressing the extracellular matrix factor Emkal1. RNA-Seq analyses on primary cell cultures revealed that metacestode-derived Echinococcus stem cells display an expanded differentiation capability and do not only form differentiated cell types of the metacestode, but also cells expressing genes specific for protoscoleces, adult worms, and oncospheres, including an ortholog of the schistosome praziquantel target, EmTRPMPZQ. Finally, we show that primary cell cultures contain a cell population expressing an ortholog of the tumour necrosis factor α receptor family and that mammalian TNFα accelerates the development of metacestode vesicles from germinative cells. Taken together, our analyses provide a robust and comprehensive characterization of the Echinococcus germinative cell transcriptome, demonstrate expanded differentiation capability of metacestode derived stem cells, and underscore the potential of primary germinative cell cultures to investigate developmental processes of the parasite. These data are relevant for studies into the role of Echinococcus stem cells in parasite development and will facilitate the design of anti-parasitic drugs that specifically act on the parasite germinative cell compartment.
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Affiliation(s)
- Michaela Herz
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | | | - Leonie Wessels
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Katharina Pätzel
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Ruth Herrmann
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Christiane Braun
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Nancy Holroyd
- Parasite Genomics, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Thomas Huckvale
- Parasite Genomics, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Monika Bergmann
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Markus Spiliotis
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Uriel Koziol
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Matthew Berriman
- Parasite Genomics, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Klaus Brehm
- Consultant Laboratory for Echinococcosis, Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
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Prabhakar AT, James CD, Youssef AH, Hossain RA, Hill RD, Bristol ML, Wang X, Dubey A, Morgan IM. A human papillomavirus 16 E2-TopBP1 dependent SIRT1-p300 acetylation switch regulates mitotic viral and human protein levels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.15.575713. [PMID: 38293041 PMCID: PMC10827094 DOI: 10.1101/2024.01.15.575713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
An interaction between human papillomavirus 16 (HPV16) E2 and the cellular proteins TopBP1 and BRD4 is required for E2 plasmid segregation function. The E2-TopBP1 interaction promotes increased mitotic E2 protein levels in U2OS and N/Tert-1 cells, as well as in human foreskin keratinocytes immortalized by HPV16 (HFK+HPV16). SIRT1 deacetylation reduces E2 protein stability and here we demonstrate that increased E2 acetylation occurs during mitosis in a TopBP1 interacting dependent manner, promoting E2 mitotic stabilization. p300 mediates E2 acetylation and acetylation is increased due to E2 switching off SIRT1 function during mitosis in a TopBP1 interacting dependent manner, confirmed by increased p53 stability and acetylation on lysine 382, a known target for SIRT1 deacetylation. SIRT1 can complex with E2 in growing cells but is unable to do so during mitosis due to the E2-TopBP1 interaction; SIRT1 is also unable to complex with p53 in mitotic E2 wild type cells but can complex with p53 outside of mitosis. E2 lysines 111 and 112 are highly conserved residues across all E2 proteins and we demonstrate that K111 hyper-acetylation occurs during mitosis, promoting E2 interaction with Topoisomerase 1 (Top1). We also demonstrate that K112 ubiquitination promotes E2 proteasomal degradation during mitosis. The results present a model in which the E2-TopBP1 complex inactivates SIRT1 during mitosis and E2 acetylation on K111 by p300 increases, promoting interaction with Top1 that protects K112 from ubiquitination and therefore E2 proteasomal degradation. Importance Human papillomaviruses are causative agents in around 5% of all human cancers. While there are prophylactic vaccines that will significantly alleviate HPV disease burden on future generations, there are currently no anti-viral strategies available for the treatment of HPV cancers. To generate such reagents, we must understand more about the HPV life cycle, and in particular about viral-host interactions. Here we describe a novel mitotic complex generated by the HPV16 E2 protein interacting with the host protein TopBP1 that controls the function of the deacetylase SIRT1. The E2-TopBP1 interaction disrupts SIRT1 function during mitosis in order to enhance acetylation and stability of viral and host proteins. This novel complex is essential for the HPV16 life cycle and represents a novel anti-viral therapeutic target.
