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Jordan MR, Oakley GG, Mayo LD, Balakrishnan L, Turchi JJ. The effect of replication protein A inhibition and post-translational modification on ATR kinase signaling. Sci Rep 2024; 14:19791. [PMID: 39187637 PMCID: PMC11347632 DOI: 10.1038/s41598-024-70589-y] [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: 06/12/2024] [Accepted: 08/19/2024] [Indexed: 08/28/2024] Open
Abstract
The ATR kinase responds to elevated levels of single-stranded DNA (ssDNA) to activate the G2/M checkpoint, regulate origin utilization, preserve fork stability, and allow DNA repair to ensure genome integrity. The intrinsic replication stress in cancer cells makes this pathway an attractive therapeutic target. The ssDNA that drives ATR signaling is sensed by the ssDNA-binding protein replication protein A (RPA), which acts as a platform for ATRIP recruitment and subsequent ATR activation by TopBP1. We have developed chemical RPA inhibitors (RPAi) that block RPA-ssDNA interactions (RPA-DBi) and RPA protein-protein interactions (RPA-PPIi); both activities are required for ATR activation. Here, we biochemically reconstitute the ATR kinase signaling pathway and demonstrate that RPA-DBi and RPA-PPIi abrogate ATR-dependent phosphorylation of target proteins with selectivity advantages over active site ATR inhibitors. We demonstrate that RPA post-translational modifications (PTMs) impact ATR kinase activation but do not alter sensitivity to RPAi. Specifically, phosphorylation of RPA32 and TopBP1 stimulate, while RPA70 acetylation does not affect ATR phosphorylation of target proteins. Collectively, this work reveals the RPAi mechanism of action to inhibit ATR signaling that can be regulated by RPA PTMs and offers insight into the anti-cancer activity of ATR pathway-targeted cancer therapeutics.
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Affiliation(s)
- Matthew R Jordan
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 64202, USA
| | - Greg G Oakley
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, 68583, USA
| | - Lindsey D Mayo
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Lata Balakrishnan
- Department of Biology, School of Science, Indiana University Indianapolis, Indianapolis, IN, 46202, USA
| | - John J Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 64202, USA.
- NERx Biosciences Inc., Indianapolis, IN, 46202, USA.
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2
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Jordan MR, Oakley GG, Mayo LD, Balakrishnan L, Turchi JJ. The Effect of Replication Protein A Inhibition and Post-Translational Modification on ATR Kinase Signaling. RESEARCH SQUARE 2024:rs.3.rs-4570504. [PMID: 39108493 PMCID: PMC11302688 DOI: 10.21203/rs.3.rs-4570504/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/11/2024]
Abstract
The ATR kinase responds to elevated levels of single-stranded DNA (ssDNA) to activate the G2/M checkpoint, regulate origin utilization, preserve fork stability, and allow DNA repair towards ensuring genome integrity. The intrinsic replication stress in cancer cells makes this pathway an attractive therapeutic target. The ssDNA that drives ATR signaling is sensed by the ssDNA-binding protein replication protein A (RPA), which acts as a platform for ATRIP recruitment and subsequent ATR activation by TopBP1. We have developed chemical RPA inhibitors (RPAi) that block RPA-ssDNA interactions, termed RPA-DBi, and RPA protein-protein interactions, termed RPA-PPIi; both activities are required for ATR activation. Here, we employ a biochemically reconstituted ATR kinase signaling pathway and demonstrate that both RPA-DBi and RPA-PPIi abrogate ATR-dependent phosphorylation of downstream target proteins. We demonstrate that RPA post-translational modifications (PTMs) impact ATR kinase activation but do not alter sensitivity to RPAi. Specifically, phosphorylation of RPA32 and TopBP1 stimulate, while RPA70 acetylation has no effect on ATR phosphorylation of target proteins. Collectively, this work reveals the RPAi mechanism of action to inhibit ATR signaling that can be regulated by RPA PTMs and offers insight into the anti-cancer activity of ATR pathway targeted cancer therapeutics.
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3
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Ren S, Bai F, Schnell V, Stanko C, Ritsch M, Schenk T, Barth E, Marz M, Wang B, Pei XH, Bierhoff H. PAPAS promotes differentiation of mammary epithelial cells and suppresses breast carcinogenesis. Cell Rep 2024; 43:113644. [PMID: 38180837 DOI: 10.1016/j.celrep.2023.113644] [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: 03/31/2023] [Revised: 10/18/2023] [Accepted: 12/19/2023] [Indexed: 01/07/2024] Open
Abstract
Extensive remodeling of the female mammary epithelium during development and pregnancy has been linked to cancer susceptibility. The faithful response of mammary epithelial cells (MECs) to hormone signaling is key to avoiding breast cancer development. Here, we show that lactogenic differentiation of murine MECs requires silencing of genes encoding ribosomal RNA (rRNA) by the antisense transcript PAPAS. Accordingly, knockdown of PAPAS derepresses rRNA genes, attenuates the response to lactogenic hormones, and induces malignant transformation. Restoring PAPAS levels in breast cancer cells reduces tumorigenicity and lung invasion and activates many interferon-regulated genes previously linked to metastasis suppression. Mechanistically, PAPAS transcription depends on R-loop formation at the 3' end of rRNA genes, which is repressed by RNase H1 and replication protein A (RPA) overexpression in breast cancer cells. Depletion of PAPAS and upregulation of RNase H1 and RPA in human breast cancer underpin the clinical relevance of our findings.
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Affiliation(s)
- Sijia Ren
- Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine (CMB), Friedrich Schiller University Jena, Hans-Knöll-Str. 2, 07745 Jena, Germany; Guangdong Provincial Key Laboratory of Regional Immunity and Diseases, International Cancer Center, Marshall Laboratory of Biomedical Engineering, Department of Anatomy and Histology, Shenzhen University Medical School, Shenzhen 518060, China; Leibniz-Institute on Aging-Fritz Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Feng Bai
- Department of Pathology, Shenzhen University Medical School, Shenzhen 518060, China
| | - Viviane Schnell
- Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine (CMB), Friedrich Schiller University Jena, Hans-Knöll-Str. 2, 07745 Jena, Germany; Leibniz-Institute on Aging-Fritz Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Clara Stanko
- Department of Hematology and Medical Oncology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany; Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), Jena University Hospital, Jena, Hans-Knöll-Str. 2, 07745 Jena, Germany
| | - Muriel Ritsch
- Bioinformatics Core Facility Jena, Friedrich Schiller University Jena, Leutragraben 1, 07743 Jena, Germany; RNA Bioinformatics/High Throughput Analysis, Faculty of Mathematics and Computer Science, Leutragraben 1, 07743 Jena, Germany
| | - Tino Schenk
- Department of Hematology and Medical Oncology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany; Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), Jena University Hospital, Jena, Hans-Knöll-Str. 2, 07745 Jena, Germany
| | - Emanuel Barth
- Bioinformatics Core Facility Jena, Friedrich Schiller University Jena, Leutragraben 1, 07743 Jena, Germany; RNA Bioinformatics/High Throughput Analysis, Faculty of Mathematics and Computer Science, Leutragraben 1, 07743 Jena, Germany
| | - Manja Marz
- Bioinformatics Core Facility Jena, Friedrich Schiller University Jena, Leutragraben 1, 07743 Jena, Germany; RNA Bioinformatics/High Throughput Analysis, Faculty of Mathematics and Computer Science, Leutragraben 1, 07743 Jena, Germany
| | - Bin Wang
- Department of General Surgery, Shenzhen Children's Hospital, Shenzhen 518060, China
| | - Xin-Hai Pei
- Guangdong Provincial Key Laboratory of Regional Immunity and Diseases, International Cancer Center, Marshall Laboratory of Biomedical Engineering, Department of Anatomy and Histology, Shenzhen University Medical School, Shenzhen 518060, China.
| | - Holger Bierhoff
- Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine (CMB), Friedrich Schiller University Jena, Hans-Knöll-Str. 2, 07745 Jena, Germany; Leibniz-Institute on Aging-Fritz Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany.
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4
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Vasilopoulos SN, Güner H, Uça Apaydın M, Pavlopoulou A, Georgakilas AG. Dual Targeting of DNA Damage Response Proteins Implicated in Cancer Radioresistance. Genes (Basel) 2023; 14:2227. [PMID: 38137049 PMCID: PMC10742610 DOI: 10.3390/genes14122227] [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: 11/26/2023] [Revised: 12/13/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023] Open
Abstract
Ionizing radiation can induce different types of DNA lesions, leading to genomic instability and ultimately cell death. Radiation therapy or radiotherapy, a major modality in cancer treatment, harnesses the genotoxic potential of radiation to target and destroy cancer cells. Nevertheless, cancer cells have the capacity to develop resistance to radiation treatment (radioresistance), which poses a major obstacle in the effective management of cancer. It has been shown that administration of platinum-based drugs to cancer patients can increase tumor radiosensitivity, but despite this, it is associated with severe adverse effects. Several lines of evidence support that activation of the DNA damage response and repair machinery in the irradiated cancer cells enhances radioresistance and cellular survival through the efficient repair of DNA lesions. Therefore, targeting of key DNA damage repair factors would render cancer cells vulnerable to the irradiation effects, increase cancer cell killing, and reduce the risk of side effects on healthy tissue. Herein, we have employed a computer-aided drug design approach for generating ab initio a chemical compound with drug-like properties potentially targeting two proteins implicated in multiple DNA repair pathways. The findings of this study could be taken into consideration in clinical decision-making in terms of co-administering radiation with DNA damage repair factor-based drugs.
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Affiliation(s)
- Spyridon N. Vasilopoulos
- DNA Damage Laboratory, Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens (NTUA), Zografou Campus, 15780 Athens, Greece;
- Department of Science and Mathematics, Deree-The American College of Greece, 6 Gravias Street, 15342 Athens, Greece
| | - Hüseyin Güner
- Izmir Biomedicine and Genome Center (IBG), 35340 Izmir, Turkey; (H.G.); (M.U.A.)
- Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, 35340 Izmir, Turkey
- Department of Molecular Biology and Genetics, Faculty of Life and Natural Science, Abdullah Gül University, 38080 Kayseri, Turkey
| | - Merve Uça Apaydın
- Izmir Biomedicine and Genome Center (IBG), 35340 Izmir, Turkey; (H.G.); (M.U.A.)
- Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, 35340 Izmir, Turkey
| | - Athanasia Pavlopoulou
- Izmir Biomedicine and Genome Center (IBG), 35340 Izmir, Turkey; (H.G.); (M.U.A.)
- Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, 35340 Izmir, Turkey
| | - Alexandros G. Georgakilas
- DNA Damage Laboratory, Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens (NTUA), Zografou Campus, 15780 Athens, Greece;
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Dueva R, Krieger LM, Li F, Luo D, Xiao H, Stuschke M, Metzen E, Iliakis G. Chemical Inhibition of RPA by HAMNO Alters Cell Cycle Dynamics by Impeding DNA Replication and G2-to-M Transition but Has Little Effect on the Radiation-Induced DNA Damage Response. Int J Mol Sci 2023; 24:14941. [PMID: 37834389 PMCID: PMC10573259 DOI: 10.3390/ijms241914941] [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: 09/01/2023] [Revised: 09/28/2023] [Accepted: 10/01/2023] [Indexed: 10/15/2023] Open
Abstract
Replication protein A (RPA) is the major single-stranded DNA (ssDNA) binding protein that is essential for DNA replication and processing of DNA double-strand breaks (DSBs) by homology-directed repair pathways. Recently, small molecule inhibitors have been developed targeting the RPA70 subunit and preventing RPA interactions with ssDNA and various DNA repair proteins. The rationale of this development is the potential utility of such compounds as cancer therapeutics, owing to their ability to inhibit DNA replication that sustains tumor growth. Among these compounds, (1Z)-1-[(2-hydroxyanilino) methylidene] naphthalen-2-one (HAMNO) has been more extensively studied and its efficacy against tumor growth was shown to arise from the associated DNA replication stress. Here, we study the effects of HAMNO on cells exposed to ionizing radiation (IR), focusing on the effects on the DNA damage response and the processing of DSBs and explore its potential as a radiosensitizer. We show that HAMNO by itself slows down the progression of cells through the cell cycle by dramatically decreasing DNA synthesis. Notably, HAMNO also attenuates the progression of G2-phase cells into mitosis by a mechanism that remains to be elucidated. Furthermore, HAMNO increases the fraction of chromatin-bound RPA in S-phase but not in G2-phase cells and suppresses DSB repair by homologous recombination. Despite these marked effects on the cell cycle and the DNA damage response, radiosensitization could neither be detected in exponentially growing cultures, nor in cultures enriched in G2-phase cells. Our results complement existing data on RPA inhibitors, specifically HAMNO, and suggest that their antitumor activity by replication stress induction may not extend to radiosensitization. However, it may render cells more vulnerable to other forms of DNA damaging agents through synthetically lethal interactions, which requires further investigation.
