scholarly journals Chromosomes with Two Intact Axial Cores Are Induced by G2 Checkpoint Override: Evidence That DNA Decatenation Is not Required to Template the Chromosome Structure

1997 ◽  
Vol 136 (1) ◽  
pp. 29-43 ◽  
Author(s):  
Paul R. Andreassen ◽  
Françoise B. Lacroix ◽  
Robert L. Margolis
Keyword(s):  
Topoisomerase Ii ◽  
Chromosome Structure ◽  
Core Structure ◽  
G2 Arrest ◽  
Normal Appearance ◽  
Physical Requirement ◽  
G2 Checkpoint ◽  
Chromosome Formation ◽  
Topo Ii ◽  
Chromosome Scaffold

Here we report that DNA decatenation is not a physical requirement for the formation of mammalian chromosomes containing a two-armed chromosome scaffold. 2-aminopurine override of G2 arrest imposed by VM-26 or ICRF-193, which inhibit topoisomerase II (topo II)–dependent DNA decatenation, results in the activation of p34cdc2 kinase and entry into mitosis. After override of a VM-26–dependent checkpoint, morphologically normal compact chromosomes form with paired axial cores containing topo II and ScII. Despite its capacity to form chromosomes of normal appearance, the chromatin remains covalently complexed with topo II at continuous levels during G2 arrest with VM-26. Override of an ICRF-193 block, which inhibits topo II–dependent decatenation at an earlier step than VM-26, also generates chromosomes with two distinct, but elongated, parallel arms containing topo II and ScII. These data demonstrate that DNA decatenation is required to pass a G2 checkpoint, but not to restructure chromatin for chromosome formation. We propose that the chromosome core structure is templated during interphase, before DNA decatenation, and that condensation of the two-armed chromosome scaffold can therefore occur independently of the formation of two intact and separate DNA helices.

scholarly journals In vivo dissection of the chromosome condensation machinery

2002 ◽  
Vol 156 (5) ◽  
pp. 805-815 ◽  
Author(s):  
Brigitte D. Lavoie ◽  
Eileen Hogan ◽  
Douglas Koshland
Keyword(s):  
Topoisomerase Ii ◽  
Mitotic Chromosome ◽  
Chromosome Structure ◽  
Histone H3 ◽  
Chromosome Condensation ◽  
Chromatin Binding ◽  
Condensin Complex ◽  
Topo Ii ◽  
Structural Maintenance Of Chromosome

The machinery mediating chromosome condensation is poorly understood. To begin to dissect the in vivo function(s) of individual components, we monitored mitotic chromosome structure in mutants of condensin, cohesin, histone H3, and topoisomerase II (topo II). In budding yeast, both condensation establishment and maintenance require all of the condensin subunits, but not topo II activity or phospho-histone H3. Structural maintenance of chromosome (SMC) protein 2, as well as each of the three non-SMC proteins (Ycg1p, Ycs4p, and Brn1p), was required for chromatin binding of the condensin complex in vivo. Using reversible condensin alleles, we show that chromosome condensation does not involve an irreversible modification of condensin or chromosomes. Finally, we provide the first evidence of a mechanistic link between condensin and cohesin function. A model discussing the functional interplay between cohesin and condensin is presented.

Anticancer Activity and Topoisomerase II Inhibition of Naphthalimides with ω-Hydroxylalkylamine Side-Chains of Different Lengths

2019 ◽  
Vol 15 (5) ◽  
pp. 550-560
Author(s):  
Mateusz D. Tomczyk ◽  
Anna Byczek-Wyrostek ◽  
Klaudia Strama ◽  
Martyna Wawszków ◽  
Przemysław Kasprzycki ◽  
...  
Keyword(s):  
Anticancer Activity ◽  
Cancer Cells ◽  
Cell Lines ◽  
Inhibitory Activity ◽  
Topoisomerase Ii ◽  
Significant Activity ◽  
Anticancer Activities ◽  
Human Colon Cancer ◽  
Substitution Pattern ◽  
Topo Ii

