1
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Justice JL, Reed TJ, Phelan B, Greco TM, Hutton JE, Cristea IM. DNA-PK and ATM drive phosphorylation signatures that antagonistically regulate cytokine responses to herpesvirus infection or DNA damage. Cell Syst 2024; 15:339-361.e8. [PMID: 38593799 PMCID: PMC11098675 DOI: 10.1016/j.cels.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 01/09/2024] [Accepted: 03/15/2024] [Indexed: 04/11/2024]
Abstract
The DNA-dependent protein kinase, DNA-PK, is an essential regulator of DNA damage repair. DNA-PK-driven phosphorylation events and the activated DNA damage response (DDR) pathways are also components of antiviral intrinsic and innate immune responses. Yet, it is not clear whether and how the DNA-PK response differs between these two forms of nucleic acid stress-DNA damage and DNA virus infection. Here, we define DNA-PK substrates and the signature cellular phosphoproteome response to DNA damage or infection with the nuclear-replicating DNA herpesvirus, HSV-1. We establish that DNA-PK negatively regulates the ataxia-telangiectasia-mutated (ATM) DDR kinase during viral infection. In turn, ATM blocks the binding of DNA-PK and the nuclear DNA sensor IFI16 to viral DNA, thereby inhibiting cytokine responses. However, following DNA damage, DNA-PK enhances ATM activity, which is required for IFN-β expression. These findings demonstrate that the DDR autoregulates cytokine expression through the opposing modulation of DDR kinases.
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Affiliation(s)
- Joshua L Justice
- Department of Molecular Biology, Princeton University, Washington Road, Princeton, NJ 08544, USA
| | - Tavis J Reed
- Department of Molecular Biology, Princeton University, Washington Road, Princeton, NJ 08544, USA
| | - Brett Phelan
- Department of Molecular Biology, Princeton University, Washington Road, Princeton, NJ 08544, USA
| | - Todd M Greco
- Department of Molecular Biology, Princeton University, Washington Road, Princeton, NJ 08544, USA
| | - Josiah E Hutton
- Department of Molecular Biology, Princeton University, Washington Road, Princeton, NJ 08544, USA
| | - Ileana M Cristea
- Department of Molecular Biology, Princeton University, Washington Road, Princeton, NJ 08544, USA.
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2
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Cowell IG, Austin CA. DNA fragility at the KMT2A/ MLL locus: insights from old and new technologies. Open Biol 2023; 13:220232. [PMID: 36629017 PMCID: PMC9832561 DOI: 10.1098/rsob.220232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Mixed-Lineage Leukaemia (MLL/KMT2A) gene is frequently rearranged in childhood and adult acute leukaemia (AL) and in secondary leukaemias occurring after therapy with DNA topoisomerase targeting anti-cancer agents such as etoposide (t-AL). MLL/KMT2A chromosome translocation break sites in AL patients fall within an 8 kb breakpoint cluster region (BCR). Furthermore, MLL/KMT2A break sites in t-AL frequently occur in a much smaller region, or hotspot, towards the 3' end of the BCR, close to the intron 11/exon 12 boundary. These findings have prompted considerable effort to uncover mechanisms behind the apparent fragility of the BCR and particularly the t-AL hotspot. Recent genome-wide analyses have demonstrated etoposide-induced DNA cleavage within the BCR, and it is tempting to conclude that this cleavage explains the distribution of translocation break sites in t-AL. However, the t-AL hotspot and the centre of the observed preferential DNA cleavage are offset by over 250 nucleotides, suggesting additional factors contribute to the distribution of t-AL break sites. We review these recent genomic datasets along with older experimental results, analysis of TOP2 DNA cleavage site preferences and DNA secondary structure features that may lead to break site selection in t-AL MLL/KMT2A translocations.
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Affiliation(s)
- Ian G. Cowell
- Biosciences Institute, The Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Caroline A. Austin
- Biosciences Institute, The Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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3
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Swan RL, Cowell IG, Austin CA. Mechanisms to repair stalled Topoisomerase II-DNA covalent complexes. Mol Pharmacol 2021; 101:24-32. [PMID: 34689119 DOI: 10.1124/molpharm.121.000374] [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: 07/21/2021] [Accepted: 10/11/2021] [Indexed: 11/22/2022] Open
Abstract
DNA topoisomerases regulate the topological state of DNA, relaxing DNA supercoils and resolving catenanes and knots that result from biological processes such as transcription and replication. DNA topoisomerase II (TOP2) enzymes achieve this by binding DNA and introducing an enzyme-bridged DNA double-strand break (DSB) where each protomer of the dimeric enzyme is covalently attached to the 5' end of the cleaved DNA via an active site tyrosine phosphodiester linkage. The enzyme then passes a second DNA duplex though the DNA break, before religation and release of the enzyme. However, this activity is potentially hazardous to the cell, as failure to complete religation leads to persistent TOP2 protein-DNA covalent complexes which are cytotoxic. Indeed, this property of topoisomerase has been exploited in cancer therapy in the form of topoisomerase poisons which block the religation stage of the reaction cycle, leading to an accumulation of topoisomerase-DNA adducts. A number of parallel cellular processes have been identified that lead to removal of these covalent TOP2-DNA complexes facilitating repair of the resulting protein-free DSB by standard DNA repair pathways. These pathways presumably arose to repair spontaneous stalled or poisoned TOP2-DNA complexes, but understanding their mechanisms also has implications for cancer therapy, particularly resistance to anti-cancer TOP2 poisons and the genotoxic side effects of these drugs. Here we review recent progress in the understanding of the processing to TOP2 DNA covalent complexes., The basic components and mechanisms plus the additional layer of complexity posed by the post-translational modifications that modulate these pathways. Significance Statement Multiple pathways have been reported for removal and repair of TOP2-DNA covalent complexes to ensure the timely and efficient repair of TOP2-DNA covalent adducts to protect the genome. Post-translational modifications such as ubiquitination and SUMOylation are involved in the regulation of TOP2-DNA complex repair. Small molecule inhibitors of these post translational modifications may help to improve outcomes of TOP2 poison chemotherapy, for example by increasing TOP2 poison cytotoxicity and reducing genotoxicity, but this remains to be determined.
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Affiliation(s)
- Rebecca L Swan
- Biosciences Institute, Newcastle University, United Kingdom
| | - Ian G Cowell
- Institute for Cell and Molecular Biosciences, Newcastle University, United Kingdom
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4
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Gottardi M, Simonetti G, Sperotto A, Nappi D, Ghelli Luserna di Rorà A, Padella A, Norata M, Giannini MB, Musuraca G, Lanza F, Cerchione C, Martinelli G. Therapeutic Targeting of Acute Myeloid Leukemia by Gemtuzumab Ozogamicin. Cancers (Basel) 2021; 13:cancers13184566. [PMID: 34572794 PMCID: PMC8469571 DOI: 10.3390/cancers13184566] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 11/16/2022] Open
Abstract
Acute myeloid leukemia (AML) is a complex hematological malignancy characterized by genetic and clinical heterogeneity and high mortality. Despite the recent introduction of novel pharmaceutical agents in hemato-oncology, few advancements have been made in AML for decades. In the last years, the therapeutic options have rapidly changed, with the approval of innovative compounds that provide new opportunities, together with new challenges for clinicians: among them, on 1 September, 2017 the Food and Drug Administration granted approval for Gemtuzumab Ozogamicin (GO) in combination with daunorubicin and cytarabine for the treatment of adult patients affected by newly diagnosed CD33+ AML. Benefits of GO-based regimens were also reported in the pre- and post-transplantation settings. Moreover, several biomarkers of GO response have been suggested, including expression of CD33 and multidrug resistance genes, cytogenetic and molecular profiles, minimal residual disease and stemness signatures. Among them, elevated CD33 expression on blast cells and non-adverse cytogenetic or molecular risk represent largely validated predictors of good response.