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Affiliation(s)
- Rositsa Dueva
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (L.M.K.); (F.L.); (D.L.); (H.X.)
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Lisa Marie Krieger
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (L.M.K.); (F.L.); (D.L.); (H.X.)
- Division of Experimental Radiation Biology, Department of Radiotherapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Fanghua Li
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (L.M.K.); (F.L.); (D.L.); (H.X.)
- West German Proton Therapy Centre Essen (WPE), 45147 Essen, Germany
| | - Daxian Luo
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (L.M.K.); (F.L.); (D.L.); (H.X.)
- Division of Experimental Radiation Biology, Department of Radiotherapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Huaping Xiao
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (L.M.K.); (F.L.); (D.L.); (H.X.)
- Division of Experimental Radiation Biology, Department of Radiotherapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiotherapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, 45147 Essen, Germany
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Eric Metzen
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - George Iliakis
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (L.M.K.); (F.L.); (D.L.); (H.X.)
- Division of Experimental Radiation Biology, Department of Radiotherapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
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Mukherjee A, Hossain Z, Erben E, Ma S, Choi JY, Kim HS. Identification of a small-molecule inhibitor that selectively blocks DNA-binding by Trypanosoma brucei replication protein A1. Nat Commun 2023; 14:4390. [PMID: 37474515 PMCID: PMC10359466 DOI: 10.1038/s41467-023-39839-x] [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: 10/12/2022] [Accepted: 06/30/2023] [Indexed: 07/22/2023] Open
Abstract
Replication Protein A (RPA) is a broadly conserved complex comprised of the RPA1, 2 and 3 subunits. RPA protects the exposed single-stranded DNA (ssDNA) during DNA replication and repair. Using structural modeling, we discover an inhibitor, JC-229, that targets RPA1 in Trypanosoma brucei, the causative parasite of African trypanosomiasis. The inhibitor is highly toxic to T. brucei cells, while mildly toxic to human cells. JC-229 treatment mimics the effects of TbRPA1 depletion, including DNA replication inhibition and DNA damage accumulation. In-vitro ssDNA-binding assays demonstrate that JC-229 inhibits the activity of TbRPA1, but not the human ortholog. Indeed, despite the high sequence identity with T. cruzi and Leishmania RPA1, JC-229 only impacts the ssDNA-binding activity of TbRPA1. Site-directed mutagenesis confirms that the DNA-Binding Domain A (DBD-A) in TbRPA1 contains a JC-229 binding pocket. Residue Serine 105 determines specific binding and inhibition of TbRPA1 but not T. cruzi and Leishmania RPA1. Our data suggest a path toward developing and testing highly specific inhibitors for the treatment of African trypanosomiasis.
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Affiliation(s)
- Aditi Mukherjee
- Public Health Research Institute, Rutgers Biomedical Health Sciences, Newark, NJ, 07103, USA
| | - Zakir Hossain
- Department of Chemistry and Biochemistry, Queens College, New York, NY, 11367, USA
| | - Esteban Erben
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Provincia de Buenos Aires, Argentina
- Escuela de Bio y Nanotecnologías (EByN), Universidad Nacional de San Martín, San Martín, Provincia de Buenos Aires, Argentina
| | - Shuai Ma
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Jun Yong Choi
- Department of Chemistry and Biochemistry, Queens College, New York, NY, 11367, USA.
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
| | - Hee-Sook Kim
- Public Health Research Institute, Rutgers Biomedical Health Sciences, Newark, NJ, 07103, USA.
- Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers Biomedical Health Sciences, Newark, NJ, 07103, USA.
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Nongpiur CGL, Verma AK, Singh RK, Ghate MM, Poluri KM, Kaminsky W, Kollipara MR. Half-sandwich ruthenium(II), rhodium(III) and iridium(III) fluorescent metal complexes containing pyrazoline based ligands: DNA binding, cytotoxicity and antibacterial activities. J Inorg Biochem 2023; 238:112059. [PMID: 36345069 DOI: 10.1016/j.jinorgbio.2022.112059] [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: 09/09/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
Abstract
A series of nine new complexes of ruthenium(II), rhodium(III), and iridium(III) incorporated with pyrazoline-based ligands were synthesized and characterized by various spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, UV-Vis spectroscopy, ESI-MS spectrometry and X-ray crystallographic studies. All the synthesized compounds were assessed for their antibacterial abilities against Gram-positive and Gram-negative bacterial strains. The compounds showed better antibacterial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus Thuringiensis), with activities superior to standard kanamycin. Antioxidant studies revealed the mild radical scavenging proficiency of the compounds. DNA binding studies using fluorescence spectroscopy showed that the compounds could bind to Salmon Milt DNA electrostatically via external contact and groove surface binding with moderate affinity. The synthesized complexes were tested for anticancer activity using cell cytotoxicity and apoptosis assays in Dalton's lymphoma (DL) cell lines. The findings were compared to cisplatin (the standard drug) under identical experimental conditions. The cell viability results showed that complex 7 induced higher cytotoxicity in the DL cell line than the other tested compounds. The results of the molecular docking analysis further suggest that selective complexes have complete contact with the active amino acids sites of anti-apoptotic Bcl-2 family protein.
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Affiliation(s)
| | | | - Rohit Kumar Singh
- Department of Zoology, Cotton University, Guwahati 781001, Assam, India
| | - Mayur Mohan Ghate
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247 667, India
| | - Krishna Mohan Poluri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247 667, India
| | - Werner Kaminsky
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Mohan Rao Kollipara
- Centre for Advanced Studies in Chemistry, North-Eastern Hill University, Shillong 793 022, India.
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Guo JT, Malik F. Single-Stranded DNA Binding Proteins and Their Identification Using Machine Learning-Based Approaches. Biomolecules 2022; 12:biom12091187. [PMID: 36139026 PMCID: PMC9496475 DOI: 10.3390/biom12091187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/11/2022] [Accepted: 08/24/2022] [Indexed: 11/25/2022] Open
Abstract
Single-stranded DNA (ssDNA) binding proteins (SSBs) are critical in maintaining genome stability by protecting the transient existence of ssDNA from damage during essential biological processes, such as DNA replication and gene transcription. The single-stranded region of telomeres also requires protection by ssDNA binding proteins from being attacked in case it is wrongly recognized as an anomaly. In addition to their critical roles in genome stability and integrity, it has been demonstrated that ssDNA and SSB-ssDNA interactions play critical roles in transcriptional regulation in all three domains of life and viruses. In this review, we present our current knowledge of the structure and function of SSBs and the structural features for SSB binding specificity. We then discuss the machine learning-based approaches that have been developed for the prediction of SSBs from double-stranded DNA (dsDNA) binding proteins (DSBs).
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Jang SW, Kim JM. The RPA inhibitor HAMNO sensitizes Fanconi anemia pathway-deficient cells. Cell Cycle 2022; 21:1468-1478. [PMID: 35506981 PMCID: PMC9278452 DOI: 10.1080/15384101.2022.2074200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The Fanconi anemia (FA) DNA repair pathway is required for DNA inter-strand crosslink (ICL) repair. Besides its role in ICL repair, FA proteins play a central role in stabilizing stalled replication forks, thereby ensuring genome integrity. We previously demonstrated that depletion of replication protein A (RPA) induces the activation of FA pathway leading to FANCD2 monoubiquitination and FANCD2 foci formation. Thus, we speculated that FA-deficient cells would be more sensitive to RPA inhibition compared to FA-proficient cells. Following treatment with RPA inhibitor HAMNO, we observed significant induction in FANCD2 monoubiquitination and foci formation as observed in RPA depletion. In addition, HAMNO treatment caused increased levels of ϒ-H2AX and S-phase accumulation in FA-deficient cells. Importantly, FA-deficient cells showed more increased sensitivity to HAMNO than FA-proficient cells. Moreover, in combination with cisplatin, HAMNO further enhanced the cytotoxicity of cisplatin in FA-deficient cells, while being less toxic against FA-proficient cells. This result suggests that RPA inhibition might be a potential therapeutic candidate for the treatment of FA pathway-deficient tumors.
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Affiliation(s)
- Seok-Won Jang
- Department of Pharmacology, Chonnam National University Medical School, Jellanamdo, 58128, Republic of Korea
| | - Jung Min Kim
- Department of Pharmacology, Chonnam National University Medical School, Jellanamdo, 58128, Republic of Korea
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Kelm JM, Samarbakhsh A, Pillai A, VanderVere-Carozza PS, Aruri H, Pandey DS, Pawelczak KS, Turchi JJ, Gavande NS. Recent Advances in the Development of Non-PIKKs Targeting Small Molecule Inhibitors of DNA Double-Strand Break Repair. Front Oncol 2022; 12:850883. [PMID: 35463312 PMCID: PMC9020266 DOI: 10.3389/fonc.2022.850883] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 02/22/2022] [Indexed: 01/09/2023] Open
Abstract
The vast majority of cancer patients receive DNA-damaging drugs or ionizing radiation (IR) during their course of treatment, yet the efficacy of these therapies is tempered by DNA repair and DNA damage response (DDR) pathways. Aberrations in DNA repair and the DDR are observed in many cancer subtypes and can promote de novo carcinogenesis, genomic instability, and ensuing resistance to current cancer therapy. Additionally, stalled or collapsed DNA replication forks present a unique challenge to the double-strand DNA break (DSB) repair system. Of the various inducible DNA lesions, DSBs are the most lethal and thus desirable in the setting of cancer treatment. In mammalian cells, DSBs are typically repaired by the error prone non-homologous end joining pathway (NHEJ) or the high-fidelity homology directed repair (HDR) pathway. Targeting DSB repair pathways using small molecular inhibitors offers a promising mechanism to synergize DNA-damaging drugs and IR while selective inhibition of the NHEJ pathway can induce synthetic lethality in HDR-deficient cancer subtypes. Selective inhibitors of the NHEJ pathway and alternative DSB-repair pathways may also see future use in precision genome editing to direct repair of resulting DSBs created by the HDR pathway. In this review, we highlight the recent advances in the development of inhibitors of the non-phosphatidylinositol 3-kinase-related kinases (non-PIKKs) members of the NHEJ, HDR and minor backup SSA and alt-NHEJ DSB-repair pathways. The inhibitors described within this review target the non-PIKKs mediators of DSB repair including Ku70/80, Artemis, DNA Ligase IV, XRCC4, MRN complex, RPA, RAD51, RAD52, ERCC1-XPF, helicases, and DNA polymerase θ. While the DDR PIKKs remain intensely pursued as therapeutic targets, small molecule inhibition of non-PIKKs represents an emerging opportunity in drug discovery that offers considerable potential to impact cancer treatment.
