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Valikhani M, Rahimian E, Ahmadi SE, Chegeni R, Safa M. Involvement of classic and alternative non-homologous end joining pathways in hematologic malignancies: targeting strategies for treatment. Exp Hematol Oncol 2021; 10:51. [PMID: 34732266 PMCID: PMC8564991 DOI: 10.1186/s40164-021-00242-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/13/2021] [Indexed: 12/31/2022] Open
Abstract
Chromosomal translocations are the main etiological factor of hematologic malignancies. These translocations are generally the consequence of aberrant DNA double-strand break (DSB) repair. DSBs arise either exogenously or endogenously in cells and are repaired by major pathways, including non-homologous end-joining (NHEJ), homologous recombination (HR), and other minor pathways such as alternative end-joining (A-EJ). Therefore, defective NHEJ, HR, or A-EJ pathways force hematopoietic cells toward tumorigenesis. As some components of these repair pathways are overactivated in various tumor entities, targeting these pathways in cancer cells can sensitize them, especially resistant clones, to radiation or chemotherapy agents. However, targeted therapy-based studies are currently underway in this area, and furtherly there are some biological pitfalls, clinical issues, and limitations related to these targeted therapies, which need to be considered. This review aimed to investigate the alteration of DNA repair elements of C-NHEJ and A-EJ in hematologic malignancies and evaluate the potential targeted therapies against these pathways.
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Affiliation(s)
- Mohsen Valikhani
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, School of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Elahe Rahimian
- Department of Medical Translational Oncology, National Center for Tumor Diseases (NCT) Dresden, Dresden, Germany
| | - Seyed Esmaeil Ahmadi
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, School of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Rouzbeh Chegeni
- Medical Laboratory Sciences, Program, College of Health and Human Sciences, Northern Illinois University, DeKalb, IL, USA
| | - Majid Safa
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, School of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran.
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2
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Fernandes SG, Shah P, Khattar E. Recent Advances in Therapeutic Application of DNA Damage Response Inhibitors against Cancer. Anticancer Agents Med Chem 2021; 22:469-484. [PMID: 34102988 DOI: 10.2174/1871520621666210608105735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/02/2021] [Accepted: 02/22/2021] [Indexed: 11/22/2022]
Abstract
DNA integrity is continuously challenged by intrinsic cellular processes and environmental agents. To overcome this genomic damage, cells have developed multiple signaling pathways collectively named as DNA damage response (DDR) and composed of three components: (i) sensor proteins, which detect DNA damage, (ii) mediators that relay the signal downstream and recruit the repair machinery, and (iii) the repair proteins, which restore the damaged DNA. A flawed DDR and failure to repair the damage lead to the accumulation of genetic lesions and increased genomic instability, which is recognized as a hallmark of cancer. Cancer cells tend to harbor increased mutations in DDR genes and often have fewer DDR pathways than normal cells. This makes cancer cells more dependent on particular DDR pathways and thus become more susceptible to compounds inhibiting those pathways compared to normal cells, which have all the DDR pathways intact. Understanding the roles of different DDR proteins in the DNA damage response and repair pathways and identification of their structures have paved the way for the development of their inhibitors as targeted cancer therapy. In this review, we describe the major participants of various DDR pathways, their significance in carcinogenesis, and focus on the inhibitors developed against several key DDR proteins.
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Affiliation(s)
- Stina George Fernandes
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
| | - Prachi Shah
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
| | - Ekta Khattar
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
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3
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Rahimian E, Amini A, Alikarami F, Pezeshki SMS, Saki N, Safa M. DNA repair pathways as guardians of the genome: Therapeutic potential and possible prognostic role in hematologic neoplasms. DNA Repair (Amst) 2020; 96:102951. [PMID: 32971475 DOI: 10.1016/j.dnarep.2020.102951] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 07/30/2020] [Accepted: 08/10/2020] [Indexed: 11/30/2022]
Abstract
DNA repair pathways, which are also identified as guardians of the genome, protect cells from frequent damage that can lead to DNA breaks. The most deleterious types of damage are double-strand breaks (DSBs), which are repaired by homologous recombination (HR) and non-homologous end joining (NHEJ). Single strand breaks (SSBs) can be corrected through base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Failure to restore DNA lesions or inappropriately repaired DNA damage culminates in genomic instability and changes in the regulation of cellular functions. Intriguingly, particular mutations and translocations are accompanied by special types of leukemia. Besides, expression patterns of certain repair genes are altered in different hematologic malignancies. Moreover, analysis of mutations in key mediators of DNA damage repair (DDR) pathways, as well as investigation of their expression and function, may provide us with emerging biomarkers of response/resistance to treatment. Therefore, defective DDR pathways can offer a rational starting point for developing DNA repair-targeted drugs. In this review, we address genetic alterations and gene/protein expression changes, as well as provide an overview of DNA repair pathways.
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Affiliation(s)
- Elahe Rahimian
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Ali Amini
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Alikarami
- Center for Childhood Cancer Research, Children's Hospital of Philadelphia (CHOP), Philadelphia, PA 19104, USA
| | - Seyed Mohammad Sadegh Pezeshki
- Thalassemia & Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Najmaldin Saki
- Thalassemia & Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Majid Safa
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.
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4
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Al-Aamri HM, Irving HR, Meehan-Andrews T, Bradley C. Determination of the DNA repair pathways utilised by acute lymphoblastic leukaemia cells following daunorubicin treatment. BMC Res Notes 2019; 12:625. [PMID: 31551083 PMCID: PMC6760046 DOI: 10.1186/s13104-019-4663-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Accepted: 09/18/2019] [Indexed: 12/25/2022] Open
Abstract
Objective DNA double strand breaks (DNA-DSBs) are among the most lethal DNA lesions leading to genomic instability and repaired by either homologous recombination (HR) or the non-homologous end joining (NHEJ) mechanisms. The purpose of this study was to assess the importance and the level of activation of non-homologous end joining (NHEJ) and homologous recombination (HR) DNA repair pathways in three cell lines, CCRF-CEM and MOLT-4 derived from T lymphocytes and SUP-B15 derived from B lymphocytes following treatment with chemotherapy agent daunorubicin. Results The Gamma histone H2AX (γH2AX) assay was used assess the effects of DNA-PK inhibitor NU7026 and RAD51 inhibitor RI-2 on repair of DNA-DSB following treatment with daunorubicin. In all cell lines, the NHEJ DNA repair pathway appeared more rapid and efficient. MOLT-4 and CCFR-CEM cells utilised both NHEJ and HR pathways for DNA-DSB repair. Whereas, SUP-B15 cells utilised only NHEJ for DSB repair, suggestive of a deficiency in HR repair pathways.
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Affiliation(s)
- Hussain Mubarak Al-Aamri
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Sciences (LIMS), La Trobe University, P.O. Box 199, Bendigo, VIC, 3552, Australia. .,Oman College of Health Sciences, PO Box 293, 620, Ruwi, Oman.
| | - Helen R Irving
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Sciences (LIMS), La Trobe University, P.O. Box 199, Bendigo, VIC, 3552, Australia.
| | - Terri Meehan-Andrews
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Sciences (LIMS), La Trobe University, P.O. Box 199, Bendigo, VIC, 3552, Australia
| | - Christopher Bradley
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Sciences (LIMS), La Trobe University, P.O. Box 199, Bendigo, VIC, 3552, Australia
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5
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Radiosensitizing activity of novel small molecule BRCA1 and DNA-PK inhibitors in lung and colon carcinoma. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2019. [DOI: 10.1016/j.jrras.2017.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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6
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Tarazi H, Saleh E, El-Awady R. In-silico screening for DNA-dependent protein kinase (DNA-PK) inhibitors: Combined homology modeling, docking, molecular dynamic study followed by biological investigation. Biomed Pharmacother 2016; 83:693-703. [DOI: 10.1016/j.biopha.2016.07.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 07/17/2016] [Accepted: 07/19/2016] [Indexed: 10/21/2022] Open
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7
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Bouley J, Saad L, Grall R, Schellenbauer A, Biard D, Paget V, Morel-Altmeyer S, Guipaud O, Chambon C, Salles B, Maloum K, Merle-Béral H, Chevillard S, Delic J. A new phosphorylated form of Ku70 identified in resistant leukemic cells confers fast but unfaithful DNA repair in cancer cell lines. Oncotarget 2016; 6:27980-8000. [PMID: 26337656 PMCID: PMC4695039 DOI: 10.18632/oncotarget.4735] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 08/03/2015] [Indexed: 12/18/2022] Open
Abstract
Ku70-dependent canonical nonhomologous end-joining (c-NHEJ) DNA repair system is fundamental to the genome maintenance and B-cell lineage. c-NHEJ is upregulated and error-prone in incurable forms of chronic lymphocytic leukemia which also displays telomere dysfunction, multiple chromosomal aberrations and the resistance to DNA damage-induced apoptosis. We identify in these cells a novel DNA damage inducible form of phospho-Ku70. In vitro in different cancer cell lines, Ku70 phosphorylation occurs in a heterodimer Ku70/Ku80 complex within minutes of genotoxic stress, necessitating its interaction with DNA damage-induced kinase pS2056-DNA-PKcs and/or pS1981-ATM. The mutagenic effects of phospho-Ku70 are documented by a defective S/G2 checkpoint, accelerated disappearance of γ-H2AX foci and kinetics of DNA repair resulting in an increased level of genotoxic stress-induced chromosomal aberrations. Together, these data unveil an involvement of phospho-Ku70 in fast but inaccurate DNA repair; a new paradigm linked to both the deregulation of c-NHEJ and the resistance of malignant cells.