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Affiliation(s)
- Michele Gottardi
- Onco Hematology, Department of Oncology, Veneto Institute of Oncology IOV, IRCCS, 31033 Padua, Italy
| | - Giorgia Simonetti
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
| | - Alessandra Sperotto
- Hematology and Transplant Center Unit, Dipartimento di Area Medica (DAME), Udine University Hospital, 33100 Udine, Italy
| | - Davide Nappi
- Department of Hematology and Cell Bone Marrow Transplantation (CBMT), Ospedale di Bolzano, 39100 Bolzano, Italy
| | - Andrea Ghelli Luserna di Rorà
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
| | - Antonella Padella
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
| | - Marianna Norata
- Hematology Unit, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
| | - Maria Benedetta Giannini
- Hematology Unit, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
| | - Gerardo Musuraca
- Hematology Unit, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
| | - Francesco Lanza
- Hematology Unit & Romagna Transplant Network, Ravenna Hospital, 48121 Ravenna, Italy
| | - Claudio Cerchione
- Hematology Unit, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
| | - Giovanni Martinelli
- Scientific Directorate, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", 47014 Meldola (FC), Italy
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5
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Swan RL, Cowell IG, Austin CA. A Role for VCP/p97 in the Processing of Drug-Stabilized TOP2-DNA Covalent Complexes. Mol Pharmacol 2021; 100:57-62. [PMID: 33941661 DOI: 10.1124/molpharm.121.000262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/14/2021] [Indexed: 12/19/2022] Open
Abstract
DNA topoisomerase II (TOP2) poisons induce protein-DNA crosslinks termed TOP2-DNA covalent complexes, in which TOP2 remains covalently bound to each end of an enzyme-induced double-strand DNA break (DSB) via a 5'-phosphotyrosyl bond. Repair of the enzyme-induced DSB first requires the removal of the TOP2 protein adduct, which, among other mechanisms, can be accomplished through the proteasomal degradation of TOP2. VCP/p97 is a AAA ATPase that utilizes energy from ATP hydrolysis to unfold protein substrates, which can facilitate proteasomal degradation by extracting target proteins from certain cellular structures (such as chromatin) and/or by aiding their translocation into the proteolytic core of the proteasome. In this study, we show that inhibition of VCP/p97 leads to the prolonged accumulation of etoposide-induced TOP2A and TOP2B complexes in a manner that is epistatic with the proteasomal pathway. VCP/p97 inhibition also reduces the etoposide-induced phosphorylation of histone H2A.X, indicative of fewer DSBs. This suggests that VCP/p97 is required for the proteasomal degradation of TOP2-DNA covalent complexes and is thus likely to be an important mediator of DSB repair after treatment with a TOP2 poison. SIGNIFICANCE STATEMENT: TOP2 poisons are chemotherapeutic agents used in the treatment of a range of cancers. A better understanding of how TOP2 poison-induced DNA damage is repaired could improve therapy with TOP2 poisons by increasing TOP2 poison cytotoxicity and reducing genotoxicity. The results presented herein suggest that repair of TOP2-DNA covalent complexes involves the protein segregase VCP/p97.
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Affiliation(s)
- Rebecca L Swan
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ian G Cowell
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Caroline A Austin
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
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6
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Swan RL, Poh LLK, Cowell IG, Austin CA. Small Molecule Inhibitors Confirm Ubiquitin-Dependent Removal of TOP2-DNA Covalent Complexes. Mol Pharmacol 2020; 98:222-233. [PMID: 32587095 PMCID: PMC7416847 DOI: 10.1124/mol.119.118893] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 06/09/2020] [Indexed: 12/13/2022] Open
Abstract
DNA topoisomerase II (TOP2) is required for the unwinding and decatenation of DNA through the induction of an enzyme-linked double-strand break (DSB) in one DNA molecule and passage of another intact DNA duplex through the break. Anticancer drugs targeting TOP2 (TOP2 poisons) prevent religation of the DSB and stabilize a normally transient intermediate of the TOP2 reaction mechanism called the TOP2-DNA covalent complex. Subsequently, TOP2 remains covalently bound to each end of the enzyme-bridged DSB, which cannot be repaired until TOP2 is removed from the DNA. One removal mechanism involves the proteasomal degradation of the TOP2 protein, leading to the liberation of a protein-free DSB. Proteasomal degradation is often regulated by protein ubiquitination, and here we show that inhibition of ubiquitin-activating enzymes reduces the processing of TOP2A- and TOP2B-DNA complexes. Depletion or inhibition of ubiquitin-activating enzymes indicated that ubiquitination was required for the liberation of etoposide-induced protein-free DSBs and is therefore an important layer of regulation in the repair of TOP2 poison-induced DNA damage. TOP2-DNA complexes stabilized by etoposide were shown to be conjugated to ubiquitin, and this was reduced by inhibition or depletion of ubiquitin-activating enzymes. SIGNIFICANCE STATEMENT: There is currently great clinical interest in the ubiquitin-proteasome system and ongoing development of specific inhibitors. The results in this paper show that the therapeutic cytotoxicity of DNA topoisomerase II (TOP2) poisons can be enhanced through combination therapy with ubiquitin-activating enzyme inhibitors or by specific inhibition of the BMI/RING1A ubiquitin ligase, which would lead to increased cellular accumulation or persistence of TOP2-DNA complexes.
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Affiliation(s)
- Rebecca L Swan
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Luke L K Poh
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ian G Cowell
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Caroline A Austin
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
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7
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Fenwarth L, Fournier E, Cheok M, Boyer T, Gonzales F, Castaigne S, Boissel N, Lambert J, Dombret H, Preudhomme C, Duployez N. Biomarkers of Gemtuzumab Ozogamicin Response for Acute Myeloid Leukemia Treatment. Int J Mol Sci 2020; 21:E5626. [PMID: 32781546 PMCID: PMC7460695 DOI: 10.3390/ijms21165626] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 08/03/2020] [Indexed: 11/27/2022] Open
Abstract
Gemtuzumab ozogamicin (GO, Mylotarg®) consists of a humanized CD33-targeted antibody-drug conjugated to a calicheamicin derivative. Growing evidence of GO efficacy in acute myeloid leukemia (AML), demonstrated by improved outcomes in CD33-positive AML patients across phase I to III clinical trials, led to the Food and Drug Administration (FDA) approval on 1 September 2017 in CD33-positive AML patients aged 2 years and older. Discrepancies in GO recipients outcome have raised significant efforts to characterize biomarkers predictive of GO response and have refined the subset of patients that may strongly benefit from GO. Among them, CD33 expression levels, favorable cytogenetics (t(8;21), inv(16)/t(16;16), t(15;17)) and molecular alterations, such as NPM1, FLT3-internal tandem duplications and other signaling mutations, represent well-known candidates. Additionally, in depth analyses including minimal residual disease monitoring, stemness expression (LSC17 score), mutations or single nucleotide polymorphisms in GO pathway genes (CD33, ABCB1) and molecular-derived scores, such as the recently set up CD33_PGx6_Score, represent promising markers to enhance GO response prediction and improve patient management.
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Affiliation(s)
- Laurène Fenwarth
- UMR 9020–UMR-S 1277–Canther–Cancer Heterogeneity, Plasticity and Resistance to Therapies, Institut de Recherche contre le Cancer de Lille, University Lille, CNRS, Inserm, CHU Lille, F-59000 Lille, France; (E.F.); (M.C.); (F.G.); (C.P.); (N.D.)
| | - Elise Fournier
- UMR 9020–UMR-S 1277–Canther–Cancer Heterogeneity, Plasticity and Resistance to Therapies, Institut de Recherche contre le Cancer de Lille, University Lille, CNRS, Inserm, CHU Lille, F-59000 Lille, France; (E.F.); (M.C.); (F.G.); (C.P.); (N.D.)
| | - Meyling Cheok
- UMR 9020–UMR-S 1277–Canther–Cancer Heterogeneity, Plasticity and Resistance to Therapies, Institut de Recherche contre le Cancer de Lille, University Lille, CNRS, Inserm, CHU Lille, F-59000 Lille, France; (E.F.); (M.C.); (F.G.); (C.P.); (N.D.)
| | - Thomas Boyer
- Laboratory of Hematology, CHU Amiens, F-80054 Amiens, France;
| | - Fanny Gonzales
- UMR 9020–UMR-S 1277–Canther–Cancer Heterogeneity, Plasticity and Resistance to Therapies, Institut de Recherche contre le Cancer de Lille, University Lille, CNRS, Inserm, CHU Lille, F-59000 Lille, France; (E.F.); (M.C.); (F.G.); (C.P.); (N.D.)
| | - Sylvie Castaigne
- Department of Hematology, CH Versailles, F-78157 Le Chesnay, France; (S.C.); (J.L.)
| | - Nicolas Boissel
- Adolescent and Young Adult Hematology Unit, Hôpital Saint-Louis, AP-HP, Université de Paris, F-75010 Paris, France;
| | - Juliette Lambert
- Department of Hematology, CH Versailles, F-78157 Le Chesnay, France; (S.C.); (J.L.)
| | - Hervé Dombret
- Department of Hematology, Hôpital Saint-Louis, AP-HP, Université de Paris, F-75010 Paris, France;
| | - Claude Preudhomme
- UMR 9020–UMR-S 1277–Canther–Cancer Heterogeneity, Plasticity and Resistance to Therapies, Institut de Recherche contre le Cancer de Lille, University Lille, CNRS, Inserm, CHU Lille, F-59000 Lille, France; (E.F.); (M.C.); (F.G.); (C.P.); (N.D.)
| | - Nicolas Duployez
- UMR 9020–UMR-S 1277–Canther–Cancer Heterogeneity, Plasticity and Resistance to Therapies, Institut de Recherche contre le Cancer de Lille, University Lille, CNRS, Inserm, CHU Lille, F-59000 Lille, France; (E.F.); (M.C.); (F.G.); (C.P.); (N.D.)