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Mazzagatti A, Engel JL, Ly P. Boveri and beyond: Chromothripsis and genomic instability from mitotic errors. Mol Cell 2024; 84:55-69. [PMID: 38029753 PMCID: PMC10842135 DOI: 10.1016/j.molcel.2023.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/30/2023] [Accepted: 11/02/2023] [Indexed: 12/01/2023]
Abstract
Mitotic cell division is tightly monitored by checkpoints that safeguard the genome from instability. Failures in accurate chromosome segregation during mitosis can cause numerical aneuploidy, which was hypothesized by Theodor Boveri over a century ago to promote tumorigenesis. Recent interrogation of pan-cancer genomes has identified unexpected classes of chromosomal abnormalities, including complex rearrangements arising through chromothripsis. This process is driven by mitotic errors that generate abnormal nuclear structures that provoke extensive yet localized shattering of mis-segregated chromosomes. Here, we discuss emerging mechanisms underlying chromothripsis from micronuclei and chromatin bridges, as well as highlight how this mutational cascade converges on the DNA damage response. A fundamental understanding of these catastrophic processes will provide insight into how initial errors in mitosis can precipitate rapid cancer genome evolution.
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Affiliation(s)
- Alice Mazzagatti
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Justin L Engel
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Peter Ly
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Cell Biology, Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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8
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Nagelli S, Westermarck J. CIP2A coordinates phosphosignaling, mitosis, and the DNA damage response. Trends Cancer 2024; 10:52-64. [PMID: 37793965 DOI: 10.1016/j.trecan.2023.09.001] [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: 07/14/2023] [Revised: 08/18/2023] [Accepted: 09/04/2023] [Indexed: 10/06/2023]
Abstract
Human cancers share requirements for phosphorylation-dependent signaling, mitotic hyperactivity, and survival after DNA damage. The oncoprotein CIP2A (cancerous inhibitor of PP2A) can coordinate all these cancer cell characteristics. In addition to controlling cancer cell phosphoproteomes via inhibition of protein phosphatase PP2A, CIP2A directly interacts with the DNA damage protein TopBP1 (topoisomerase II-binding protein 1). Consequently, CIP2A allows DNA-damaged cells to enter mitosis and is essential for mitotic cells that are defective in homologous recombination (HR)-mediated DNA repair (e.g., BRCA mutants). The CIP2A-TopBP1 complex is also important for clustering fragmented chromosomes at mitosis. Clinically, CIP2A is a disease driver for basal-like triple-negative breast cancer (BL-TNBC) and a promising cancer therapy target across many cancer types.
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Affiliation(s)
- Srikar Nagelli
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland; Institute of Biomedicine and FICANWest Cancer Center, University of Turku, Turku, Finland
| | - Jukka Westermarck
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland; Institute of Biomedicine and FICANWest Cancer Center, University of Turku, Turku, Finland; InFLAMES Research Flagship Center, University of Turku, Turku, Finland.
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9
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Stracker TH, Osagie OI, Escorcia FE, Citrin DE. Exploiting the DNA Damage Response for Prostate Cancer Therapy. Cancers (Basel) 2023; 16:83. [PMID: 38201511 PMCID: PMC10777950 DOI: 10.3390/cancers16010083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
Prostate cancers that progress despite androgen deprivation develop into castration-resistant prostate cancer, a fatal disease with few treatment options. In this review, we discuss the current understanding of prostate cancer subtypes and alterations in the DNA damage response (DDR) that can predispose to the development of prostate cancer and affect its progression. We identify barriers to conventional treatments, such as radiotherapy, and discuss the development of new therapies, many of which target the DDR or take advantage of recurring genetic alterations in the DDR. We place this in the context of advances in understanding the genetic variation and immune landscape of CRPC that could help guide their use in future treatment strategies. Finally, we discuss several new and emerging agents that may advance the treatment of lethal disease, highlighting selected clinical trials.
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Affiliation(s)
- Travis H. Stracker
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (O.I.O.); (F.E.E.); (D.E.C.)
| | - Oloruntoba I. Osagie
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (O.I.O.); (F.E.E.); (D.E.C.)
| | - Freddy E. Escorcia
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (O.I.O.); (F.E.E.); (D.E.C.)
- Molecular Imaging Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Deborah E. Citrin
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (O.I.O.); (F.E.E.); (D.E.C.)