Background: The substituted 1,8-Naphthalimides (1H-benzo[de]isoquinoline-1,3(2H)- diones) are known as DNA intercalators stabilizing DNA-Topoisomerase II complexes. This interaction disrupts the cleavage-relegation equilibrium of Topo II, resulting in formation of broken strands of DNA. Objective: To investigate the influence of type of substituents and substitution positions in 1,8- naphthalimde skeleton on the inhibition of Topoisomerase II activity. Methods: The starting 1,8-naphthalimide were prepared from acenaphthene by introduction of appropriate substituents followed by condensation with ω-hydroxylakylamines of different chain length. The substituents were introduced to 1,8-naphthalimide molecule by nucleophilic substitution of leaving groups like nitro or bromo present in 4 or 4,5- positions using the ω- hydroxylalkylamines. The bioactivity of obtained compounds was examined in model cell lines. Results: Antiproliferative activity of selected compounds against HCT 116 human colon cancer cells, human non-small cell lung cells A549 and non-tumorigenic BEAS-2B human bronchial epithelium cells was examined. Several of investigated compounds exhibit a significant activity (IC50 µM to 7 µM) against model cancer cell lines. It was demonstrated that upon treatment with concentration of 200 µM, all derivatives display Topo II inhibitory activity, which may be compared with activity of Amonafide. Conclusion: The replacement of the nitro groups in the chromophore slightly reduces its anticancer activities, whereas the presence of both nitro group and ω-hydroxylalkylamine chain resulted in seriously increased anticancer activity. Obtained compounds showed Topo II inhibitory activity, moreover, influence of the substitution pattern on the ability to inhibit Topo II activity and cancer cells proliferation was observed.

Synthesis and anticancer evaluation of sulfur containing 9-anilinoacridines

2021 ◽  
Vol 16 ◽  
Author(s):  
Pranav Gupta ◽  
Radhika V. Kumar ◽  
Chul-Hoon Kwon ◽  
Zhe-Sheng Chen
Keyword(s):  
Cell Cycle ◽  
Anticancer Activity ◽  
Topoisomerase Ii ◽  
Critical Role ◽  
K562 Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
In Vivo Models ◽  
Topo Ii ◽  
Sulfur Containing

Background: DNA topoisomerases are a class of enzymes that play a critical role in fundamental biological processes of replication, transcription, recombination, repair and chromatin remodeling. Amsacrine (m-AMSA), the best-known compound of 9-anilinoacridines series was one of the first DNA-intercalating agents to be considered as a Topoisomerase II inhibitor. Objective: A series of sulfur containing 9-anilinoacridines related to amsacrine were synthesized and evaluated for their anticancer activity. Methods: Cell viability was assessed by the MTT assay. The topoisomerase II inhibitory assay was performed using the Human topoisomerase II Assay kit and flow cytometry was used to evaluate the effects on cell cycle of K562 cells. Molecular docking was performed using Schrödinger Maestro program. Results: Compound 36 was found to be the most cytotoxic of the sulfide series against SW620, K562, and MCF-7. The limited SAR suggested the importance of the methansulfonamidoacetamide side chain functionality, the lipophilicity and relative metabolic stability of 36 in contributing to the cytotoxicity. Topoisomerase II α inhibitory activity appeared to be involved in the cytotoxicity of 36 through inhibition of decatenation of kinetoplast DNA (kDNA) in a concentration dependent manner. Cell cycle analysis further showed the Topo II inhibition through accumulation of K562 cells in G2/M phase of cell cycle. Docking of 36 into the Topo II α-DNA complex suggested that it may be an allosteric inhibitor of Topo II α. Conclusion: Compound 36 exhibits anticancer activity by inhibiting topoisomerase II and it could further be evaluated in in vivo models.

scholarly journals Mitotic chromatin condensation in vitro using somatic cell extracts and nuclei with variable levels of endogenous topoisomerase II.

1990 ◽  
Vol 111 (6) ◽  
pp. 2839-2850 ◽  
Author(s):  
E R Wood ◽  
W C Earnshaw
Keyword(s):  
Topoisomerase Ii ◽  
Condensation Reaction ◽  
Chromatin Condensation ◽  
Condensation Process ◽  
Interphase Nuclei ◽  
Culture Cells ◽  
Cell Extracts ◽  
Topo Ii ◽  
Species Specific

We report the development of a new method for producing mitotic extracts from tissue culture cells. These extracts reproducibly promote the condensation of chromatin in vitro when incubated with purified interphase nuclei. This condensation reaction is not species specific, since nuclei from chicken, human, and hamster cell lines all undergo chromatin condensation upon incubation with the extract. We have used this extract to investigate the role of DNA topoisomerase II (topo II) in the chromosome condensation process. Chromatin condensation does not require the presence of soluble topo II in the mitotic extract. However, the extent of formation of discrete chromosome-like structures correlates with the level of endogenous topo II present in the interphase nuclei. Our results further suggest that chromatin condensation in this extract may involve two processes: chromatin compaction and resolution into discrete chromosomes.

