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Goff NJ, Mikhova M, Schmidt JC, Meek K. DNA-PK: A synopsis beyond synapsis. DNA Repair (Amst) 2024; 141:103716. [PMID: 38996771 DOI: 10.1016/j.dnarep.2024.103716] [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: 06/26/2024] [Accepted: 06/27/2024] [Indexed: 07/14/2024]
Abstract
Given its central role in life, DNA is remarkably easy to damage. Double strand breaks (DSBs) are the most toxic form of DNA damage, and DSBs pose the greatest danger to genomic integrity. In higher vertebrates, the non-homologous end joining pathway (NHEJ) is the predominate pathway that repairs DSBs. NHEJ has three steps: 1) DNA end recognition by the DNA dependent protein kinase [DNA-PK], 2) DNA end-processing by numerous NHEJ accessory factors, and 3) DNA end ligation by the DNA ligase IV complex (LX4). Although this would appear to be a relatively simple mechanism, it has become increasingly apparent that it is not. Recently, much insight has been derived regarding the mechanism of non-homologous end joining through a proliferation of cryo-EM studies, structure-function mutational experiments informed by these new structural data, and novel single-molecule imaging approaches. An emerging consensus in the field is that NHEJ progresses from initial DSB end recognition by DNA-PK to synapsis of the two DNA ends in a long-range synaptic complex where ends are held too far apart (115 Å) for ligation, and then progress to a short-range synaptic complex where ends are positioned close enough for ligation. What was surprising from these structural studies was the observation of two distinct types of DNA-PK dimers that represent NHEJ long-range complexes. In this review, we summarize current knowledge about the function of the distinct NHEJ synaptic complexes and align this new information with emerging cellular single-molecule microscopy studies as well as with previous studies of DNA-PK's function in repair.
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Affiliation(s)
- Noah J Goff
- College of Veterinary Medicine, Department of Microbiology Genetics & Immunology, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Mariia Mikhova
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA; Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, 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
| | - Katheryn Meek
- College of Veterinary Medicine, Department of Microbiology Genetics & Immunology, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
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2
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Wu J, Song L, Lu M, Gao Q, Xu S, Zhou P, Ma T. The multifaceted functions of DNA-PKcs: implications for the therapy of human diseases. MedComm (Beijing) 2024; 5:e613. [PMID: 38898995 PMCID: PMC11185949 DOI: 10.1002/mco2.613] [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: 08/10/2023] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 06/21/2024] Open
Abstract
The DNA-dependent protein kinase (DNA-PK), catalytic subunit, also known as DNA-PKcs, is complexed with the heterodimer Ku70/Ku80 to form DNA-PK holoenzyme, which is well recognized as initiator in the nonhomologous end joining (NHEJ) repair after double strand break (DSB). During NHEJ, DNA-PKcs is essential for both DNA end processing and end joining. Besides its classical function in DSB repair, DNA-PKcs also shows multifaceted functions in various biological activities such as class switch recombination (CSR) and variable (V) diversity (D) joining (J) recombination in B/T lymphocytes development, innate immunity through cGAS-STING pathway, transcription, alternative splicing, and so on, which are dependent on its function in NHEJ or not. Moreover, DNA-PKcs deficiency has been proven to be related with human diseases such as neurological pathogenesis, cancer, immunological disorder, and so on through different mechanisms. Therefore, it is imperative to summarize the latest findings about DNA-PKcs and diseases for better targeting DNA-PKcs, which have shown efficacy in cancer treatment in preclinical models. Here, we discuss the multifaceted roles of DNA-PKcs in human diseases, meanwhile, we discuss the progresses of DNA-PKcs inhibitors and their potential in clinical trials. The most updated review about DNA-PKcs will hopefully provide insights and ideas to understand DNA-PKcs associated diseases.
