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Miramova A, Gartner A, Ivanov D. How to sensitize glioblastomas to temozolomide chemotherapy: a gap-centered view. Front Cell Dev Biol 2024; 12:1436563. [PMID: 39011394 PMCID: PMC11246897 DOI: 10.3389/fcell.2024.1436563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Accepted: 06/17/2024] [Indexed: 07/17/2024] Open
Abstract
Temozolomide (TMZ) is a methylating agent used as the first-line drug in the chemotherapy of glioblastomas. However, cancer cells eventually acquire resistance, necessitating the development of TMZ-potentiating therapy agents. TMZ induces several DNA base adducts, including O 6 -meG, 3-meA, and 7-meG. TMZ cytotoxicity stems from the ability of these adducts to directly (3-meA) or indirectly (O 6 -meG) impair DNA replication. Although TMZ toxicity is generally attributed to O 6 -meG, other alkylated bases can be similarly important depending on the status of various DNA repair pathways of the treated cells. In this mini-review we emphasize the necessity to distinguish TMZ-sensitive glioblastomas, which do not express methylguanine-DNA methyltransferase (MGMT) and are killed by the futile cycle of mismatch repair (MMR) of the O 6 -meG/T pairs, vs. TMZ-resistant MGMT-positive or MMR-negative glioblastomas, which are selected in the course of the treatment and are killed only at higher TMZ doses by the replication-blocking 3-meA. These two types of cells can be TMZ-sensitized by inhibiting different DNA repair pathways. However, in both cases, the toxic intermediates appear to be ssDNA gaps, a vulnerability also seen in BRCA-deficient cancers. PARP inhibitors (PARPi), which were initially developed to treat BRCA1/2-deficient cancers by synthetic lethality, were re-purposed in clinical trials to potentiate the effects of TMZ. We discuss how the recent advances in our understanding of the genetic determinants of TMZ toxicity might lead to new approaches for the treatment of glioblastomas by inhibiting PARP1 and other enzymes involved in the repair of alkylation damage (e.g., APE1).
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Affiliation(s)
- Alila Miramova
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Anton Gartner
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
- Graduate School for Health Sciences and Technology, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea
| | - Dmitri Ivanov
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea
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2
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Gomes NP, Frederick B, Jacobsen JR, Chapnick D, Su TT. A High Throughput Screen with a Clonogenic Endpoint to Identify Radiation Modulators of Cancer. Radiat Res 2023; 199:132-147. [PMID: 36583948 PMCID: PMC10000021 DOI: 10.1667/rade-22-00086.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 11/11/2022] [Indexed: 12/31/2022]
Abstract
Clonogenic assays evaluate the ability of single cells to proliferate and form colonies. This process approximates the regrowth and recurrence of tumors after treatment with radiation or chemotherapy, and thereby provides a drug discovery platform for compounds that block this process. However, because of their labor-intensive and cumbersome nature, adapting canonical clonogenic assays for high throughput screening (HTS) has been challenging. We overcame these barriers by developing an integrated system that automates cell- and liquid-handling, irradiation, dosimetry, drug administration, and incubation. Further, we developed a fluorescent live-cell based automated colony scoring methodology that identifies and counts colonies precisely based upon actual nuclei number rather than colony area, thereby eliminating errors in colony counts caused by radiation induced changes in colony morphology. We identified 13 cell lines from 7 cancer types, where radiation is a standard treatment module, that exhibit identical radiation and chemoradiation response regardless of well format and are amenable to miniaturization into small-well HTS formats. We performed pilot screens through a 1,584 compound NCI Diversity Set library using two cell lines representing different cancer indications. Radiation modulators identified in the pilot screens were validated in traditional clonogenic assays, providing proof-of-concept for the screen. The integrated methodology, hereafter "clonogenic HTS", exhibits excellent robustness (Z' values > 0.5) and shows high reproducibility (>95%). We propose that clonogenic HTS we developed can function as a drug discovery platform to identify compounds that inhibit tumor regrowth following radiation therapy, to identify new efficacious pair-wise combinations of known oncologic therapies, or to identify novel modulators ofapproved therapies.
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Affiliation(s)
| | | | | | | | - Tin Tin Su
- SuviCa, Inc., Boulder, Colorado 80307-3131
- Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Colorado, 80309-0347
- Molecular and Cellular Oncology Program, University of Colorado Cancer Center, Aurora, Colorado 80045
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3
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Radin DP, Smith G, Moushiaveshi V, Wolf A, Bases R, Tsirka SE. Lucanthone Targets Lysosomes to Perturb Glioma Proliferation, Chemoresistance and Stemness, and Slows Tumor Growth In Vivo. Front Oncol 2022; 12:852940. [PMID: 35494072 PMCID: PMC9048484 DOI: 10.3389/fonc.2022.852940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 03/22/2022] [Indexed: 12/12/2022] Open
Abstract
Glioblastoma is the most common and aggressive primary brain tumor in adults. Median survival time remains at 16-20 months despite multimodal treatment with surgical resection, radiation, temozolomide and tumor-treating fields therapy. After genotoxic stress glioma cells initiate cytoprotective autophagy, which contributes to treatment resistance, limiting the efficacy of these therapies and providing an avenue for glioma recurrence. Antagonism of autophagy steps has recently gained attention as it may enhance the efficacy of classical chemotherapies and newer immune-stimulating therapies. The modulation of autophagy in the clinic is limited by the low potency of common autophagy inhibitors and the inability of newer ones to cross the blood-brain barrier. Herein, we leverage lucanthone, an anti-schistosomal agent which crosses the blood-brain barrier and was recently reported to act as an autophagy inhibitor in breast cancer cells. Our studies show that lucanthone was toxic to glioma cells by inhibiting autophagy. It enhanced anti-glioma temozolomide (TMZ) efficacy at sub-cytotoxic concentrations, and suppressed the growth of stem-like glioma cells and temozolomide-resistant glioma stem cells. In vivo lucanthone slowed tumor growth: reduced numbers of Olig2+ glioma cells, normalized tumor vasculature, and reduced tumor hypoxia. We propose that lucanthone may serve to perturb a mechanism of temozolomide resistance and allow for successful treatment of TMZ-resistant glioblastoma.