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Affiliation(s)
- Julien Bouley
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France.,Laboratoire de Spectrométrie de Masse, Stallergens, 92160 Antony, France
| | - Lina Saad
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France
| | - Romain Grall
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France
| | - Amelie Schellenbauer
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France
| | - Denis Biard
- Institut de Maladies Emergentes et des Thérapies Innovantes (iMETI), Service d'Etude des Prions et des Infections Atypiques (SEPIA), CEA, 92265 Fontenay aux Roses, France
| | - Vincent Paget
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France
| | - Sandrine Morel-Altmeyer
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France
| | - Olivier Guipaud
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France.,Laboratoire de Radiopathologie et de Thérapies Expérimentales, Institut de Radioprotection et de Sureté Nucléaire (IRSN), 92265 Fontenay aux Roses, France
| | - Christophe Chambon
- Service de Spectrométrie de Masse, INRA Theix, 63122 St Genès Champanelle, France
| | - Bernard Salles
- UMR 1331 TOXALIM, INRA/INP/UPS, F-31027 Toulouse, France
| | - Karim Maloum
- Service d'Hématologie Biologique, Hôpital Pitié-Salpêtrière, 75000 Paris, France
| | - Hélène Merle-Béral
- Service d'Hématologie Biologique, Hôpital Pitié-Salpêtrière, 75000 Paris, France.,Université Pierre et Marie Curie, Paris VI, INSERM, UMR-S 872, Programmed Cell Death and Physiopathology of Tumor Cells, Centre de Recherche des Cordeliers 75000 Paris, France
| | - Sylvie Chevillard
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France
| | - Jozo Delic
- Laboratoire de Cancérologie Expérimentale, Institut de Radiobiologie Cellulaire et Moléculaire (IRCM), Commissariat à l'Energie Atomique et aux Energies Renouvelables (CEA), 92265 Fontenay aux Roses, France
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8
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Dual TORK/DNA-PK inhibition blocks critical signaling pathways in chronic lymphocytic leukemia. Blood 2016; 128:574-83. [DOI: 10.1182/blood-2016-02-700328] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/20/2016] [Indexed: 12/29/2022] Open
Abstract
Key Points
TORK/DNA-PK inhibition induces cytotoxicity and blocks signaling pathways important for CLL survival, proliferation, and drug resistance. Preliminary clinical effects of TORK/DNA-PK inhibition show 7 of 8 CLL patients with decreased lymphadenopathy.
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9
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DNA repair of myeloma plasma cells correlates with clinical outcome: the effect of the nonhomologous end-joining inhibitor SCR7. Blood 2016; 128:1214-25. [PMID: 27443291 DOI: 10.1182/blood-2016-01-691618] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 06/08/2016] [Indexed: 12/26/2022] Open
Abstract
DNA repair activity of malignant cells seems to influence therapeutic outcome and patients' survival. Herein, we investigated the mechanistic basis for the link between DNA repair efficiency and response to antimyeloma therapy. Nucleotide excision repair (NER), interstrand cross-links repair (ICL/R), double-strand breaks repair (DSB/R), and chromatin structure were evaluated in multiple myeloma (MM) cell lines (melphalan-sensitive RPMI8226; melphalan-resistant LR5) and bone marrow plasma cells (BMPCs) from MM patients who responded (n = 17) or did not respond (n = 9) to subsequent melphalan therapy. The effect of DSB/R inhibition was also evaluated. Responders' BMPCs showed slower rates of NER and DSB/R (P <0022), similar rates of ICL/R, and more condensed chromatin structure compared with nonresponders. Moreover, apoptosis rates of BMPCs were inversely correlated with individual DNA repair efficiency and were higher in responders' cells compared with those of nonresponders (P = .0011). Similarly, RPMI8226 cells showed slower rates of NER and DSB/R, comparable rates of ICL/R, more condensed chromatin structure, and higher sensitivity than LR5 cells. Interestingly, cotreatment of BMPCs or cell lines with DSB/R inhibitors significantly reduced the rates of DSB/R and increased melphalan sensitivity of the cells, with the nonhomologous end-joining inhibitor SCR7 showing the strongest effect. Together, responders' BMPCs are characterized by lower efficiencies of NER and DSB/R mechanisms, resulting in higher accumulation of the extremely cytotoxic ICLs and DSBs lesions, which in turn triggers the induction of the apoptotic pathway. Moreover, the enhancement of melphalan cytotoxicity by DSB/R inhibition offers a promising strategy toward improvement of existing antimyeloma regimens.
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10
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Dolman MEM, van der Ploeg I, Koster J, Bate-Eya LT, Versteeg R, Caron HN, Molenaar JJ. DNA-Dependent Protein Kinase As Molecular Target for Radiosensitization of Neuroblastoma Cells. PLoS One 2015; 10:e0145744. [PMID: 26716839 PMCID: PMC4696738 DOI: 10.1371/journal.pone.0145744] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 12/08/2015] [Indexed: 11/18/2022] Open
Abstract
Tumor cells might resist therapy with ionizing radiation (IR) by non-homologous end-joining (NHEJ) of IR-induced double-strand breaks. One of the key players in NHEJ is DNA-dependent protein kinase (DNA-PK). The catalytic subunit of DNA-PK, i.e. DNA-PKcs, can be inhibited with the small-molecule inhibitor NU7026. In the current study, the in vitro potential of NU7026 to radiosensitize neuroblastoma cells was investigated. DNA-PKcs is encoded by the PRKDC (protein kinase, DNA-activated, catalytic polypeptide) gene. We showed that PRKDC levels were enhanced in neuroblastoma patients and correlated with a more advanced tumor stage and poor prognosis, making DNA-PKcs an interesting target for radiosensitization of neuroblastoma tumors. Optimal dose finding for combination treatment with NU7026 and IR was performed using NGP cells. One hour pre-treatment with 10 μM NU7026 synergistically sensitized NGP cells to 0.63 Gy IR. Radiosensitizing effects of NU7026 increased in time, with maximum effects observed from 96 h after IR-exposure on. Combined treatment of NGP cells with 10 μM NU7026 and 0.63 Gy IR resulted in apoptosis, while no apoptotic response was observed for either of the therapies alone. Inhibition of IR-induced DNA-PK activation by NU7026 confirmed the capability of NGP cells to, at least partially, resist IR by NHEJ. NU7026 also synergistically radiosensitized other neuroblastoma cell lines, while no synergistic effect was observed for low DNA-PKcs-expressing non-cancerous fibroblasts. Results obtained for NU7026 were confirmed by PRKDC knockdown in NGP cells. Taken together, the current study shows that DNA-PKcs is a promising target for neuroblastoma radiosensitization.
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Affiliation(s)
- M. Emmy M. Dolman
- Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
- * E-mail:
| | - Ida van der Ploeg
- Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Jan Koster
- Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Laurel Tabe Bate-Eya
- Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Rogier Versteeg
- Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Huib N. Caron
- Department of Pediatric Oncology, Emma Kinderziekenhuis, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Jan J. Molenaar
- Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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11
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Dungl DA, Maginn EN, Stronach EA. Preventing Damage Limitation: Targeting DNA-PKcs and DNA Double-Strand Break Repair Pathways for Ovarian Cancer Therapy. Front Oncol 2015. [PMID: 26579492 DOI: 10.3389/fonc.2015.00240] [] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Platinum-based chemotherapy is the cornerstone of ovarian cancer treatment, and its efficacy is dependent on the generation of DNA damage, with subsequent induction of apoptosis. Inappropriate or aberrant activation of the DNA damage response network is associated with resistance to platinum, and defects in DNA repair pathways play critical roles in determining patient response to chemotherapy. In ovarian cancer, tumor cell defects in homologous recombination - a repair pathway activated in response to double-strand DNA breaks (DSB) - are most commonly associated with platinum-sensitive disease. However, despite initial sensitivity, the emergence of resistance is frequent. Here, we review strategies for directly interfering with DNA repair pathways, with particular focus on direct inhibition of non-homologous end joining (NHEJ), another DSB repair pathway. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a core component of NHEJ and it has shown considerable promise as a chemosensitization target in numerous cancer types, including ovarian cancer where it functions to promote platinum-induced survival signaling, via AKT activation. The development of pharmacological inhibitors of DNA-PKcs is on-going, and clinic-ready agents offer real hope to patients with chemoresistant disease.