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10
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Ummethum H, Li J, Lisby M, Oestergaard V. Emerging roles of the CIP2A-TopBP1 complex in genome integrity. NAR Cancer 2023; 5:zcad052. [PMID: 37829116 PMCID: PMC10566317 DOI: 10.1093/narcan/zcad052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 08/27/2023] [Accepted: 09/24/2023] [Indexed: 10/14/2023] Open
Abstract
CIP2A is an inhibitor of the tumour suppressor protein phosphatase 2A. Recently, CIP2A was identified as a synthetic lethal interactor of BRCA1 and BRCA2 and a driver of basal-like breast cancers. In addition, a joint role of TopBP1 (topoisomerase IIβ-binding protein 1) and CIP2A for maintaining genome integrity during mitosis was discovered. TopBP1 has multiple functions as it is a scaffold for proteins involved in DNA replication, transcriptional regulation, cell cycle regulation and DNA repair. Here, we briefly review details of the CIP2A-TopBP1 interaction, its role in maintaining genome integrity, its involvement in cancer and its potential as a therapeutic target.
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Affiliation(s)
- Henning Ummethum
- Department of Biology, University of Copenhagen, Copenhagen 2200, Denmark
| | - Jiayi Li
- Department of Biology, University of Copenhagen, Copenhagen 2200, Denmark
| | - Michael Lisby
- Department of Biology, University of Copenhagen, Copenhagen 2200, Denmark
| | - Vibe H Oestergaard
- Department of Biology, University of Copenhagen, Copenhagen 2200, Denmark
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11
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van Vugt MATM, Tijsterman M. POLQ to the rescue for double-strand break repair during mitosis. Nat Struct Mol Biol 2023; 30:1828-1830. [PMID: 37996664 DOI: 10.1038/s41594-023-01168-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Affiliation(s)
- Marcel A T M van Vugt
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Lin FT, Liu K, Garan LAW, Folly-Kossi H, Song Y, Lin SJ, Lin WC. A small-molecule inhibitor of TopBP1 exerts anti-MYC activity and synergy with PARP inhibitors. Proc Natl Acad Sci U S A 2023; 120:e2307793120. [PMID: 37878724 PMCID: PMC10622895 DOI: 10.1073/pnas.2307793120] [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: 05/09/2023] [Accepted: 09/19/2023] [Indexed: 10/27/2023] Open
Abstract
We have previously identified TopBP1 (topoisomerase IIβ-binding protein 1) as a promising target for cancer therapy, given its role in the convergence of Rb, PI(3)K/Akt, and p53 pathways. Based on this, we conducted a large-scale molecular docking screening to identify a small-molecule inhibitor that specifically targets the BRCT7/8 domains of TopBP1, which we have named 5D4. Our studies show that 5D4 inhibits TopBP1 interactions with E2F1, mutant p53, and Cancerous Inhibitor of Protein Phosphatase 2A. This leads to the activation of E2F1-mediated apoptosis and the inhibition of mutant p53 gain of function. In addition, 5D4 disrupts the interaction of TopBP1 with MIZ1, which in turn allows MIZ1 to bind to its target gene promoters and repress MYC activity. Moreover, 5D4 inhibits the association of the TopBP1-PLK1 complex and prevents the formation of Rad51 foci. When combined with inhibitors of PARP1/2 or PARP14, 5D4 synergizes to effectively block cancer cell proliferation. Our animal studies have demonstrated the antitumor activity of 5D4 in breast and ovarian cancer xenograft models. Moreover, the effectiveness of 5D4 is further enhanced when combined with a PARP1/2 inhibitor talazoparib. Taken together, our findings strongly support the potential use of TopBP1-BRCT7/8 inhibitors as a targeted cancer therapy.