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Affiliation(s)
- Daniel P. Radin
- Department of Pharmacological Sciences, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
- Stony Brook Medical Scientist Training Program, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
| | - Gregory Smith
- Department of Pharmacological Sciences, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
| | - Victoria Moushiaveshi
- Department of Pharmacological Sciences, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
| | - Alexandra Wolf
- Department of Pharmacological Sciences, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
| | - Robert Bases
- Department of Radiology, Montefiore Medical Center, New York City, NY, United States
- Department of Radiation Oncology, Montefiore Medical Center, New York City, NY, United States
| | - Stella E. Tsirka
- Department of Pharmacological Sciences, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
- *Correspondence: Stella E. Tsirka,
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4
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Huang R, Zhou PK. DNA damage repair: historical perspectives, mechanistic pathways and clinical translation for targeted cancer therapy. Signal Transduct Target Ther 2021; 6:254. [PMID: 34238917 PMCID: PMC8266832 DOI: 10.1038/s41392-021-00648-7] [Citation(s) in RCA: 239] [Impact Index Per Article: 79.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/28/2021] [Accepted: 05/13/2021] [Indexed: 02/06/2023] Open
Abstract
Genomic instability is the hallmark of various cancers with the increasing accumulation of DNA damage. The application of radiotherapy and chemotherapy in cancer treatment is typically based on this property of cancers. However, the adverse effects including normal tissues injury are also accompanied by the radiotherapy and chemotherapy. Targeted cancer therapy has the potential to suppress cancer cells' DNA damage response through tailoring therapy to cancer patients lacking specific DNA damage response functions. Obviously, understanding the broader role of DNA damage repair in cancers has became a basic and attractive strategy for targeted cancer therapy, in particular, raising novel hypothesis or theory in this field on the basis of previous scientists' findings would be important for future promising druggable emerging targets. In this review, we first illustrate the timeline steps for the understanding the roles of DNA damage repair in the promotion of cancer and cancer therapy developed, then we summarize the mechanisms regarding DNA damage repair associated with targeted cancer therapy, highlighting the specific proteins behind targeting DNA damage repair that initiate functioning abnormally duo to extrinsic harm by environmental DNA damage factors, also, the DNA damage baseline drift leads to the harmful intrinsic targeted cancer therapy. In addition, clinical therapeutic drugs for DNA damage and repair including therapeutic effects, as well as the strategy and scheme of relative clinical trials were intensive discussed. Based on this background, we suggest two hypotheses, namely "environmental gear selection" to describe DNA damage repair pathway evolution, and "DNA damage baseline drift", which may play a magnified role in mediating repair during cancer treatment. This two new hypothesis would shed new light on targeted cancer therapy, provide a much better or more comprehensive holistic view and also promote the development of new research direction and new overcoming strategies for patients.
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Affiliation(s)
- Ruixue Huang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, Hunan, China
| | - Ping-Kun Zhou
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, AMMS, Beijing, China.
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5
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Silva V, Gil-Martins E, Silva B, Rocha-Pereira C, Sousa ME, Remião F, Silva R. Xanthones as P-glycoprotein modulators and their impact on drug bioavailability. Expert Opin Drug Metab Toxicol 2021; 17:441-482. [PMID: 33283552 DOI: 10.1080/17425255.2021.1861247] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Introduction: P-glycoprotein (P-gp) is an important efflux pump responsible for the extruding of many endogenous and exogenous substances out of the cells. P-gp can be modulated by different molecules - including xanthone derivatives - to surpass the multidrug resistance (MDR) phenomenon through P-gp inhibition, or to serve as an antidotal strategy in intoxication scenarios through P-gp induction/activation.Areas covered: This review provides a perspective on P-gp modulators, with particular focus on xanthonic derivatives, highlighting their ability to modulate P-gp expression and/or activity, and the potential impact of these effects on the pharmacokinetics, pharmacodynamics and toxicity of P-gp substrates.Expert opinion: Xanthones, of natural or synthetic origin, are able to modulate P-gp, interfering with its protein synthesis or with its mechanism of action, by decreasing or increasing its efflux capacity. These modulatory effects make the xanthonic scaffold a promising source of new derivatives with therapeutic potential. However, the mechanisms beyond the xanthones-mediated P-gp modulation and the chemical characteristics that make them more potent P-gp inhibitors or inducers/activators are still understudied. Furthermore, a new window of opportunity exists in the neuropathologies field, where xanthonic derivatives with potential to modulate P-gp should be further explored to optimize the prevention/treatment of brain pathologies.
