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Abstract
Malignant glioma is a devastating disease affecting both adults and children with limited treatment strategies. Pre-clinical animal studies are critical to the development and planning of novel treatment designs for human clinical trials. Topoisomerases has been a target of interest in the treatment of high grade gliomas, such as glioblastoma, in the past years. Here we assess pre-clinical glioma literature with the aim to identify predictive variables that favour treatment outcomes from topoisomerase inhibition. Data was extracted from 90 experimental comparisons, this was divided based on available survival (n = 61) and tumor volume (n = 29) data. The meta-analysis revealed that the overall effect of topoisomerase inhibition prolonged survival by a factor of 1.33 (95% CI: 1.23–1.43) and reduced tumor growth by a factor of 3.21 (95% CI: 1.99–5.88), with considerable between-study heterogeneity. Multivariable meta-regression identified glioma model, type of control, route of drug administration and drug of choice to be predictive of improved survival outcome. Publication bias assessment by contour-enhanced funnel plots, Egger’s regression test and trim and fill analysis showed evidence of publication bias in all studies. This study identified multiple study design factors that should be taken into consideration to improve the translation of pre-clinical investigation of topoisomerase inhibition into clinical use.
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Posavec Marjanović M, Crawford K, Ahel I. PARP, transcription and chromatin modeling. Semin Cell Dev Biol 2016; 63:102-113. [PMID: 27677453 DOI: 10.1016/j.semcdb.2016.09.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/14/2016] [Accepted: 09/23/2016] [Indexed: 12/21/2022]
Abstract
Compaction mode of chromatin and chromatin highly organised structures regulate gene expression. Posttranslational modifications, histone variants and chromatin remodelers modulate the compaction, structure and therefore function of specific regions of chromatin. The generation of poly(ADP-ribose) (PAR) is emerging as one of the key signalling events on sites undergoing chromatin structure modulation. PAR is generated locally in response to stresses. These include genotoxic stress but also differentiation signals, metabolic and hormonal cues. A pictures emerges in which transient PAR formation is essential to orchestrate chromatin remodelling and transcription factors allowing the cell to adapt to alteration in its environment. This review summarizes the diverse factors of ADP-ribosylation in the adaptive regulation of chromatin structure and transcription.
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Affiliation(s)
| | - Kerryanne Crawford
- Sir William Dunn School of Pathology, University of Oxford, S Parks Rd, Oxford OX1 3RE, UK
| | - Ivan Ahel
- Sir William Dunn School of Pathology, University of Oxford, S Parks Rd, Oxford OX1 3RE, UK,.
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Preferential binding of hot spot mutant p53 proteins to supercoiled DNA in vitro and in cells. PLoS One 2013; 8:e59567. [PMID: 23555710 PMCID: PMC3608670 DOI: 10.1371/journal.pone.0059567] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 02/19/2013] [Indexed: 11/21/2022] Open
Abstract
Hot spot mutant p53 (mutp53) proteins exert oncogenic gain-of-function activities. Binding of mutp53 to DNA is assumed to be involved in mutp53-mediated repression or activation of several mutp53 target genes. To investigate the importance of DNA topology on mutp53-DNA recognition in vitro and in cells, we analyzed the interaction of seven hot spot mutp53 proteins with topologically different DNA substrates (supercoiled, linear and relaxed) containing and/or lacking mutp53 binding sites (mutp53BS) using a variety of electrophoresis and immunoprecipitation based techniques. All seven hot spot mutp53 proteins (R175H, G245S, R248W, R249S, R273C, R273H and R282W) were found to have retained the ability of wild-type p53 to preferentially bind circular DNA at native negative superhelix density, while linear or relaxed circular DNA was a poor substrate. The preference of mutp53 proteins for supercoiled DNA (supercoil-selective binding) was further substantiated by competition experiments with linear DNA or relaxed DNA in vitro and ex vivo. Using chromatin immunoprecipitation, the preferential binding of mutp53 to a sc mutp53BS was detected also in cells. Furthermore, we have shown by luciferase reporter assay that the DNA topology influences p53 regulation of BAX and MSP/MST1 promoters. Possible modes of mutp53 binding to topologically constrained DNA substrates and their biological consequences are discussed.