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8
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Sciascia N, Wu W, Zong D, Sun Y, Wong N, John S, Wangsa D, Ried T, Bunting SF, Pommier Y, Nussenzweig A. Suppressing proteasome mediated processing of topoisomerase II DNA-protein complexes preserves genome integrity. eLife 2020; 9:e53447. [PMID: 32057297 PMCID: PMC7089766 DOI: 10.7554/elife.53447] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/12/2020] [Indexed: 12/19/2022] Open
Abstract
Topoisomerase II (TOP2) relieves topological stress in DNA by introducing double-strand breaks (DSBs) via a transient, covalently linked TOP2 DNA-protein intermediate, termed TOP2 cleavage complex (TOP2cc). TOP2ccs are normally rapidly reversible, but can be stabilized by TOP2 poisons, such as the chemotherapeutic agent etoposide (ETO). TOP2 poisons have shown significant variability in their therapeutic effectiveness across different cancers for reasons that remain to be determined. One potential explanation for the differential cellular response to these drugs is in the manner by which cells process TOP2ccs. Cells are thought to remove TOP2ccs primarily by proteolytic degradation followed by DNA DSB repair. Here, we show that proteasome-mediated repair of TOP2cc is highly error-prone. Pre-treating primary splenic mouse B-cells with proteasome inhibitors prevented the proteolytic processing of trapped TOP2ccs, suppressed the DNA damage response (DDR) and completely protected cells from ETO-induced genome instability, thereby preserving cellular viability. When degradation of TOP2cc was suppressed, the TOP2 enzyme uncoupled itself from the DNA following ETO washout, in an error-free manner. This suggests a potential mechanism of developing resistance to topoisomerase poisons by ensuring rapid TOP2cc reversal.
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Affiliation(s)
- Nicholas Sciascia
- Laboratory of Genome Integrity, National Institutes of HealthBethesdaUnited States
- Institute for Biomedical Sciences, George Washington UniversityWashingtonUnited States
| | - Wei Wu
- Laboratory of Genome Integrity, National Institutes of HealthBethesdaUnited States
| | - Dali Zong
- Laboratory of Genome Integrity, National Institutes of HealthBethesdaUnited States
| | - Yilun Sun
- Developmental Therapeutics Branch, National Institutes of HealthBethesdaUnited States
| | - Nancy Wong
- Laboratory of Genome Integrity, National Institutes of HealthBethesdaUnited States
| | - Sam John
- Laboratory of Genome Integrity, National Institutes of HealthBethesdaUnited States
| | - Darawalee Wangsa
- Genetics Branch National Cancer Institute, National Institutes of HealthBethesdaUnited States
| | - Thomas Ried
- Genetics Branch National Cancer Institute, National Institutes of HealthBethesdaUnited States
| | - Samuel F Bunting
- Department of Molecular Biology and Biochemistry, Rutgers UniversityPiscatawayUnited States
| | - Yves Pommier
- Developmental Therapeutics Branch, National Institutes of HealthBethesdaUnited States
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Institutes of HealthBethesdaUnited States
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9
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Carr MI, Zimmermann A, Chiu LY, Zenke FT, Blaukat A, Vassilev LT. DNA-PK Inhibitor, M3814, as a New Combination Partner of Mylotarg in the Treatment of Acute Myeloid Leukemia. Front Oncol 2020; 10:127. [PMID: 32117773 PMCID: PMC7031257 DOI: 10.3389/fonc.2020.00127] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/24/2020] [Indexed: 02/03/2023] Open
Abstract
Despite significant advances in the treatment of acute myeloid leukemia (AML) the long-term prognosis remains relatively poor and there is an urgent need for improved therapies with increased potency and tumor selectivity. Mylotarg is the first AML-targeting drug from a new generation of antibody drug conjugate (ADC) therapies aiming at the acute leukemia cell compartment with increased specificity. This agent targets leukemia cells for apoptosis with a cytotoxic payload, calicheamicin, carried by a CD33-specific antibody. Calicheamicin induces DNA double strand breaks (DSB) which, if left unrepaired, lead to cell cycle arrest and apoptosis in cancer cells. However, repair of DSB by the non-homologous end joining pathway driven by DNA-dependent protein kinase (DNA-PK) can reduce the efficacy of calicheamicin. M3814 is a novel, potent and selective inhibitor of DNA-PK. This compound effectively blocks DSB repair, strongly potentiates the antitumor activity of ionizing radiation and DSB-inducing chemotherapeutics and is currently under clinical investigation. Suppressing DSB repair with M3814 synergistically enhanced the apoptotic activity of calicheamicin in cultured AML cells. Combination of M3814 with Mylotarg in two AML xenograft models, MV4-11 and HL-60, demonstrated increased efficacy and significantly improved survival benefit without elevated body weight loss. Our results support a new application for pharmacological DNA-PK inhibitors as enhancers of Mylotarg and a potential new combination treatment option for AML patients.
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Affiliation(s)
- Michael I. Carr
- Translational Innovation Platform Oncology, EMD Serono Research and Development Institute, Inc., Billerica, MA, United States
| | - Astrid Zimmermann
- Translational Innovation Platform Oncology, Merck KGaA, Darmstadt, Germany
| | - Li-Ya Chiu
- Translational Innovation Platform Oncology, EMD Serono Research and Development Institute, Inc., Billerica, MA, United States
| | - Frank T. Zenke
- Translational Innovation Platform Oncology, Merck KGaA, Darmstadt, Germany
| | - Andree Blaukat
- Translational Innovation Platform Oncology, Merck KGaA, Darmstadt, Germany
| | - Lyubomir T. Vassilev
- Translational Innovation Platform Oncology, EMD Serono Research and Development Institute, Inc., Billerica, MA, United States
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10
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Cowell IG, Ling EM, Swan RL, Brooks MLW, Austin CA. The Deubiquitinating Enzyme Inhibitor PR-619 is a Potent DNA Topoisomerase II Poison. Mol Pharmacol 2019; 96:562-572. [PMID: 31515282 PMCID: PMC6776009 DOI: 10.1124/mol.119.117390] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 09/06/2019] [Indexed: 12/13/2022] Open
Abstract
2,6-Diaminopyridine-3,5-bis(thiocyanate) (PR-619) is a broad-spectrum deubiquitinating enzyme (DUB) inhibitor that has been employed in cell-based studies as a tool to investigate the role of ubiquitination in various cellular processes. Here, we demonstrate that in addition to its action as a DUB inhibitor, PR-619 is a potent DNA topoisomerase II (TOP2) poison, inducing both DNA topoisomerase IIα (TOP2A) and DNA topoisomerase IIβ (TOP2B) covalent DNA complexes with similar efficiency to the archetypal TOP2 poison etoposide. However, in contrast to etoposide, which induces TOP2-DNA complexes with a pan-nuclear distribution, PR-619 treatment results in nucleolar concentration of TOP2A and TOP2B. Notably, neither the induction of TOP2-DNA covalent complexes nor their nucleolar concentration are due to TOP2 hyperubiquitination since both occur even under conditions of depleted ubiquitin. Like etoposide, since PR-619 affected TOP2 enzyme activity in in vitro enzyme assays as well as in live cells, we conclude that PR-619 interacts directly with TOP2A and TOP2B. The concentration at which PR-619 exhibits robust cellular DUB inhibitor activity (5-20 μM) is similar to the lowest concentration at which TOP2 poison activity was detected (above 20 μM), which suggests that caution should be exercised when employing this DUB inhibitor in cell-based studies.