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Affiliation(s)
- Vera Silva
- UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Eva Gil-Martins
- UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Bárbara Silva
- UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Carolina Rocha-Pereira
- UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Maria Emília Sousa
- CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental, Terminal de Cruzeiros do Porto de Leixões, Matosinhos, Portugal.,Laboratório de Química Orgânica e Farmacêutica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Fernando Remião
- UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Renata Silva
- UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
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6
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Yu X, Feng L, Liu D, Zhang L, Wu B, Jiang W, Han Z, Cheng S. Quantitative proteomics reveals the novel co-expression signatures in early brain development for prognosis of glioblastoma multiforme. Oncotarget 2017; 7:14161-71. [PMID: 26895104 PMCID: PMC4924705 DOI: 10.18632/oncotarget.7416] [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: 10/23/2015] [Accepted: 01/29/2016] [Indexed: 12/25/2022] Open
Abstract
Although several researches have explored the similarity across development and tumorigenesis in cellular behavior and underlying molecular mechanisms, not many have investigated the developmental characteristics at proteomic level and further extended to cancer clinical outcome. In this study, we used iTRAQ to quantify the protein expression changes during macaque rhesus brain development from fetuses at gestation 70 days to after born 5 years. Then, we performed weighted gene co-expression network analysis (WGCNA) on protein expression data of brain development to identify co-expressed modules that highly expressed on distinct development stages, including early stage, middle stage and late stage. Moreover, we used the univariate cox regression model to evaluate the prognostic potentials of these genes in two independent glioblastoma multiforme (GBM) datasets. The results showed that the modules highly expressed on early stage contained more reproducible prognostic genes, including ILF2, CCT7, CCT4, RPL10A, MSN, PRPS1, TFRC and APEX1. These genes were not only associated with clinical outcome, but also tended to influence chemoresponse. These signatures identified from embryonic brain development might contribute to precise prediction of GBM prognosis and identification of novel drug targets in GBM therapies. Thus, the development could become a viable reference model for researching cancers, including identifying novel prognostic markers and promoting new therapies.
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Affiliation(s)
- Xuexin Yu
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Lin Feng
- State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, Cancer Institute and Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100021, China
| | - Dianming Liu
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Lianfeng Zhang
- Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
| | - Bo Wu
- Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China
| | - Wei Jiang
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Zujing Han
- BGI Tech Solutions Co. Ltd., Yantian District, Shenzhen 518083, China
| | - Shujun Cheng
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China.,State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, Cancer Institute and Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100021, China
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7
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da Silva VBR, Campos BRKL, de Oliveira JF, Decout JL, do Carmo Alves de Lima M. Medicinal chemistry of antischistosomal drugs: Praziquantel and oxamniquine. Bioorg Med Chem 2017; 25:3259-3277. [DOI: 10.1016/j.bmc.2017.04.031] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/21/2017] [Accepted: 04/26/2017] [Indexed: 12/20/2022]
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8
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Doherty R, Madhusudan S. DNA Repair Endonucleases: Physiological Roles and Potential as Drug Targets. ACTA ACUST UNITED AC 2015; 20:829-41. [PMID: 25877151 DOI: 10.1177/1087057115581581] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/22/2015] [Indexed: 12/15/2022]
Abstract
Genomic DNA is constantly exposed to endogenous and exogenous damaging agents. To overcome these damaging effects and maintain genomic stability, cells have robust coping mechanisms in place, including repair of the damaged DNA. There are a number of DNA repair pathways available to cells dependent on the type of damage induced. The removal of damaged DNA is essential to allow successful repair. Removal of DNA strands is achieved by nucleases. Exonucleases are those that progressively cut from DNA ends, and endonucleases make single incisions within strands of DNA. This review focuses on the group of endonucleases involved in DNA repair pathways, their mechanistic functions, roles in cancer development, and how targeting these enzymes is proving to be an exciting new strategy for personalized therapy in cancer.
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Affiliation(s)
- Rachel Doherty
- Laboratory of Molecular Oncology, Academic Unit of Oncology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham University Hospitals, Nottingham, UK
| | - Srinivasan Madhusudan
- Laboratory of Molecular Oncology, Academic Unit of Oncology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham University Hospitals, Nottingham, UK
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9
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Goldstein M, Kastan MB. The DNA Damage Response: Implications for Tumor Responses to Radiation and Chemotherapy. Annu Rev Med 2015; 66:129-43. [DOI: 10.1146/annurev-med-081313-121208] [Citation(s) in RCA: 303] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michael Goldstein
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27710; ,
| | - Michael B. Kastan
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27710; ,
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10
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Curtin NJ. Inhibiting the DNA damage response as a therapeutic manoeuvre in cancer. Br J Pharmacol 2014; 169:1745-65. [PMID: 23682925 DOI: 10.1111/bph.12244] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 03/20/2013] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED The DNA damage response (DDR), consisting of an orchestrated network of proteins effecting repair and signalling to cell cycle arrest, to allow time to repair, is essential for cell viability and to prevent DNA damage being passed on to daughter cells. The DDR is dysregulated in cancer with some pathways up-regulated and others down-regulated or lost. Up-regulated pathways can confer resistance to anti-cancer DNA damaging agents. Therefore, inhibitors of key components of these pathways have the potential to prevent this therapeutic resistance. Conversely, defects in a particular DDR pathway may lead to dependence on a complementary pathway. Inhibition of this complementary pathway may result in tumour-specific cell killing. Thus, inhibitors of the DDR have the potential to increase the efficacy of DNA damaging chemotherapy and radiotherapy and have single-agent activity against tumours with a specific DDR defect. This review describes the compounds that have been designed to inhibit specific DDR targets and summarizes the pre-clinical and clinical evaluation of these inhibitors of DNA damage signalling and repair. LINKED ARTICLES This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.