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Affiliation(s)
- Jinghong Wu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Liwei Song
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Mingjun Lu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Qing Gao
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Shaofa Xu
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Ping‐Kun Zhou
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Teng Ma
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
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3
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Rojas-Barón L, Hermosilla C, Taubert A, Velásquez ZD. Toxoplasma gondii infection-induced host cellular DNA damage is strain-dependent and leads to the activation of the ATM-dependent homologous recombination pathway. Front Cell Infect Microbiol 2024; 14:1374659. [PMID: 38524184 PMCID: PMC10957594 DOI: 10.3389/fcimb.2024.1374659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 02/26/2024] [Indexed: 03/26/2024] Open
Abstract
Toxoplasma gondii is a globally occurring apicomplexan parasite that infects humans and animals. Globally, different typical and atypical haplotypes of T. gondii induce varying pathologies in hosts. As an obligate intracellular protozoon, T. gondii was shown to interfere with host cell cycle progression, leading to mitotic spindle alteration, chromosome segregation errors and cytokinesis failure which all may reflect chromosomal instability. Referring to strain-dependent virulence, we here studied the potential of different T. gondii strains (RH, Me49 and NED) to drive DNA damage in primary endothelial host cells. Utilizing microscopic analyses, comet assays and γ-H2AX quantification, we demonstrated a strain-dependent induction of binucleated host cells, DNA damage and DNA double strand breaks, respectively, in T. gondii-infected cells with the RH strain driving the most prominent effects. Interestingly, only the NED strain significantly triggered micronuclei formation in T. gondii-infected cells. Focusing on the RH strain, we furthermore demonstrated that T. gondii-infected primary host cells showed a DNA damage response by activating the ATM-dependent homologous recombination (HR) pathway. In contrast, key molecules of the nonhomologous DNA end joining (NHEJ) pathway were either not affected or downregulated in RH-infected host cells, suggesting that this pathway is not activated by infection. In conclusion, current finding suggests that T. gondii infection affects the host cell genome integrity in a strain-dependent manner by causing DNA damage and chromosomal instability.
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Affiliation(s)
| | | | | | - Zahady D. Velásquez
- Institute of Parasitology, Biomedical Research Center Seltersberg, Justus Liebig University Giessen, Giessen, Germany
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4
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Bin Y, Wei S, Chen R, Zhang H, Ren J, Liu P, Xin Z, Zhang T, Yang H, Wang K, Feng Z, Sun X, Chen Z, Zhang H. Dclre1c-Mutation-Induced Immunocompromised Mice Are a Novel Model for Human Xenograft Research. Biomolecules 2024; 14:180. [PMID: 38397417 PMCID: PMC10887050 DOI: 10.3390/biom14020180] [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: 11/08/2023] [Revised: 01/20/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024] Open
Abstract
Severe combined immunodeficient (SCID) mice serve as a critical model for human xenotransplantation studies, yet they often suffer from low engraftment rates and susceptibility to graft-versus-host disease (GVHD). Moreover, certain SCID strains demonstrate 'immune leakage', underscoring the need for novel model development. Here, we introduce an SCID mouse model with a targeted disruption of the dclre1c gene, encoding Artemis, which is essential for V(D)J recombination and DNA repair during T cell receptor (TCR) and B cell receptor (BCR) assembly. Artemis deficiency precipitates a profound immunodeficiency syndrome, marked by radiosensitivity and compromised T and B lymphocyte functionality. Utilizing CRISPR/Cas9-mediated gene editing, we generated dclre1c-deficient mice with an NOD genetic background. These mice exhibited a radiosensitive SCID phenotype, with pronounced DNA damage and defective thymic, splenic and lymph node development, culminating in reduced T and B lymphocyte populations. Notably, both cell lines and patient-derived tumor xenografts were successfully engrafted into these mice. Furthermore, the human immune system was effectively rebuilt following peripheral blood mononuclear cells (PBMCs) transplantation. The dclre1c-knockout NOD mice described herein represent a promising addition to the armamentarium of models for xenotransplantation, offering a valuable platform for advancing human immunobiological research.