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Affiliation(s)
- Daniela A Dungl
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Elaina N Maginn
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Euan A Stronach
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
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12
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Dungl DA, Maginn EN, Stronach EA. Preventing Damage Limitation: Targeting DNA-PKcs and DNA Double-Strand Break Repair Pathways for Ovarian Cancer Therapy. Front Oncol 2015. [PMID: 26579492 DOI: 10.3389/fonc.2015.00240]+[] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Platinum-based chemotherapy is the cornerstone of ovarian cancer treatment, and its efficacy is dependent on the generation of DNA damage, with subsequent induction of apoptosis. Inappropriate or aberrant activation of the DNA damage response network is associated with resistance to platinum, and defects in DNA repair pathways play critical roles in determining patient response to chemotherapy. In ovarian cancer, tumor cell defects in homologous recombination - a repair pathway activated in response to double-strand DNA breaks (DSB) - are most commonly associated with platinum-sensitive disease. However, despite initial sensitivity, the emergence of resistance is frequent. Here, we review strategies for directly interfering with DNA repair pathways, with particular focus on direct inhibition of non-homologous end joining (NHEJ), another DSB repair pathway. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a core component of NHEJ and it has shown considerable promise as a chemosensitization target in numerous cancer types, including ovarian cancer where it functions to promote platinum-induced survival signaling, via AKT activation. The development of pharmacological inhibitors of DNA-PKcs is on-going, and clinic-ready agents offer real hope to patients with chemoresistant disease.
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Affiliation(s)
- Daniela A Dungl
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Elaina N Maginn
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Euan A Stronach
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
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13
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Dungl DA, Maginn EN, Stronach EA. Preventing Damage Limitation: Targeting DNA-PKcs and DNA Double-Strand Break Repair Pathways for Ovarian Cancer Therapy. Front Oncol 2015; 5:240. [PMID: 26579492 PMCID: PMC4620694 DOI: 10.3389/fonc.2015.00240] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/10/2015] [Indexed: 12/22/2022] Open
Abstract
Platinum-based chemotherapy is the cornerstone of ovarian cancer treatment, and its efficacy is dependent on the generation of DNA damage, with subsequent induction of apoptosis. Inappropriate or aberrant activation of the DNA damage response network is associated with resistance to platinum, and defects in DNA repair pathways play critical roles in determining patient response to chemotherapy. In ovarian cancer, tumor cell defects in homologous recombination – a repair pathway activated in response to double-strand DNA breaks (DSB) – are most commonly associated with platinum-sensitive disease. However, despite initial sensitivity, the emergence of resistance is frequent. Here, we review strategies for directly interfering with DNA repair pathways, with particular focus on direct inhibition of non-homologous end joining (NHEJ), another DSB repair pathway. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a core component of NHEJ and it has shown considerable promise as a chemosensitization target in numerous cancer types, including ovarian cancer where it functions to promote platinum-induced survival signaling, via AKT activation. The development of pharmacological inhibitors of DNA-PKcs is on-going, and clinic-ready agents offer real hope to patients with chemoresistant disease.
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Affiliation(s)
- Daniela A Dungl
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Elaina N Maginn
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Euan A Stronach
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
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14
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Tichý A, Novotná E, Ďurišová K, Šalovská B, Sedlaříková R, Pejchal J, Zárybnická L, Vávrová J, Šinkorová Z, Řezáčová M. Radio-Sensitization of Human Leukaemic MOLT-4 Cells by DNA-Dependent Protein Kinase Inhibitor, NU7026. ACTA MEDICA (HRADEC KRÁLOVÉ) 2015; 55:66-73. [DOI: 10.14712/18059694.2015.57] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In this paper we describe the influence of NU7026, a specific inhibitor of DNA-dependent protein kinase, phosphoinositide 3-kinase, and ATM-kinase on molecular and cellular mechanisms triggered by ionising irradiation in human T-lymphocyte leukaemic MOLT-4 cells. We studied the effect of this inhibitor (10 μM) combined with gammaradiation (1 Gy) leading to DNA damage response and induction of apoptosis. We used methods for apoptosis assessment (cell viability count and flow-cytometric analysis) and cell cycle analysis (DNA content measurement) and we detected expression and post-translational modifications (Western blotting) of proteins involved in DNA repair signalling pathways. Pre-treatment with NU7026 resulted into decreased activation of checkpoint kinase-2 (Thr68), p53 (Ser15and Ser392), and histone H2A.X (Ser139) 2 hours after irradiation. Subsequently, combination of radiation and inhibitor led to decreased amount of cells in G2-phase arrest and into increased apoptosis after 72 hours. Our results indicate that in leukaemic cells the pre-incubation with inhibitor NU7026 followed by low doses of ionising radiation results in radio-sensitising of MOLT-4 cells via diminished DNA repair and delayed but pronounced apoptosis. This novel approach might offer new strategies in combined treatment of leukaemia diseases.
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15
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Gruppi F, Hejazi L, Christov PP, Krishnamachari S, Turesky RJ, Rizzo CJ. Characterization of nitrogen mustard formamidopyrimidine adduct formation of bis(2-chloroethyl)ethylamine with calf thymus DNA and a human mammary cancer cell line. Chem Res Toxicol 2015; 28:1850-60. [PMID: 26285869 DOI: 10.1021/acs.chemrestox.5b00297] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A robust, quantitative ultraperformance liquid chromatography ion trap multistage scanning mass spectrometric (UPLC/MS(3)) method was established to characterize and measure five guanine adducts formed by reaction of the chemotherapeutic nitrogen mustard (NM) bis(2-chloroethyl)ethylamine with calf thymus (CT) DNA. In addition to the known N7-guanine (NM-G) adduct and its cross-link (G-NM-G), the ring-opened formamidopyrimidine (FapyG) monoadduct (NM-FapyG) and cross-links in which one (FapyG-NM-G) or both (FapyG-NM-FapyG) guanines underwent ring-opening to FapyG units were identified. Authentic standards of all adducts were synthesized and characterized by NMR and mass spectrometry. These adducts were quantified in CT DNA treated with NM (1 μM) as their deglycosylated bases. A two-stage neutral thermal hydrolysis was developed to mitigate the artifactual formation of ring-opened FapyG adducts involving hydrolysis of the cationic adduct at 37 °C, followed by hydrolysis of the FapyG adducts at 95 °C. The limit of quantification values ranged between 0.3 and 1.6 adducts per 10(7) DNA bases when the equivalent of 5 μg of DNA hydrolysate was assayed on column. The principal adduct formed was the G-NM-G cross-link, followed by the NM-G monoadduct; the FapyG-NM-G cross-link adduct; and the FapyG-NM-FapyG was below the limit of detection. The NM-FapyG adducts were formed in CT DNA at a level ∼20% that of the NM-G adduct. NM-FapyG has not been previously quanitified, and the FapyG-NM-G and FapyG-NM-FapyG adducts have not been previously characterized. Our validated analytical method was then applied to measure DNA adduct formation in the MDA-MB-231 mammary tumor cell line exposed to NM (100 μM) for 24 h. The major adduct formed was NM-G (970 adducts per 10(7) bases), followed by G-NM-G (240 adducts per 10(7) bases), NM-FapyG (180 adducts per 10(7) bases), and, last, the FapyG-NM-G cross-link adduct (6.0 adducts per 10(7) bases). These lesions are expected to contribute to NM-mediated toxicity and genotoxicity in vivo.