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Affiliation(s)
- Ian G Cowell
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Elise M Ling
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Rebecca L Swan
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Matilda L W Brooks
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Caroline A Austin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
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11
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Effect of TDP2 on the Level of TOP2-DNA Complexes and SUMOylated TOP2-DNA Complexes. Int J Mol Sci 2018; 19:ijms19072056. [PMID: 30011940 PMCID: PMC6073685 DOI: 10.3390/ijms19072056] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/05/2018] [Accepted: 07/11/2018] [Indexed: 11/19/2022] Open
Abstract
DNA topoisomerase II (TOP2) activity involves a normally transient double-strand break intermediate in which the enzyme is coupled to DNA via a 5′-phosphotyrosyl bond. However, etoposide and other topoisomerase drugs poison the enzyme by stabilising this enzyme-bridged break, resulting in the accumulation of TOP2-DNA covalent complexes with cytotoxic consequences. The phosphotyrosyl diesterase TDP2 appears to be required for efficient repair of this unusual type of DNA damage and can remove 5′-tyrosine adducts from a double-stranded oligonucleotide substrate. Here, we adapt the trapped in agarose DNA immunostaining (TARDIS) assay to investigate the role of TDP2 in the removal of TOP2-DNA complexes in vitro and in cells. We report that TDP2 alone does not remove TOP2-DNA complexes from genomic DNA in vitro and that depletion of TDP2 in cells does not slow the removal of TOP2-DNA complexes. Thus, if TDP2 is involved in repairing TOP2 adducts, there must be one or more prior steps in which the protein-DNA complex is processed before TDP2 removes the remaining 5′ tyrosine DNA adducts. While this is partly achieved through the degradation of TOP2 adducts by the proteasome, a proteasome-independent mechanism has also been described involving the SUMOylation of TOP2 by the ZATT E3 SUMO ligase. The TARDIS assay was also adapted to measure the effect of TDP2 knockdown on levels of SUMOylated TOP2-DNA complexes, which together with levels of double strand breaks were unaffected in K562 cells following etoposide exposure and proteasomal inhibition.
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Tadi SK, Tellier-Lebègue C, Nemoz C, Drevet P, Audebert S, Roy S, Meek K, Charbonnier JB, Modesti M. PAXX Is an Accessory c-NHEJ Factor that Associates with Ku70 and Has Overlapping Functions with XLF. Cell Rep 2017; 17:541-555. [PMID: 27705800 DOI: 10.1016/j.celrep.2016.09.026] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 08/31/2016] [Accepted: 09/09/2016] [Indexed: 01/19/2023] Open
Abstract
In mammalian cells, classical non-homologous end joining (c-NHEJ) is critical for DNA double-strand break repair induced by ionizing radiation and during V(D)J recombination in developing B and T lymphocytes. Recently, PAXX was identified as a c-NHEJ core component. We report here that PAXX-deficient cells exhibit a cellular phenotype uncharacteristic of a deficiency in c-NHEJ core components. PAXX-deficient cells display normal sensitivity to radiomimetic drugs, are proficient in transient V(D)J recombination assays, and do not shift toward higher micro-homology usage in plasmid repair assays. Although PAXX-deficient cells lack c-NHEJ phenotypes, PAXX forms a stable ternary complex with Ku bound to DNA. Formation of this complex involves an interaction with Ku70 and requires a bare DNA extension for stability. Moreover, the relatively weak Ku-dependent stimulation of LIG4/XRCC4 activity by PAXX is unmasked by XLF ablation. Thus, PAXX plays an accessory role during c-NHEJ that is largely overlapped by XLF's function.
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Affiliation(s)
- Satish K Tadi
- Cancer Research Center of Marseille, CNRS UMR7258, INSERM U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, 13273 Marseille, France
| | - Carine Tellier-Lebègue
- Institute for Integrative Biology of the Cell (I2BC), IBITECS, CEA, CNRS, University Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Clément Nemoz
- Institute for Integrative Biology of the Cell (I2BC), IBITECS, CEA, CNRS, University Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Pascal Drevet
- Institute for Integrative Biology of the Cell (I2BC), IBITECS, CEA, CNRS, University Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Stéphane Audebert
- Cancer Research Center of Marseille, CNRS UMR7258, INSERM U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, 13273 Marseille, France
| | - Sunetra Roy
- Department of Microbiology & Molecular Genetics, and Department of Pathobiology & Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Katheryn Meek
- Department of Microbiology & Molecular Genetics, and Department of Pathobiology & Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Jean-Baptiste Charbonnier
- Institute for Integrative Biology of the Cell (I2BC), IBITECS, CEA, CNRS, University Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, INSERM U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, 13273 Marseille, France.
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Allam WR, Ashour ME, Waly AA, El-Khamisy S. Role of Protein Linked DNA Breaks in Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1007:41-58. [PMID: 28840551 DOI: 10.1007/978-3-319-60733-7_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Topoisomerases are a group of specialized enzymes that function to maintain DNA topology by introducing transient DNA breaks during transcription and replication. As a result of abortive topoisomerases activity, topoisomerases catalytic intermediates may be trapped on the DNA forming topoisomerase cleavage complexes (Topcc). Topoisomerases trapping on the DNA is the mode of action of several anticancer drugs, it lead to formation of protein linked DAN breaks (PDBs). PDBs are now considered as one of the most dangerous forms of endogenous DNA damage and a major threat to genomic stability. The repair of PDBs involves both the sensing and repair pathways. Unsuccessful repair of PDBs leads to different signs of genomic instabilities such as chromosomal rearrangements and cancer predisposition. In this chapter we will summarize the role of topoisomerases induced PDBs, identification and signaling, repair, role in transcription. We will also discuss the role of PDBs in cancer with a special focus on prostate cancer.
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Affiliation(s)
- Walaa R Allam
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt.
| | - Mohamed E Ashour
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
| | - Amr A Waly
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
| | - Sherif El-Khamisy
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt. .,Krebs Institute and Sheffield Institute for Nucleic Acids, Department of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK.
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14
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Yan H, Tammaro M, Liao S. Collision of Trapped Topoisomerase 2 with Transcription and Replication: Generation and Repair of DNA Double-Strand Breaks with 5' Adducts. Genes (Basel) 2016; 7:genes7070032. [PMID: 27376333 PMCID: PMC4962002 DOI: 10.3390/genes7070032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/17/2016] [Accepted: 06/24/2016] [Indexed: 11/23/2022] Open
Abstract
Topoisomerase 2 (Top2) is an essential enzyme responsible for manipulating DNA topology during replication, transcription, chromosome organization and chromosome segregation. It acts by nicking both strands of DNA and then passes another DNA molecule through the break. The 5′ end of each nick is covalently linked to the tyrosine in the active center of each of the two subunits of Top2 (Top2cc). In this configuration, the two sides of the nicked DNA are held together by the strong protein-protein interactions between the two subunits of Top2, allowing the nicks to be faithfully resealed in situ. Top2ccs are normally transient, but can be trapped by cancer drugs, such as etoposide, and subsequently processed into DSBs in cells. If not properly repaired, these DSBs would lead to genome instability and cell death. Here, I review the current understanding of the mechanisms by which DSBs are induced by etoposide, the unique features of such DSBs and how they are repaired. Implications for the improvement of cancer therapy will be discussed.
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Affiliation(s)
- Hong Yan
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA.
| | - Margaret Tammaro
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA.
| | - Shuren Liao
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA.
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15
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Lyckesvärd MN, Kapoor N, Ingeson-Carlsson C, Carlsson T, Karlsson JO, Postgård P, Himmelman J, Forssell-Aronsson E, Hammarsten O, Nilsson M. Linking loss of sodium-iodide symporter expression to DNA damage. Exp Cell Res 2016; 344:120-131. [PMID: 27108928 DOI: 10.1016/j.yexcr.2016.04.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/18/2016] [Accepted: 04/20/2016] [Indexed: 12/11/2022]
Abstract
Radiotherapy of thyroid cancer with I-131 is abrogated by inherent loss of radioiodine uptake due to loss of sodium iodide symporter (NIS) expression in poorly differentiated tumor cells. It is also known that ionizing radiation per se down-regulates NIS (the stunning effect), but the mechanism is unknown. Here we investigated whether loss of NIS-mediated iodide transport may be elicited by DNA damage. Calicheamicin, a fungal toxin that specifically cleaves double-stranded DNA, induced a full scale DNA damage response mediated by the ataxia-telangiectasia mutated (ATM) kinase in quiescent normal thyrocytes. At sublethal concentrations (<1nM) calicheamicin blocked NIS mRNA expression and transepithelial iodide transport as stimulated by thyrotropin; loss of function occurred at a much faster rate than after I-131 irradiation. KU-55933, a selective ATM kinase inhibitor, partly rescued NIS expression and iodide transport in DNA-damaged cells. Prolonged ATM inhibition in healthy cells also repressed NIS-mediated iodide transport. ATM-dependent loss of iodide transport was counteracted by IGF-1. Together, these findings indicate that NIS, the major iodide transporter of the thyroid gland, is susceptible to DNA damage involving ATM-mediated mechanisms. This uncovers novel means of poor radioiodine uptake in thyroid cells subjected to extrinsic or intrinsic genotoxic stress.