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Bandyopadhyay K, Li P, Gjerset RA. CK2-mediated hyperphosphorylation of topoisomerase I targets serine 506, enhances topoisomerase I-DNA binding, and increases cellular camptothecin sensitivity. PLoS One 2012. [PMID: 23185622 PMCID: PMC3503890 DOI: 10.1371/journal.pone.0050427] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Topoisomerase I is the target for a potent class of chemotherapeutic drugs derived from the plant alkaloid camptothecin that includes irinotecan and topotecan. In this study we have identified a novel site of CK2-mediated topoisomerase I (topo I) phosphorylation at serine 506 (PS506) that is relevant to topo I function and to cellular responses to these topo I-targeted drugs. CK2 treatment induced hyperphosphorylation of recombinant topo I and expression of the PS506 epitope, and resulted in increased binding of topo I to supercoiled plasmid DNA. Hyperphosphorylated topo I was approximately three times more effective than the basal phosphorylated enzyme at relaxing plasmid supercoils but had similar DNA cleavage activity once bound to DNA. The PS506 epitope was expressed in cancer cell lines with elevated CK2 activity, hyperphosphorylated topo I, and increased sensitivity to camptothecin. In contrast, PS506 was not detected in normal cells or cancer cell lines with lower levels of CK2 activity. By experimentally manipulating CK2 activity in cancer cell lines, we demonstrate a cause and effect relationship between CK2 activity, PS506 expression, camptothecin-induced cellular DNA damage, and cellular camptothecin sensitivity. Our results show that the PS506 epitope is an indicator of dysregulated, hyperphosphorylated topo I in cancer cells, and may thus serve as a diagnostic or prognostic biomarker and predict tumor responsiveness to widely used topo I-targeted therapies.
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MESH Headings
- Antineoplastic Agents, Phytogenic/pharmacology
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Camptothecin/pharmacology
- Casein Kinase II/genetics
- Casein Kinase II/metabolism
- Cell Line, Tumor
- DNA Fragmentation/drug effects
- DNA Topoisomerases, Type I/genetics
- DNA Topoisomerases, Type I/metabolism
- DNA, Superhelical/metabolism
- Drug Resistance, Neoplasm/drug effects
- Drug Resistance, Neoplasm/genetics
- Epitopes
- Gene Expression Regulation, Neoplastic/drug effects
- Humans
- Phosphorylation/drug effects
- Plasmids
- Serine/genetics
- Serine/metabolism
- Topoisomerase I Inhibitors/pharmacology
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Affiliation(s)
- Keya Bandyopadhyay
- Torrey Pines Institute for Molecular Studies, San Diego, California, United States of America
| | - Pingchuan Li
- Torrey Pines Institute for Molecular Studies, San Diego, California, United States of America
| | - Ruth A. Gjerset
- Torrey Pines Institute for Molecular Studies, San Diego, California, United States of America
- * E-mail:
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Tomicic MT, Kaina B. Topoisomerase degradation, DSB repair, p53 and IAPs in cancer cell resistance to camptothecin-like topoisomerase I inhibitors. Biochim Biophys Acta Rev Cancer 2012; 1835:11-27. [PMID: 23006513 DOI: 10.1016/j.bbcan.2012.09.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/13/2012] [Accepted: 09/15/2012] [Indexed: 12/11/2022]
Abstract
Topoisomerase I (TOP1) inhibitors applied in cancer therapy such as topotecan and irinotecan are derivatives of the natural alkaloid camptothecin (CPT). The mechanism of CPT poisoning of TOP1 rests on inhibition of the re-ligation function of the enzyme resulting in the stabilization of the TOP1-cleavable complex. In the presence of CPTs this enzyme-DNA complex impairs transcription and DNA replication, resulting in fork stalling and the formation of DNA double-strand breaks (DSB) in proliferating cells. As with most chemotherapeutics, intrinsic and acquired drug resistance represents a hurdle that limits the success of CPT therapy. Preclinical data indicate that resistance to CPT-based drugs might be caused by factors such as (a) poor drug accumulation in the tumor, (b) high rate of drug efflux, (c) mutations in TOP1 leading to failure in CPT docking, or (d) altered signaling triggered by the drug-TOP1-DNA complex, (e) expression of DNA repair proteins, and (f) failure to activate cell death pathways. This review will focus on the issues (d-f). We discuss degradation of TOP1 as part of the repair pathway in the processing of TOP1 associated DNA damage, give a summary of proteins involved in repair of CPT-induced replication mediated DSB, and highlight the role of p53 and inhibitors of apoptosis proteins (IAPs), particularly XIAP and survivin, in cancer cell resistance to CPT-like chemotherapeutics.