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Affiliation(s)
- Francesca Gruppi
- Departments of Chemistry and Biochemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Leila Hejazi
- Masonic Cancer Center and Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota , 2231 Sixth Street South East, Minneapolis, Minnesota 55455, United States
| | - Plamen P Christov
- Departments of Chemistry and Biochemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Sesha Krishnamachari
- Masonic Cancer Center and Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota , 2231 Sixth Street South East, Minneapolis, Minnesota 55455, United States
| | - Robert J Turesky
- Masonic Cancer Center and Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota , 2231 Sixth Street South East, Minneapolis, Minnesota 55455, United States
| | - Carmelo J Rizzo
- Departments of Chemistry and Biochemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville, Tennessee 37235, United States
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16
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Spryszyńska S, Smok-Pieniążek A, Ferlińska M, Roszak J, Nocuń M, Stępnik M. The influence of ATM, ATR, DNA-PK inhibitors on the cytotoxic and genotoxic effects of dibenzo[def,p]chrysene on human hepatocellular cancer cell line HepG2. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 791:12-24. [PMID: 26338538 DOI: 10.1016/j.mrgentox.2015.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/09/2015] [Accepted: 07/21/2015] [Indexed: 02/06/2023]
Abstract
The effect of inhibitors of phosphatidylinositol-3-kinase related kinases (PIKK): ataxia-telangiectasia mutated (ATM), ATM- and Rad3-related (ATR) and DNA-dependent protein kinase (DNA-PK) on the response of HepG2 human liver cancer cells to dibenzo[def,p]chrysene (DBC) was investigated. High cytotoxicity of DBC (IC50=0.1μM) was observed after 72h incubation. PIKK inhibitors: KU55933 (5μM), NU7026 (10μM) or caffeine (1 and 2mM) when used alone did not significantly influence the cytotoxicity. However, two combinations: KU55933/NU7026 and caffeine/NU7026 significantly increased HepG2 viability (by 25%) after treatment with DBC at 0.5μM. The cytoprotective effect was confirmed by cell cycle and apoptosis/necrosis analysis. DNA damage level after exposure to DBC assessed by comet assay (single strand breaks) showed a long persistence and significant decrease after incubation of the cells in the presence the inhibitors (the combination of KU55933+NU7026 showed the strongest effect). Weak induction of reactive oxygen species (ROS) by DBC (0.5μM) was observed. Although, KU55933 and NU7026 when used alone did not increase ROS levels in the cells, their combination induced the ROS increase and moderately enhanced ROS generation by DBC. We propose a mechanism how cells with damaged DNA after exposure to DBC and under the condition of PIKK inhibition, may be at higher risk of undergoing malignant transformation.
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Affiliation(s)
- Sylwia Spryszyńska
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Łódź, Poland.
| | - Anna Smok-Pieniążek
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Łódź, Poland.
| | - Magdalena Ferlińska
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Łódź, Poland.
| | - Joanna Roszak
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Łódź, Poland.
| | - Marek Nocuń
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Łódź, Poland.
| | - Maciej Stępnik
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Łódź, Poland.
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17
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Andrs M, Korabecny J, Jun D, Hodny Z, Bartek J, Kuca K. Phosphatidylinositol 3-Kinase (PI3K) and phosphatidylinositol 3-kinase-related kinase (PIKK) inhibitors: importance of the morpholine ring. J Med Chem 2014; 58:41-71. [PMID: 25387153 DOI: 10.1021/jm501026z] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Phosphatidylinositol 3-kinases (PI3Ks) and phosphatidylinositol 3-kinase-related protein kinases (PIKKs) are two related families of kinases that play key roles in regulation of cell proliferation, metabolism, migration, survival, and responses to diverse stresses including DNA damage. To design novel efficient strategies for treatment of cancer and other diseases, these kinases have been extensively studied. Despite their different nature, these two kinase families have related origin and share very similar kinase domains. Therefore, chemical inhibitors of these kinases usually carry analogous structural motifs. The most common feature of these inhibitors is a critical hydrogen bond to morpholine oxygen, initially present in the early nonspecific PI3K and PIKK inhibitor 3 (LY294002), which served as a valuable chemical tool for development of many additional PI3K and PIKK inhibitors. While several PI3K pathway inhibitors have recently shown promising clinical responses, inhibitors of the DNA damage-related PIKKs remain thus far largely in preclinical development.
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Affiliation(s)
- Martin Andrs
- Biomedical Research Center, University Hospital Hradec Kralove , Sokolska 81, 500 05 Hradec Kralove, Czech Republic
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18
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Rosen DB, Leung LY, Louie B, Cordeiro JA, Conroy A, Shapira I, Fields SZ, Cesano A, Hawtin RE. Quantitative measurement of alterations in DNA damage repair (DDR) pathways using single cell network profiling (SCNP). J Transl Med 2014; 12:184. [PMID: 24965603 PMCID: PMC4099151 DOI: 10.1186/1479-5876-12-184] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 06/18/2014] [Indexed: 01/21/2023] Open
Abstract
Background Homologous recombination repair (HRR) pathway deficiencies have significant implications for cancer predisposition and treatment strategies. Improved quantitative methods for functionally characterizing these deficiencies are required to accurately identify patients at risk of developing cancer and to identify mechanisms of drug resistance or sensitivity. Methods Flow cytometry-based single cell network profiling (SCNP) was used to measure drug-induced activation of DNA damage response (DDR) proteins in cell lines with defined HRR pathway mutations (including ATM-/-, ATM+/-, BRCA1+/-, BRCA2-/-) and in primary acute myeloid leukemia (AML) samples. Both non-homologous end joining (NHEJ) and HRR pathways were examined by measuring changes in intracellular readouts (including p-H2AX, p-ATM, p-DNA-PKcs, p-53BP1, p-RPA2/32, p-BRCA1, p-p53, and p21) in response to exposure to mechanistically distinct genotoxins. The cell cycle S/G2/M phase CyclinA2 marker was used to normalize for proliferation rates. Results Etoposide induced proliferation-independent DNA damage and activation of multiple DDR proteins in primary AML cells and ATM +/+but not ATM -/- cell lines. Treatment with the PARPi AZD2281 +/- temozolomide induced DNA damage in CyclinA2+ cells in both primary AML cells and cell lines and distngiushed cell lines deficient (BRCA2-/-) or impaired (BRCA1+/-) in HRR activity from BRCA1+/+ cell lines based on p-H2AX induction. Application of this assay to primary AML samples identified heterogeneous patterns of repair activity including muted or proficient activation of NHEJ and HRR pathways and predominant activation of NHEJ in a subset of samples. Conclusions SCNP identified functional DDR readouts in both NHEJ and HRR pathways, which can be applied to identify cells with BRCA1+/- haploinsuffiency and characterize differential DDR pathway functionality in primary clinical samples.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Rachael E Hawtin
- Research, Nodality Inc,, 170 Harbor Way, Suite 200, South San Francisco, CA 94080, USA.
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19
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Niazi MT, Mok G, Heravi M, Lee L, Vuong T, Aloyz R, Panasci L, Muanza T. Effects of dna-dependent protein kinase inhibition by NU7026 on dna repair and cell survival in irradiated gastric cancer cell line N87. ACTA ACUST UNITED AC 2014; 21:91-6. [PMID: 24764698 DOI: 10.3747/co.21.1509] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
UNLABELLED Repair of radiation-induced dna double-strand breaks is a key mechanism in cancer cell radio-resistance. The synthesized compound NU7026 specifically inhibits dna-dependent protein kinase (dna-pk) within the non-homologous end-joining repair mechanism. Earlier studies demonstrated increased radiosensitivity in dna-pk deficient cells compared with wild-type cells. In chronic leukemia cells, NU7026 appears to enhance the cytotoxic effect of chlorambucil. The radio-modifying effects of NU7026 on cell survival, cell cycle, apoptosis, and dna double-strand break repair have yet to be studied in gastric cancer cells. METHODS The gastric cancer cell line N87 was treated with 0 Gy or 4 Gy in the presence of NU7026 at a dose range of 0-20 μmol/L. Clonogenic assays were used to assess cell survival after treatment. Cell-cycle distribution was analyzed using propidium iodide with fluorescence-activated cell sorting. Apoptosis was detected using annexin-V and propidium iodide with fluorescence-activated cell sorting. The γH2AX assay was used to measure dna double-strand breaks. RESULTS Statistically significant increases in G2/M arrest were observed in N87 cells treated with radiation and NU7026 compared with those treated with radiation alone (p = 0.0004). Combined treatment also led to an increase in apoptosis (p = 0.01). At 24 hours, the γH2AX analysis revealed more dna double-strand breaks in N87 cells treated with radiation and NU7026 than in those treated with radiation alone (p = 0.04). Clonogenic assays demonstrated declining cell survival as both the radiation and the NU7026 dose increased. The dose enhancement factor at 0.1 survival fraction was 1.28 when N87 cells were treated with 4 Gy radiation and 5 μmol/L NU7026. CONCLUSIONS In gastric cancer cells, NU7026 appears to enhance the cytotoxic effect of irradiation as assessed by clonogenic assays. This increased cytotoxicity might be the result of an increase in dna double-strand breaks resulting in G2/M cell arrest and possibly higher levels of apoptosis.