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Affiliation(s)
- Madeleine Nordén Lyckesvärd
- Sahlgrenska Cancer Center, University of Gothenburg, Göteborg, Sweden; Department of Medical Chemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden
| | - Nirmal Kapoor
- Department of Medical Chemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden
| | - Camilla Ingeson-Carlsson
- Sahlgrenska Cancer Center, University of Gothenburg, Göteborg, Sweden; Department of Medical Chemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden
| | - Therese Carlsson
- Sahlgrenska Cancer Center, University of Gothenburg, Göteborg, Sweden; Department of Medical Chemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden
| | - Jan-Olof Karlsson
- Department of Medical Chemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden
| | - Per Postgård
- Department of Radiation Physics, University of Gothenburg, Göteborg, Sweden
| | - Jakob Himmelman
- Department of Radiation Physics, University of Gothenburg, Göteborg, Sweden
| | | | - Ola Hammarsten
- Department of Clinical Chemistry, University of Gothenburg, Göteborg, Sweden
| | - Mikael Nilsson
- Sahlgrenska Cancer Center, University of Gothenburg, Göteborg, Sweden; Department of Medical Chemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden.
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16
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Lee KC, Bramley RL, Cowell IG, Jackson GH, Austin CA. Proteasomal inhibition potentiates drugs targeting DNA topoisomerase II. Biochem Pharmacol 2016; 103:29-39. [PMID: 26794000 PMCID: PMC5071433 DOI: 10.1016/j.bcp.2015.12.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 12/22/2015] [Indexed: 01/15/2023]
Abstract
The reaction mechanism of DNA topoisomerase II (TOP2) involves a covalent double-strand break intermediate in which the enzyme is coupled to DNA via a 5′-phosphotyrosyl bond. This normally transient enzyme-bridged break is stabilised by drugs such as mitoxantrone, mAMSA, etoposide, doxorubicin, epirubicin and idarubicin, which are referred to as TOP2 poisons. Removal of topoisomerase II by the proteasome is involved in the repair of these lesions. In K562 cells, inhibiting the proteasome with MG132 significantly potentiated the growth inhibition by these six drugs that target topoisomerase II, and the highest level of potentiation was observed with mitoxantrone. Mitoxantrone also showed the greatest potentiation by MG132 in three Nalm 6 cell lines with differing levels of TOP2A or TOP2B. Mitoxantrone was also potentiated by the clinically used proteasome inhibitor PS341 (Velcade). We have also shown that proteasome inhibition with MG132 in K562 cells reduces the rate of removal of mitoxantrone or etoposide stabilised topoisomerase complexes from DNA, suggesting a possible mechanism for the potentiation of topoisomerase II drugs by proteasomal inhibition.
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Affiliation(s)
- Ka C Lee
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Rebecca L Bramley
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Ian G Cowell
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Graham H Jackson
- Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Caroline A Austin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom.
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17
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Abstract
Abnormal cytoplasmic accumulation of Fused in Sarcoma (FUS) in neurons defines subtypes of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). FUS is a member of the FET protein family that includes Ewing's sarcoma (EWS) and TATA-binding protein-associated factor 2N (TAF15). FET proteins are predominantly localized to the nucleus, where they bind RNA and DNA to modulate transcription, mRNA splicing, and DNA repair. In ALS cases with FUS inclusions (ALS-FUS), mutations in the FUS gene cause disease, whereas FTLD cases with FUS inclusions (FTLD-FUS) do not harbor FUS mutations. Notably, in FTLD-FUS, all FET proteins accumulate with their nuclear import receptor Transportin 1 (TRN1), in contrast ALS-FUS inclusions are exclusively positive for FUS. In the present study, we show that induction of DNA damage replicates several pathologic hallmarks of FTLD-FUS in immortalized human cells and primary human neurons and astrocytes. Treatment with the antibiotic calicheamicin γ1, which causes DNA double-strand breaks, leads to the cytoplasmic accumulation of FUS, TAF15, EWS, and TRN1. Moreover, cytoplasmic translocation of FUS is mediated by phosphorylation of its N terminus by the DNA-dependent protein kinase. Finally, we observed elevated levels of phospho-H2AX in FTLD-FUS brains, indicating that DNA damage occurs in patients. Together, our data reveal a novel regulatory mechanism for FUS localization in cells and suggest that DNA damage may contribute to the accumulation of FET proteins observed in human FTLD-FUS cases, but not in ALS-FUS.
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Cowan AJ, Laszlo GS, Estey EH, Walter RB. Antibody-based therapy of acute myeloid leukemia with gemtuzumab ozogamicin. Front Biosci (Landmark Ed) 2013; 18:1311-34. [PMID: 23747885 DOI: 10.2741/4181] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Antibodies have created high expectations for effective yet tolerated therapeutics in acute myeloid leukemia (AML). Hitherto the most exploited target is CD33, a myeloid differentiation antigen found on AML blasts in most patients and, perhaps, leukemic stem cells in some. Treatment efforts have focused on conjugated antibodies, particularly gemtuzumab ozogamicin (GO), an anti-CD33 antibody carrying a toxic calicheamicin-g 1 derivative that, after intracellular hydrolytic release, induces DNA strand breaks, apoptosis, and cell death. Serving as paradigm for this strategy, GO was the first anti-cancer immunoconjugate to obtain regulatory approval in the U.S. While efficacious as monotherapy in acute promyelocytic leukemia (APL), GO alone induces remissions in less than 25-35% of non-APL AML patients. However, emerging data from well controlled trials now indicate that GO improves survival for many non-APL AML patients, supporting the conclusion that CD33 is a clinically relevant target for some disease subsets. It is thus unfortunate that GO has become unavailable in many parts of the world, and the drug's usefulness should be reconsidered and selected patients granted access to this immunoconjugate.
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Affiliation(s)
- Andrew J Cowan
- Hematology/Oncology Fellowship Program, University of Washington, Seattle, WA, USA
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19
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Liu S, Opiyo SO, Manthey K, Glanzer JG, Ashley AK, Amerin C, Troksa K, Shrivastav M, Nickoloff JA, Oakley GG. Distinct roles for DNA-PK, ATM and ATR in RPA phosphorylation and checkpoint activation in response to replication stress. Nucleic Acids Res 2012; 40:10780-94. [PMID: 22977173 PMCID: PMC3510507 DOI: 10.1093/nar/gks849] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
DNA damage encountered by DNA replication forks poses risks of genome destabilization, a
precursor to carcinogenesis. Damage checkpoint systems cause cell cycle arrest, promote
repair and induce programed cell death when damage is severe. Checkpoints are critical
parts of the DNA damage response network that act to suppress cancer. DNA damage and
perturbation of replication machinery causes replication stress, characterized by
accumulation of single-stranded DNA bound by replication protein A (RPA), which triggers
activation of ataxia telangiectasia and Rad3 related (ATR) and phosphorylation of the
RPA32, subunit of RPA, leading to Chk1 activation and arrest. DNA-dependent protein kinase
catalytic subunit (DNA-PKcs) [a kinase related to ataxia telangiectasia mutated (ATM) and
ATR] has well characterized roles in DNA double-strand break repair, but poorly understood
roles in replication stress-induced RPA phosphorylation. We show that DNA-PKcs mutant
cells fail to arrest replication following stress, and mutations in RPA32 phosphorylation
sites targeted by DNA-PKcs increase the proportion of cells in mitosis, impair ATR
signaling to Chk1 and confer a G2/M arrest defect. Inhibition of ATR and DNA-PK (but not
ATM), mimic the defects observed in cells expressing mutant RPA32. Cells expressing mutant
RPA32 or DNA-PKcs show sustained H2AX phosphorylation in response to replication stress
that persists in cells entering mitosis, indicating inappropriate mitotic entry with
unrepaired damage.
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Affiliation(s)
- Shengqin Liu
- Department of Oral Biology, University of Nebraska Medical Center, Omaha, NE 68583, USA
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20
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Lee KC, Padget K, Curtis H, Cowell IG, Moiani D, Sondka Z, Morris NJ, Jackson GH, Cockell SJ, Tainer JA, Austin CA. MRE11 facilitates the removal of human topoisomerase II complexes from genomic DNA. Biol Open 2012; 1:863-73. [PMID: 23213480 PMCID: PMC3507232 DOI: 10.1242/bio.20121834] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 06/13/2012] [Indexed: 11/27/2022] Open
Abstract
Topoisomerase II creates a double-strand break intermediate with topoisomerase covalently coupled to the DNA via a 5′-phosphotyrosyl bond. These intermediate complexes can become cytotoxic protein-DNA adducts and DSB repair at these lesions requires removal of topoisomerase II. To analyse removal of topoisomerase II from genomic DNA we adapted the trapped in agarose DNA immunostaining assay. Recombinant MRE11 from 2 sources removed topoisomerase IIα from genomic DNA in vitro, as did MRE11 immunoprecipitates isolated from A-TLD or K562 cells. Basal topoisomerase II complex levels were very high in A-TLD cells lacking full-length wild type MRE11, suggesting that MRE11 facilitates the processing of topoisomerase complexes that arise as part of normal cellular metabolism. In K562 cells inhibition of MRE11, PARP or replication increased topoisomerase IIα and β complex levels formed in the absence of an anti-topoisomerase II drug.
