-
Archives of Toxicology Jun 2018Dronedarone is used to treat patients with cardiac arrhythmias and has been reported to be associated with liver injury. Our previous mechanistic work demonstrated that...
Dronedarone is used to treat patients with cardiac arrhythmias and has been reported to be associated with liver injury. Our previous mechanistic work demonstrated that DNA damage-induced apoptosis contributes to the cytotoxicity of dronedarone. In this study, we examined further the underlying mechanisms and found that after a 24-h treatment of HepG2 cells, dronedarone caused cytotoxicity, G1-phase cell cycle arrest, suppression of topoisomerase II, and DNA damage in a concentration-dependent manner. We also investigated the role of cytochrome P450s (CYPs)-mediated metabolism in the dronedarone-induced toxicity using our previously established HepG2 cell lines expressing individually 14 human CYPs (1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 3A4, 3A5, and 3A7). We demonstrated that CYP3A4, 3A5, and 2D6 were the major enzymes that metabolize dronedarone, and that CYP3A7, 2E1, 2C19, 2C18, 1A1, and 2B6 also metabolize dronedarone, but to a lesser extent. Our data showed that the cytotoxicity of dronedarone was decreased in CYP3A4-, 3A5-, or 2D6-overexpressing cells compared to the control HepG2 cells, indicating that the parent dronedarone has higher potency than the metabolites to induce cytotoxicity in these cells. In contrast, cytotoxicity was increased in CYP1A1-overexpressing cells, demonstrating that CYP1A1 exerts an opposite effect in dronedarone's toxicity, comparing to CYP3A4, 3A5, or 2D6. We also studied the involvement of topoisomerase II in dronedarone-induced toxicity, and demonstrated that the overexpression of topoisomerase II caused an increase in cell viability and a decrease in γ-H2A.X induction, suggesting that suppression of topoisomerase II may be one of the mechanisms involved in dronedarone-induced liver toxicity.
Topics: Cell Culture Techniques; Cell Cycle; Cell Survival; Cytochrome P-450 Enzyme System; DNA Damage; DNA Topoisomerases, Type II; Dronedarone; Hep G2 Cells; Histones; Humans; Liver
PubMed: 29616291
DOI: 10.1007/s00204-018-2196-x -
Molecular Cell Jul 2019Topoisomerase II (TOP2) relieves torsional stress by forming transient cleavage complex intermediates (TOP2ccs) that contain TOP2-linked DNA breaks (DSBs). While TOP2ccs...
Topoisomerase II (TOP2) relieves torsional stress by forming transient cleavage complex intermediates (TOP2ccs) that contain TOP2-linked DNA breaks (DSBs). While TOP2ccs are normally reversible, they can be "trapped" by chemotherapeutic drugs such as etoposide and subsequently converted into irreversible TOP2-linked DSBs. Here, we have quantified etoposide-induced trapping of TOP2ccs, their conversion into irreversible TOP2-linked DSBs, and their processing during DNA repair genome-wide, as a function of time. We find that while TOP2 chromatin localization and trapping is independent of transcription, it requires pre-existing binding of cohesin to DNA. In contrast, the conversion of trapped TOP2ccs to irreversible DSBs during DNA repair is accelerated 2-fold at transcribed loci relative to non-transcribed loci. This conversion is dependent on proteasomal degradation and TDP2 phosphodiesterase activity. Quantitative modeling shows that only two features of pre-existing chromatin structure-namely, cohesin binding and transcriptional activity-can be used to predict the kinetics of TOP2-induced DSBs.