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Affiliation(s)
- M T Niazi
- Segal Cancer Centre, Department of Oncology, Division of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, QC
| | - G Mok
- Department of Oncology, Division of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, QC
| | - M Heravi
- Department of Experimental Medicine, McGill University, Montreal, QC
| | - L Lee
- McGill University, Montreal, QC
| | - T Vuong
- Segal Cancer Centre, Department of Oncology, Division of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, QC
| | - R Aloyz
- Segal Cancer Centre, Lady Davis Institute of Research, Jewish General Hospital, McGill University, Montreal, QC
| | - L Panasci
- Segal Cancer Centre, Department of Oncology, Division of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, QC
| | - T Muanza
- Segal Cancer Centre, Department of Oncology, Division of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, QC
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20
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Radiosensitizing activity of a novel Benzoxazine through the promotion of apoptosis and inhibition of DNA repair. Invest New Drugs 2014; 32:424-35. [DOI: 10.1007/s10637-014-0079-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 02/24/2014] [Indexed: 12/13/2022]
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21
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Millard M, Gallagher JD, Olenyuk BZ, Neamati N. A selective mitochondrial-targeted chlorambucil with remarkable cytotoxicity in breast and pancreatic cancers. J Med Chem 2013; 56:9170-9. [PMID: 24147900 DOI: 10.1021/jm4012438] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrogen mustards, widely used as chemotherapeutics, have limited safety and efficacy. Mitochondria lack a functional nucleotide excision repair mechanism to repair DNA adducts and are sensitive to alkylating agents. Importantly, cancer cells have higher intrinsic mitochondrial membrane potential (Δψmt) than normal cells. Therefore, selectively targeting nitrogen mustards to cancer cell mitochondria based on Δψmt could overcome those limitations. Herein, we describe the design, synthesis, and evaluation of Mito-Chlor, a triphenylphosphonium derivative of the nitrogen mustard chlorambucil. We show that Mito-Chlor localizes to cancer cell mitochondria where it acts on mtDNA to arrest cell cycle and induce cell death, resulting in a 80-fold enhancement of cell kill in a panel of breast and pancreatic cancer cell lines that are insensitive to the parent drug. Significantly, Mito-Chlor delayed tumor progression in a mouse xenograft model of human pancreatic cancer. This is a first example of repurposing chlorambucil, a drug not used in breast and pancreatic cancer treatment, as a novel drug candidate for these diseases.
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Affiliation(s)
- Melissa Millard
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California , 1985 Zonal Avenue, Los Angeles, California 90089, United States
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22
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Shawi M, Chu TW, Martinez-Marignac V, Yu Y, Gryaznov SM, Johnston JB, Lees-Miller SP, Assouline SE, Autexier C, Aloyz R. Telomerase contributes to fludarabine resistance in primary human leukemic lymphocytes. PLoS One 2013; 8:e70428. [PMID: 23922990 PMCID: PMC3726637 DOI: 10.1371/journal.pone.0070428] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/17/2013] [Indexed: 12/17/2022] Open
Abstract
We report that Imetelstat, a telomerase inhibitor that binds to the RNA component of telomerase (hTR), can sensitize primary CLL lymphocytes to fludarabine in vitro. This effect was observed in lymphocytes from clinically resistant cases and with cytogenetic abnormalities associated with bad prognosis. Imetelstat mediated-sensitization to fludarabine was not associated with telomerase activity, but with the basal expression of Ku80. Since both Imetelstat and Ku80 bind hTR, we assessed 1) if Ku80 and Imetelstat alter each other's binding to hTR in vitro and 2) the effect of an oligonucleotide complementary to the Ku binding site in hTR (Ku oligo) on the survival of primary CLL lymphocytes exposed to fludarabine. We show that Imetelstat interferes with the binding of Ku70/80 (Ku) to hTR and that the Ku oligo can sensitize CLL lymphocytes to FLU. Our results suggest that Ku binding to hTR may contribute to fludarabine resistance in CLL lmphocytes. This is the first report highlighting the potentially broad effectiveness of Imetelstat in CLL, and the potential biological and clinical implications of a functional interaction between Ku and hTR in primary human cancer cells.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Catalytic Domain/drug effects
- Chromosome Deletion
- Chromosomes, Human, Pair 11
- Chromosomes, Human, Pair 17
- DNA Helicases/genetics
- DNA Helicases/metabolism
- Drug Resistance, Neoplasm/genetics
- Enzyme Activation
- Gene Expression Regulation, Leukemic/drug effects
- Histones/metabolism
- Humans
- Indoles/pharmacology
- Ku Autoantigen
- Leukemia, Lymphoid/drug therapy
- Leukemia, Lymphoid/genetics
- Leukemia, Lymphoid/metabolism
- Middle Aged
- Niacinamide/analogs & derivatives
- Niacinamide/pharmacology
- Oligonucleotides
- Phosphorylation
- Protein Binding/drug effects
- Telomerase/chemistry
- Telomerase/genetics
- Telomerase/metabolism
- Vidarabine/analogs & derivatives
- Vidarabine/pharmacology
- Vidarabine/therapeutic use
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Affiliation(s)
- May Shawi
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
- Bloomfield Centre for Research in Ageing, Jewish General Hospital, Montreal, Quebec, Canada
| | - Tsz Wai Chu
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
- Bloomfield Centre for Research in Ageing, Jewish General Hospital, Montreal, Quebec, Canada
| | - Veronica Martinez-Marignac
- Lady Davis Institute for Medical Research & Cancer Segal Center, Jewish General Hospital, Montreal, Quebec, Canada
| | - Y. Yu
- University of Calgary, Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, Calgary, Alberta, Canada
| | | | - James B. Johnston
- Manitoba Institute of Cell Biology, Cancer Care Manitoba, Winnipeg, Manitoba, Canada
| | - Susan P. Lees-Miller
- University of Calgary, Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, Calgary, Alberta, Canada
| | - Sarit E. Assouline
- Oncology Department, McGill University, Montreal, Quebec, Canada
- Lady Davis Institute for Medical Research & Cancer Segal Center, Jewish General Hospital, Montreal, Quebec, Canada
| | - Chantal Autexier
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
- Bloomfield Centre for Research in Ageing, Jewish General Hospital, Montreal, Quebec, Canada
| | - Raquel Aloyz
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
- Oncology Department, McGill University, Montreal, Quebec, Canada
- Lady Davis Institute for Medical Research & Cancer Segal Center, Jewish General Hospital, Montreal, Quebec, Canada
- * E-mail:
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23
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McLuckie KE, Di Antonio M, Zecchini H, Xian J, Caldas C, Krippendorff BF, Tannahill D, Lowe C, Balasubramanian S. G-quadruplex DNA as a molecular target for induced synthetic lethality in cancer cells. J Am Chem Soc 2013; 135:9640-3. [PMID: 23782415 PMCID: PMC3964824 DOI: 10.1021/ja404868t] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Indexed: 12/16/2022]
Abstract
Synthetic lethality is a genetic concept in which cell death is induced by the combination of mutations in two sensitive genes, while mutation of either gene alone is not sufficient to affect cell survival. Synthetic lethality can also be achieved "chemically" by combination of drug-like molecules targeting distinct but cooperative pathways. Previously, we reported that the small molecule pyridostatin (PDS) stabilizes G-quadruplexes (G4s) in cells and elicits a DNA damage response by causing the formation of DNA double strand breaks (DSB). Cell death mediated by ligand-induced G4 stabilization can be potentiated in cells deficient in DNA damage repair genes. Here, we demonstrate that PDS acts synergistically both with NU7441, an inhibitor of the DNA-PK kinase crucial for nonhomologous end joining repair of DNA DSBs, and BRCA2-deficient cells that are genetically impaired in homologous recombination-mediated DSB repair. G4 targeting ligands have potential as cancer therapeutic agents, acting synergistically with inhibition or mutation of the DNA damage repair machinery.