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Affiliation(s)
- Jeremy M. Kelm
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | - Amirreza Samarbakhsh
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | - Athira Pillai
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | | | - Hariprasad Aruri
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | - Deepti S. Pandey
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | | | - John J. Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States,NERx Biosciences, Indianapolis, IN, United States,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Navnath S. Gavande
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States,Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, United States,*Correspondence: Navnath S. Gavande, ; orcid.org/0000-0002-2413-0235
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VanderVere-Carozza PS, Gavande NS, Jalal SI, Pollok KE, Ekinci E, Heyza J, Patrick SM, Masters A, Turchi JJ, Pawelczak KS. In Vivo Targeting Replication Protein A for Cancer Therapy. Front Oncol 2022; 12:826655. [PMID: 35251993 PMCID: PMC8895377 DOI: 10.3389/fonc.2022.826655] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/18/2022] [Indexed: 02/04/2023] Open
Abstract
Replication protein A (RPA) plays essential roles in DNA replication, repair, recombination, and the DNA damage response (DDR). Retrospective analysis of lung cancer patient data demonstrates high RPA expression as a negative prognostic biomarker for overall survival in smoking-related lung cancers. Similarly, relative expression of RPA is a predictive marker for response to chemotherapy. These observations are consistent with the increase in RPA expression serving as an adaptive mechanism that allows tolerance of the genotoxic stress resulting from carcinogen exposure. We have developed second-generation RPA inhibitors (RPAis) that block the RPA-DNA interaction and optimized formulation for in vivo analyses. Data demonstrate that unlike first-generation RPAis, second-generation molecules show increased cellular permeability and induce cell death via apoptosis. Second-generation RPAis elicit single-agent in vitro anticancer activity across a broad spectrum of cancers, and the cellular response suggests existence of a threshold before chemical RPA exhaustion induces cell death. Chemical RPA inhibition potentiates the anticancer activity of a series of DDR inhibitors and traditional DNA-damaging cancer therapeutics. Consistent with chemical RPA exhaustion, we demonstrate that the effects of RPAi on replication fork dynamics are similar to other known DDR inhibitors. An optimized formulation of RPAi NERx 329 was developed that resulted in single-agent anticancer activity in two non-small cell lung cancer models. These data demonstrate a unique mechanism of action of RPAis eliciting a state of chemical RPA exhaustion and suggest they will provide an effective therapeutic option for difficult-to-treat lung cancers.
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Affiliation(s)
| | - Navnath S. Gavande
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States,Department of Pharmaceutical Sciences, Wayne State University College of Pharmacy and Health Sciences, Detroit, MI, United States
| | - Shadia I. Jalal
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Karen E. Pollok
- Herman B. Wells Center for Pediatric Research, Departments of Pediatrics, Pharmacology and Toxicology, Medical and Molecular Genetics Indiana University Simon Comprehensive Cancer Center, Indianapolis, IN, United States
| | - Elmira Ekinci
- Department of Oncology, Wayne State University School of Medicine and Barbara Ann Karmanos Cancer Institute, Detroit, MI, United States
| | - Joshua Heyza
- Department of Oncology, Wayne State University School of Medicine and Barbara Ann Karmanos Cancer Institute, Detroit, MI, United States
| | - Steve M. Patrick
- Department of Oncology, Wayne State University School of Medicine and Barbara Ann Karmanos Cancer Institute, Detroit, MI, United States
| | - Andi Masters
- Indiana University Cancer Center, Indiana University School of Medicine, Indianapolis, IN, United States
| | - John J. Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States,NERx BioSciences, Indianapolis, IN, United States,*Correspondence: John J. Turchi, ; Katherine S. Pawelczak,
| | - Katherine S. Pawelczak
- NERx BioSciences, Indianapolis, IN, United States,*Correspondence: John J. Turchi, ; Katherine S. Pawelczak,
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12
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Transcription/Replication Conflicts in Tumorigenesis and Their Potential Role as Novel Therapeutic Targets in Multiple Myeloma. Cancers (Basel) 2021; 13:cancers13153755. [PMID: 34359660 PMCID: PMC8345052 DOI: 10.3390/cancers13153755] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/13/2021] [Accepted: 07/22/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Multiple myeloma is a hematologic cancer characterized by the accumulation of malignant plasma cells in the bone marrow. It remains a mostly incurable disease due to the inability to overcome refractory disease and drug-resistant relapse. Oncogenic transformation of PC in multiple myeloma is thought to occur within the secondary lymphoid organs. However, the precise molecular events leading to myelomagenesis remain obscure. Here, we identified genes involved in the prevention and the resolution of conflicts between the replication and transcription significantly overexpressed during the plasma cell differentiation process and in multiple myeloma cells. We discussed the potential role of these factors in myelomagenesis and myeloma biology. The specific targeting of these factors might constitute a new therapeutic strategy in multiple myeloma. Abstract Plasma cells (PCs) have an essential role in humoral immune response by secretion of antibodies, and represent the final stage of B lymphocytes differentiation. During this differentiation, the pre-plasmablastic stage is characterized by highly proliferative cells that start to secrete immunoglobulins (Igs). Thus, replication and transcription must be tightly regulated in these cells to avoid transcription/replication conflicts (TRCs), which could increase replication stress and lead to genomic instability. In this review, we analyzed expression of genes involved in TRCs resolution during B to PC differentiation and identified 41 genes significantly overexpressed in the pre-plasmablastic stage. This illustrates the importance of mechanisms required for adequate processing of TRCs during PCs differentiation. Furthermore, we identified that several of these factors were also found overexpressed in purified PCs from patients with multiple myeloma (MM) compared to normal PCs. Malignant PCs produce high levels of Igs concomitantly with cell cycle deregulation. Therefore, increasing the TRCs occurring in MM cells could represent a potent therapeutic strategy for MM patients. Here, we describe the potential roles of TRCs resolution factors in myelomagenesis and discuss the therapeutic interest of targeting the TRCs resolution machinery in MM.
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Ninou AH, Lehto J, Chioureas D, Stigsdotter H, Schelzig K, Åkerlund E, Gudoityte G, Joneborg U, Carlson J, Jonkers J, Seashore-Ludlow B, Gustafsson NMS. PFKFB3 Inhibition Sensitizes DNA Crosslinking Chemotherapies by Suppressing Fanconi Anemia Repair. Cancers (Basel) 2021; 13:cancers13143604. [PMID: 34298817 PMCID: PMC8306909 DOI: 10.3390/cancers13143604] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/13/2021] [Accepted: 07/15/2021] [Indexed: 12/25/2022] Open
Abstract
Simple Summary DNA-damaging chemotherapeutics, such as platinum drugs, are cornerstones in cancer treatment. The efficacy of such treatment is intimately linked to the DNA repair capacity of the cancer cells, as DNA damage above a tolerable threshold culminates in cell death. Cancer cells often have deregulated DNA repair mechanisms, making them initially more sensitive to DNA-damaging chemotherapies. Unfortunately, over time, cancer cells often develop resistance to such treatments by rewiring their DNA damage response pathways. Here, we identify that targeting the recognized anti-cancer target 6-phosphofructo-2-kinase/fructose-2,6,-bisphophatase 3 (PFKFB3), commonly overexpressed in cancer, with the small molecule inhibitor KAN0438757, selectively sensitizes cancer cells to platinum drugs, including treatment-resistant cancer cells, while sparing normal cells. Mechanistically, PFKFB3 promotes tolerance to and the repair of platinum-induced DNA interstrand crosslinks (ICLs) through modulation of the Fanconi anemia (FA) DNA repair pathway. Thus targeting PFKFB3 opens up therapeutic possibilities to improve the efficacy of ICL-inducing cancer treatments. Abstract Replicative repair of interstrand crosslinks (ICL) generated by platinum chemotherapeutics is orchestrated by the Fanconi anemia (FA) repair pathway to ensure resolution of stalled replication forks and the maintenance of genomic integrity. Here, we identify novel regulation of FA repair by the cancer-associated glycolytic enzyme PFKFB3 that has functional consequences for replication-associated ICL repair and cancer cell survival. Inhibition of PFKFB3 displays a cancer-specific synergy with platinum compounds in blocking cell viability and restores sensitivity in treatment-resistant models. Notably, the synergies are associated with DNA-damage-induced chromatin association of PFKFB3 upon cancer transformation, which further increases upon platinum resistance. FA pathway activation triggers the PFKFB3 assembly into nuclear foci in an ATR- and FANCM-dependent manner. Blocking PFKFB3 activity disrupts the assembly of key FA repair factors and consequently prevents fork restart. This results in an incapacity to replicate cells to progress through S-phase, an accumulation of DNA damage in replicating cells, and fork collapse. We further validate PFKFB3-dependent regulation of FA repair in ex vivo cultures from cancer patients. Collectively, targeting PFKFB3 opens up therapeutic possibilities to improve the efficacy of ICL-inducing cancer treatments.
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Affiliation(s)
- Anna Huguet Ninou
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
- Kancera AB, Karolinska Science Park, 171 48 Solna, Sweden
| | - Jemina Lehto
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
- Kancera AB, Karolinska Science Park, 171 48 Solna, Sweden
| | - Dimitrios Chioureas
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
| | - Hannah Stigsdotter
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
| | - Korbinian Schelzig
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
| | - Emma Åkerlund
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
| | - Greta Gudoityte
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
| | - Ulrika Joneborg
- Department of Women’s and Children’s Health, Karolinska Institutet, 171 21 Stockholm, Sweden;
| | - Joseph Carlson
- Department of Oncology and Pathology, Karolinska Institutet, 171 76 Stockholm, Sweden;
- Department of Pathology and Laboratory Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Jos Jonkers
- Oncode Institute and Division of Molecular Pathology, The Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands;
| | - Brinton Seashore-Ludlow
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
| | - Nina Marie Susanne Gustafsson
- Science for Life Laboratory, Department of Oncology and Pathology, Karolinska Institutet, 171 21 Stockholm, Sweden; (A.H.N.); (J.L.); (D.C.); (H.S.); (K.S.); (E.Å.); (G.G.); (B.S.-L.)
- Correspondence:
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14
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Ray U, Raghavan SC. Understanding the DNA double-strand break repair and its therapeutic implications. DNA Repair (Amst) 2021; 106:103177. [PMID: 34325086 DOI: 10.1016/j.dnarep.2021.103177] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 06/25/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022]
Abstract
Repair of DNA double-strand breaks (DSBs) and its regulation are tightly integrated inside cells. Homologous recombination, nonhomologous end joining and microhomology mediated end joining are three major DSB repair pathways in mammalian cells. Targeting proteins associated with these repair pathways using small molecule inhibitors can prove effective in tumors, especially those with deregulated repair. Sensitization of cancer to current age therapy including radio and chemotherapy, using small molecule inhibitors is promising and warrant further development. Although several are under clinical trial, till date no repair inhibitor is approved for commercial use in cancer patients, with the exception of PARP inhibitors targeting single-strand break repair. Based on molecular profiling of repair proteins, better prognostic and therapeutic output can be achieved in patients. In the present review, we highlight the different mechanisms of DSB repair, chromatin dynamics to provide repair accessibility and modulation of inhibitors in association with molecular profiling and current gold standard treatment modalities for cancer.
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Affiliation(s)
- Ujjayinee Ray
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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15
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Par S, Vaides S, VanderVere-Carozza PS, Pawelczak KS, Stewart J, Turchi JJ. OB-Folds and Genome Maintenance: Targeting Protein-DNA Interactions for Cancer Therapy. Cancers (Basel) 2021; 13:3346. [PMID: 34283091 PMCID: PMC8269290 DOI: 10.3390/cancers13133346] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/09/2021] [Accepted: 07/01/2021] [Indexed: 12/14/2022] Open
Abstract
Genome stability and maintenance pathways along with their requisite proteins are critical for the accurate duplication of genetic material, mutation avoidance, and suppression of human diseases including cancer. Many of these proteins participate in these pathways by binding directly to DNA, and a subset employ oligonucleotide/oligosaccharide binding folds (OB-fold) to facilitate the protein-DNA interactions. OB-fold motifs allow for sequence independent binding to single-stranded DNA (ssDNA) and can serve to position specific proteins at specific DNA structures and then, via protein-protein interaction motifs, assemble the machinery to catalyze the replication, repair, or recombination of DNA. This review provides an overview of the OB-fold structural organization of some of the most relevant OB-fold containing proteins for oncology and drug discovery. We discuss their individual roles in DNA metabolism, progress toward drugging these motifs and their utility as potential cancer therapeutics. While protein-DNA interactions were initially thought to be undruggable, recent reports of success with molecules targeting OB-fold containing proteins suggest otherwise. The potential for the development of agents targeting OB-folds is in its infancy, but if successful, would expand the opportunities to impinge on genome stability and maintenance pathways for more effective cancer treatment.