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Affiliation(s)
- Yixiao Bin
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
- School of Basic Medical Sciences, Shaanxi University of Chinese Medicine, Xianyang 712046, China
| | - Sanhua Wei
- Department of Obstetrics and Gynecology, Reproductive Medicine Center, Tang Du Hospital, Fourth Military Medical University, Xi’an 710038, China;
| | - Ruo Chen
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Haowei Zhang
- Department of Occupational & Environmental Health and the Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University, Xi’an 710032, China;
| | - Jing Ren
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
- School of Basic Medical Sciences, Shaanxi University of Chinese Medicine, Xianyang 712046, China
| | - Peijuan Liu
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Zhiqian Xin
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Tianjiao Zhang
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Haijiao Yang
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Ke Wang
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Zhuan Feng
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Xiuxuan Sun
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Zhinan Chen
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
| | - Hai Zhang
- Department of Cell Biology, National Translational Science Center for Molecular Medicine, Fourth Military Medical University, Xi’an 710032, China; (Y.B.); (R.C.); (J.R.); (P.L.); (Z.X.); (T.Z.); (H.Y.); (K.W.); (Z.F.); (X.S.)
- State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Fourth Military Medical University, Xi’an 710032, China
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Liu H, Huang R, Shan J, Xie X, Wang C, Hu P, Sun X. Artemis as Predictive Biomarker of Responsiveness to Preoperative Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer. Curr Oncol 2024; 31:535-546. [PMID: 38248122 PMCID: PMC10814650 DOI: 10.3390/curroncol31010037] [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: 11/07/2023] [Revised: 01/15/2024] [Accepted: 01/15/2024] [Indexed: 01/23/2024] Open
Abstract
The aim of this study was to identify Artemis as a predictive biomarker for guiding preoperative chemoradiotherapy in locally advanced rectal cancer. The resection specimens were collected from 50 patients with rectal cancer who underwent preoperative chemoradiotherapy. Artemis expression in biopsy tissues was evaluated using immunohistochemical staining according to the percentage of positively stained cells combined with staining intensity. Among the 50 patients, 36 (72%) had a weakly positive Artemis protein expression, 10 (20%) had a moderately positive expression, and 4 (8%) showed a strongly positive expression. The criteria of magnetic resonance imaging tumor regression grade (mrTRG) and pathological rectal cancer regression grade (RCRG) were used to assess the tumor response to chemoradiotherapy. Correlation analysis shows that there is a significant negative correlation between high Artemis immunoscore and treatment response (r = -0.532, p < 0.001). The results imply that high Artemis expression was associated with poor treatment response. Our study suggested a potential role of Artemis as a predictive biomarker of the tumor response to preoperative chemoradiotherapy in patients with locally advanced rectal cancer.
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Affiliation(s)
- Hai Liu
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China; (H.L.); (R.H.); (J.S.); (X.X.)
| | - Runying Huang
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China; (H.L.); (R.H.); (J.S.); (X.X.)
| | - Jingjing Shan
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China; (H.L.); (R.H.); (J.S.); (X.X.)
| | - Xuyun Xie
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China; (H.L.); (R.H.); (J.S.); (X.X.)
| | - Chongwei Wang
- Department of Pathology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China;
| | - Peng Hu
- Department of Radiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China;
| | - Xiaonan Sun
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China; (H.L.); (R.H.); (J.S.); (X.X.)
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6
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De Bragança S, Dillingham MS, Moreno-Herrero F. Recent insights into eukaryotic double-strand DNA break repair unveiled by single-molecule methods. Trends Genet 2023; 39:924-940. [PMID: 37806853 DOI: 10.1016/j.tig.2023.09.004] [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: 06/14/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023]
Abstract
Genome integrity and maintenance are essential for the viability of all organisms. A wide variety of DNA damage types have been described, but double-strand breaks (DSBs) stand out as one of the most toxic DNA lesions. Two major pathways account for the repair of DSBs: homologous recombination (HR) and non-homologous end joining (NHEJ). Both pathways involve complex DNA transactions catalyzed by proteins that sequentially or cooperatively work to repair the damage. Single-molecule methods allow visualization of these complex transactions and characterization of the protein:DNA intermediates of DNA repair, ultimately allowing a comprehensive breakdown of the mechanisms underlying each pathway. We review current understanding of the HR and NHEJ responses to DSBs in eukaryotic cells, with a particular emphasis on recent advances through the use of single-molecule techniques.
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Affiliation(s)
- Sara De Bragança
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain
| | - Mark S Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain.