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Affiliation(s)
- Keith
I. E. McLuckie
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
| | - Marco Di Antonio
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
- Department of Chemistry,
University
of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
| | - Heather Zecchini
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
| | - Jian Xian
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
- Department of Oncology, University
of Cambridge, Hills Road, Cambridge, CB2 0XZ, United Kingdom
| | - Carlos Caldas
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
- Department of Oncology, University
of Cambridge, Hills Road, Cambridge, CB2 0XZ, United Kingdom
| | - Ben-Fillippo Krippendorff
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
| | - David Tannahill
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
| | - Christopher Lowe
- Department of Chemistry,
University
of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
| | - Shankar Balasubramanian
- Cancer Research UK
Cambridge
Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, United
Kingdom
- Department of Chemistry,
University
of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
- School of Clinical Medicine, University
of Cambridge, Cambridge, CB2 0SP, United Kingdom
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24
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Davidson D, Wang Y, Aloyz R, Panasci L. The PARP inhibitor ABT-888 synergizes irinotecan treatment of colon cancer cell lines. Invest New Drugs 2013; 31:461-8. [PMID: 23054213 PMCID: PMC3857790 DOI: 10.1007/s10637-012-9886-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 09/26/2012] [Indexed: 12/18/2022]
Abstract
Poly [ADP-ribose] polymerase-1 (PARP-1) localizes rapidly to sites of DNA damage and has been associated with various repair mechanisms including base excision repair (BER) and homologous recombination/non-homologous end joining (HRR/NHEJ). PARP-1 acts by adding poly-ADP ribose side chains to target proteins (PARylation) altering molecular interactions and functions. Recently small molecule inhibitors of PARP-1 have been shown to have significant clinical potential and third generation PARP inhibitors are currently being investigated in clinical trials. These drugs alone or in combination with radio/chemotherapy have resulted in meaningful patient responses and an increase in survival in metastatic breast cancer cases bearing BRCA-deficient or triple negative tumors and BRCA-deficient ovarian cancer patients. ABT-888, a potent PARP-1 inhibitor, sensitizes many cancer cells in-vitro and in-vivo to temozolomide. As such, we hypothesized that colon cancers would be sensitized to the DNA damaging chemotherapeutic agents, oxaliplatin and irinotecan, by ABT-888. Using colon cancer cell lines significant synergy was observed between ABT-888 and irinotecan at concentrations of ABT-888 as low as 0.125 μM. The level of synergy observed correlated with the degree of PARP1 inhibition as measured biochemically in cell lysates. ABT-888 at concentrations of 0.5-4 μM resulted in synergy with oxaliplatin. Furthermore, 24 h post treatment combinations of ABT-888/irinotecan generally resulted in increased G2/M cell cycle arrest and increased levels of DNA damage, followed by increased levels of apoptosis 48 h post treatment. In conclusion this study suggests that ABT-888 may be a clinically effective adjuvant to current colon cancer therapies that include the use of irinotecan and/or oxaliplatin.
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Affiliation(s)
- David Davidson
- Montreal Centre for Experimental Therapeutics in Cancer-Segal Cancer Center-Lady Davis Institute-Jewish General Hospital, McGill University, 3755, Côte Sainte Catherine Road, Montréal, Québec H3T 1E2, Canada
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25
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Amrein L, Shawi M, Grenier J, Aloyz R, Panasci L. The phosphatidylinositol-3 kinase I inhibitor BKM120 induces cell death in B-chronic lymphocytic leukemia cells in vitro. Int J Cancer 2013; 133:247-52. [PMID: 23238639 DOI: 10.1002/ijc.27989] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 11/29/2012] [Indexed: 11/12/2022]
Abstract
BKM120, a pan class I PI3K inhibitor, was cytotoxic in the majority of primary B-chronic lymphocytic leukemia (CLL) lymphocytes, including samples from patients who have a high-risk for poor response to treatment (patient with del11 and del17) at clinically obtainable concentrations. The PI3Kδ inhibitor Cal-101 is cytotoxic in B-CLL lymphocytes in vitro and is active in the treatment of CLL in vivo. Interestingly, we demonstrated that BKM120 is 3.6 fold more toxic than Cal-101 in malignant B-CLL lymphocytes in vitro. BKM120 cytotoxicity correlated with the basal expression of proteins involved in the PI3K/Akt pathway. A protein signature of PI3K pathway proteins predicts the response to BKM120 treatment. In the primary B-CLL lymphocytes tested in vitro, BKM120 decreased the phosphorylation status of molecular biomarkers used as indicators of PI3K pathway inhibition in vivo. Also, BKM120 induced apoptosis in primary B-CLL cells culture in the presence and absence of stromal cell support. Our findings suggest that BKM120 should be tested clinically in CLL.
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Affiliation(s)
- Lilian Amrein
- Department of Oncology, Faculty of Medicine, McGill University, Lady Davis Institute-Segal Cancer Center from the Jewish General Hospital, Montreal, Quebec, Canada
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Tang J, Wang JY, Parker LL. Detection of early Abl kinase activation after ionizing radiation by using a peptide biosensor. Chembiochem 2012; 13:665-73. [PMID: 22334513 PMCID: PMC3429332 DOI: 10.1002/cbic.201100763] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Indexed: 12/15/2022]
Abstract
The ubiquitously expressed Abl protein is a non-receptor tyrosine kinase that undergoes nuclear-cytoplasmic shuttling and is involved in many signaling pathways in the cell. Nuclear Abl is activated by DNA damage to regulate DNA repair, cell-cycle checkpoints and apoptosis. Previous studies have established that ataxia telangiectasia mutated (ATM) activates nuclear Abl by phosphorylating serine 465 (S465) in the kinase domain in response to ionizing radiation (IR). Using a peptide biosensor that specifically reports on the Abl kinase activity, we found that an Abl-S465A mutant, which is not capable of being activated by ATM through the canonical site, was still activated rapidly after IR. We established that DNA-dependent protein kinase (DNAPK) is likely to be responsible for a second pathway to activate Abl early on in the response to IR through phosphorylation at a site other than S465. Our findings show that nuclear and cytoplasmic Abl kinase is activated early on (within 5 min) in response to IR by both ATM and DNAPK, and that although one or the other of these kinases is required, either one is sufficient to activate Abl. These results support the concept of early Abl recruitment by both the ATM and the DNAPK pathways to regulate nuclear events triggered by DNA damage and potentially communicate them to proteins in the cytoplasm.
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Affiliation(s)
- Jiabin Tang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Center for Cancer Research, Purdue University, West Lafayette, IN 47907, Fax: (+001) 765-496-1496
| | - Jean Y. Wang
- Department of Medicine and Division of Hematology-Oncology, Moores Cancer Center, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Laurie L. Parker
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Center for Cancer Research, Purdue University, West Lafayette, IN 47907, Fax: (+001) 765-496-1496
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27
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Jowsey PA, Williams FM, Blain PG. DNA damage responses in cells exposed to sulphur mustard. Toxicol Lett 2012; 209:1-10. [DOI: 10.1016/j.toxlet.2011.11.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/26/2011] [Accepted: 11/09/2011] [Indexed: 12/25/2022]
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Aziz K, Nowsheen S, Pantelias G, Iliakis G, Gorgoulis VG, Georgakilas AG. Targeting DNA damage and repair: embracing the pharmacological era for successful cancer therapy. Pharmacol Ther 2011; 133:334-50. [PMID: 22197993 DOI: 10.1016/j.pharmthera.2011.11.010] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 12/19/2022]
Abstract
DNA is under constant assault from genotoxic agents which creates different kinds of DNA damage. The precise replication of the genome and the continuous surveillance of its integrity are critical for survival and the avoidance of carcinogenesis. Cells have evolved an arsenal of repair pathways and cell cycle checkpoints to detect and repair DNA damage. When repair fails, typically cell cycle progression is halted and apoptosis is initiated. Here, we review the different sources and types of DNA damage including DNA replication stress and oxidative stress, the repair pathways that cells utilize to repair damaged DNA, and discuss their biological significance, especially with reference to cancer induction and cancer therapy. We also describe the main methodologies currently used for the detection of DNA damage with their strengths and limitations. We conclude with an outline as to how this information can be used to identify novel pharmacological targets for DNA repair pathways or enhancers of DNA damage to develop improved treatment strategies that will benefit cancer patients.
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Affiliation(s)
- K Aziz
- Department of Radiation Oncology & Molecular Radiation Sciences, Johns Hopkins School of Medicine, Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD 21231, USA
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Guaragna A, Chiaviello A, Paolella C, D'Alonzo D, Palumbo G, Palumbo G. Synthesis and evaluation of folate-based chlorambucil delivery systems for tumor-targeted chemotherapy. Bioconjug Chem 2011; 23:84-96. [PMID: 22121907 DOI: 10.1021/bc200410d] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The development of tumor-targeting drug delivery systems, able to selectively transport cytotoxic agents into the tumor site by exploiting subtle morphological and physiological differences between healthy and malignant cells, currently stands as one of the most attractive anticancer strategies used to overcome the selectivity problems of conventional chemotherapy. Owing to frequent overexpression of folate receptors (FRs) on the surface of malignant cells, conjugation of cytotoxic agents to folic acid (FA) via suitable linkers have demonstrated to enhance selective drug delivery to the tumor site. Herein, the chemical synthesis and biological evaluation of two novel folate-conjugates bearing the anticancer agent chlorambucil (CLB) tethered to either an aminoether (4,7,10-trioxa-1,13-tridecanediamine) or a pseudo-β-dipeptide (β-Ala-ED-β-Ala) linker is reported. The two drug delivery systems have been prepared in high overall yields (54% and 34%) through straightforward and versatile synthetic routes. Evaluation of cell specificity was examined using three leukemic cell lines, undifferentiated U937 (not overexpressing FRs, FR(-)), TPA-differentiated U937 (overexpressing FRs, FR(+)), and TK6 (FR(+)) cells. Both conjugates exhibited high specificity only to FR(+) cells (particularly TK6), demonstrating comparable antitumor activity to CLB in its free form. These data confirm the reliability of folate-based drug delivery systems for targeted antitumor therapy; likewise, they lay the foundations for the development of other folate-conjugates with antitumor potential.