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Affiliation(s)
- N J Curtin
- Northern Institute for Cancer Research, Medical School, Newcastle University, Newcastle upon Tyne, UK.
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11
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Thétiot-Laurent SAL, Boissier J, Robert A, Meunier B. Chemotherapie gegen Schistosomiasis. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201208390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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12
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Thétiot-Laurent SAL, Boissier J, Robert A, Meunier B. Schistosomiasis chemotherapy. Angew Chem Int Ed Engl 2013; 52:7936-56. [PMID: 23813602 DOI: 10.1002/anie.201208390] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Indexed: 01/08/2023]
Abstract
After malaria, schistosomiasis (or bilharzia) is the second most prevalent disease in Africa, and is occurring in over 70 countries in tropical and subtropical regions. It is estimated that 600 million people are at risk of infection, 200 million people are infected, and at least 200,000 deaths per year are associated with the disease. All schistosome species are transmitted through contact with fresh water that is infested with free-swimming forms of the parasite, which is known as cercariae and produced by snails. When located in the blood vessels of the host, larval and adult schistosomes digest red cells to acquire amino acids for growth and development. Vaccine candidates have been unsuccessful up to now. Against such devastating parasitic disease, the antischistosomal arsenal is currently limited to a single drug, praziquantel, which has been used for more than 35 years. Because the question of the reduction of the activity of praziquantel was raised recently, it is thus urgent to create new and safe antischistosomal drugs that should be combined with praziquantel to develop efficient bitherapies.
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Affiliation(s)
- Sophie A-L Thétiot-Laurent
- Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, BP 44099, 31077 Toulouse cedex 4, France
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13
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Mitchell S, Steventon G, Waring R. Drug peptide conjugates in human urine? Xenobiotica 2013; 44:89-93. [PMID: 23777287 DOI: 10.3109/00498254.2013.806838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
1. Once in a while, during drug metabolism studies, an unusual or unexpected pathway is unearthed. 2. Such quirky finds open a refreshing hiatus, providing a departure from the, perhaps now mundane, textbook routes. 3. This brief missive draws attention to an interesting anecdote that may be unknown to some and concerns a substituted thioxanthenone drug.
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Affiliation(s)
- Stephen Mitchell
- Computational and Systems Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London , London , UK
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14
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Abbotts R, Madhusudan S. Targeting DNA base excision repair: a new strategy for personalised cancer therapy. Clin Med (Lond) 2012. [DOI: 10.7861/clinmedicine.12-6-s42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Abstract
Dysregulation of DNA damage repair and signalling to cell cycle checkpoints, known as the DNA damage response (DDR), is associated with a predisposition to cancer and affects responses to DNA-damaging anticancer therapy. Dysfunction of one DNA repair pathway may be compensated for by the function of another compensatory DDR pathway, which may be increased and contribute to resistance to DNA-damaging chemotherapy and radiotherapy. Therefore, DDR pathways make an ideal target for therapeutic intervention; first, to prevent or reverse therapy resistance; and second, using a synthetic lethal approach to specifically kill cancer cells that are dependent on a compensatory DNA repair pathway for survival in the context of cancer-associated oxidative and replicative stress. These hypotheses are currently being tested in the laboratory and are being translated into clinical studies.
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Affiliation(s)
- Nicola J Curtin
- Newcastle University, Northern Institute for Cancer Research, Newcastle upon Tyne NE2 4HH, UK.
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16
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Bobola MS, Kolstoe DD, Blank A, Chamberlain MC, Silber JR. Repair of 3-methyladenine and abasic sites by base excision repair mediates glioblastoma resistance to temozolomide. Front Oncol 2012; 2:176. [PMID: 23230562 PMCID: PMC3515961 DOI: 10.3389/fonc.2012.00176] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/05/2012] [Indexed: 12/11/2022] Open
Abstract
Alkylating agents have long played a central role in the adjuvant therapy of glioblastoma (GBM). More recently, inclusion of temozolomide (TMZ), an orally administered methylating agent with low systemic toxicity, during and after radiotherapy has markedly improved survival. Extensive in vitro and in vivo evidence has shown that TMZ-induced O(6)-methylguanine (O(6)-meG) mediates GBM cell killing. Moreover, low or absent expression of O(6)-methylguanine-DNA methyltransferase (MGMT), the sole human repair protein that removes O(6)-meG from DNA, is frequently associated with longer survival in GBMs treated with TMZ, promoting interest in developing inhibitors of MGMT to counter resistance. However, the clinical efficacy of TMZ is unlikely to be due solely to O(6)-meG, as the agent produces approximately a dozen additional DNA adducts, including cytotoxic N3-methyladenine (3-meA) and abasic sites. Repair of 3-meA and abasic sites, both of which are produced in greater abundance than O(6)-meG, is mediated by the base excision repair (BER) pathway, and occurs independently of removal of O(6)-meG. These observations indicate that BER activities are also potential targets for strategies to potentiate TMZ cytotoxicity. Here we review the evidence that 3-meA and abasic sites mediate killing of GBM cells. We also present in vitro and in vivo evidence that alkyladenine-DNA glycosylase, the sole repair activity that excises 3-meA from DNA, and Ape1, the major human abasic site endonuclease, mediate TMZ resistance in GBMs and represent potential anti-resistance targets.