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Affiliation(s)
- Sui Par
- Indiana University Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (S.P.); (S.V.)
| | - Sofia Vaides
- Indiana University Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (S.P.); (S.V.)
| | | | | | - Jason Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA;
| | - John J. Turchi
- Indiana University Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (S.P.); (S.V.)
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- NERx Biosciences, Indianapolis, IN 46202, USA;
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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16
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Andrade MJ, Van Lonkhuyzen DR, Upton Z, Satyamoorthy K. RPA facilitates rescue of keratinocytes from UVB radiation damage through insulin-like growth factor-I signalling. J Cell Sci 2021; 134:jcs255786. [PMID: 34137442 DOI: 10.1242/jcs.255786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 05/10/2021] [Indexed: 01/19/2023] Open
Abstract
UVBR-induced photolesions in genomic DNA of keratinocytes impair cellular functions and potentially determine the cell fate post-irradiation. The ability of insulin-like growth factor-I (IGF-I) to rescue epidermal keratinocytes after photodamage via apoptosis prevention and photolesion removal was recently demonstrated using in vitro two-dimensional and three-dimensional skin models. Given the limited knowledge of specific signalling cascades contributing to post-UVBR IGF-I effects, we used inhibitors to investigate the impact of blockade of various signalling mediators on IGF-I photoprotection. IGF-I treatment, in the presence of signalling inhibitors, particularly TDRL-505, which targets replication protein A (RPA), impaired activation of IGF-1R downstream signalling, diminished cyclobutane pyrimidine dimer removal, arrested growth, reduced cell survival and increased apoptosis. Further, the transient partial knockdown of RPA was found to abrogate IGF-I-mediated responses in keratinocytes, ultimately affecting photoprotection and, thereby, establishing that RPA is required for IGF-I function. Our findings thus elucidate the importance of RPA in linking the damage response activation, cell cycle regulation, repair and survival pathways, separately initiated by IGF-I upon UVBR-induced damage. This information is potentially imperative for the development of effective sunburn and photodamage repair strategies. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Melisa J Andrade
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
- Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland 4059, Australia
| | - Derek R Van Lonkhuyzen
- Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland 4059, Australia
| | - Zee Upton
- Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland 4059, Australia
- Skin Research Institute of Singapore, Agency for Science, Technology and Research, Singapore138648
| | - Kapaettu Satyamoorthy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
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17
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POT1 stability and binding measured by fluorescence thermal shift assays. PLoS One 2021; 16:e0245675. [PMID: 33784306 PMCID: PMC8009405 DOI: 10.1371/journal.pone.0245675] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/03/2021] [Indexed: 11/19/2022] Open
Abstract
The protein POT1 (Protection of Telomeres 1) is an integral part of the shelterin complex that protects the ends of human chromosomes from degradation or end fusions. It is the only component of shelterin that binds single-stranded DNA. We describe here the application of two separate fluorescent thermal shift assays (FTSA) that provide quantitative biophysical characterization of POT1 stability and its interactions. The first assay uses Sypro Orange™ and monitors the thermal stability of POT1 and its binding under a variety of conditions. This assay is useful for the quality control of POT1 preparations, for biophysical characterization of its DNA binding and, potentially, as an efficient screening tool for binding of small molecule drug candidates. The second assay uses a FRET-labeled human telomeric G-quadruplex structure that reveals the effects of POT1 binding on thermal stability from the DNA frame of reference. These complementary assays provide efficient biophysical approaches for the quantitative characterization of multiple aspects of POT1 structure and function. The results from these assays provide thermodynamics details of POT1 folding, the sequence selectivity of its DNA binding and the thermodynamic profile for its binding to its preferred DNA binding sequence. Most significantly, results from these assays elucidate two mechanisms for the inhibition of POT1 -DNA interactions. The first is by competitive inhibition at the POT1 DNA binding site. The second is indirect and is by stabilization of G-quadruplex formation within the normal POT1 single-stranded DNA sequence to prevent POT1 binding.
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18
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Inhibitors of DNA double-strand break repair at the crossroads of cancer therapy and genome editing. Biochem Pharmacol 2020; 182:114195. [DOI: 10.1016/j.bcp.2020.114195] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/03/2020] [Accepted: 08/10/2020] [Indexed: 12/17/2022]
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Wu X, Zhong Y, Chen Q, Zhang X, Zhang H. Enhancer of mRNA Decapping protein 4 (EDC4) interacts with replication protein a (RPA) and contributes to Cisplatin resistance in cervical Cancer by alleviating DNA damage. Hereditas 2020; 157:41. [PMID: 33054858 PMCID: PMC7560020 DOI: 10.1186/s41065-020-00154-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/25/2020] [Indexed: 11/24/2022] Open
Abstract
Background Cervical cancer (CC) is the third most common gynecological malignancy around the world. Cisplatin is an effective drug, but cisplatin resistance is a vital factor limiting the clinical usage of cisplatin. Enhancer of mRNA decapping protein 4 (EDC4) is a known regulator of mRNA decapping, which was related with genome stability and sensitivity of drugs. This research was to investigate the mechanism of EDC4 on cisplatin resistance in CC. Two human cervical cancer cell lines, HeLa and SiHa, were used to investigate the role of EDC4 on cisplatin resistance in vitro. The knockdown or overexpression of EDC4 or replication protein A (RPA) in HeLa or SiHa cells was performed by transfection. Cell viability was analyzed by MTT assay. The growth of cancer cells was evaluated by colony formation assay. DNA damage was measured by γH2AX (a sensitive DNA damage response marker) immunofluorescent staining. The binding of EDC4 and RPA was analyzed by immunoprecipitation. Results EDC4 knockdown in cervical cancer cells (HeLa and SiHa) enhanced cisplatin sensitivity and cisplatin induced cell growth inhibition and DNA damage. EDC4 overexpression reduced DNA damage caused by cisplatin and enhanced cell growth of cervical cancer cells. EDC4 could interact with RPA and promote RPA phosphorylation. RPA knockdown reversed the inhibitory effect of EDC4 on cisplatin-induced DNA damage. Conclusion The present results indicated that EDC4 is responsible for the cisplatin resistance partly through interacting with RPA in cervical cancer by alleviating DNA damage. This study indicated that EDC4 or RPA may be novel targets to combat chemotherapy resistance in cervical cancer. Graphical abstract ![]()
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Affiliation(s)
- Xiaoling Wu
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Xi'an Jiaotong University, No. 157 Xiwu Road, Xincheng District, Xi'an City, 710004, Shaanxi Province, China.
| | - Youwen Zhong
- School of Economics and Finance, Xi'an Jiaotong University, Xi'an City, 710061, Shaanxi Province, China
| | - Qing Chen
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Xi'an Jiaotong University, No. 157 Xiwu Road, Xincheng District, Xi'an City, 710004, Shaanxi Province, China
| | - Xin Zhang
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Xi'an Jiaotong University, No. 157 Xiwu Road, Xincheng District, Xi'an City, 710004, Shaanxi Province, China
| | - Hua Zhang
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Xi'an Jiaotong University, No. 157 Xiwu Road, Xincheng District, Xi'an City, 710004, Shaanxi Province, China
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20
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Dueva R, Iliakis G. Replication protein A: a multifunctional protein with roles in DNA replication, repair and beyond. NAR Cancer 2020; 2:zcaa022. [PMID: 34316690 PMCID: PMC8210275 DOI: 10.1093/narcan/zcaa022] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/23/2020] [Accepted: 08/27/2020] [Indexed: 02/07/2023] Open
Abstract
Single-stranded DNA (ssDNA) forms continuously during DNA replication and is an important intermediate during recombination-mediated repair of damaged DNA. Replication protein A (RPA) is the major eukaryotic ssDNA-binding protein. As such, RPA protects the transiently formed ssDNA from nucleolytic degradation and serves as a physical platform for the recruitment of DNA damage response factors. Prominent and well-studied RPA-interacting partners are the tumor suppressor protein p53, the RAD51 recombinase and the ATR-interacting proteins ATRIP and ETAA1. RPA interactions are also documented with the helicases BLM, WRN and SMARCAL1/HARP, as well as the nucleotide excision repair proteins XPA, XPG and XPF–ERCC1. Besides its well-studied roles in DNA replication (restart) and repair, accumulating evidence shows that RPA is engaged in DNA activities in a broader biological context, including nucleosome assembly on nascent chromatin, regulation of gene expression, telomere maintenance and numerous other aspects of nucleic acid metabolism. In addition, novel RPA inhibitors show promising effects in cancer treatment, as single agents or in combination with chemotherapeutics. Since the biochemical properties of RPA and its roles in DNA repair have been extensively reviewed, here we focus on recent discoveries describing several non-canonical functions.
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Affiliation(s)
- Rositsa Dueva
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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21
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Lee KJ, Mann E, Wright G, Piett CG, Nagel ZD, Gassman NR. Exploiting DNA repair defects in triple negative breast cancer to improve cell killing. Ther Adv Med Oncol 2020; 12:1758835920958354. [PMID: 32994807 PMCID: PMC7502856 DOI: 10.1177/1758835920958354] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/19/2020] [Indexed: 12/13/2022] Open
Abstract
Background: The lack of molecular targets for triple negative breast cancer (TNBC) has limited treatment options and reduced survivorship. Identifying new molecular targets may help improve patient survival and decrease recurrence and metastasis. As DNA repair defects are prevalent in breast cancer, we evaluated the expression and repair capacities of DNA repair proteins in preclinical models. Methods: DNA repair capacity was analyzed in four TNBC cell lines, MDA-MB-157 (MDA-157), MDA-MB-231 (MDA-231), MDA-MB-468 (MDA-468), and HCC1806, using fluorescence multiplex host cell reactivation (FM-HCR) assays. Expression of DNA repair genes was analyzed with RNA-seq, and protein expression was evaluated with immunoblot. Responses to the combination of DNA damage response inhibitors and primary chemotherapy drugs doxorubicin or carboplatin were evaluated in the cell lines. Results: Defects in base excision and nucleotide excision repair were observed in preclinical TNBC models. Gene expression analysis showed a limited correlation between these defects. Loss in protein expression was a better indicator of these DNA repair defects. Over-expression of PARP1, XRCC1, RPA, DDB1, and ERCC1 was observed in TNBC preclinical models, and likely contributed to altered sensitivity to chemotherapy and DNA damage response (DDR) inhibitors. Improved cell killing was achieved when primary therapy was combined with DDR inhibitors for ATM, ATR, or CHK1. Conclusion: Base excision and nucleotide excision repair pathways may offer new molecular targets for TNBC. The functional status of DNA repair pathways should be considered when evaluating new therapies and may improve the targeting for primary and combination therapies with DDR inhibitors.