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Affiliation(s)
- Annalisa Guaragna
- Dipartimento di Chimica Organica e Biochimica, Università di Napoli Federico II, via Cinthia 4, Naples, Italy.
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Hanakahi L. Effect of the Inositol Polyphosphate InsP6 on DNA-PK–Dependent Phosphorylation. Mol Cancer Res 2011; 9:1366-76. [DOI: 10.1158/1541-7786.mcr-11-0230] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Effects of the novel DNA dependent protein kinase inhibitor, IC486241, on the DNA damage response to doxorubicin and cisplatin in breast cancer cells. Invest New Drugs 2011; 30:1736-42. [PMID: 21567185 DOI: 10.1007/s10637-011-9678-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 04/26/2011] [Indexed: 01/09/2023]
Abstract
The purpose of this study was to determine the degree to which the novel DNA-PKcs inhibitor, IC486241 (ICC), synergizes the cytotoxicity of DNA damaging agents in 3 genetically diverse breast cancer cell lines. The sulforhodamine B (SRB) assay was employed as a primary screening method to determine the in-vitro cytotoxicity and the degree of synergy of ICC in combination with the topoisomerase II inhibitor, doxorubicin, or the DNA cross linking agent, cisplatin. Molecular mechanisms underlying drug toxicity were probed using immunostaining and flow cytometry, as well as, the alkaline comet assay to detect DNA damage. In this study, improved cytotoxicity and significant synergy were observed with both anticancer agents in the presence of nontoxic concentrations of ICC. Moreover, ICC decreased doxorubicin-induced DNA-PKcs autophosphorylation on Ser2056 and increased doxorubicin-induced DNA fragmentation. In conclusion, the novel DNA-PKcs inhibitor, ICC, synergistically sensitized 3 breast cancer cell lines to doxorubicin and cisplatin. Enhanced efficacy of doxorubicin was achieved by inhibiting non-homologous end joining resulting in increased accumulation of DNA damage.
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Economopoulou P, Pappa V, Papageorgiou S, Dervenoulas J, Economopoulos T. Abnormalities of DNA repair mechanisms in common hematological malignancies. Leuk Lymphoma 2011; 52:567-82. [DOI: 10.3109/10428194.2010.551155] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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33
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Yan C, Lu J, Zhang G, Gan T, Zeng Q, Shao Z, Duerksen-Hughes PJ, Yang J. Benzo[a]pyrene induces complex H2AX phosphorylation patterns by multiple kinases including ATM, ATR, and DNA-PK. Toxicol In Vitro 2011; 25:91-9. [DOI: 10.1016/j.tiv.2010.09.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Revised: 09/03/2010] [Accepted: 09/24/2010] [Indexed: 10/19/2022]
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Dual inhibition of the homologous recombinational repair and the nonhomologous end-joining repair pathways in chronic lymphocytic leukemia therapy. Leuk Res 2011; 35:1080-6. [PMID: 21281966 DOI: 10.1016/j.leukres.2011.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 01/07/2011] [Accepted: 01/09/2011] [Indexed: 11/21/2022]
Abstract
Resistance to chlorambucil in chronic lymphocytic leukemia (CLL) has been associated with increased DNA repair. Specifically, inhibition of either c-abl, which modulates Rad51 directed homologous recombination or DNA-PK dependent nonhomologous end joining has been shown to sensitize primary CLL lymphocytes to chlorambucil. Here we report that inhibition of c-abl can result in a compensatory increase in DNA-PK and thus inhibition of both c-abl and DNA-PK optimally sensitizes CLL lymphocytes to chlorambucil. In this paper we report a drug-induced compensatory change between two DNA repair pathways with potential therapeutic implications in CLL therapy.
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Davidson D, Coulombe Y, Martinez-Marignac VL, Amrein L, Grenier J, Hodkinson K, Masson JY, Aloyz R, Panasci L. Irinotecan and DNA-PKcs inhibitors synergize in killing of colon cancer cells. Invest New Drugs 2011; 30:1248-56. [PMID: 21221710 DOI: 10.1007/s10637-010-9626-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 12/19/2010] [Indexed: 12/27/2022]
Abstract
This study sought to measure the degree of synergy induced by specific small molecule inhibitors of DNA-PK [NU7026 and IC486241 (ICC)], a major component of the non-homologous end-joining (NHEJ) pathway, with SN38 or oxaliplatin. Synergy between the DNA damaging drugs and the DNA-PK inhibitors was assessed using the sulforhodamine-B assay (SRB). Effects of drug combinations on cell cycle and DNA-PK activity were determined using flow cytometry and western blot analysis. DNA damage was assessed via comet assay and quantification of γH2AX. The role of homologous recombination repair (HRR) was determined by nuclear Rad51 protein levels and a GFP reporter recombination assay. Significant reductions in the IC(50) values of SN38 were observed at 5 and 10 μM of DNA-PK inhibitors. Moreover, at 1-2 μM (attainable concentrations with ICC in mice) these DNA-PKcs inhibitors demonstrated synergistic reductions in the IC(50) of SN38. Flow cytometric data indicated that SN38 and SN38 in combination with DNA-PKcs inhibitors showed dramatic G2/M arrest at 24 h. Furthermore, reduced phosphorylation of DNA-PKcs and increased DNA damage were observed at this time point with SN38 in combination with DNA-PKcs inhibitors as compared to cells treated with SN38 alone. SN38 alone and in the presence of ICC increased nuclear Rad51 protein levels. Furthermore, inhibition of DNA-PKcs increased HRR suggesting that NHEJ is a negative regulator of HRR. These data indicate that small molecule inhibitors of DNA-PKcs dramatically enhance the efficacy of SN38 in colon cancer cell lines.
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Affiliation(s)
- David Davidson
- Montreal Centre for Experimental Therapeutics in Cancer-Lady Davis Institute-Jewish General Hospital, McGill University, 3755, Côte Sainte Catherine Road, Montréal, Québec, H3T 1E2, Canada
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36
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Elliott SL, Crawford C, Mulligan E, Summerfield G, Newton P, Wallis J, Mainou-Fowler T, Evans P, Bedwell C, Durkacz BW, Willmore E. Mitoxantrone in combination with an inhibitor of DNA-dependent protein kinase: a potential therapy for high risk B-cell chronic lymphocytic leukaemia. Br J Haematol 2010; 152:61-71. [PMID: 21083655 DOI: 10.1111/j.1365-2141.2010.08425.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Defects in the DNA damage response pathway [e.g. del(17p)] are associated with drug-resistant B-cell chronic lymphocytic leukaemia (CLL). We previously demonstrated that over-expression of DNA-dependent protein kinase (DNA-PK) correlates with chemo-resistance and that inhibition of DNA-PK sensitizes CLL cells to chemotherapeutics. Here, we investigated expression of DNA-PK and other proteins that impact on drug resistance, and evaluated the effects of a DNA-PK inhibitor (NU7441) on mitoxantrone-induced cytotoxicity in CLL cells. NU7441 sensitized cells from 42/49 CLL samples to mitoxantrone, with sensitization ranging from 2- to 200-fold Co-culture of CLL cells in conditioned stromal medium increased chemoresistance but did not reduce sensitization by NU7441. Mitoxantrone treatment induced γH2AX foci and NU7441 increased their longevity (24 h). NU7441 prevented mitoxantrone-induced autophosphorylation of the DNA-PK catalytic subunit (DNA-PKcs) at Ser 2056, confirming that DNA-PK participates in repair of mitoxantrone-induced DNA damage. del(17p) cases were more resistant to mitoxantrone than del(13q) cases, but were resensitized (7-16 fold) by co-incubation with NU7441. Expression of DNA-PKcs, Ku80, P-glycoprotein and topoisomerase IIβ were significantly higher in del(17p) cases. PRKDC mRNA levels correlated with DNA-PKcs protein expression, which predicted shorter survival. These data confirm the potential of DNA-PK as a therapeutic target in poor prognosis CLL.