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Affiliation(s)
- Fang-Tsyr Lin
- Section of Hematology/Oncology, Department of Medicine, Baylor College of Medicine, Houston, TX77030
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX77030
| | - Kang Liu
- Section of Hematology/Oncology, Department of Medicine, Baylor College of Medicine, Houston, TX77030
| | - Lidija A. Wilhelms Garan
- Section of Hematology/Oncology, Department of Medicine, Baylor College of Medicine, Houston, TX77030
- Cancer and Cell Biology Graduate Program, Baylor College of Medicine, Houston, TX77030
| | - Helena Folly-Kossi
- Section of Hematology/Oncology, Department of Medicine, Baylor College of Medicine, Houston, TX77030
| | - Yongcheng Song
- Department of Pharmacology, Baylor College of Medicine, Houston, TX77030
| | - Shwu-Jiuan Lin
- Department of Pharmaceutical Sciences, School of Pharmacy, Taipei Medical University, Taipei11031, Taiwan
- PhD Program in Clinical Drug Development of Herbal Medicine, College of Pharmacy, Taipei Medical University, Taipei 11031, Taiwan
| | - Weei-Chin Lin
- Section of Hematology/Oncology, Department of Medicine, Baylor College of Medicine, Houston, TX77030
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX77030
- Cancer and Cell Biology Graduate Program, Baylor College of Medicine, Houston, TX77030
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX77030
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13
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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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14
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Vedula CP, Ganem NJ. CIP2A and TOPBP1: Molecular lassos that herd pulverized micronuclear chromosomes. Mol Cell 2023; 83:1964-1966. [PMID: 37327773 DOI: 10.1016/j.molcel.2023.05.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 05/23/2023] [Accepted: 05/23/2023] [Indexed: 06/18/2023]
Abstract
Lin et al.1 demonstrate that acentric chromosome fragments generated within micronuclei are tethered by the CIP2A-TOPBP1 complex during mitosis, thus promoting clustered segregation of the fragments to a single daughter cell nucleus and facilitating re-ligation with limited chromosomal scattering and loss.
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Affiliation(s)
- Chaithanya P Vedula
- Department of Pharmacology, Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
| | - Neil J Ganem
- Department of Pharmacology, Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA.
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15
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Xue Y, Durocher D. A mitotic glue for shattered chromosomes. Nature 2023:10.1038/d41586-023-01890-5. [PMID: 37316590 DOI: 10.1038/d41586-023-01890-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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16
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Trivedi P, Steele CD, Au FKC, Alexandrov LB, Cleveland DW. Mitotic tethering enables inheritance of shattered micronuclear chromosomes. Nature 2023; 618:1049-1056. [PMID: 37316668 PMCID: PMC10424572 DOI: 10.1038/s41586-023-06216-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 05/12/2023] [Indexed: 06/16/2023]
Abstract
Chromothripsis, the shattering and imperfect reassembly of one (or a few) chromosome(s)1, is an ubiquitous2 mutational process generating localized and complex chromosomal rearrangements that drive genome evolution in cancer. Chromothripsis can be initiated by mis-segregation errors in mitosis3,4 or DNA metabolism5-7 that lead to entrapment of chromosomes within micronuclei and their subsequent fragmentation in the next interphase or following mitotic entry6,8-10. Here we use inducible degrons to demonstrate that chromothriptically produced pieces of a micronucleated chromosome are tethered together in mitosis by a protein complex consisting of mediator of DNA damage checkpoint 1 (MDC1), DNA topoisomerase II-binding protein 1 (TOPBP1) and cellular inhibitor of PP2A (CIP2A), thereby enabling en masse segregation to the same daughter cell. Such tethering is shown to be crucial for the viability of cells undergoing chromosome mis-segregation and shattering after transient inactivation of the spindle assembly checkpoint. Transient, degron-induced reduction in CIP2A following chromosome micronucleation-dependent chromosome shattering is shown to drive acquisition of segmental deletions and inversions. Analyses of pancancer tumour genomes showed that expression of CIP2A and TOPBP1 was increased overall in cancers with genomic rearrangements, including copy number-neutral chromothripsis with minimal deletions, but comparatively reduced in cancers with canonical chromothripsis in which deletions were frequent. Thus, chromatin-bound tethers maintain the proximity of fragments of a shattered chromosome enabling their re-encapsulation into, and religation within, a daughter cell nucleus to form heritable, chromothriptically rearranged chromosomes found in the majority of human cancers.
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Affiliation(s)
- Prasad Trivedi
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Christopher D Steele
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
- Department of Bioengineering, University of California at San Diego, La Jolla, CA, USA
- Moores Cancer Center, University of California at San Diego, La Jolla, CA, USA
| | - Franco K C Au
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Ludmil B Alexandrov
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
- Department of Bioengineering, University of California at San Diego, La Jolla, CA, USA
- Moores Cancer Center, University of California at San Diego, La Jolla, CA, USA
| | - Don W Cleveland
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA, USA.
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA.
- Moores Cancer Center, University of California at San Diego, La Jolla, CA, USA.