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Affiliation(s)
- Maja T Tomicic
- Department of Toxicology, University Medical Center Mainz, Germany.
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Christmann M, Tomicic MT, Gestrich C, Roos WP, Bohr VA, Kaina B. WRN protects against topo I but not topo II inhibitors by preventing DNA break formation. DNA Repair (Amst) 2008; 7:1999-2009. [PMID: 18805512 DOI: 10.1016/j.dnarep.2008.08.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 07/15/2008] [Accepted: 08/25/2008] [Indexed: 12/24/2022]
Abstract
The Werner syndrome helicase/3'-exonuclease (WRN) is a major component of the DNA repair and replication machinery. To analyze whether WRN is involved in the repair of topoisomerase-induced DNA damage we utilized U2-OS cells, in which WRN is stably down-regulated (wrn-kd), and the corresponding wild-type cells (wrn-wt). We show that cells not expressing WRN are hypersensitive to the toxic effect of the topoisomerase I inhibitor topotecan, but not to the topoisomerase II inhibitor etoposide. This was shown by mass survival assays, colony formation and induction of apoptosis. Upon topotecan treatment WRN deficient cells showed enhanced DNA replication inhibition and S-phase arrest, whereas after treatment with etoposide they showed the same cell cycle response as the wild-type. A considerable difference between WRN and wild-type cells was observed for DNA single- and double-strand break formation in response to topotecan. Topotecan induced DNA single-strand breaks 6h after treatment. In both wrn-wt and wrn-kd cells these breaks were repaired at similar kinetics. However, in wrn-kd but not wrn-wt cells they were converted into DNA double-strand breaks (DSBs) at high frequency, as shown by neutral comet assay and phosphorylation of H2AX. Our data provide evidence that WRN is involved in the repair of topoisomerase I, but not topoisomerase II-induced DNA damage, most likely via preventing the conversion of DNA single-strand breaks into DSBs during the resolution of stalled replication forks at topo I-DNA complexes. We suggest that the WRN status of tumor cells impacts anticancer therapy with topoisomerase I, but not topoisomerase II inhibitors.
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Affiliation(s)
- Markus Christmann
- Department of Toxicology, University of Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
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Søe K, Hartung S, Grosse F. Human topoisomerase I forms double cleavage complexes on natural DNA. Biochem Biophys Res Commun 2006; 349:178-85. [PMID: 16930551 DOI: 10.1016/j.bbrc.2006.08.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Accepted: 08/04/2006] [Indexed: 11/22/2022]
Abstract
DNA topoisomerase I releases torsional stress generated in chromatin during transcription and replication. Usually topoisomerase I is recognized to work as a monomer, but previously we have shown that two molecules can form a dimer-like protein-protein complex on a 'suicide' DNA substrate resulting in a topoisomerase I double cleavage complex. Here we show that during the normal relaxation reaction a considerable fraction of human topoisomerase I formed transient dimers on plasmid DNA too. Recombinant as well as topoisomerase I purified from human cells formed double cleavage complexes within a distance of 12 or 14 nucleotides. When topoisomerase I was isolated from camptothecin-treated HeLa cells, a considerable fraction migrated to the same position as topoisomerase I bearing a covalently bound 12-to-14-mer oligonucleotide. Taken together our data suggest that human topoisomerase I double cleavage complexes are part of the normal catalytic cycle of this enzyme that occur in vitro and possibly also in vivo.