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Affiliation(s)
- Michael S. Bobola
- Department of Neurological Surgery, University of Washington Medical CenterSeattle, WA, USA
| | - Douglas D. Kolstoe
- Department of Neurological Surgery, University of Washington Medical CenterSeattle, WA, USA
| | - A. Blank
- Department of Neurological Surgery, University of Washington Medical CenterSeattle, WA, USA
| | - Marc C. Chamberlain
- Department of Neurological Surgery, University of Washington Medical CenterSeattle, WA, USA
- Department of Neurology, University of Washington Medical CenterSeattle, WA, USA
| | - John R. Silber
- Department of Neurological Surgery, University of Washington Medical CenterSeattle, WA, USA
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17
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Ruiz FM, Francis SM, Tintoré M, Ferreira R, Gil-Redondo R, Morreale A, Ortiz ÁR, Eritja R, Fàbrega C. Receptor-based virtual screening and biological characterization of human apurinic/apyrimidinic endonuclease (Ape1) inhibitors. ChemMedChem 2012; 7:2168-78. [PMID: 23109358 DOI: 10.1002/cmdc.201200372] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 09/26/2012] [Indexed: 12/25/2022]
Abstract
The endonucleolytic activity of human apurinic/apyrimidinic endonuclease (AP endo, Ape1) is a major factor in maintaining the integrity of the genome. Conversely, as an undesired effect, Ape1 overexpression has been linked to resistance to radio- and chemotherapeutic treatments in several human tumors. Inhibition of Ape1 using siRNA or the expression of a dominant negative form of the protein has been shown to sensitize cells to DNA-damaging agents, including various chemotherapeutic agents. Therefore, inhibition of the enzymatic activity of Ape1 might result in a potent antitumor therapy. A number of small molecules have been described as Ape1 inhibitors; however, those compounds are in the early stages of development. Herein we report the identification of new compounds as potential Ape1 inhibitors through a docking-based virtual screening technique. Some of the compounds identified have in vitro activities in the low-to-medium micromolar range. Interaction of these compounds with the Ape1 protein was observed by mass spectrometry. These molecules also potentiate the cytotoxicity of the chemotherapeutic agent methyl methanesulfonate in fibrosarcoma cells. This study demonstrates the power of docking and virtual screening techniques as initial steps in the design of new drugs, and opens the door to the development of a new generation of Ape1 inhibitors.
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Naidu MD, Agarwal R, Pena LA, Cunha L, Mezei M, Shen M, Wilson DM, Liu Y, Sanchez Z, Chaudhary P, Wilson SH, Waring MJ. Lucanthone and its derivative hycanthone inhibit apurinic endonuclease-1 (APE1) by direct protein binding. PLoS One 2011; 6:e23679. [PMID: 21935361 PMCID: PMC3174134 DOI: 10.1371/journal.pone.0023679] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 07/23/2011] [Indexed: 01/06/2023] Open
Abstract
Lucanthone and hycanthone are thioxanthenone DNA intercalators used in the 1980s as antitumor agents. Lucanthone is in Phase I clinical trial, whereas hycanthone was pulled out of Phase II trials. Their potential mechanism of action includes DNA intercalation, inhibition of nucleic acid biosyntheses, and inhibition of enzymes like topoisomerases and the dual function base excision repair enzyme apurinic endonuclease 1 (APE1). Lucanthone inhibits the endonuclease activity of APE1, without affecting its redox activity. Our goal was to decipher the precise mechanism of APE1 inhibition as a prerequisite towards development of improved therapeutics that can counteract higher APE1 activity often seen in tumors. The IC(50) values for inhibition of APE1 incision of depurinated plasmid DNA by lucanthone and hycanthone were 5 µM and 80 nM, respectively. The K(D) values (affinity constants) for APE1, as determined by BIACORE binding studies, were 89 nM for lucanthone/10 nM for hycanthone. APE1 structures reveal a hydrophobic pocket where hydrophobic small molecules like thioxanthenones can bind, and our modeling studies confirmed such docking. Circular dichroism spectra uncovered change in the helical structure of APE1 in the presence of lucanthone/hycanthone, and notably, this effect was decreased (Phe266Ala or Phe266Cys or Trp280Leu) or abolished (Phe266Ala/Trp280Ala) when hydrophobic site mutants were employed. Reduced inhibition by lucanthone of the diminished endonuclease activity of hydrophobic mutant proteins (as compared to wild type APE1) supports that binding of lucanthone to the hydrophobic pocket dictates APE1 inhibition. The DNA binding capacity of APE1 was marginally inhibited by lucanthone, and not at all by hycanthone, supporting our hypothesis that thioxanthenones inhibit APE1, predominantly, by direct interaction. Finally, lucanthone-induced degradation was drastically reduced in the presence of short and long lived free radical scavengers, e.g., TRIS and DMSO, suggesting that the mechanism of APE1 breakdown may involve free radical-induced peptide bond cleavage.
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Affiliation(s)
- Mamta D Naidu
- Biology Department, Brookhaven National Laboratory, Upton, New York, United States of America.