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17
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Lin YF, Hu Q, Mazzagatti A, Valle-Inclán JE, Maurais EG, Dahiya R, Guyer A, Sanders JT, Engel JL, Nguyen G, Bronder D, Bakhoum SF, Cortés-Ciriano I, Ly P. Mitotic clustering of pulverized chromosomes from micronuclei. Nature 2023; 618:1041-1048. [PMID: 37165191 PMCID: PMC10307639 DOI: 10.1038/s41586-023-05974-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 03/17/2023] [Indexed: 05/12/2023]
Abstract
Complex genome rearrangements can be generated by the catastrophic pulverization of missegregated chromosomes trapped within micronuclei through a process known as chromothripsis1-5. As each chromosome contains a single centromere, it remains unclear how acentric fragments derived from shattered chromosomes are inherited between daughter cells during mitosis6. Here we tracked micronucleated chromosomes with live-cell imaging and show that acentric fragments cluster in close spatial proximity throughout mitosis for asymmetric inheritance by a single daughter cell. Mechanistically, the CIP2A-TOPBP1 complex prematurely associates with DNA lesions within ruptured micronuclei during interphase, which poises pulverized chromosomes for clustering upon mitotic entry. Inactivation of CIP2A-TOPBP1 caused acentric fragments to disperse throughout the mitotic cytoplasm, stochastically partition into the nucleus of both daughter cells and aberrantly misaccumulate as cytoplasmic DNA. Mitotic clustering facilitates the reassembly of acentric fragments into rearranged chromosomes lacking the extensive DNA copy-number losses that are characteristic of canonical chromothripsis. Comprehensive analysis of pan-cancer genomes revealed clusters of DNA copy-number-neutral rearrangements-termed balanced chromothripsis-across diverse tumour types resulting in the acquisition of known cancer driver events. Thus, distinct patterns of chromothripsis can be explained by the spatial clustering of pulverized chromosomes from micronuclei.
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Affiliation(s)
- Yu-Fen Lin
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Qing Hu
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alice Mazzagatti
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jose Espejo Valle-Inclán
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, UK
| | - Elizabeth G Maurais
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Rashmi Dahiya
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alison Guyer
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Interdisciplinary Biomedical Graduate Program, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jacob T Sanders
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
| | - Justin L Engel
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Giaochau Nguyen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Daniel Bronder
- Human Oncology and Pathogenesis Program, Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Samuel F Bakhoum
- Human Oncology and Pathogenesis Program, Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Isidro Cortés-Ciriano
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, UK.
| | - Peter Ly
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Cell Biology, Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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18
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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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19
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Groelly FJ, Fawkes M, Dagg RA, Blackford AN, Tarsounas M. Targeting DNA damage response pathways in cancer. Nat Rev Cancer 2023; 23:78-94. [PMID: 36471053 DOI: 10.1038/s41568-022-00535-5] [Citation(s) in RCA: 200] [Impact Index Per Article: 200.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/01/2022] [Indexed: 12/12/2022]
Abstract
Cells have evolved a complex network of biochemical pathways, collectively known as the DNA damage response (DDR), to prevent detrimental mutations from being passed on to their progeny. The DDR coordinates DNA repair with cell-cycle checkpoint activation and other global cellular responses. Genes encoding DDR factors are frequently mutated in cancer, causing genomic instability, an intrinsic feature of many tumours that underlies their ability to grow, metastasize and respond to treatments that inflict DNA damage (such as radiotherapy). One instance where we have greater insight into how genetic DDR abrogation impacts on therapy responses is in tumours with mutated BRCA1 or BRCA2. Due to compromised homologous recombination DNA repair, these tumours rely on alternative repair mechanisms and are susceptible to chemical inhibitors of poly(ADP-ribose) polymerase (PARP), which specifically kill homologous recombination-deficient cancer cells, and have become a paradigm for targeted cancer therapy. It is now clear that many other synthetic-lethal relationships exist between DDR genes. Crucially, some of these interactions could be exploited in the clinic to target tumours that become resistant to PARP inhibition. In this Review, we discuss state-of-the-art strategies for DDR inactivation using small-molecule inhibitors and highlight those compounds currently being evaluated in the clinic.
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Affiliation(s)
- Florian J Groelly
- Genome Stability and Tumourigenesis Group, Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Matthew Fawkes
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Rebecca A Dagg
- Genome Stability and Tumourigenesis Group, Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Andrew N Blackford
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
| | - Madalena Tarsounas
- Genome Stability and Tumourigenesis Group, Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK.
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