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Affiliation(s)
- Ka Cheong Lee
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University , Newcastle upon Tyne NE2 4HH , UK
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21
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Bajinskis A, Olsson G, Harms-Ringdahl M. The indirect effect of radiation reduces the repair fidelity of NHEJ as verified in repair deficient CHO cell lines exposed to different radiation qualities and potassium bromate. Mutat Res 2011; 731:125-32. [PMID: 22207102 DOI: 10.1016/j.mrfmmm.2011.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 12/02/2011] [Accepted: 12/13/2011] [Indexed: 10/14/2022]
Abstract
The complexity of DNA lesions induced by ionizing radiation is mainly dependent on radiation quality, where the indirect action of radiation may contribute to different extent depending on the type of radiation under study. The effect of indirect action of radiation can be investigated by using agents that induce oxidative DNA damage or by applying free radical scavengers. The aim of this study was to investigate the role of the indirect effect of radiation for the repair fidelity of non-homologous end-joining (NHEJ), homologous recombination repair (HRR) and base excision repair (BER) when DNA damage of different complexity was induced by gamma radiation, alpha particles or from base damages (8-oxo-dG) induced by potassium bromate (KBrO(3)). CHO cells lines deficient in XRCC3 (HRR) irs1SF, XRCC7 (NHEJ) V3-3 and XRCC1 (BER) EM9 were irradiated in the absence or presence of the free radical scavenger dimethyl sulfoxide (DMSO). The endpoints investigated included rate of cell proliferation by the DRAG assay, clonogenic cell survival and the level of primary DNA damage by the comet assay. The results revealed that the indirect effect of low-LET radiation significantly reduced the repair fidelity of both NHEJ and HRR pathways. For high-LET radiation the indirect effect of radiation also significantly reduced the repair fidelity for the repair deficient cell lines. The results suggest further that the repair fidelity of the error prone NHEJ repair pathway is more impaired by the indirect effect of high-LET radiation relative to the other repair pathways studied. The response to bromate observed for the two DSB repair deficient cell lines strongly support earlier studies that bromate induces complex DNA damages. The significantly reduced repair fidelity of irs1SF and V3-3 suggests that NHEJ as well as HRR are needed for the repair, and that complex DSBs are formed after bromate exposure.
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Affiliation(s)
- Ainars Bajinskis
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
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Schonn I, Hennesen J, Dartsch DC. Ku70 and Rad51 vary in their importance for the repair of doxorubicin- versus etoposide-induced DNA damage. Apoptosis 2011; 16:359-69. [PMID: 21107697 DOI: 10.1007/s10495-010-0564-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
For DNA targeting anticancer drugs, cellular DNA repair mechanisms may cause resistance and hamper the therapeutic outcome. DNA damage induced by topoisomerase IIα inhibitors like etoposide and anthracyclines, which are a mainstay of cancer therapy, is also repaired in many cell types, but the impact and precise mechanisms of this repair are still obscure. To investigate the DNA damage response of human adenocarcinoma HT29-cells to doxorubicin and to compare the involvement of Ku70 and Rad51 in the repair of doxorubicin- versus etoposide-induced DNA damage, we assessed cell cycle distribution and cell death, DNA damage, proteins relevant for repair by homologous recombination and non-homologous end-joining, and clonogenicity following exposure to doxorubicin at clinically achievable concentrations. Also, we assessed changes in the repair kinetics after siRNA-mediated attenuation of Ku70 or Rad51 expression. We found that exposure to doxorubicin for 24 h induced a substantial amount of DNA damage that was largely repaired when doxorubicin was removed and the cells were maintained in drug-free medium. Nevertheless, a pronounced G(2)/M arrest occurred at times when repair was maximal. This was followed by a distinct increase in cell death and loss of clonogenicity. In this regard, responses to doxorubicin and etoposide were similar. However, distinct differences in the repair process following doxorubicin versus etoposide were seen in concentration dependency, time-course and requirement of Ku70 and Rad51 proteins. In spite of the shared molecular target of doxorubicin and etoposide, DNA lesions induced by these compounds are repaired differently.
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Affiliation(s)
- Ilona Schonn
- Clinical Pharmacy, Institute of Pharmacy, Hamburg University, Bundesstrasse 45, Hamburg, Germany.
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23
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Peddi P, Loftin CW, Dickey JS, Hair JM, Burns KJ, Aziz K, Francisco DC, Panayiotidis MI, Sedelnikova OA, Bonner WM, Winters TA, Georgakilas AG. DNA-PKcs deficiency leads to persistence of oxidatively induced clustered DNA lesions in human tumor cells. Free Radic Biol Med 2010; 48:1435-43. [PMID: 20193758 PMCID: PMC2901171 DOI: 10.1016/j.freeradbiomed.2010.02.033] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/22/2010] [Accepted: 02/23/2010] [Indexed: 02/07/2023]
Abstract
DNA-dependent protein kinase (DNA-PK) is a key non-homologous-end-joining (NHEJ) nuclear serine/threonine protein kinase involved in various DNA metabolic and damage signaling pathways contributing to the maintenance of genomic stability and prevention of cancer. To examine the role of DNA-PK in processing of non-DSB clustered DNA damage, we have used three models of DNA-PK deficiency, i.e., chemical inactivation of its kinase activity by the novel inhibitors IC86621 and NU7026, knockdown and complete absence of the protein in human breast cancer (MCF-7) and glioblastoma cell lines (MO59-J/K). A compromised DNA-PK repair pathway led to the accumulation of clustered DNA lesions induced by gamma-rays. Tumor cells lacking protein expression or with inhibited kinase activity showed a marked decrease in their ability to process oxidatively induced non-DSB clustered DNA lesions measured using a modified version of pulsed-field gel electrophoresis or single-cell gel electrophoresis (comet assay). In all cases, DNA-PK inactivation led to a higher level of lesion persistence even after 24-72h of repair. We suggest a model in which DNA-PK deficiency affects the processing of these clusters first by compromising base excision repair and second by the presence of catalytically inactive DNA-PK inhibiting the efficient processing of these lesions owing to the failure of DNA-PK to disassociate from the DNA ends. The information rendered will be important for understanding not only cancer etiology in the presence of an NHEJ deficiency but also cancer treatments based on the induction of oxidative stress and inhibition of cluster repair.
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Affiliation(s)
- Prakash Peddi
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
| | - Charles W. Loftin
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
| | - Jennifer S. Dickey
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20895, USA
| | - Jessica M. Hair
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
| | - Kara J. Burns
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
| | - Khaled Aziz
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
| | - Dave C. Francisco
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
| | - Mihalis I. Panayiotidis
- Department of Pathology, Medical School, University of Ioannina, University Campus, 45110, Ioannina, Greece
| | - Olga A. Sedelnikova
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20895, USA
| | - William M. Bonner
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20895, USA
| | - Thomas A. Winters
- Nuclear Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alexandros G. Georgakilas
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
- Corresponding author: Alexandros G. Georgakilas, Address: Biology Department, Thomas Harriot College of Arts and Sciences, Howell Science Complex N418, East Carolina University, Greenville, NC 27858. Tel: 252-328-5446, Fax: 252-328-4178,
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24
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Muslimović A, Nyström S, Gao Y, Hammarsten O. Numerical analysis of etoposide induced DNA breaks. PLoS One 2009; 4:e5859. [PMID: 19516899 PMCID: PMC2689654 DOI: 10.1371/journal.pone.0005859] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 04/27/2009] [Indexed: 11/18/2022] Open
Abstract
Background Etoposide is a cancer drug that induces strand breaks in cellular DNA by inhibiting topoisomerase II (topoII) religation of cleaved DNA molecules. Although DNA cleavage by topoisomerase II always produces topoisomerase II-linked DNA double-strand breaks (DSBs), the action of etoposide also results in single-strand breaks (SSBs), since religation of the two strands are independently inhibited by etoposide. In addition, recent studies indicate that topoisomerase II-linked DSBs remain undetected unless topoisomerase II is removed to produce free DSBs. Methodology/Principal Findings To examine etoposide-induced DNA damage in more detail we compared the relative amount of SSBs and DSBs, survival and H2AX phosphorylation in cells treated with etoposide or calicheamicin, a drug that produces free DSBs and SSBs. With this combination of methods we found that only 3% of the DNA strand breaks induced by etoposide were DSBs. By comparing the level of DSBs, H2AX phosphorylation and toxicity induced by etoposide and calicheamicin, we found that only 10% of etoposide-induced DSBs resulted in histone H2AX phosphorylation and toxicity. There was a close match between toxicity and histone H2AX phosphorylation for calicheamicin and etoposide suggesting that the few etoposide-induced DSBs that activated H2AX phosphorylation were responsible for toxicity. Conclusions/Significance These results show that only 0.3% of all strand breaks produced by etoposide activate H2AX phosphorylation and suggests that over 99% of the etoposide induced DNA damage does not contribute to its toxicity.