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19
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Gajbhiye V, Jain NK. The treatment of Glioblastoma Xenografts by surfactant conjugated dendritic nanoconjugates. Biomaterials 2011; 32:6213-25. [DOI: 10.1016/j.biomaterials.2011.04.057] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 04/22/2011] [Indexed: 10/18/2022]
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20
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Abbotts R, Madhusudan S. Human AP endonuclease 1 (APE1): from mechanistic insights to druggable target in cancer. Cancer Treat Rev 2010; 36:425-35. [PMID: 20056333 DOI: 10.1016/j.ctrv.2009.12.006] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/02/2009] [Accepted: 12/07/2009] [Indexed: 01/16/2023]
Abstract
DNA base excision repair (BER) is critically involved in the processing of DNA base damage induced by alkylating agents. Pharmacological inhibition of BER (using PARP inhibitors), either alone or in combination with chemotherapy has recently shown promise in clinical trials. Human apurinic/apyrimidinic endonuclease 1(APE1) is an essential BER protein that is involved in the processing of potentially cytotoxic abasic sites that are obligatory intermediates in BER. Here we provide a summary of the basic mechanistic role of APE1 in DNA repair and redox regulation and highlight preclinical and clinical data that confirm APE1 as a valid anticancer drug target. Development of small molecule inhibitors of APE1 is an area of intense research and current evidence using APE1 inhibitors has demonstrated potentiation of cytotoxicity of alkylating agents in preclinical models implying translational applications in cancer patients.
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Affiliation(s)
- Rachel Abbotts
- Translational DNA Repair Group, Laboratory of Molecular Oncology, Academic Unit of Oncology, School of Molecular Medical Sciences, University of Nottingham, Nottingham, UK
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21
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Naidu MD, Mason JM, Pica RV, Fung H, Peña LA. Radiation resistance in glioma cells determined by DNA damage repair activity of Ape1/Ref-1. JOURNAL OF RADIATION RESEARCH 2010; 51:393-404. [PMID: 20679741 DOI: 10.1269/jrr.09077] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Since radiation therapy remains a primary treatment modality for gliomas, the radioresistance of glioma cells and targets to modify their radiation tolerance are of significant interest. Human apurinic endonuclease 1 (Ape1, Ref-1, APEX, HAP1, AP endo) is a multifunctional protein involved in base excision repair of DNA and a redox-dependent transcriptional co-activator. This study investigated whether there is a direct relationship between Ape1 and radioresistance in glioma cells, employing the human U87 and U251 cell lines. U87 is intrinsically more radioresistant than U251, which is partly attributable to more cycling U251 cells found in G2/M, the most radiosensitive cell stage, while more U87 cells are found in S and G1, the more radioresistant cell stages. But observed radioresistance is also related to Ape1 activity. U87 has higher levels of Ape1 than does U251, as assessed by Western blot and enzyme activity assays (approximately 1.5-2 fold higher in cycling cells, and approximately 10 fold higher at G2/M). A direct relationship was seen in cells transfected with CMV-Ape1 constructs; there was a dose-dependent relationship between increasing Ape1 overexpression and increasing radioresistance. Conversely, knock down by siRNA or by pharmacological down regulation of Ape1 resulted in decreased radioresistance. The inhibitors lucanthone and CRT004876 were employed, the former a thioxanthene previously under clinical evaluation as a radiosensitizer for brain tumors and the latter a more specific Ape1 inhibitor. These data suggest that Ape1 may be a useful target for modifying radiation tolerance.
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Affiliation(s)
- Mamta D Naidu
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA
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22
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Reed AM, Fishel ML, Kelley MR. Small-molecule inhibitors of proteins involved in base excision repair potentiate the anti-tumorigenic effect of existing chemotherapeutics and irradiation. Future Oncol 2009; 5:713-26. [PMID: 19519210 DOI: 10.2217/fon.09.31] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
There has been a recent upsurge in the development of small-molecule inhibitors specific to DNA repair proteins or proteins peripherally involved in base excision repair and the DNA damage response. These specific, nominally toxic inhibitors are able to potentiate the effect of existing cancer cell treatments in a wide array of cancers. One of the largest obstacles to overcome in the treatment of cancer is incomplete killing with initial cancer treatments, leading to resistant cancer. The progression of our understanding of cancer and normal cell responses to DNA damage has allowed us to develop biomarkers that we can use to help us predict responses of cancers, more specifically target cancer cells and overcome resistance. Initial successes using these small-molecule DNA repair inhibitors in target-validation experiments and in the early stages of clinical trials indicate an important role for these inhibitors, and allow for the possibility of a future in which cancers are potentially treated in a highly specific, individual manner.
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Affiliation(s)
- April M Reed
- Department of Pediatrics, Section of Hematology/Oncology, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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23
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Abstract
The DNA base excision repair (BER) pathway repairs alkylation and oxidative DNA damage caused by endogenous and exogenous agents, including chemotherapeutic agents. Upon removal of the damaged base AP endonuclease 1 (Ape1), a critical component of the pathway cleaves the abasic site to facilitate repair. Ape1 is a multifunctional protein which plays a role not only in DNA repair but it also functions as a reduction-oxidation factor, known as Ref-1 in the literature, to increase the DNA binding ability of several transcription factors involved in different growth signaling pathways. Elevated levels of Ape1 have been linked to resistance to chemotherapy, poor prognosis, and poor survival. Reducing the amount of Ape1 protein in cancer cells and tumors using RNA interference and anti-sense oligonucleotide technology sensitizes mammalian tumor cells to a variety of laboratory and chemotherapeutic agents. Therefore, selective inhibition of Ape1's DNA repair activity is a promising avenue to develop novel cancer therapeutics.