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Affiliation(s)
- Kent Søe
- Leibniz Institute for Age Research, Fritz Lipmann Institute (FLI), Biochemical Group, Beutenbergstrasse 11, D-07745 Jena, Germany
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Baumann C, Boehden GS, Bürkle A, Wiesmüller L. Poly(ADP-RIBOSE) polymerase-1 (Parp-1) antagonizes topoisomerase I-dependent recombination stimulation by P53. Nucleic Acids Res 2006; 34:1036-49. [PMID: 16473854 PMCID: PMC1363779 DOI: 10.1093/nar/gkj509] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PARP-1 interacts with and poly(ADP-ribosyl)ates p53 and topoisomerase I, which both participate in DNA recombination. Previously, we showed that PARP-1 downregulates homology-directed double-strand break (DSB) repair. We also discovered that, despite the well-established role of p53 as a global suppressor of error-prone recombination, p53 enhances homologous recombination (HR) at the RARα breakpoint cluster region (bcr) comprising topoisomerase I recognition sites. Using an SV40-based assay and isogenic cell lines differing in the p53 and PARP-1 status we demonstrate that PARP-1 counteracts HR enhancement by p53, although DNA replication was largely unaffected. When the same DNA element was integrated in an episomal recombination plasmid, both p53 and PARP-1 exerted anti-recombinogenic rather than stimulatory activities. Strikingly, with DNA substrates integrated into cellular chromosomes, enhancement of HR by p53 and antagonistic PARP-1 action was seen, very similar to the HR of viral minichromosomes. siRNA-mediated knockdown revealed the essential role of topoisomerase I in this regulatory mechanism. However, after I-SceI-meganuclease-mediated cleavage of the chromosomally integrated substrate, no topoisomerase I-dependent effects by p53 and PARP-1 were observed. Our data further indicate that PARP-1, probably through topoisomerase I interactions rather than poly(ADP-ribosyl)ation, prevents p53 from stimulating spontaneous HR on chromosomes via topoisomerase I activity.
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Affiliation(s)
- Cindy Baumann
- Universitätsfrauenklinik, Prittwitzstrasse 43D-89075 Ulm, Germany
| | - Gisa S. Boehden
- Universitätsfrauenklinik, Prittwitzstrasse 43D-89075 Ulm, Germany
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität HamburgMartinistraße 52, D-20251 Hamburg, Germany
| | - Alexander Bürkle
- Molecular Toxicology Group, Department of Biology, University of KonstanzD-78457 Konstanz, Germany
| | - Lisa Wiesmüller
- Universitätsfrauenklinik, Prittwitzstrasse 43D-89075 Ulm, Germany
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität HamburgMartinistraße 52, D-20251 Hamburg, Germany
- To whom correspondence should be addressed. Tel: +49 731 500 27640; Fax: +49 731 500 26674;
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Abstract
The p53 tumor suppressor protein is a transcription factor that mediates the cell's response to various kinds of stress by preventing cell division and/or inducing apoptosis. p53 gene mutations have been detected in nearly 50% of human cancers. These gene aberrations are mostly missense point mutations located predominantly in the central DNA-binding domain. In addition to the classical inactivating mutations, there are also dominant-negative, gain-of-function, temperature-sensitive, and cold-sensitive, discriminating, superactive p53 mutations, and some mutations that do not inactivate p53 activity. Several approaches have been developed for detection and analyses of p53 mutations: first, immunochemical methods have been developed to detect p53 protein levels; second, molecular analyses targeting changes in DNA structure are utilized; and third, functional assays are used to explore the biological properties of the p53 protein. Functional analysis of separated alleles in yeast targets the transactivation capability of the p53 protein expressed in yeast cells. This method uses p53 mRNA isolated from cells and tissues to produce a p53 product by RT-PCR. This method has undergone continuous improvement and now serves as a powerful tool for distinguishing various functional types of p53 mutations. Understanding the exact impact of p53 mutation on its function is an important prerequisite for establishment of efficient anti-cancer therapies.