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Affiliation(s)
- Aida Muslimović
- Institute of Biomedicine, Department of Clinical Chemistry and Transfusion Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Susanne Nyström
- Institute of Biomedicine, Department of Clinical Chemistry and Transfusion Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Yue Gao
- Institute of Biomedicine, Department of Clinical Chemistry and Transfusion Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Ola Hammarsten
- Institute of Biomedicine, Department of Clinical Chemistry and Transfusion Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- * E-mail:
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25
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Haag P, Viktorsson K, Lindberg ML, Kanter L, Lewensohn R, Stenke L. Deficient activation of Bak and Bax confers resistance to gemtuzumab ozogamicin-induced apoptotic cell death in AML. Exp Hematol 2009; 37:755-66. [DOI: 10.1016/j.exphem.2009.03.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 02/25/2009] [Accepted: 03/02/2009] [Indexed: 11/27/2022]
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26
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Abstract
Cells, which lacked the activity of the nuclease Artemis, retained approximately 10% of unrepaired double strand breaks (DSBs) at later timepoints after ionizing radiation. Ionizing radiation induced hyperphosphorylation of Artemis mainly by ATM and in ATM deficient cells to a minor extent by DNA PK. After induction of DSBs with modified ends by a high dose of calicheamicin gamma1, Artemis was phosphorylated by DNA PK. The type of calicheamicin gamma1-induced DSBs is likely to represent a subclass of DSBs induced by ionizing radiation. DNA PK-dependent phosphorylation of Artemis after treatment with DSB inducing agents increased the cellular retention of Artemis, maintained its interaction with DNA ends and activated its endonucleolytic activity. The following model is suggested: ATM-dependent phosphorylation of Artemis after ionizing radiation could prevent DNA PK-dependent phosphorylation and activation of undesired endonucleolytic activity at DSBs, which do not require endonucleolytic processing by Artemis. The Artemis:DNA PK complex could be involved in the repair of DSBs, which carry modified ends and are refractory to repair by otherwise lesion specific enzymes because of the presence of an inhibitory lesion in the opposite strand.
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Affiliation(s)
- Kirsten Dahm
- Genome Damage and Stability Centre, University of Sussex, BN1 9RQ, Brighton, UK.
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27
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Yu J, Palmer C, Alenghat T, Li Y, Kao G, Lazar MA. The corepressor silencing mediator for retinoid and thyroid hormone receptor facilitates cellular recovery from DNA double-strand breaks. Cancer Res 2006; 66:9316-22. [PMID: 16982777 DOI: 10.1158/0008-5472.can-06-1902] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cells are frequently challenged by DNA double-strand breaks (DSB) that threaten their normal function and survival. In mammalian cells, the repair of DSBs is predominantly mediated by the DNA-dependent protein kinase (DNA-PK) complex. We unexpectedly found that the corepressor silencing mediator for retinoid and thyroid hormone receptor (SMRT) associates with the DNA-PK repair complex. The SMRT/histone deacetylase 3 complex is required for the transcriptional repressive property of the Ku70 subunit of the repair complex. Moreover, SMRT, but not the related Nuclear Receptor Corepressor, is required for cellular recovery from DNA DSBs induced by ionizing radiation or DNA damage-inducing drugs. Thus, the corepressor SMRT plays a novel and critical role in the cellular response to DSBs.
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Affiliation(s)
- Jiujiu Yu
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6149, USA
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28
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Cole KD, Gaigalas A, Akerman B. Single-molecule measurements of trapped and migrating circular DNA during electrophoresis in agarose gels. Electrophoresis 2006; 27:4396-407. [PMID: 17117465 DOI: 10.1002/elps.200600347] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effect of agarose gel concentration and field strength on the electrophoretic trapping of open (relaxed) circular DNA was investigated using microscopic measurements of individual molecules stained with a fluorescent dye. Three open circles with sizes of 52.5, 115, and 220 kbp were trapped by the electric field (6 V/cm) and found to be predominately fixed and stretched at a single point in the gel. The length of the stretched circles did not significantly change with agarose concentration of the gels (mass fractions of 0.0025, 0.01, and 0.02). The relaxation kinetics of the trapped circles was also measured in the gels. The relaxation of the large open circles was found to be a slow process, taking several seconds. The velocity and average length of the 52.5 kbp open circles and 48.5 kbp linear DNA were measured during electrophoresis in the agarose gels. The velocity increased when the agarose concentrations were lowered, but the average length of the open-circle DNA (during electrophoresis) did not significantly change with agarose gel concentrations. The circles move through the gels by cycles of stretching and relaxation during electrophoresis. Linear dichroism was also used to investigate the trapping and alignment of the 52.5 kbp open circles. The results in this study provide information that can be used to improve electrophoretic separations of circular DNA, an important form of genetic material and commonly used to clone DNA.
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Affiliation(s)
- Kenneth D Cole
- National Institute of Standards and Technology, Gaithersburg, MD, USA.
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29
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Sung PA, Libura J, Richardson C. Etoposide and illegitimate DNA double-strand break repair in the generation of MLL translocations: new insights and new questions. DNA Repair (Amst) 2006; 5:1109-18. [PMID: 16809075 DOI: 10.1016/j.dnarep.2006.05.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Faithful repair of chromosomal double-strand breaks (DSBs) is central to genome integrity and the suppression of genome rearrangements including translocations that are a hallmark of leukemia, lymphoma, and soft-tissue sarcomas [B. Elliott, M. Jasin, Double-strand breaks and translocations in cancer, Cell. Mol. Life Sci. 59 (2002) 373-385; D.C. van Gent, J.H. Hoeijmakers, R. Kanaar, Chromosomal stability and the DNA double-stranded break connection, Nat. Rev. Genet. 2 (2001) 196-206]. Chemotherapy agents that target the essential cellular enzyme topoisomerase II (topo II) are known promoters of DSBs and are associated with therapy-related leukemias. There is a clear clinical association between previous exposure to etoposide and therapy-related acute myeloid leukemia (t-AML) characterized by chromosomal rearrangements involving the mixed lineage leukemia (MLL) gene on chromosome band 11q23 [C.A. Felix, Leukemias related to treatment with DNA topoisomerase II inhibitors, Med. Pediatr. Oncol. 36 (2001) 525-535]. Most MLL rearrangements initiate within a well-characterized 8.3 kb region that contains both putative topo II cleavage recognition sequences and repetitive elements leading to the logical hypothesis that MLL is particularly susceptible to aberrant cleavage and homology-mediated fusion to repetitive elements located on novel chromosome partners. In this review, we will discuss the findings and implications of recent attempts to confirm this hypothesis.
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Affiliation(s)
- P A Sung
- Institute for Cancer Genetics, Department of Pathology, Columbia University, New York, NY 10032, USA
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30
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Lu HR, Zhu H, Huang M, Chen Y, Cai YJ, Miao ZH, Zhang JS, Ding J. Reactive Oxygen Species Elicit Apoptosis by Concurrently Disrupting Topoisomerase II and DNA-Dependent Protein Kinase. Mol Pharmacol 2005; 68:983-94. [PMID: 16024664 DOI: 10.1124/mol.105.011544] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Reactive oxygen species (ROS) are produced by all aerobic cells and have been implicated in the regulation of diverse cellular functions, including intracellular signaling, transcription activation, proliferation, and apoptosis. Salvicine, a novel diterpenoid quinone compound, demonstrates a broad spectrum of antitumor activities. Although salvicine is known to trap the DNA-topoisomerase II (Topo II) complex and induce DNA double-strand breaks (DSBs), its precise antitumor mechanisms remain to be clarified. In this study, we investigated whether salvicine altered the levels of ROS in breast cancer MCF-7 cells and whether these ROS contributed to the observed antitumoral activity. Our data revealed that salvicine stimulated intracellular ROS production and subsequently elicited notable DSBs. The addition of N-acetyl cysteine (NAC), an antioxidant, effectively attenuated the salvicine-induced ROS enhancement and subsequent DNA DSBs. Heat treatment reversed the accumulation of DNA DSBs, and the addition of NAC attenuated the Topo II-DNA cleavable complexes formation and the growth inhibition of salvicine-treated JN394top2-4 yeast cells, collectively indicating that Topo II is a target of the salvicine-induced ROS. On the other hand, when examining the impact of salvicine on DNA repair pathways, we unexpectedly observed that salvicine selectively down-regulated the catalytic subunit of DNA-dependent protein kinase (DNA-PK(CS)) protein levels and repressed DNA-PK kinase activity; both of these effects were attenuated by NAC pretreatment of MCF-7 cells. Finally and most importantly, NAC attenuated salvicine-induced apoptosis and cytotoxicity in MCF-7 cells. These results indicate that apart from its direct actions, salvicine generates ROS that modulate DNA damage and repair, contributing to the comprehensive biological consequences of salvicine treatment, such as DNA DSBs, apoptosis, and cytotoxicity in tumor cells. The finding of salvicine-induced ROS provides new evidence for the molecular mechanisms of this compound. Moreover, the effects of salvicine-induced ROS on Topo II and DNA-PK give new insights into the diverse biological activities of ROS.