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7
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Vogt A, He Y, Lees-Miller SP. How to fix DNA breaks: new insights into the mechanism of non-homologous end joining. Biochem Soc Trans 2023; 51:1789-1800. [PMID: 37787023 PMCID: PMC10657183 DOI: 10.1042/bst20220741] [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: 08/26/2023] [Revised: 08/26/2023] [Accepted: 09/22/2023] [Indexed: 10/04/2023]
Abstract
Non-homologous end joining (NHEJ) is the major pathway for the repair of ionizing radiation-induced DNA double-strand breaks (DSBs) in human cells and is essential for the generation of mature T and B cells in the adaptive immune system via the process of V(D)J recombination. Here, we review how recently determined structures shed light on how NHEJ complexes function at DNA DSBs, emphasizing how multiple structures containing the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) may function in NHEJ. Together, these studies provide an explanation for how NHEJ proteins assemble to detect and protect DSB ends, then proceed, through DNA-PKcs-dependent autophosphorylation, to a ligation-competent complex.
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Affiliation(s)
- Alex Vogt
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, U.S.A
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, U.S.A
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, U.S.A
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, U.S.A
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, U.S.A
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, U.S.A
| | - Susan P. Lees-Miller
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre and Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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8
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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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9
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Bian X, Sun C, Cheng J, Hong B. Targeting DNA Damage Repair and Immune Checkpoint Proteins for Optimizing the Treatment of Endometrial Cancer. Pharmaceutics 2023; 15:2241. [PMID: 37765210 PMCID: PMC10536053 DOI: 10.3390/pharmaceutics15092241] [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: 06/05/2023] [Revised: 08/04/2023] [Accepted: 08/12/2023] [Indexed: 09/29/2023] Open
Abstract
The dependence of cancer cells on the DNA damage response (DDR) pathway for the repair of endogenous- or exogenous-factor-induced DNA damage has been extensively studied in various cancer types, including endometrial cancer (EC). Targeting one or more DNA damage repair protein with small molecules has shown encouraging treatment efficacy in preclinical and clinical models. However, the genes coding for DDR factors are rarely mutated in EC, limiting the utility of DDR inhibitors in this disease. In the current review, we recapitulate the functional role of the DNA repair system in the development and progression of cancer. Importantly, we discuss strategies that target DDR proteins, including PARP, CHK1 and WEE1, as monotherapies or in combination with cytotoxic agents in the treatment of EC and highlight the compounds currently being evaluated for their efficacy in EC in clinic. Recent studies indicate that the application of DNA damage agents in cancer cells leads to the activation of innate and adaptive immune responses; targeting immune checkpoint proteins could overcome the immune suppressive environment in tumors. We further summarize recently revolutionized immunotherapies that have been completed or are now being evaluated for their efficacy in advanced EC and propose future directions for the development of DDR-based cancer therapeutics in the treatment of EC.
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Affiliation(s)
- Xing Bian
- College of Biological and Pharmaceutical Engineering, West Anhui University, Lu’an 237012, China; (X.B.); (C.S.); (J.C.)
| | - Chuanbo Sun
- College of Biological and Pharmaceutical Engineering, West Anhui University, Lu’an 237012, China; (X.B.); (C.S.); (J.C.)
| | - Jin Cheng
- College of Biological and Pharmaceutical Engineering, West Anhui University, Lu’an 237012, China; (X.B.); (C.S.); (J.C.)
| | - Bo Hong
- Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
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10
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Watanabe G, Lieber MR. The flexible and iterative steps within the NHEJ pathway. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 180-181:105-119. [PMID: 37150451 PMCID: PMC10205690 DOI: 10.1016/j.pbiomolbio.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/28/2023] [Accepted: 05/04/2023] [Indexed: 05/09/2023]
Abstract
Cellular and biochemical studies of nonhomologous DNA end joining (NHEJ) have long established that nuclease and polymerase action are necessary for the repair of a very large fraction of naturally-arising double-strand breaks (DSBs). This conclusion is derived from NHEJ studies ranging from yeast to humans and all genetically-tractable model organisms. Biochemical models derived from recent real-time and structural studies have yet to incorporate physical space or timing for DNA end processing. In real-time single molecule FRET (smFRET) studies, we analyzed NHEJ synapsis of DNA ends in a defined biochemical system. We described a Flexible Synapsis (FS) state in which the DNA ends were in proximity via only Ku and XRCC4:DNA ligase 4 (X4L4), and in an orientation that would not yet permit ligation until base pairing between one or more nucleotides of microhomology (MH) occurred, thereby allowing an in-line Close Synapsis (CS) state. If no MH was achievable, then XLF was critical for ligation. Neither FS or CS required DNA-PKcs, unless Artemis activation was necessary to permit local resection and subsequent base pairing between the two DNA ends being joined. Here we conjecture on possible 3D configurations for this FS state, which would spatially accommodate the nuclease and polymerase processing steps in an iterative manner. The FS model permits repeated attempts at ligation of at least one strand at the DSB after each round of nuclease or polymerase action. In addition to activation of Artemis, other possible roles for DNA-PKcs are discussed.