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Affiliation(s)
- Jana Smardová
- Department of Pathology and Anatomy, University Hospital Brno, Jihlavská 20, 625 00 Brno, Czech Republic.
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Ohneseit PA, Prager D, Kehlbach R, Rodemann HP. Cell cycle effects of topotecan alone and in combination with irradiation. Radiother Oncol 2005; 75:237-45. [PMID: 15890420 DOI: 10.1016/j.radonc.2005.03.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2004] [Revised: 01/20/2005] [Accepted: 03/08/2005] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND PURPOSE To elucidate the role of TP53 on differential effects of topoisomerase I inhibitor topotecan (Hycamtin on radiation sensitivity. MATERIALS AND METHODS Cell cycle distribution and protein expression of TP53, p21(WAF1/CIP1) and cyclin B was studied in CCD32 lung fibroblasts, glioblastoma cell lines U118 (mutant TP53), and U87 (wildtype TP53) after treatment with topotecan (0.05 and 1 microM) and/or ionizing radiation (2 Gy). RESULTS Cell cycle effects varied with topotecan concentration, resulting in G1 arrest (1 microM), or S/G2/M arrest (0.05 microM), and was modified differentially in fibroblasts and in glioblastoma cells in combination with irradiation. Phosphorylation of TP53 and expression of p21(WAF1/CIP1) was induced by IR and/or topotecan in CCD32 cells, and in U118 cells after topotecan treatment, accompanied by cyclin B degradation. In U87 cells only 1 microM topotecan generated phosphorylation of TP53 and p21(WAF1/CIP1) expression; 0.05 microM caused stabilization of cyclin B. CONCLUSIONS The antagonistic effect of combined topotecan/irradiation treatment in fibroblasts was most likely due to an immediate radiation induced G1 arrest, but was not observed in p53 wildtype glioblastoma cells. Thus, the impact of TP53 on the topotecan response remains indistinct, and is obviously influenced by other genomic alterations acquired by tumor cells.
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Affiliation(s)
- Petra A Ohneseit
- Section of Radiobiology and Molecular Environmental Research, Department of Radiation Oncology, University of Tübingen, Germany
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Webb M, Ebeler S. Comparative analysis of topoisomerase IB inhibition and DNA intercalation by flavonoids and similar compounds: structural determinates of activity. Biochem J 2005; 384:527-41. [PMID: 15312049 PMCID: PMC1134138 DOI: 10.1042/bj20040474] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Flavonoids and other polyphenolic compounds have been shown to inhibit human topoisomerase IB (topo I) through both inhibition of relaxation activity and through stabilization of the cleavable complex (poisoning). Some flavonoids have also been shown to intercalate DNA, and an association of topoisomerase inhibition with intercalation has been noted. We surveyed 34 polyphenolic compounds, primarily flavonoid glycones and aglycones, for their ability to inhibit topo I and to intercalate DNA using an in vitro gel electrophoresis method. We show that the most potent topo I poisons are the flavones and flavonols, and that these generally, but not always, are found to be DNA intercalators. There was no clear correlation, however, of topo-I-poisoning activity with the degree of DNA unwinding. Surprisingly, both DNA intercalation and topo I poisoning were shown to occur with some flavone glycones, including the C-glycosylflavone orientin. Inhibition of relaxation activity by flavonoids was found to be difficult to quantify and was most likely to be due to non-specific inhibition through flavonoid aggregation. As part of a structure-activity analysis, we also investigated the acid-base chemistry of flavonoids and determined that many flavonoids show acid-base activity with a pK(a) in the physiological pH region. For this reason, subtle pH changes can have significant effects on solution activity of flavonoids and their concomitant biological activity. In addition, these effects may be complicated by pH-dependent aggregation and oxidative degradation. Finally, we develop a simple model for the intercalation of flavonoids into DNA and discuss possible consequences of intercalation and topoisomerase inhibition on a number of cellular processes.
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Affiliation(s)
- Michael R. Webb
- Department of Viticulture and Enology, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, U.S.A
| | - Susan E. Ebeler
- Department of Viticulture and Enology, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, U.S.A
- To whom correspondence should be addressed (email )
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