Topics: Chromosome Breakage; Chromosomes; DNA; DNA Breaks, Double-Stranded; DNA Repair; DNA Topoisomerases, Type II; DNA-Binding Proteins; Etoposide; Gene Conversion; HCT116 Cells; Humans; Kinetics; Multiprotein Complexes; Poly-ADP-Ribose Binding Proteins; Topoisomerase II Inhibitors; Torsion, Mechanical; Transcription, Genetic; Translocation, Genetic
PubMed: 31202577
DOI: 10.1016/j.molcel.2019.04.030 -
Oncogene Jul 2015Genome instability is a hallmark of cancer cells. Chromosome instability (CIN), which is often mutually exclusive from hypermutation genotypes, represents a distinct... (Review)
Review
Genome instability is a hallmark of cancer cells. Chromosome instability (CIN), which is often mutually exclusive from hypermutation genotypes, represents a distinct subtype of genome instability. Hypermutations in cancer cells are due to defects in DNA repair genes, but the cause of CIN is still elusive. However, because of the extensive chromosomal abnormalities associated with CIN, its cause is likely a defect in a network of genes that regulate mitotic checkpoints and chromosomal organization and segregation. Emerging evidence has shown that the chromosomal decatenation checkpoint, which is critical for chromatin untangling and packing during genetic material duplication, is defective in cancer cells with CIN. The decatenation checkpoint is known to be regulated by a family of enzymes called topoisomerases. Among them, the gene encoding topoisomerase IIα (TOP2A) is commonly altered at both gene copy number and gene expression level in cancer cells. Thus, abnormal alterations of TOP2A, its interacting proteins, and its modifications may have a critical role in CIN in human cancers. Clinically, a large arsenal of topoisomerase inhibitors has been used to suppress DNA replication in cancer. However, they often lead to the secondary development of leukemia because of their effect on the chromosomal decatenation checkpoint. Therefore, topoisomerase drugs must be used judiciously and administered on an individual basis. In this review, we highlight the biological function of TOP2A in chromosome segregation and the mechanisms that regulate this enzyme's expression and activity. We also review the roles of TOP2A and related proteins in human cancers, and raise a perspective for how to target TOP2A in personalized cancer therapy.
Topics: Animals; Antigens, Neoplasm; Chromosomal Instability; Chromosome Segregation; DNA Topoisomerases, Type II; DNA-Binding Proteins; Disease Progression; Humans; Neoplasms; Poly-ADP-Ribose Binding Proteins; Precision Medicine; Topoisomerase II Inhibitors
PubMed: 25328138
DOI: 10.1038/onc.2014.332 -
ELife Mar 2018Type II topoisomerases manage DNA supercoiling and aid chromosome segregation using a complex, ATP-dependent duplex strand passage mechanism. Type IIB topoisomerases and...
Type II topoisomerases manage DNA supercoiling and aid chromosome segregation using a complex, ATP-dependent duplex strand passage mechanism. Type IIB topoisomerases and their homologs support both archaeal/plant viability and meiotic recombination. Topo VI, a prototypical type IIB topoisomerase, comprises two Top6A and two Top6B protomers; how these subunits cooperate to engage two DNA segments and link ATP turnover to DNA transport is poorly understood. Using multiple biochemical approaches, we show that Top6B, which harbors the ATPase activity of topo VI, recognizes and exploits the DNA crossings present in supercoiled DNA to stimulate subunit dimerization by ATP. Top6B self-association in turn induces extensive DNA bending, which is needed to support duplex cleavage by Top6A. Our observations explain how topo VI tightly coordinates DNA crossover recognition and ATP binding with strand scission, providing useful insights into the operation of type IIB topoisomerases and related meiotic recombination and GHKL ATPase machineries.
Topics: Adenosine Triphosphate; Archaeal Proteins; DNA Cleavage; DNA Topoisomerases, Type II; DNA, Superhelical; Methanosarcina; Nucleic Acid Conformation; Protein Subunits
PubMed: 29595473
DOI: 10.7554/eLife.31724 -
Toxicological Sciences : An Official... Mar 2024Anthracyclines, such as doxorubicin (adriamycin), daunorubicin, or epirubicin, rank among the most effective agents in classical anticancer chemotherapy. However,...
Anthracyclines, such as doxorubicin (adriamycin), daunorubicin, or epirubicin, rank among the most effective agents in classical anticancer chemotherapy. However, cardiotoxicity remains the main limitation of their clinical use. Topoisomerase IIβ has recently been identified as a plausible target of anthracyclines in cardiomyocytes. We examined the putative topoisomerase IIβ selective agent XK469 as a potential cardioprotective and designed several new analogs. In our experiments, XK469 inhibited both topoisomerase isoforms (α and β) and did not induce topoisomerase II covalent complexes in isolated cardiomyocytes and HL-60, but induced proteasomal degradation of topoisomerase II in these cell types. The cardioprotective potential of XK469 was studied on rat neonatal cardiomyocytes, where dexrazoxane (ICRF-187), the only clinically approved cardioprotective, was effective. Initially, XK469 prevented daunorubicin-induced toxicity and p53 phosphorylation in cardiomyocytes. However, it only partially prevented the phosphorylation of H2AX and did not affect DNA damage measured by Comet Assay. It also did not compromise the daunorubicin antiproliferative effect in HL-60 leukemic cells. When administered to rabbits to evaluate its cardioprotective potential in vivo, XK469 failed to prevent the daunorubicin-induced cardiac toxicity in either acute or chronic settings. In the following in vitro analysis, we found that prolonged and continuous exposure of rat neonatal cardiomyocytes to XK469 led to significant toxicity. In conclusion, this study provides important evidence on the effects of XK469 and its combination with daunorubicin in clinically relevant doses in cardiomyocytes. Despite its promising characteristics, long-term treatments and in vivo experiments have not confirmed its cardioprotective potential.