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Affiliation(s)
- Kevin J Lee
- College of Medicine, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Elise Mann
- College of Medicine, University of South Alabama, Mobile, AL, USA
| | - Griffin Wright
- College of Medicine, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Cortt G Piett
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Zachary D Nagel
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Natalie R Gassman
- Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36607, USA
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22
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Lai H, Liu C, Hou L, Lin W, Chen T, Hong A. TRPM8-regulated calcium mobilization plays a critical role in synergistic chemosensitization of Borneol on Doxorubicin. Theranostics 2020; 10:10154-10170. [PMID: 32929340 PMCID: PMC7481425 DOI: 10.7150/thno.45861] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 07/31/2020] [Indexed: 02/06/2023] Open
Abstract
Background: Lung cancer has a high mortality rate and is resistant to multiple chemotherapeutics. Natural Borneol (NB) is a monoterpenoid compound that facilitates the bioavailability of drugs. In this study, we investigated the effects of NB on chemosensitivity in the A549 human lung adenocarcinoma cell line and to elucidate therapeutic molecular target of NB. Methods: The chemosensitivity effects of NB in A549 cells were examined by MTT assay. The mechanism of NB action was evaluated using flow cytometry and Western blotting assays. Surface plasmon resonance (SPR) and LC-MS combined analysis (MS-SPRi) was performed to elucidate the candidate molecular target of NB. The chemosensitizing capacity of NB in vivo was assessed in nude mice bearing A549 tumors. Results: NB pretreatment sensitized A549 cells to low doxorubicin (DOX) dosage, leading to a 15.7% to 41.5% increase in apoptosis. This increase was correlated with ERK and AKT inactivation and activation of phospho-p38 MAPK, phospho-JNK, and phosphor-p53. Furthermore, this synergism depends on reactive oxygen species (ROS) generation. MS-SPRi analysis revealed that transient receptor potential melastatin-8 (TRPM8) is the candidate target of NB in potentiating DOX killing potency. Genetically, TRPM8 knock-down significantly suppresses the chemosensitizing effects of NB and inhibits ROS generation through restraining calcium mobilization. Moreover, pretreatment with NB synergistically enhances the anticancer effects of DOX to delay tumor progression in vivo. Conclusions: These results suggest that TRPM8 may be a valid therapeutic target in the potential application of NB, and show that NB is a chemosensitizer for lung cancer treatment.
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Affiliation(s)
- Haoqiang Lai
- Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
- Department of Chemistry, Jinan University, Guangzhou, 510632, China
| | - Chang Liu
- Department of Chemistry, Jinan University, Guangzhou, 510632, China
| | - Liyuan Hou
- Department of Chemistry, Jinan University, Guangzhou, 510632, China
| | - Wenwei Lin
- Department of Chemistry, Jinan University, Guangzhou, 510632, China
| | - Tianfeng Chen
- Department of Chemistry, Jinan University, Guangzhou, 510632, China
| | - An Hong
- Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
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23
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Hu Y, Guo M. Synthetic lethality strategies: Beyond BRCA1/2 mutations in pancreatic cancer. Cancer Sci 2020; 111:3111-3121. [PMID: 32639661 PMCID: PMC7469842 DOI: 10.1111/cas.14565] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 06/15/2020] [Accepted: 07/02/2020] [Indexed: 12/11/2022] Open
Abstract
Cancer cells are often characterized by abnormalities in DNA damage response including defects in cell cycle checkpoints and/or DNA repair. Synthetic lethality between DNA damage repair (DDR) pathways has provided a paradigm for cancer therapy by targeting DDR. The successful example is that cancer cells with BRCA1/2 mutations are sensitized to poly(adenosine diphosphate [ADP]-ribose)polymerase (PARP) inhibitors. Beyond the narrow scope of defects in the BRCA pathway, "BRCAness" provides more opportunities for synthetic lethality strategy. In human pancreatic cancer, frequent mutations were found in cell cycle and DDR genes, including P16, P73, APC, MLH1, ATM, PALB2, and MGMT. Combined DDR inhibitors and chemotherapeutic agents are under preclinical or clinical trials. Promoter region methylation was found frequently in cell cycle and DDR genes. Epigenetics joins the Knudson's "hit" theory and "BRCAness." Aberrant epigenetic changes in cell cycle or DDR regulators may serve as a new avenue for synthetic lethality strategy in pancreatic cancer.
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Affiliation(s)
- Yunlong Hu
- Department of Gastroenterology and Hepatology, Chinese PLA General Hospital, Beijing, China
| | - Mingzhou Guo
- Department of Gastroenterology and Hepatology, Chinese PLA General Hospital, Beijing, China.,Henan Key Laboratory for Esophageal Cancer Research, Zhengzhou University, Zhengzhou, China.,State Key Laboratory of Kidney Diseases, Chinese PLA General Hospital, Beijing, China
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24
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Havrylyuk D, Heidary DK, Sun Y, Parkin S, Glazer EC. Photochemical and Photobiological Properties of Pyridyl-pyrazol(in)e-Based Ruthenium(II) Complexes with Sub-micromolar Cytotoxicity for Phototherapy. ACS OMEGA 2020; 5:18894-18906. [PMID: 32775891 PMCID: PMC7408248 DOI: 10.1021/acsomega.0c02079] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/10/2020] [Indexed: 05/09/2023]
Abstract
The discovery of new light-triggered prodrugs based on ruthenium (II) complexes is a promising approach for photoactivated chemotherapy (PACT). The light-mediated activation of "strained" Ru(II) polypyridyl complexes resulted in ligand release and produced a ligand-deficient metal center capable of forming covalent adducts with biomolecules such as DNA. Based on the strategy of exploiting structural distortion to activate photochemistry, biologically active small molecules were coordinated to a Ru(II) scaffold to create light-triggered dual-action agents. Thirteen new Ru(II) complexes with pyridyl-pyrazol(in)e ligands were synthesized, and their photochemical reactivity and anticancer properties were investigated. Isomeric bidentate ligands were investigated, where "regular" ligands (where the coordinated nitrogens in the heterocycles are linked by C-C atoms) were compared to "inverse" isomers (where the coordinated nitrogens in the heterocycles are linked by C-N atoms). Coordination of the regular 3-(pyrid-2-yl)-pyrazol(in)es to a Ru(II) bis-dimethylphenanthroline scaffold yielded photoresponsive compounds with promising photochemical and biological properties, in contrast to the inverse 1-(pyrid-2-yl)-pyrazolines. The introduction of a phenyl ring to the 1N-pyrazoline cycle increased the distortion in complexes and improved ligand release upon light irradiation (470 nm) up to 5-fold in aqueous media. Compounds 1-8, containing pyridyl-pyrazol(in)e ligands, were at least 20-80-fold more potent than the parent pyridyl-pyrazol(in)es, and exhibited biological activity in the dark, with half-maximal inhibitory concentration (IC50) values ranging from 0.2 to 7.6 μM in the HL60 cell line, with complete growth inhibition upon light irradiation. The diversification of coligands and introduction of a carboxylic acid into the Ru(II) complex resulted in compounds 9-12, with up to 146-fold improved phototoxicity indices compared with complexes 1-8.
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25
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Gavande NS, VanderVere-Carozza PS, Pawelczak KS, Vernon TL, Jordan MR, Turchi JJ. Structure-Guided Optimization of Replication Protein A (RPA)-DNA Interaction Inhibitors. ACS Med Chem Lett 2020; 11:1118-1124. [PMID: 32550990 DOI: 10.1021/acsmedchemlett.9b00440] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
Replication protein A (RPA) is the major human single stranded DNA (ssDNA)-binding protein, playing essential roles in DNA replication, repair, recombination, and DNA-damage response (DDR). Inhibition of RPA-DNA interactions represents a therapeutic strategy for cancer drug discovery and has great potential to provide single agent anticancer activity and to synergize with both common DNA damaging chemotherapeutics and newer targeted anticancer agents. In this letter, a new series of analogues based on our previously reported TDRL-551 (4) compound were designed to improve potency and physicochemical properties. Molecular docking studies guided molecular insights, and further SAR exploration led to the identification of a series of novel compounds with low micromolar RPA inhibitory activity, increased solubility, and excellent cellular up-take. Among a series of analogues, compounds 43, 44, 45, and 46 hold promise for further development of novel anticancer agents.
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Affiliation(s)
- Navnath S. Gavande
- Department of Medicine, Indiana University School of Medicine (IUSM), Indianapolis, Indiana 46202, United States
- Department of Pharmaceutical Sciences, Wayne State University College of Pharmacy and Health Sciences, Detroit, Michigan 48201, United States
| | - Pamela S. VanderVere-Carozza
- Department of Medicine, Indiana University School of Medicine (IUSM), Indianapolis, Indiana 46202, United States
| | - Katherine S. Pawelczak
- NERx Biosciences, 212 W 10th Street Suite A480, Indianapolis, Indiana 46202, United States
| | - Tyler L. Vernon
- Department of Medicine, Indiana University School of Medicine (IUSM), Indianapolis, Indiana 46202, United States
| | - Matthew R. Jordan
- Department of Medicine, Indiana University School of Medicine (IUSM), Indianapolis, Indiana 46202, United States
| | - John J. Turchi
- Department of Medicine, Indiana University School of Medicine (IUSM), Indianapolis, Indiana 46202, United States
- NERx Biosciences, 212 W 10th Street Suite A480, Indianapolis, Indiana 46202, United States
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine (IUSM), Indianapolis, Indiana 46202, United States
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26
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Maurissen TL, Woltjen K. Synergistic gene editing in human iPS cells via cell cycle and DNA repair modulation. Nat Commun 2020; 11:2876. [PMID: 32513994 PMCID: PMC7280248 DOI: 10.1038/s41467-020-16643-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/13/2020] [Indexed: 01/08/2023] Open
Abstract
Precise gene editing aims at generating single-nucleotide modifications to correct or model human disease. However, precision editing with nucleases such as CRIPSR-Cas9 has seen limited success due to poor efficiency and limited practicality. Here, we establish a fluorescent DNA repair assay in human induced pluripotent stem (iPS) cells to visualize and quantify the frequency of DNA repair outcomes during monoallelic and biallelic targeting. We found that modulating both DNA repair and cell cycle phase via defined culture conditions and small molecules synergistically enhanced the frequency of homology-directed repair (HDR). Notably, targeting in homozygous reporter cells results in high levels of editing with a vast majority of biallelic HDR outcomes. We then leverage efficient biallelic HDR with mixed ssODN repair templates to generate heterozygous mutations. Synergistic gene editing represents an effective strategy to generate precise genetic modifications in human iPS cells. Precision editing with CRISPR-Cas9 often suffers from poor efficiency. Here the authors identify culture conditions and small molecules that synergize to promote homology-directed repair (HDR) in induced pluripotent stem (iPS) cells.
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Affiliation(s)
- Thomas L Maurissen
- Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.,Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, 606-8507, Japan
| | - Knut Woltjen
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, 606-8507, Japan.
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27
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Amir M, Mohammad T, Dohare R, Islam A, Ahmad F, Imtaiyaz Hassan M. Structure, function and therapeutic implications of OB-fold proteins: A lesson from past to present. Brief Funct Genomics 2020; 19:377-389. [PMID: 32393969 DOI: 10.1093/bfgp/elaa008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Oligonucleotide/oligosaccharide-binding (OB)-fold proteins play essential roles in the regulation of genome and its correct transformation to the subsequent generation. To maintain the genomic stability, OB-fold proteins are implicated in various cellular processes including DNA replication, DNA repair, cell cycle regulation and maintenance of telomere. The diverse functional spectrums of OB-fold proteins are mainly due to their involvement in protein-DNA and protein-protein complexes. Mutations and consequential structural alteration in the OB-fold proteins often lead to severe diseases. Here, we have investigated the structure, function and mode of action of OB-fold proteins (RPA, BRCA2, DNA ligases and SSBs1/2) in cellular pathways and their relationship with diseases and their possible use in therapeutic intervention. Due to the crucial role of OB-fold proteins in regulating the key physiological process, a detailed structural understanding in the context of underlying mechanism of action and cellular complexity offers a new avenue to target OB-proteins for therapeutic intervention.