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Affiliation(s)
- Go Watanabe
- Departments of Pathology, Biochemistry, Molecular Microbiology & Immunology, and Section of Molecular & Computational Biology (Department of Biological Sciences), University of Southern California, Los Angeles, CA, 90089-9176, USA
| | - Michael R Lieber
- Departments of Pathology, Biochemistry, Molecular Microbiology & Immunology, and Section of Molecular & Computational Biology (Department of Biological Sciences), University of Southern California, Los Angeles, CA, 90089-9176, USA.
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Ogana HA, Hurwitz S, Hsieh CL, Geng H, Müschen M, Bhojwani D, Wolf MA, Larocque J, Lieber MR, Kim YM. Artemis inhibition as a therapeutic strategy for acute lymphoblastic leukemia. Front Cell Dev Biol 2023; 11:1134121. [PMID: 37082620 PMCID: PMC10111164 DOI: 10.3389/fcell.2023.1134121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
As effective therapies for relapse and refractory B-cell acute lymphoblastic leukemia (B-ALL) remain problematic, novel therapeutic strategies are needed. Artemis is a key endonuclease in V(D)J recombination and nonhomologous end joining (NHEJ) of DNA double-strand break (DSB) repair. Inhibition of Artemis would cause chromosome breaks during maturation of RAG-expressing T- and B-cells. Though this would block generation of new B- and T-cells temporarily, it could be oncologically beneficial for reducing the proliferation of B-ALL and T-ALL cells by causing chromosome breaks in these RAG-expressing tumor cells. Currently, pharmacological inhibition is not available for Artemis. According to gene expression analyses from 207 children with high-risk pre-B acute lymphoblastic leukemias high Artemis expression is correlated with poor outcome. Therefore, we evaluated four compounds (827171, 827032, 826941, and 825226), previously generated from a large Artemis targeted drug screen. A biochemical assay using a purified Artemis:DNA-PKcs complex shows that the Artemis inhibitors 827171, 827032, 826941, 825226 have nanomolar IC50 values for Artemis inhibition. We compared these 4 compounds to a DNA-PK inhibitor (AZD7648) in three patient-derived B-ALL cell lines (LAX56, BLQ5 and LAX7R) and in two mature B-cell lines (3301015 and 5680001) as controls. We found that pharmacological Artemis inhibition substantially decreases proliferation of B-ALL cell lines while normal mature B-cell lines are not markedly affected. Inhibition of DNA-PKcs (which regulates Artemis) using the DNA-PK inhibitor AZD7648 had minor effects on these same primary patient-derived ALL lines, indicating that inhibition of V(D)J hairpin opening requires direct inhibition of Artemis, rather than indirect suppression of the kinase that regulates Artemis. Our data provides a basis for further evaluation of pharmacological Artemis inhibition of proliferation of B- and T-ALL.
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Affiliation(s)
- Heather A. Ogana
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Samantha Hurwitz
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Chih-Lin Hsieh
- Department of Urology, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Huimin Geng
- Department of Laboratory Medicine, UCSF, San Francisco, CA, United States
| | - Markus Müschen
- Department of Immunobiology, Center of Molecular and Cellular Oncology, Yale University, New Haven, CT, United States
| | - Deepa Bhojwani
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | | | | | - Michael R. Lieber
- Departments of Pathology, The Molecular and Computational Biology Section of the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Biochemistry and Molecular Biology, Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Yong Mi Kim
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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