Topics: Rats; Animals; Rabbits; Topoisomerase II Inhibitors; Anthracyclines; Cardiotoxicity; Daunorubicin; Doxorubicin; Antibiotics, Antineoplastic; DNA Topoisomerases, Type II; DNA Damage; Quinoxalines
PubMed: 38290791
DOI: 10.1093/toxsci/kfae008 -
Scientific Reports Mar 2020Anthracyclines used in the treatment of acute myelogenous leukemia (AML) inhibit the activity of the mammalian topoisomerase II (topo II) isoforms, topo II α and topo...
Anthracyclines used in the treatment of acute myelogenous leukemia (AML) inhibit the activity of the mammalian topoisomerase II (topo II) isoforms, topo II α and topo IIβ. In 230 patients with non-M3 AML who received frontline ara-C/daunorubicin we determined expression of topo IIα and topo IIβ by RT-PCR and its relationship to immunophenotype (IP) and outcomes. Treatment outcomes were analyzed by logistic or Cox regression. In 211 patients, available for analysis, topo IIα expression was significantly lower than topo IIβ (P < 0.0001). In contrast to topo IIα, topo IIβ was significantly associated with blast percentage in marrow or blood (P = 0.0001), CD7 (P = 0.01), CD14 (P < 0.0001) and CD54 (P < 0.0001). Event free survival was worse for CD56-negative compared to CD56-high (HR = 1.9, 95% CI [1.0-3.5], p = 0.04), and overall survival was worse for CD-15 low as compared to CD15-high (HR = 2.2, 95% CI [1.1-4.2], p = 0.02). Ingenuity pathway analysis indicated topo IIβ and immunophenotype markers in a network associated with cell-to-cell signaling, hematological system development/function and inflammatory response. Topo IIβ expression reflects disease biology of highly proliferative disease and distinct IP but does not appear to be an independent variable influencing outcome in adult AML patients treated with anthracycline-based therapy.
Topics: Adult; Aged; Aged, 80 and over; Antigens, CD; Antineoplastic Agents; Cohort Studies; Cytarabine; DNA Topoisomerases, Type II; Daunorubicin; Female; Humans; Immunophenotyping; Leukemia, Myeloid, Acute; Male; Middle Aged; Poly-ADP-Ribose Binding Proteins; RNA, Messenger; Topoisomerase II Inhibitors; Treatment Outcome; Young Adult
PubMed: 32218491
DOI: 10.1038/s41598-020-62345-9 -
Molecules (Basel, Switzerland) Feb 2023This study evaluated the genotoxicity of Ethanol Extract (EEEp), Dichloromethane Fraction (FDCMEp) and isoeleutherin isolated from , using the micronucleus test and the...
This study evaluated the genotoxicity of Ethanol Extract (EEEp), Dichloromethane Fraction (FDCMEp) and isoeleutherin isolated from , using the micronucleus test and the impact of structural alterations on toxicity and molecular docking (topoisomerase II and DNA complex). The extract was obtained by maceration and fractionation in a chromatography column. The genotoxicity was evaluated by the micronucleus test in human hepatoma cells (HepG2). Isoeleutherin was the starting molecule in the search for analogues by structural similarity, using the ZINC and e-Molecules databases. Isoeleutherin and analogues were subjected to in silico toxicity prediction, and compounds free of toxicological risks (CP13, CP14, CP17 and isoeleutherin) were selected for molecular docking in Topoisomerase II (PDB: 1ZXM). In the micronucleus test, isoeleutherin was less genotoxic. Among the 22 isoeleutherin analogues there were variations in the toxicity profile. Molecular docking studies showed that the compounds have good complementarity in the active site with important hydrogens bonds. Therefore, the structural changes of isoeleutherin led to the obtaining of a molecule with a lower mutagenic potential, and the CP13 can be considered a prototype compound for the development of new molecules with pharmacological potential.
Topics: Humans; Molecular Docking Simulation; Caspase 8; DNA Damage; DNA Topoisomerases, Type II
PubMed: 36838618
DOI: 10.3390/molecules28041630 -
ELife Aug 2021DNA loop extrusion by condensins and decatenation by DNA topoisomerase II (topo II) are thought to drive mitotic chromosome compaction and individualization. Here, we...