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Affiliation(s)
- Sarah L Elliott
- Newcastle Cancer Centre at the NorthernInstitute for Cancer Research, Medical School, Newcastle University, Newcastle upon Tyne, UK
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Amrein L, Hernandez TA, Ferrario C, Johnston J, Gibson SB, Panasci L, Aloyz R. Dasatinib sensitizes primary chronic lymphocytic leukaemia lymphocytes to chlorambucil and fludarabine in vitro. Br J Haematol 2009; 143:698-706. [PMID: 19062342 DOI: 10.1111/j.1365-2141.2008.07418.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The dual c-abl/Src kinase inhibitor, dasatinib, utilized to treat chronic myeloid leukaemia (CML) when used at clinically attainable sublethal concentrations, synergistically sensitized primary chronic lymphocytic leukaemia (CLL) lymphocytes to chlorambucil and fludarabine. In contrast, dasatinib alone demonstrated toxicity to CLL lymphocytes at concentrations that are generally not clinically attainable. Dasatinib resistance and poorer dasatinib-mediated sensitization to chlorambucil and fludarabine was associated with higher expression of c-abl protein levels. In contrast, chlorambucil and fludarabine resistance correlated with basal p53 protein levels. Moreover, Western blot analysis after in vitro treatment of primary CLL lymphocytes with dasatinib, chlorambucil and/or fludarabine, showed that dasatinib: (i) inhibited c-abl function (e.g. downregulation of c-abl protein levels and decreased the phosphorylation of a c-abl downstream target, Dok2), (ii) decreased chlorambucil/fludarabine induced accumulation of p53 protein levels, (iii) altered the response to chlorambucil/fludarabine induced DNA-damage as evidenced by an increase in chlorambucil/fludarabine-induced H2AX phosphorylation, and (iv) accentuated the c-abl downregulation induced by chlorambucil/fludarabine. Our results suggest that dasatinib in combination with chlorambucil or fludarabine may improve the therapy of CLL.
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Affiliation(s)
- Lilian Amrein
- Lady Davis Institute for Medical Research-Cancer Segal Center, Sir MB Davis-Jewish General Hospital, Montreal, Canada
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Abstract
The concept of combining targeted agents for the treatment of acute myeloid leukemia (AML) is a relatively new but potentially promising area of investigation. A number of targeted agents may have limited single-agent activity but could show significant promise when used in conjunction with other types of similar compounds. Combinations of targeted agents may effectively interrupt multiple pathways in either a linear or parallel fashion. There are currently numerous combination regimens under investigation at either the preclinical or clinical levels, including histone deacetylase (HDAC) and CDK inhibitors; HDAC and proteasome inhibitors; HDAC and NF-kappaB (IKKbeta) inhibitors; CHK1 and MEK1/2 inhibitors; and BCL-2 antagonists and CDK inhibitors. Although combinations of targeted agents will not displace conventional cytotoxic regimens in AML or related disorders in the foreseeable future, these combinations clearly warrant further attention.
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Affiliation(s)
- Steven Grant
- Virginia Commonwealth University/Massey Cancer Center, 401 College Street, PO Box 980035, Richmond, VA 23298-0035, USA.
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[First-line therapy of chronic lymphocytic leukemia in the elderly: be careful with overtreatment]. Presse Med 2008; 38:140-2. [PMID: 19004611 DOI: 10.1016/j.lpm.2008.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 09/22/2008] [Accepted: 10/06/2008] [Indexed: 11/24/2022] Open
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40
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Yang C, Betti C, Singh S, Toor A, Vaughan A. Impaired NHEJ function in multiple myeloma. Mutat Res 2008; 660:66-73. [PMID: 19028508 DOI: 10.1016/j.mrfmmm.2008.10.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 10/08/2008] [Accepted: 10/17/2008] [Indexed: 11/19/2022]
Abstract
Multiple myeloma (MM) is characterized by multiple chromosomal aberrations. To assess the contribution of DNA repair to this phenotype, ionizing radiation was used to induce DNA double strand breaks in three MM cell lines. Clonogenic survival assays showed U266 (SF4=15.3+6.4%) and RPMI 8226 (SF4=12.6.0+1.7%) were radiation sensitive while OPM2 was resistant (SF4=78.9+4.1%). Addition of the DNA-PK inhibitor NU7026 showed the expected suppression in radiation survival in OPM2 but increased survival in both radiation sensitive cell lines. To examine non-homologous end joining (NHEJ) repair in these lines, the ability of protein extracts to support in vitro DNA repair was measured. Among the three MM cell lines analyzed, RPMI 8226 demonstrated impaired blunt ended DNA ligation using a ligation-mediated PCR technique. In a bacterial based functional assay to rejoin a DNA break within the beta-galactosidase gene, RPMI 8226 demonstrated a 4-fold reduction in rejoining fidelity compared to U266, with OPM2 showing an intermediate capacity. Ionizing radiation induced a robust gamma-H2AX response in OPM2 but only a modest increase in each radiation sensitive cell line perhaps related to the high level of gamma-H2AX in freshly plated cells. Examination of gamma-H2AX foci in RPMI 8226 cells confirmed data from Western blots where a significant number of foci were present in freshly plated untreated cells which diminished over 24h of culture. Based on the clonogenic survival and functional repair assays, all three cell lines exhibited corrupt NHEJ repair. We conclude that suppression of aberrant NHEJ function using the DNA-PK inhibitor NU7026 may facilitate access of DNA ends to an intact homologous recombination repair pathway, paradoxically increasing survival after irradiation. These data provide insight into the deregulation of DNA repair at the site of DNA breaks in MM that may underpin the characteristic genomic instability of this disease.
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Affiliation(s)
- Clara Yang
- Department of Radiation Oncology, University of California, Davis, CA 95817, USA
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DNA-Dependent Protein Kinase Is a Therapeutic Target and an Indicator of Poor Prognosis in B-Cell Chronic Lymphocytic Leukemia. Clin Cancer Res 2008; 14:3984-92. [DOI: 10.1158/1078-0432.ccr-07-5158] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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The kinase inhibitor dasatinib induces apoptosis in chronic lymphocytic leukemia cells in vitro with preference for a subgroup of patients with unmutated IgVH genes. Blood 2008; 112:1443-52. [PMID: 18550857 DOI: 10.1182/blood-2007-11-123984] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Src family kinases (SFKs) were described to be overexpressed in chronic lymphocytic leukemia (CLL). We wished to examine the effects of the Src and Abl kinase inhibitor dasatinib on the intracellular signaling and survival of CLL cells. Dasa-tinib showed a dose- and time-dependent reduction of global tyrosine phosphorylation and of activating phosphotyrosine levels of SFKs. Treatment with 100 nM dasatinib led to decreased levels of the activated, phosphorylated forms of Akt, Erk1/2, and p38, and induced PARP cleavage through caspase activity. In Mec1 and JVM-3 cell lines, dasatinib increased p53 protein levels and inhibited proliferation. In freshly isolated CLL cells, dasatinib reduced the expression of Mcl-1 and Bcl-x(L). Combination of 5 microM dasatinib and fludarabine increased the apoptosis induction of each by approximately 50%. In 15 primary CLL samples, cells with unmutated immunoglobulin variable heavy chain (IgV(H)) genes were more sensitive to dasatinib than those with mutated IgV(H) genes (P = .002). In summary, dasatinib shows potent inhibitory effects on the survival of CLL cells in vitro, most prominently in samples obtained from patients with unfavorable prognostic features.
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Sampath D, Plunkett W. The role of DNA repair in chronic lymphocytic leukemia pathogenesis and chemotherapy resistance. Curr Oncol Rep 2007; 9:361-7. [PMID: 17706164 DOI: 10.1007/s11912-007-0048-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Front-line therapy for chronic lymphocytic leukemia (CLL) with alkylating agents is associated with low rates of complete remission and no improvement in overall survival. The ability of CLL cells to efficiently repair alkylator-induced damage to DNA might explain this lack of response. Novel strategies that inhibit DNA repair, such as combinations of alkylating agents, purine nucleoside analogues, and immunotherapy, have produced durable clinical and molecular remission in both untreated and relapsed CLL. This review evaluates the contribution of DNA repair processes in the development of resistance to chemotherapy and the impact of therapies that exploit the DNA repair capacity of CLL cells to therapeutic advantage.
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Affiliation(s)
- Deepa Sampath
- Department of Experimental Therapeutics, Unit 71, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
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