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Affiliation(s)
- Hua-Rui Lu
- Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Peoples Republic of China
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31
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Linenberger ML. CD33-directed therapy with gemtuzumab ozogamicin in acute myeloid leukemia: progress in understanding cytotoxicity and potential mechanisms of drug resistance. Leukemia 2004; 19:176-82. [PMID: 15592433 DOI: 10.1038/sj.leu.2403598] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
CD33 is expressed on the malignant blast cells in most cases of acute myeloid leukemia (AML) but not on normal hematopoietic pluripotent stem cells. Antibody-based therapies for AML have, therefore, focused on CD33 as a suitable tumor-associated target antigen. The most promising results have been obtained with gemtuzumab ozogamicin (GO, Mylotarg), a humanized IgG(4) anti-CD33 monoclonal antibody joined to a calicheamicin-gamma(1) derivative. Engagement of CD33 by GO results in immunoconjugate internalization and hydrolytic release of the toxic calicheamicin moiety, which, in turn, causes DNA damage and cell death. Since 2000, when GO was approved for clinical use, treatment trials and pilot studies have revealed potential expanded applications along with additional limitations. At the same time, correlative biological and in vitro functional studies have further characterized CD33 expression patterns in AML, the significance of CD33-antibody interactions, pathways involved in GO-induced cytotoxicity and potential drug resistance mechanisms. This review summarizes the recent data addressing mechanisms of GO action and discusses their relevance with regard to clinical applications and the limitations of using experimental model systems to mimic in vivo conditions. As the first drug conjugate approved for clinical use, GO serves as an important paradigm for other immunoconjugates against internalizing tumor antigens.
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Affiliation(s)
- M L Linenberger
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
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32
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Willmore E, de Caux S, Sunter NJ, Tilby MJ, Jackson GH, Austin CA, Durkacz BW. A novel DNA-dependent protein kinase inhibitor, NU7026, potentiates the cytotoxicity of topoisomerase II poisons used in the treatment of leukemia. Blood 2004; 103:4659-65. [PMID: 15010369 DOI: 10.1182/blood-2003-07-2527] [Citation(s) in RCA: 210] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report for the first time the use of a selective small-molecule inhibitor of DNA repair to potentiate topoisomerase II (topo II) poisons, identifying DNA-dependent protein kinase (DNA-PK) as a potential target for leukemia therapy. Topo II poisons form cleavable complexes that are processed to DNA double-strand breaks (DSBs). DNA-PK mediates nonhomologous end joining (NHEJ). Inhibition of this DSB repair pathway may sensitize cells to topo II poisons. We investigated the effects of a novel DNA-PK inhibitor, NU7026 (2-(morpholin-4-yl)-benzo[h]chomen-4-one), on the response to topo II poisons using K562 leukemia cells. NU7026 (10 microM) potentiated the growth inhibition of idarubicin, daunorubicin, doxorubicin, etoposide, amsacrine (mAMSA), and mitroxantrone with potentiation factors at 50% growth inhibition ranging from approximately 19 for mAMSA to approximately 2 for idarubicin (potentiation of etoposide was confirmed by clonogenic assay). In contrast, NU7026 did not potentiate camptothecin or cytosine arabinoside (araC). NU7026 did not affect the levels of etoposide-induced topo IIalpha or beta cleavable complexes. NU7026 alone had no effect on cell cycle distribution, but etoposide-induced accumulation in G2/M was increased by NU7026. A concentration-dependent increase in etoposide-induced DSB levels was increased by NU7026. The mechanism of NU7026 potentiation of topo II poisons involves inhibition of NHEJ and a G2/M checkpoint arrest.
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Affiliation(s)
- Elaine Willmore
- School of Cell and Molecular Biosciences, University of Newcastle-upon-Tyne Medical School, Newcastle-upon-Tyne NE2 4HH, United Kingdom
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33
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Ismail IH, Mårtensson S, Moshinsky D, Rice A, Tang C, Howlett A, McMahon G, Hammarsten O. SU11752 inhibits the DNA-dependent protein kinase and DNA double-strand break repair resulting in ionizing radiation sensitization. Oncogene 2004; 23:873-82. [PMID: 14661061 DOI: 10.1038/sj.onc.1207303] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Loss of the DNA-dependent protein kinase (DNA-PK) results in increased sensitivity to ionizing radiation due to inefficient repair of DNA double-strand breaks. Overexpression of DNA-PK in tumor cells conversely results in resistance to ionizing radiation. It is therefore possible that inhibition of DNA-PK will enhance the preferential killing of tumor cells by radiotherapy. Available inhibitors of DNA-PK, like wortmannin, are cytotoxic and stop the cell cycle because they inhibit phoshatidylinositol-3-kinases at 100-fold lower concentrations required to inhibit DNA-PK. In an effort to develop a specific DNA-PK inhibitor, we have characterized SU11752, from a three-substituted indolin-2-ones library. SU11752 and wortmannin were equally potent inhibitors of DNA-PK. In contrast, inhibition of the phoshatidylinositol-3-kinase p110gamma required 500-fold higher concentration of SU11752. Thus, SU11752 was a more selective inhibitor of DNA-PK than wortmannin. Inhibition kinetics and a direct assay for ATP binding showed that SU11752 inhibited DNA-PK by competing with ATP. SU11752 inhibited DNA double-strand break repair in cells and gave rise to a five-fold sensitization to ionizing radiation. At concentrations of SU11752 that inhibited DNA repair, cell cycle progression was still normal and ATM kinase activity was not inhibited. We conclude that SU11752 defines a new class of drugs that may serve as a starting point for the development of specific DNA-PK inhibitors.
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Affiliation(s)
- Ismail Hassan Ismail
- Department of Clinical Chemistry, Göteborg University, Sahlgrenska University Hospital, Göteborg 41345, Sweden
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Block WD, Yu Y, Lees-Miller SP. Phosphatidyl inositol 3-kinase-like serine/threonine protein kinases (PIKKs) are required for DNA damage-induced phosphorylation of the 32 kDa subunit of replication protein A at threonine 21. Nucleic Acids Res 2004; 32:997-1005. [PMID: 14872059 PMCID: PMC373400 DOI: 10.1093/nar/gkh265] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Replication protein A (RPA) is a single-stranded DNA (ssDNA) binding protein involved in various processes, including nucleotide excision repair and DNA replication. The 32 kDa subunit of RPA (RPA32) is phosphorylated in response to various DNA-damaging agents, and two protein kinases, ataxia-telangiectasia mutated (ATM) and the DNA-dependent protein kinase (DNA-PK) have been implicated in DNA damage-induced phosphorylation of RPA32. However, the relative roles of ATM and DNA-PK in the site-specific DNA damage-induced phosphorylation of RPA32 have not been reported. Here we generated a phosphospecific antibody that recognizes Thr21-phosphorylated RPA32. We show that both DNA-PK and ATM phosphorylate RPA32 on Thr21 in vitro. Ionizing radiation (IR)-induced phosphorylation of RPA32 on Thr21 was defective in ATM-deficient cells, while camptothecin (CPT)-induced phosphorylation of RPA32 on Thr21 was defective in cells lacking functional DNA-PK. Neither ATM nor DNA-PK was required for etoposide (ETOP)-induced RPA32 Thr21 phosphorylation. However, two inhibitors of the ATM- and Rad3-related (ATR) protein kinase activity prevented ETOP-induced Thr21 phosphorylation. Inhibition of DNA replication prevented both the IR- and CPT-induced phosphorylation of Thr21, whereas ETOP-induced Thr21 phosphorylation did not require active DNA replication. Thus, the regulation of RPA32 Thr21 phosphorylation by multiple DNA damage response protein kinases suggests that Thr21 phosphorylation of RPA32 is a crucial step within the DNA damage response.
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Affiliation(s)
- Wesley D Block
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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