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28
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Tan J, Wang X, Phoon L, Yang H, Lan L. Resolution of ROS‐induced G‐quadruplexes and R‐loops at transcriptionally active sites is dependent on BLM helicase. FEBS Lett 2020; 594:1359-1367. [DOI: 10.1002/1873-3468.13738] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/23/2019] [Accepted: 01/15/2020] [Indexed: 12/21/2022]
Affiliation(s)
- Jun Tan
- Massachusetts General Hospital Cancer Center Harvard Medical School Charlestown MA USA
- Department of Radiation Oncology Harvard Medical School Massachusetts General Hospital Boston MA USA
| | - Xiangyu Wang
- Massachusetts General Hospital Cancer Center Harvard Medical School Charlestown MA USA
- Department of Radiation Oncology Harvard Medical School Massachusetts General Hospital Boston MA USA
| | - Laiyee Phoon
- Massachusetts General Hospital Cancer Center Harvard Medical School Charlestown MA USA
- Department of Radiation Oncology Harvard Medical School Massachusetts General Hospital Boston MA USA
| | - Haibo Yang
- Massachusetts General Hospital Cancer Center Harvard Medical School Charlestown MA USA
- Department of Radiation Oncology Harvard Medical School Massachusetts General Hospital Boston MA USA
| | - Li Lan
- Massachusetts General Hospital Cancer Center Harvard Medical School Charlestown MA USA
- Department of Radiation Oncology Harvard Medical School Massachusetts General Hospital Boston MA USA
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29
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Drugging the R-loop interactome: RNA-DNA hybrid binding proteins as targets for cancer therapy. DNA Repair (Amst) 2019; 84:102642. [DOI: 10.1016/j.dnarep.2019.102642] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 05/16/2019] [Accepted: 07/02/2019] [Indexed: 02/07/2023]
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30
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Li G, Zhang P, Zhang W, Lei Z, He J, Meng J, Di T, Yan W. Identification of key genes and pathways in Ewing's sarcoma patients associated with metastasis and poor prognosis. Onco Targets Ther 2019; 12:4153-4165. [PMID: 31213834 PMCID: PMC6549663 DOI: 10.2147/ott.s195675] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/27/2019] [Indexed: 12/22/2022] Open
Abstract
Background: Ewing sarcoma (ES) is the second commonest primary malignant bone neoplasm. Metastatic status at diagnosis strongly predicted poor prognosis of Ewing sarcoma patients. Yet little was known about the underlying mechanism of ES metastasis. Purpose:This study intended to identify the relationship between key genes/pathways and metastasis/poor prognosis in Ewing's sarcoma patients by using bioinformatic method. Methods: In this study, multi-center sequencing data were obtained from the GEO database, including gene and miRNA expression profile and prognosis information of ES patients. Differentially expressed genes (DEGs) were identified between primary and metastasis ES samples by the GEO2R online tool. Gene ontology (Go) and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analyses of DEGs were performed. And PPI network analyses were conducted. The ES patient’s prognostic information was employed for survival analysis, and the potential relationship between miRNAs and key genes was analyzed. Results: The results showed that a total of 298 and 428 DEGs were screened out in metastasis samples based on GSE17618 and GSE12102 dataset compared to primary samples respectively. The most significantly enriched KEGG pathway was the mismatch repair (MMR) pathway. MSH2, MSH6, RPA2, and RFC2 that belong to the MMR pathway were identified as key genes. Moreover, the expression of key genes was increased in metastasis samples compared with primary ones and was associated with poor event-free and overall survival of ES patients. The negative correlation of the expression level of the key genes with patients prognosis also supported by TCGA sarcoma database. Furthermore, knockdown of EWSR/FLI1 fusion in ES cell line A673 down-regulates the expression of the 4 key genes was revealed by GDS4962. Conclusion: In conclusion, the present study indicated that the key genes promote our understanding of the molecular mechanisms underlying the development of ES metastasis, and might be used as molecular targets and diagnostic biomarkers for the treatment of ES.
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Affiliation(s)
- Guoqi Li
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
| | - Piao Zhang
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
| | - Wenkan Zhang
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
| | - Zhong Lei
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
| | - Jiaming He
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
| | - Jiahong Meng
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
| | - Tuoyu Di
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
| | - Weiqi Yan
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, People's Republic of China
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31
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Gooding AJ, Zhang B, Gunawardane L, Beard A, Valadkhan S, Schiemann WP. The lncRNA BORG facilitates the survival and chemoresistance of triple-negative breast cancers. Oncogene 2018; 38:2020-2041. [PMID: 30467380 DOI: 10.1038/s41388-018-0586-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/10/2018] [Accepted: 10/12/2018] [Indexed: 12/31/2022]
Abstract
Disseminated breast cancer cells employ adaptive molecular responses following cytotoxic therapeutic insult which promotes their survival and subsequent outgrowth. Here we demonstrate that expression of the pro-metastatic lncRNA BORG (BMP/OP-Responsive Gene) is greatly induced within triple-negative breast cancer (TNBC) cells subjected to environmental and chemotherapeutic stresses commonly faced by TNBC cells throughout the metastatic cascade. This stress-mediated induction of BORG expression fosters the survival of TNBC cells and renders them resistant to the cytotoxic effects of doxorubicin both in vitro and in vivo. The chemoresistant traits of BORG depend upon its robust activation of the NF-κB signaling axis via a novel BORG-mediated feed-forward signaling loop, and via its ability to bind and activate RPA1. Indeed, genetic and pharmacologic inhibition of NF-κB signaling or the DNA-binding activity of RPA1 abrogates the pro-survival features of BORG and renders BORG-expressing TNBCs sensitive to doxorubicin-induced cytotoxicity. These findings suggest that therapeutic targeting of BORG or its downstream molecular effectors may provide a novel means to alleviate TNBC recurrence.
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Affiliation(s)
- Alex J Gooding
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Bing Zhang
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Lalith Gunawardane
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Abigail Beard
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Saba Valadkhan
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, 44106, USA.
| | - William P Schiemann
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA.
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32
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Byrne BM, Oakley GG. Replication protein A, the laxative that keeps DNA regular: The importance of RPA phosphorylation in maintaining genome stability. Semin Cell Dev Biol 2018; 86:112-120. [PMID: 29665433 DOI: 10.1016/j.semcdb.2018.04.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/30/2018] [Accepted: 04/06/2018] [Indexed: 11/25/2022]
Abstract
The eukaryotic ssDNA-binding protein, Replication protein A (RPA), was first discovered almost three decades ago. Since then, much progress has been made to elucidate the critical roles for RPA in DNA metabolic pathways that help promote genomic stability. The canonical RPA heterotrimer (RPA1-3) is an essential coordinator of DNA metabolism that interacts with ssDNA and numerous protein partners to coordinate its roles in DNA replication, repair, recombination and telomere maintenance. An alternative form of RPA, termed aRPA, is formed by a complex of RPA4 with RPA1 and RPA3. aRPA is expressed differentially in cells compared to canonical RPA and has been shown to inhibit canonical RPA function while allowing for regular maintenance of cell viability. Interestingly, while aRPA is defective in DNA replication and cell cycle progression, it was shown to play a supporting role in nucleotide excision repair and recombination. The binding domains of canonical RPA interact with a growing number of partners involved in numerous genome maintenance processes. The protein interactions of the RPA-ssDNA complex are not only governed by competition between the binding proteins but also by post-translation modifications such as phosphorylation. Phosphorylation of RPA2 is an important post-translational modification of the RPA complex, and is essential for directing context-specific functions of the RPA complex in the DNA damage response. Due to the importance of RPA in cellular metabolism, it was identified as an appealing target for chemotherapeutic drug development that could be used in future cancer treatment regimens.
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Affiliation(s)
- Brendan M Byrne
- University of Nebraska Medical Center Department of Oral Biology, Lincoln NE, USA.
| | - Gregory G Oakley
- University of Nebraska Medical Center Department of Oral Biology, Lincoln NE, USA; Eppley Cancer Center, Omaha NE, USA.
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33
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Yates M, Maréchal A. Ubiquitylation at the Fork: Making and Breaking Chains to Complete DNA Replication. Int J Mol Sci 2018; 19:E2909. [PMID: 30257459 PMCID: PMC6213728 DOI: 10.3390/ijms19102909] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/20/2018] [Accepted: 09/24/2018] [Indexed: 12/11/2022] Open
Abstract
The complete and accurate replication of the genome is a crucial aspect of cell proliferation that is often perturbed during oncogenesis. Replication stress arising from a variety of obstacles to replication fork progression and processivity is an important contributor to genome destabilization. Accordingly, cells mount a complex response to this stress that allows the stabilization and restart of stalled replication forks and enables the full duplication of the genetic material. This response articulates itself on three important platforms, Replication Protein A/RPA-coated single-stranded DNA, the DNA polymerase processivity clamp PCNA and the FANCD2/I Fanconi Anemia complex. On these platforms, the recruitment, activation and release of a variety of genome maintenance factors is regulated by post-translational modifications including mono- and poly-ubiquitylation. Here, we review recent insights into the control of replication fork stability and restart by the ubiquitin system during replication stress with a particular focus on human cells. We highlight the roles of E3 ubiquitin ligases, ubiquitin readers and deubiquitylases that provide the required flexibility at stalled forks to select the optimal restart pathways and rescue genome stability during stressful conditions.
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Affiliation(s)
- Maïlyn Yates
- Department of Biology, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada.
| | - Alexandre Maréchal
- Department of Biology, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada.
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34
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Protein interactomes of protein phosphatase 2A B55 regulatory subunits reveal B55-mediated regulation of replication protein A under replication stress. Sci Rep 2018; 8:2683. [PMID: 29422626 PMCID: PMC5805732 DOI: 10.1038/s41598-018-21040-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 01/24/2018] [Indexed: 11/24/2022] Open
Abstract
The specific function of PP2A, a major serine/threonine phosphatase, is mediated by regulatory targeting subunits, such as members of the B55 family. Although implicated in cell division and other pathways, the specific substrates and functions of B55 targeting subunits are largely undefined. In this study we identified over 100 binding proteins of B55α and B55β in Xenopus egg extracts that are involved in metabolism, mitochondria function, molecular trafficking, cell division, cytoskeleton, DNA replication, DNA repair, and cell signaling. Among the B55α and B55β-associated proteins were numerous mitotic regulators, including many substrates of CDK1. Consistently, upregulation of B55α accelerated M-phase exit and inhibited M-phase entry. Moreover, specific substrates of CDK2, including factors of DNA replication and chromatin remodeling were identified within the interactomes of B55α and B55β, suggesting a role for these phosphatase subunits in DNA replication. In particular, we confirmed in human cells that B55α binds RPA and mediates the dephosphorylation of RPA2. The B55-RPA association is disrupted after replication stress, consistent with the induction of RPA2 phosphorylation. Thus, we report here a new mechanism that accounts for both how RPA phosphorylation is modulated by PP2A and how the phosphorylation of RPA2 is abruptly induced after replication stress.
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35
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Gavande NS, VanderVere-Carozza P, Mishra AK, Vernon TL, Pawelczak KS, Turchi JJ. Design and Structure-Guided Development of Novel Inhibitors of the Xeroderma Pigmentosum Group A (XPA) Protein-DNA Interaction. J Med Chem 2017; 60:8055-8070. [PMID: 28933851 DOI: 10.1021/acs.jmedchem.7b00780] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
XPA is a unique and essential protein required for the nucleotide excision DNA repair pathway and represents a therapeutic target in oncology. Herein, we are the first to develop novel inhibitors of the XPA-DNA interaction through structure-guided drug design efforts. Ester derivatives of the compounds 1 (X80), 22, and 24 displayed excellent inhibitory activity (IC50 of 0.82 ± 0.18 μM and 1.3 ± 0.22 μM, respectively) but poor solubility. We have synthesized novel amide derivatives that retain potency and have much improved solubility. Furthermore, compound 1 analogs exhibited good specificity for XPA over RPA (replication protein A), another DNA-binding protein that participates in the nucleotide excision repair (NER) pathway. Importantly, there were no significant interactions observed by the X80 class of compounds directly with DNA. Molecular docking studies revealed a mechanistic model for the interaction, and these studies could serve as the basis for continued analysis of structure-activity relationships and drug development efforts of this novel target.