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Affiliation(s)
- Aditi Bapat
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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24
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Fishel ML, Kelley MR. The DNA base excision repair protein Ape1/Ref-1 as a therapeutic and chemopreventive target. Mol Aspects Med 2007; 28:375-95. [PMID: 17560642 DOI: 10.1016/j.mam.2007.04.005] [Citation(s) in RCA: 205] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 04/15/2007] [Indexed: 10/23/2022]
Abstract
With our growing understanding of the pathways involved in cell proliferation and signaling, targeted therapies, in the treatment of cancer are entering the clinical arena. New and emerging targets are proteins involved in DNA repair pathways. Inhibition of various proteins in the DNA repair pathways sensitizes cancer cells to DNA damaging agents such as chemotherapy and/or radiation. We study the apurinic endonuclease 1/redox factor-1 (Ape1/Ref-1) and believe that its crucial function in DNA repair and reduction-oxidation or redox signaling make it an excellent target for sensitizing tumor cells to chemotherapy. Ape1/Ref-1 is an essential enzyme in the base excision repair (BER) pathway which is responsible for the repair of DNA caused by oxidative and alkylation damage. As importantly, Ape1/Ref-1 also functions as a redox factor maintaining transcription factors in an active reduced state. Ape1/Ref-1 stimulates the DNA binding activity of numerous transcription factors that are involved in cancer promotion and progression such as AP-1 (Fos/Jun), NFkappaB, HIF-1alpha, CREB, p53 and others. We will discuss what is known regarding the pharmacological targeting of the DNA repair activity, as well as the redox activity of Ape1/Ref-1, and explore the budding clinical utility of inhibition of either of these functions in cancer treatment. A brief discussion of the effect of polymorphisms in its DNA sequence is included because of Ape1/Ref-1's importance to maintenance and integrity of the genome. Experimental modification of Ape1/Ref-1 activity changes the response of cells and of organisms to DNA damaging agents, suggesting that Ape1/Ref-1 may also be a productive target of chemoprevention. In this review, we will provide an overview of Ape1/Ref-1's activities and explore the potential of this protein as a target in cancer treatment as well as its role in chemoprevention.
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Affiliation(s)
- Melissa L Fishel
- Department of Pediatrics (Section of Hematology/Oncology), Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, United States
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25
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Bobola MS, Finn LS, Ellenbogen RG, Geyer JR, Berger MS, Braga JM, Meade EH, Gross ME, Silber JR. Apurinic/apyrimidinic endonuclease activity is associated with response to radiation and chemotherapy in medulloblastoma and primitive neuroectodermal tumors. Clin Cancer Res 2006; 11:7405-14. [PMID: 16243814 DOI: 10.1158/1078-0432.ccr-05-1068] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers resistance to radiation- and alkylator-induced cytotoxic abasic sites in human cells. We assayed apurinic/apyrimidinic endonuclease activity in medulloblastomas and primitive neuroectodermal tumors (PNET) to establish correlates with tumor and patient characteristics and with response to adjuvant radiation plus multiagent chemotherapy. EXPERIMENTAL DESIGN Ap endo activity was assayed in 52 medulloblastomas and 10 PNETs from patients 0.4 to 21 years old. Ape1/Ref-1, the predominant human Ap endo activity, was measured in 42 medulloblastomas by immunostaining. Cox proportional hazards regression models were used to analyze the association of activity with time to tumor progression (TTP). RESULTS Tumor Ap endo activity varied 180-fold and was significantly associated with age and gender. Tumor Ape1/Ref-1 was detected almost exclusively in nuclei. In a multivariate model, with Ap endo activity entered as a continuous variable, the hazard ratio for progression after adjuvant treatment in 46 medulloblastomas and four PNETs increased by a factor of 1.073 for every 0.01 unit increase in activity (P < or = 0.001) and was independent of age and gender. Suppressing Ap endo activity in a human medulloblastoma cell line significantly increased sensitivity to 1,3-bis(2-chlororethyl)-1-nitrosourea and temozolomide, suggesting that the association of tumor activity with TTP reflected, at least in part, abasic site repair. CONCLUSIONS Our data (a) suggest that Ap endo activity promotes resistance to radiation plus chemotherapy in medulloblastomas/PNETs, (b) provide a potential marker of treatment outcome, and (c) suggest clinical use of Ap endo inhibitors to overcome resistance.
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MESH Headings
- Adolescent
- Adult
- Antineoplastic Agents, Alkylating/pharmacology
- Blotting, Western
- Brain/drug effects
- Brain/enzymology
- Brain/radiation effects
- Brain Neoplasms/enzymology
- Brain Neoplasms/pathology
- Brain Neoplasms/therapy
- Carmustine/pharmacology
- Cell Line, Tumor
- Cell Nucleus/enzymology
- Cell Survival/drug effects
- Cell Survival/genetics
- Child
- Child, Preschool
- Combined Modality Therapy
- DNA-(Apurinic or Apyrimidinic Site) Lyase/genetics
- DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism
- Disease Progression
- Dose-Response Relationship, Drug
- Female
- Humans
- Immunohistochemistry
- Infant
- Infant, Newborn
- Male
- Medulloblastoma/enzymology
- Medulloblastoma/pathology
- Medulloblastoma/therapy
- Multivariate Analysis
- Neuroectodermal Tumors, Primitive/enzymology
- Neuroectodermal Tumors, Primitive/pathology
- Neuroectodermal Tumors, Primitive/therapy
- Oligonucleotides, Antisense/genetics
- RNA, Small Interfering/genetics
- Time Factors
- Transfection
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Affiliation(s)
- Michael S Bobola
- Division of Neurosurgery, Department of Surgery, Children's Hospital and Regional Medical Center, Seattle, WA 98105, USA.