DNA loop extrusion by condensins and decatenation by DNA topoisomerase II (topo II) are thought to drive mitotic chromosome compaction and individualization. Here, we reveal that the linker histone H1.8 antagonizes condensins and topo II to shape mitotic chromosome organization. In vitro chromatin reconstitution experiments demonstrate that H1.8 inhibits binding of condensins and topo II to nucleosome arrays. Accordingly, H1.8 depletion in egg extracts increased condensins and topo II levels on mitotic chromatin. Chromosome morphology and Hi-C analyses suggest that H1.8 depletion makes chromosomes thinner and longer through shortening the average loop size and reducing the DNA amount in each layer of mitotic loops. Furthermore, excess loading of condensins and topo II to chromosomes by H1.8 depletion causes hyper-chromosome individualization and dispersion. We propose that condensins and topo II are essential for chromosome individualization, but their functions are tuned by the linker histone to keep chromosomes together until anaphase.
Topics: Adenosine Triphosphatases; Animals; Cell Extracts; Chromatin; Chromosomes; DNA Topoisomerases, Type II; DNA-Binding Proteins; Female; Histones; Models, Biological; Multiprotein Complexes; Oocytes; Spindle Apparatus; Xenopus laevis
PubMed: 34406118
DOI: 10.7554/eLife.68918 -
The Journal of Biological Chemistry Dec 2017Resveratrol, a polyphenol found in various plant sources, has gained attention as a possible agent responsible for the purported health benefits of certain foods, such...
Resveratrol, a polyphenol found in various plant sources, has gained attention as a possible agent responsible for the purported health benefits of certain foods, such as red wine. Despite annual multi-million dollar market sales as a nutriceutical, there is little consensus about the physiological roles of resveratrol. One suggested molecular target of resveratrol is eukaryotic topoisomerase II (topo II), an enzyme essential for chromosome segregation and DNA supercoiling homeostasis. Interestingly, resveratrol is chemically similar to ICRF-187, a clinically approved chemotherapeutic that stabilizes an ATP-dependent dimerization interface in topo II to block enzyme activity. Based on this similarity, we hypothesized that resveratrol may antagonize topo II by a similar mechanism. Using a variety of biochemical assays, we find that resveratrol indeed acts through the ICRF-187 binding locus, but that it inhibits topo II by preventing ATPase domain dimerization rather than stabilizing it. This work presents the first comprehensive analysis of the biochemical effects of both ICRF-187 and resveratrol on the human isoforms of topo II, and reveals a new mode for the allosteric regulation of topo II through modulation of ATPase status. Natural polyphenols related to resveratrol that have been shown to impact topo II function may operate in a similar manner.
Topics: Adenosine Triphosphatases; Allosteric Regulation; Amino Acid Substitution; DNA Topoisomerases, Type II; Dexrazoxane; Humans; Models, Molecular; Molecular Structure; Mutagenesis, Site-Directed; Poly-ADP-Ribose Binding Proteins; Protein Interaction Domains and Motifs; Protein Multimerization; Resveratrol; Saccharomyces cerevisiae Proteins; Topoisomerase II Inhibitors
PubMed: 29074616
DOI: 10.1074/jbc.M117.810580 -
ELife Jan 2022DNA topoisomerase VI (topo VI) is a type IIB DNA topoisomerase found predominantly in archaea and some bacteria, but also in plants and algae. Since its discovery, topo...
DNA topoisomerase VI (topo VI) is a type IIB DNA topoisomerase found predominantly in archaea and some bacteria, but also in plants and algae. Since its discovery, topo VI has been proposed to be a DNA decatenase; however, robust evidence and a mechanism for its preferential decatenation activity was lacking. Using single-molecule magnetic tweezers measurements and supporting ensemble biochemistry, we demonstrate that topo VI preferentially unlinks, or decatenates DNA crossings, in comparison to relaxing supercoils, through a preference for certain DNA crossing geometries. In addition, topo VI demonstrates a significant increase in ATPase activity, DNA binding and rate of strand passage, with increasing DNA writhe, providing further evidence that topo VI is a DNA crossing sensor. Our study strongly suggests that topo VI has evolved an intrinsic preference for the unknotting and decatenation of interlinked chromosomes by sensing and preferentially unlinking DNA crossings with geometries close to 90°.
Topics: Archaeal Proteins; DNA Topoisomerases, Type II; DNA, Catenated; Methanosarcina; Single Molecule Imaging; Stereoisomerism
PubMed: 35076393
DOI: 10.7554/eLife.67021