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Affiliation(s)
- Navnath S Gavande
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Pamela VanderVere-Carozza
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Akaash K Mishra
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States.,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Tyler L Vernon
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Katherine S Pawelczak
- NERx Biosciences , 212 W 10th Street, Suite A480, Indianapolis, Indiana 46202, United States
| | - John J Turchi
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States.,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States.,NERx Biosciences , 212 W 10th Street, Suite A480, Indianapolis, Indiana 46202, United States
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36
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Fujii N. Potential Strategies to Target Protein-Protein Interactions in the DNA Damage Response and Repair Pathways. J Med Chem 2017; 60:9932-9959. [PMID: 28654754 DOI: 10.1021/acs.jmedchem.7b00358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review article discusses some insights about generating novel mechanistic inhibitors of the DNA damage response and repair (DDR) pathways by focusing on protein-protein interactions (PPIs) of the key DDR components. General requirements for PPI strategies, such as selecting the target PPI site on the basis of its functionality, are discussed first. Next, on the basis of functional rationale and biochemical feasibility to identify a PPI inhibitor, 26 PPIs in DDR pathways (BER, MMR, NER, NHEJ, HR, TLS, and ICL repair) are specifically discussed for inhibitor discovery to benefit cancer therapies using a DNA-damaging agent.
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Affiliation(s)
- Naoaki Fujii
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital , 262 Danny Thomas Place, MS1000, Memphis, Tennessee 38105, United States
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Interactive Roles of DNA Helicases and Translocases with the Single-Stranded DNA Binding Protein RPA in Nucleic Acid Metabolism. Int J Mol Sci 2017; 18:ijms18061233. [PMID: 28594346 PMCID: PMC5486056 DOI: 10.3390/ijms18061233] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 05/30/2017] [Accepted: 06/01/2017] [Indexed: 01/05/2023] Open
Abstract
Helicases and translocases use the energy of nucleoside triphosphate binding and hydrolysis to unwind/resolve structured nucleic acids or move along a single-stranded or double-stranded polynucleotide chain, respectively. These molecular motors facilitate a variety of transactions including replication, DNA repair, recombination, and transcription. A key partner of eukaryotic DNA helicases/translocases is the single-stranded DNA binding protein Replication Protein A (RPA). Biochemical, genetic, and cell biological assays have demonstrated that RPA interacts with these human molecular motors physically and functionally, and their association is enriched in cells undergoing replication stress. The roles of DNA helicases/translocases are orchestrated with RPA in pathways of nucleic acid metabolism. RPA stimulates helicase-catalyzed DNA unwinding, enlists translocases to sites of action, and modulates their activities in DNA repair, fork remodeling, checkpoint activation, and telomere maintenance. The dynamic interplay between DNA helicases/translocases and RPA is just beginning to be understood at the molecular and cellular levels, and there is still much to be learned, which may inform potential therapeutic strategies.
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Patrone JD, Waterson AG, Fesik SW. Recent advancements in the discovery of protein-protein interaction inhibitors of replication protein A. MEDCHEMCOMM 2017; 8:259-267. [PMID: 30108742 PMCID: PMC6071986 DOI: 10.1039/c6md00460a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 11/02/2016] [Indexed: 01/08/2023]
Abstract
Due to the relatively high rate of DNA damage that can occur during cell cycle progression, the DNA damage response (DDR) pathway is critical for the survival of eukaryotic cells. Replication protein A (RPA) is an essential cell cycle checkpoint protein that mediates the initiation of the DDR by binding to single-stranded DNA (ssDNA) and recruiting response partners via protein-protein interactions (PPIs). This important role of RPA in initiating the DDR and cell survival has led to interest within the scientific community to investigate RPA as a potential cancer drug discovery target. To this end, RPA inhibitors have been explored via a variety of methods. This review summarizes the structure and function of RPA and highlights recent efforts to discover inhibitors of RPA-protein interactions.
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Affiliation(s)
- James D Patrone
- Department of Chemistry , Rollins College , 1000 Holt Ave , Winter Park , FL 32789 , USA
| | - Alex G Waterson
- Department of Chemistry , Vanderbilt University , Nashville , TN 37232 , USA .
- Department of Pharmacology , Vanderbilt University School of Medicine , Nashville , TN 37232 , USA
| | - Stephen W Fesik
- Department of Chemistry , Vanderbilt University , Nashville , TN 37232 , USA .
- Department of Pharmacology , Vanderbilt University School of Medicine , Nashville , TN 37232 , USA
- Department of Biochemistry , Vanderbilt University School of Medicine , Nashville , TN 37232 , USA
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Nucleotide Excision Repair: From Neurodegeneration to Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1007:17-39. [PMID: 28840550 DOI: 10.1007/978-3-319-60733-7_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
DNA damage poses a constant threat to genome integrity taking a variety of shapes and arising by normal cellular metabolism or environmental insults. Human syndromes, characterized by increased cancer pre-disposition or early onset of age-related pathology and developmental abnormalities, often result from defective DNA damage responses and compromised genome integrity. Over the last decades intensive research worldwide has made important contributions to our understanding of the molecular mechanisms underlying genomic instability and has substantiated the importance of DNA repair in cancer prevention in the general population. In this chapter, we discuss Nucleotide Excision Repair pathway, the causative role of its components in disease-related pathology and recent technological achievements that decipher mutational landscapes and may facilitate pathological classification and personalized therapy.
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Jang SW, Jung JK, Kim JM. Replication Protein A (RPA) deficiency activates the Fanconi anemia DNA repair pathway. Cell Cycle 2016; 15:2336-45. [PMID: 27398742 DOI: 10.1080/15384101.2016.1201621] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The Fanconi anemia (FA) pathway regulates DNA inter-strand crosslink (ICL) repair. Despite our greater understanding of the role of FA in ICL repair, its function in the preventing spontaneous genome instability is not well understood. Here, we show that depletion of replication protein A (RPA) activates the FA pathway. RPA1 deficiency increases chromatin recruitment of FA core complex, leading to FANCD2 monoubiquitination (FANCD2-Ub) and foci formation in the absence of DNA damaging agents. Importantly, ATR depletion, but not ATM, abolished RPA1 depletion-induced FANCD2-Ub, suggesting that ATR activation mediated FANCD2-Ub. Interestingly, we found that depletion of hSSB1/2-INTS3, a single-stranded DNA-binding protein complex, induces FANCD2-Ub, like RPA1 depletion. More interestingly, depletion of either RPA1 or INTS3 caused increased accumulation of DNA damage in FA pathway deficient cell lines. Taken together, these results indicate that RPA deficiency induces activation of the FA pathway in an ATR-dependent manner, which may play a role in the genome maintenance.
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Affiliation(s)
- Seok-Won Jang
- a Department of Pharmacology , Medical Research Center for Gene Regulation, Chonnam National University Medical School , Gwangju , Korea
| | - Jin Ki Jung
- a Department of Pharmacology , Medical Research Center for Gene Regulation, Chonnam National University Medical School , Gwangju , Korea
| | - Jung Min Kim
- a Department of Pharmacology , Medical Research Center for Gene Regulation, Chonnam National University Medical School , Gwangju , Korea
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Wu Y, Lu J, Kang T. Human single-stranded DNA binding proteins: guardians of genome stability. Acta Biochim Biophys Sin (Shanghai) 2016; 48:671-7. [PMID: 27217471 DOI: 10.1093/abbs/gmw044] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 04/15/2016] [Indexed: 01/03/2023] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) are essential for maintaining the integrity of the genome in all organisms. All processes related to DNA, such as replication, excision, repair, and recombination, require the participation of SSBs whose oligonucleotide/oligosaccharide-binding (OB)-fold domain is responsible for the interaction with single-stranded DNA (ssDNA). For a long time, the heterotrimeric replication protein A (RPA) complex was believed to be the only nuclear SSB in eukaryotes to participate in ssDNA processing, while mitochondrial SSBs that are conserved with prokaryotic SSBs were shown to be essential for maintaining genome stability in eukaryotic mitochondria. In recent years, two new proteins, hSSB1 and hSSB2 (human SSBs 1/2), were identified and have better sequence similarity to bacterial and archaeal SSBs than RPA. This review summarizes the current understanding of these human SSBs in DNA damage repair and in cell-cycle checkpoint activation following DNA damage, as well as their relationships with cancer.
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Affiliation(s)
- Yuanzhong Wu
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Jinping Lu
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Tiebang Kang
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
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Patrone JD, Pelz NF, Bates BS, Souza-Fagundes EM, Vangamudi B, Camper DV, Kuznetsov AG, Browning CF, Feldkamp MD, Frank AO, Gilston BA, Olejniczak ET, Rossanese OW, Waterson AG, Chazin WJ, Fesik SW. Identification and Optimization of Anthranilic Acid Based Inhibitors of Replication Protein A. ChemMedChem 2016; 11:893-9. [PMID: 26748787 PMCID: PMC4838552 DOI: 10.1002/cmdc.201500479] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 12/08/2015] [Indexed: 01/19/2023]
Abstract
Replication protein A (RPA) is an essential single-stranded DNA (ssDNA)-binding protein that initiates the DNA damage response pathway through protein-protein interactions (PPIs) mediated by its 70N domain. The identification and use of chemical probes that can specifically disrupt these interactions is important for validating RPA as a cancer target. A high-throughput screen (HTS) to identify new chemical entities was conducted, and 90 hit compounds were identified. From these initial hits, an anthranilic acid based series was optimized by using a structure-guided iterative medicinal chemistry approach to yield a cell-penetrant compound that binds to RPA70N with an affinity of 812 nm. This compound, 2-(3- (N-(3,4-dichlorophenyl)sulfamoyl)-4-methylbenzamido)benzoic acid (20 c), is capable of inhibiting PPIs mediated by this domain.
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Affiliation(s)
- James D Patrone
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Chemistry, Rollins College, 1000 Holt Avenue, Winter Park, FL, 32789, USA
| | - Nicholas F Pelz
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Brittney S Bates
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | | | | | - Demarco V Camper
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Alexey G Kuznetsov
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Carrie F Browning
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Michael D Feldkamp
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Andreas O Frank
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Benjamin A Gilston
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Edward T Olejniczak
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Olivia W Rossanese
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Alex G Waterson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Walter J Chazin
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Stephen W Fesik
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA.
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA.
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA.
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43
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Gavande NS, VanderVere-Carozza PS, Hinshaw HD, Jalal SI, Sears CR, Pawelczak KS, Turchi JJ. DNA repair targeted therapy: The past or future of cancer treatment? Pharmacol Ther 2016; 160:65-83. [PMID: 26896565 DOI: 10.1016/j.pharmthera.2016.02.003] [Citation(s) in RCA: 258] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The repair of DNA damage is a complex process that relies on particular pathways to remedy specific types of damage to DNA. The range of insults to DNA includes small, modest changes in structure including mismatched bases and simple methylation events to oxidized bases, intra- and interstrand DNA crosslinks, DNA double strand breaks and protein-DNA adducts. Pathways required for the repair of these lesions include mismatch repair, base excision repair, nucleotide excision repair, and the homology directed repair/Fanconi anemia pathway. Each of these pathways contributes to genetic stability, and mutations in genes encoding proteins involved in these pathways have been demonstrated to promote genetic instability and cancer. In fact, it has been suggested that all cancers display defects in DNA repair. It has also been demonstrated that the ability of cancer cells to repair therapeutically induced DNA damage impacts therapeutic efficacy. This has led to targeting DNA repair pathways and proteins to develop anti-cancer agents that will increase sensitivity to traditional chemotherapeutics. While initial studies languished and were plagued by a lack of specificity and a defined mechanism of action, more recent approaches to exploit synthetic lethal interaction and develop high affinity chemical inhibitors have proven considerably more effective. In this review we will highlight recent advances and discuss previous failures in targeting DNA repair to pave the way for future DNA repair targeted agents and their use in cancer therapy.