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26
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Bases R. Clonogenicity of human leukemic cells protected from cell-lethal agents by heat shock protein 70. Cell Stress Chaperones 2005; 10:37-45. [PMID: 15832946 PMCID: PMC1074569 DOI: 10.1379/csc-58r.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Pretreatment of human leukemia THP-1 cells with heat shock protein Hsp70 (Hsp70) protected them from the cell-lethal effects of the topoisomerase II inhibitor, lucanthone and from ionizing radiation. Cell viability was scored in clonogenic assays of single cells grown in liquid medium containing 0.5% methyl cellulose. Colonies were observed and rapidly scored after staining with the tetrazolium salt, 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide. The frequency of abasic sites in the deoxyribonucleic acid (DNA) of THP-1 cells was reduced when these cells were treated with Hsp70. Hsp70 is presumed to have protected the cells by promoting repair of cell DNA, in agreement with previous studies that showed that Hsp70 enhanced base excision repair by purified enzymes. The shoulders of radiation dose-response curves were enhanced by pretreatment of cells with Hsp70 and, importantly, were reduced when cells were transfected with ribonucleic acid designed to silence Hsp70. Hsp70 influenced repair of sublethal damage after radiation.
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Affiliation(s)
- Robert Bases
- Departments of Radiology and Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY 10467, USA.
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27
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Abstract
Abasic sites in HeLa cell DNA were increased in frequency by exposing the cells to lucanthone. Cell growth in the presence of lucanthone caused progressive accumulation of abasic sites and loss of cellular DNA. After 2 hr in 8 microM lucanthone, the abundance of abasic sites was 2.4 fold greater than the background of 9.9 +/- 2.0 SE abasic sites/10(6) nucleotides; 80 microM lucanthone in the growth medium increased the level 12.6 +/- 2.5 SE fold and decreased the DNA content in HeLa cells to one-half of the value obtained in untreated cells. The frequency of abasic sites in cellular DNA was determined by the aldehyde reactive probe method, with reference to abasic sites created in plasmid pBR322. The ability of lucanthone to inhibit the normal repair of abasic sites might reflect inhibition of apurinic/apyrimidinic endonuclease (HAP1) by the drug, thereby preventing an early step in the base excision repair pathway. Unrepaired abasic sites prevalent after ionizing radiation are cytotoxic lesions that promote DNA strand breaks. These results suggest a rationale for the joint lethal effects of lucanthone and ionizing radiation in cells and the accelerated tumor regression observed in cancer patients who received the combined therapy.
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Affiliation(s)
- Frances Mendez
- Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210 Street, Bronx, NY 10467, USA
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28
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Abstract
Brain metastases are an increasingly common complication in patients with systemic cancer. The optimal treatment for each patient depends on careful evaluation of several factors: the location, size, and number of brain metastases; the patient's age, general condition, and neurologic status; and the extent of systemic cancer to name a few. For patients with a single brain metastasis and limited systemic disease, the standard treatment is surgical resection followed by whole brain radiation therapy. In patients with a small, single metastasis, stereotactic radiosurgery is probably comparable to surgery. Patients with several metastases (up to three) and controlled systemic disease can be treated with whole-brain radiation and stereotactic radiosurgery. Patients with multiple metastases (more than three) are generally treated with whole-brain radiation alone. Radiosurgery is effective in treating patients with a limited number of recurrent brain metastases and stable systemic diseases. Surgery may have a role in patients with a large symptomatic recurrent lesion producing mass effect. Reirradiation and chemotherapy may have a limited role in patients with multiple recurrent metastases.
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Affiliation(s)
- P Y Wen
- Division of Neuro-oncology, Department of Neurology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA,02115, USA
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29
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Dassonneville L, Bailly C. Stimulation of topoisomerase II-mediated DNA cleavage by an indazole analogue of lucanthone. Biochem Pharmacol 1999; 58:1307-12. [PMID: 10487533 DOI: 10.1016/s0006-2952(99)00221-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lucanthone is an antitumour drug used as an adjuvant in radiation therapy. The drug intercalates into DNA and inhibits topoisomerase II. An indazole analogue of lucanthone (IA-5) was examined for its ability to modulate topoisomerase II-DNA cleavable complex formation in vitro. The drug contains a methylbenzothiopyranoindazole chromophore instead of the methyl-thioxanthenone nucleus of lucanthone. Using a radiolabelled linear plasmid DNA as a substrate, both lucanthone and the indazole analogue were shown to promote the cleavage of DNA by human topoisomerase II. Sequencing experiments with different restriction fragments indicated that the indazole drug promoted DNA cleavage primarily at sites having a C on the 3' side of the cleaved bond (-1 position). By contrast, in the same sequencing methodology lucanthone exerted a much weaker effect on topoisomerase II. The sequence selectivity of IA-5 is reminiscent of that of the anticancer drug mitoxantrone and its anthrapyrazole analogue losoxantrone, which is structurally close to IA-5. Binding to DNA and topoisomerase II inhibition are two distinct processes contributing separately to the cytotoxic activity of the indazole drug.
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Affiliation(s)
- L Dassonneville
- Laboratoire de Pharmacologie Antitumorale du Centre Oscar Lambret and INSERM Unite 524, IRCL, Lille, France
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