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Affiliation(s)
- Navnath S Gavande
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | | | - Hilary D Hinshaw
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Shadia I Jalal
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Catherine R Sears
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | | | - John J Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, United States; NERx Biosciences, Indianapolis, IN 46202, United States; Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
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Xu Q, Wang F, Xiang Y, Zhang X, Zhao ZA, Gao Z, Liu W, Lu X, Liu Y, Yu XJ, Wang H, Huang J, Yi Z, Gao S, Li L. Maternal BCAS2 protects genomic integrity in mouse early embryonic development. Development 2015; 142:3943-53. [PMID: 26428007 DOI: 10.1242/dev.129841] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 09/24/2015] [Indexed: 11/20/2022]
Abstract
Mammalian early embryos maintain accurate genome integrity for proper development within a programmed timeline despite constant assaults on their DNA by replication, DNA demethylation and genetic defects transmitted from germ cells. However, how genome integrity is safeguarded during mammalian early embryonic development remains unclear. BCAS2 (breast carcinoma amplified sequence 2), a core component of the PRP19 complex involved in pre-mRNA splicing, plays an important role in the DNA damage response through the RPA complex, a key regulator in the maintenance of genome integrity. Currently, the physiological role of BCAS2 in mammals is unknown. We now report that BCAS2 responds to endogenous and exogenous DNA damage in mouse zygotes. Maternal depletion of BCAS2 compromises the DNA damage response in early embryos, leading to developmental arrest at the two- to four-cell stage accompanied by the accumulation of damaged DNA and micronuclei. Furthermore, BCAS2 mutants that are unable to bind RPA1 fail in DNA repair during the zygotic stage. In addition, phosphorylated RPA2 cannot localise to the DNA damage sites in mouse zygotes with disrupted maternal BCAS2. These data suggest that BCAS2 might function through the RPA complex during DNA repair in zygotes. Together, our results reveal that maternal BCAS2 maintains the genome integrity of early embryos and is essential for female mouse fertility.
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Affiliation(s)
- Qianhua Xu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fengchao Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Yunlong Xiang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaoxin Zhang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhen-Ao Zhao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zheng Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenbo Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xukun Lu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yusheng Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xing-Jiang Yu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Haibin Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jun Huang
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhenjiang 310058, China
| | - Zhaohong Yi
- College of Biological Science and Engineering, Beijing University of Agriculture, Beijing 102206, China
| | - Shaorong Gao
- School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Lei Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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Mishra AK, Dormi SS, Turchi AM, Woods DS, Turchi JJ. Chemical inhibitor targeting the replication protein A-DNA interaction increases the efficacy of Pt-based chemotherapy in lung and ovarian cancer. Biochem Pharmacol 2014; 93:25-33. [PMID: 25449597 DOI: 10.1016/j.bcp.2014.10.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 10/22/2014] [Accepted: 10/23/2014] [Indexed: 01/28/2023]
Abstract
Platinum-based chemotherapeutics exert their therapeutic efficacy via the formation of DNA adducts which interfere with DNA replication, transcription and cell division and ultimately induce cell death. Repair and tolerance of these Pt-DNA lesions by nucleotide excision repair (NER) and homologous recombination (HR) can substantially reduce the effectiveness of therapy. Inhibition of these repair pathways, therefore, holds the potential to sensitize cancer cells to Pt treatment and increase clinical efficacy. Replication Protein A (RPA) plays essential roles in both NER and HR, along with its role in DNA replication and DNA damage checkpoint activation. Each of these functions is, in part, mediated by RPA binding to single-stranded DNA (ssDNA). Here we report the synthesis and characterization of novel derivatives of RPA small molecule inhibitors and their activity in models of epithelial ovarian cancer (EOC) and non-small cell lung cancer (NSCLC). We have synthesized analogs of our previously reported RPA inhibitor TDRL-505 and determined the structure-activity relationships. These data led us to the identification of TDRL-551, which exhibited a greater than 2-fold increase in in vitro activity. TDRL-551 showed synergy with Pt in tissue culture models of EOC and in vivo efficacy, as a single agent and in combination with platinum, in a NSCLC xenograft model. These data demonstrate the utility of RPA inhibition in EOC and NSCLC and the potential in developing novel anticancer therapeutics that target RPA-DNA interactions.
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Affiliation(s)
- Akaash K Mishra
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Silvana S Dormi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Alaina M Turchi
- NERx Biosciences Inc. 351W. 10th Street, Suite 510, Indianapolis, IN 46202, USA
| | - Derek S Woods
- NERx Biosciences Inc. 351W. 10th Street, Suite 510, Indianapolis, IN 46202, USA
| | - John J Turchi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA; NERx Biosciences Inc. 351W. 10th Street, Suite 510, Indianapolis, IN 46202, USA.
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Glanzer JG, Liu S, Wang L, Mosel A, Peng A, Oakley GG. RPA inhibition increases replication stress and suppresses tumor growth. Cancer Res 2014; 74:5165-72. [PMID: 25070753 DOI: 10.1158/0008-5472.can-14-0306] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The ATR/Chk1 pathway is a critical surveillance network that maintains genomic integrity during DNA replication by stabilizing the replication forks during normal replication to avoid replication stress. One of the many differences between normal cells and cancer cells is the amount of replication stress that occurs during replication. Cancer cells with activated oncogenes generate increased levels of replication stress. This creates an increased dependency on the ATR/Chk1 pathway in cancer cells and opens up an opportunity to preferentially kill cancer cells by inhibiting this pathway. In support of this idea, we have identified a small molecule termed HAMNO ((1Z)-1-[(2-hydroxyanilino)methylidene]naphthalen-2-one), a novel protein interaction inhibitor of replication protein A (RPA), a protein involved in the ATR/Chk1 pathway. HAMNO selectively binds the N-terminal domain of RPA70, effectively inhibiting critical RPA protein interactions that rely on this domain. HAMNO inhibits both ATR autophosphorylation and phosphorylation of RPA32 Ser33 by ATR. By itself, HAMNO treatment creates DNA replication stress in cancer cells that are already experiencing replication stress, but not in normal cells, and it acts synergistically with etoposide to kill cancer cells in vitro and slow tumor growth in vivo. Thus, HAMNO illustrates how RPA inhibitors represent candidate therapeutics for cancer treatment, providing disease selectivity in cancer cells by targeting their differential response to replication stress. Cancer Res; 74(18); 5165-72. ©2014 AACR.
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Affiliation(s)
- Jason G Glanzer
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Shengqin Liu
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Ling Wang
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Adam Mosel
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Aimin Peng
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, Nebraska. Eppley Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska
| | - Greg G Oakley
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, Nebraska. Eppley Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska.
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Enhanced Radiosensitivity and G2/M Arrest were Observed in Radioresistant Esophageal Cancer Cells by Knocking Down RPA Expression. Cell Biochem Biophys 2014; 70:887-91. [DOI: 10.1007/s12013-014-9995-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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48
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Jekimovs C, Bolderson E, Suraweera A, Adams M, O’Byrne KJ, Richard DJ. Chemotherapeutic compounds targeting the DNA double-strand break repair pathways: the good, the bad, and the promising. Front Oncol 2014; 4:86. [PMID: 24795863 PMCID: PMC4001069 DOI: 10.3389/fonc.2014.00086] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 04/08/2014] [Indexed: 01/09/2023] Open
Abstract
The repair of DNA double-strand breaks (DSBs) is a critical cellular mechanism that exists to ensure genomic stability. DNA DSBs are the most deleterious type of insult to a cell's genetic material and can lead to genomic instability, apoptosis, or senescence. Incorrectly repaired DNA DSBs have the potential to produce chromosomal translocations and genomic instability, potentially leading to cancer. The prevalence of DNA DSBs in cancer due to unregulated growth and errors in repair opens up a potential therapeutic window in the treatment of cancers. The cellular response to DNA DSBs is comprised of two pathways to ensure DNA breaks are repaired: homologous recombination and non-homologous end joining. Identifying chemotherapeutic compounds targeting proteins involved in these DNA repair pathways has shown promise as a cancer therapy for patients, either as a monotherapy or in combination with genotoxic drugs. From the beginning, there have been a number of chemotherapeutic compounds that have yielded successful responses in the clinic, a number that have failed (CGK-733 and iniparib), and a number of promising targets for future studies identified. This review looks in detail at how the cell responds to these DNA DSBs and investigates the chemotherapeutic avenues that have been and are currently being explored to target this repair process.
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Affiliation(s)
- Christian Jekimovs
- Cancer and Ageing Research Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Emma Bolderson
- Cancer and Ageing Research Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Amila Suraweera
- Cancer and Ageing Research Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Mark Adams
- Cancer and Ageing Research Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kenneth J. O’Byrne
- Cancer and Ageing Research Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Derek J. Richard
- Cancer and Ageing Research Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
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Carvalho JFS, Kanaar R. Targeting homologous recombination-mediated DNA repair in cancer. Expert Opin Ther Targets 2014; 18:427-58. [PMID: 24491188 DOI: 10.1517/14728222.2014.882900] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
INTRODUCTION DNA is the target of many traditional non-specific chemotherapeutic drugs. New drugs or therapeutic approaches with a more rational and targeted component are mandatory to improve the success of cancer therapy. The homologous recombination (HR) pathway is an attractive target for the development of inhibitors because cancer cells rely heavily on HR for repair of DNA double-strand breaks resulting from chemotherapeutic treatments. Additionally, the discovery that poly(ADP)ribose polymerase-1 inhibitors selectively kill cells with genetic defects in HR has spurned an even greater interest in inhibitors of HR. AREAS COVERED HR drives the repair of broken DNA via numerous protein-mediated sequential DNA manipulations. Due to extensive number of steps and proteins involved, the HR pathway provides a rich pool of potential drug targets. This review discusses the latest developments concerning the strategies being explored to inhibit HR. Particular attention is given to the identification of small molecule inhibitors of key HR proteins, including the BRCA proteins and RAD51. EXPERT OPINION Current HR inhibitors are providing the basis for pharmaceutical development of more potent and specific inhibitors to be applied in mono- or combinatorial therapy regimes, while novel targets will be uncovered by experiments aimed to gain a deeper mechanistic understanding of HR and its subpathways.
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Affiliation(s)
- João F S Carvalho
- Erasmus MC Cancer Institute, Department of Genetics, Department of Radiation Oncology, Cancer Genomics Netherlands , PO Box 2040, 3000 CA Rotterdam , The Netherlands
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50
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Frank AO, Feldkamp MD, Kennedy JP, Waterson AG, Pelz NF, Patrone JD, Vangamudi B, Camper DV, Rossanese OW, Chazin WJ, Fesik SW. Discovery of a potent inhibitor of replication protein a protein-protein interactions using a fragment-linking approach. J Med Chem 2013; 56:9242-50. [PMID: 24147804 DOI: 10.1021/jm401333u] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Replication protein A (RPA), the major eukaryotic single-stranded DNA (ssDNA)-binding protein, is involved in nearly all cellular DNA transactions. The RPA N-terminal domain (RPA70N) is a recruitment site for proteins involved in DNA-damage response and repair. Selective inhibition of these protein-protein interactions has the potential to inhibit the DNA-damage response and to sensitize cancer cells to DNA-damaging agents without affecting other functions of RPA. To discover a potent, selective inhibitor of the RPA70N protein-protein interactions to test this hypothesis, we used NMR spectroscopy to identify fragment hits that bind to two adjacent sites in the basic cleft of RPA70N. High-resolution X-ray crystal structures of RPA70N-ligand complexes revealed how these fragments bind to RPA and guided the design of linked compounds that simultaneously occupy both sites. We have synthesized linked molecules that bind to RPA70N with submicromolar affinity and minimal disruption of RPA's interaction with ssDNA.
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Affiliation(s)
- Andreas O Frank
- Department of Biochemistry, Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
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