scholarly journals Molecular docking analysis of α-Topoisomerase II with δ-Carboline derivatives as potential anticancer agents

2021 ◽  
Vol 17 (1) ◽  
pp. 249-265
Author(s):  
Selvaraj Ayyamperumal ◽  
Keyword(s):  
Molecular Docking ◽  
Anticancer Agents ◽  
Active Sites ◽  
Topoisomerase Ii ◽  
Binding Free Energy ◽  
Free Energy Calculations ◽  
Dynamics Simulation ◽  
Docking Analysis ◽  
Topo Ii ◽  
Molecular Docking Analysis

The enzyme, α-topoisomerase II (α-Topo II), is known to regulate efficiently the topology of DNA. It is highly expressed in rapidly proliferating cells and plays an important role in replication, transcription and chromosome organisation. This has prompted several investigators to pursue α-Topo II inhibitors as anticancer agents. δ-Carboline, a natural product, and its synthetic derivatives are known to exert potent anticancer activity by selectively targeting α-Topo II. Therefore, it is of interest to design carboline derivatives fused with pyrrolidine-2,5-dione in this context. δ-Carbolines fused with pyrrolidine-2,5-dione are of interest because the succinimide part of fused heteroaromatic molecule can interact with the ATP binding pocket via the hydrogen bond network with selectivity towards α-Topo II. The 300 derivatives designed were subjected to the Lipinski rule of 5, ADMET and toxicity prediction. The designed compounds were further analysed using molecular docking analysis on the active sites of the α-Topo II crystal structure (PDB ID:1ZXM). Molecular dynamic simulations were also performed to compare the binding mode and stability of the protein-ligand complexes. Compounds with ID numbers AS89, AS104, AS119, AS209, AS239, AS269, and AS299 show good binding activity compared to the co-crystal ligand. Molecular Dynamics simulation studies show that the ligand binding to α-Topo II in the ATP domain is stableand the protein-ligand conformation remains unchanged. Binding free energy calculations suggest that seven molecules designed are potential inhibitors for α-Topo II for further consideration as anticancer agents.

scholarly journals Rearrangements of the MLL gene in therapy-related acute myeloid leukemia in patients previously treated with agents targeting DNA- topoisomerase II

Blood ◽  
1993 ◽  
Vol 82 (12) ◽  
pp. 3705-3711 ◽  
Author(s):  
HJ Super ◽  
NR McCabe ◽  
MJ Thirman ◽  
RA Larson ◽  
MM Le Beau ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Topoisomerase Ii ◽  
De Novo ◽  
Chromosome Band ◽  
Dna Topoisomerase Ii ◽  
Dna Topoisomerase ◽  
Mll Gene ◽  
Topo Ii ◽  
Acute Myeloid

Chromosome band 11q23 is frequently involved in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) de novo, as well as in myelodysplastic syndromes (MDS) and lymphoma. Five percent to 15% of patients treated with chemotherapy for a primary neoplasm develop therapy-related AML (t-AML) that may show rearrangements, usually translocations involving band 11q23 or, less often, 21q22. These leukemias develop after a relatively short latent period and often follow the use of drugs that inhibit the activity of DNA-topoisomerase II (topo II). We previously identified a gene, MLL (myeloid-lymphoid leukemia or mixed-lineage leukemia), at 11q23 that is involved in the de novo leukemias. We have studied 17 patients with t-MDS/t-AML, 12 of whom had cytogenetically detectable 11q23 rearrangements. Ten of the 12 t-AML patients had received topo II inhibitors and 9 of these, all with balanced translocations of 11q23, had MLL rearrangements on Southern blot analysis. None of the patients who had not received topo II inhibitors showed an MLL rearrangement. Of the 5 patients lacking 11q23 rearrangements, some of whom had monoblastic features, none had an MLL rearrangement, although 4 had received topo II inhibitors. Our study indicates that the MLL gene rearrangements are similar both in AML that develops de novo and in t-AML. The association of exposure to topo II- reactive chemotherapy with 11q23 rearrangements involving the MLL gene in t-AML suggests that topo II may play a role in the aberrant recombination events that occur in this region both in AML de novo and in t-AML.

scholarly journals Topoisomerase II alpha is associated with the mammalian centromere in a cell cycle- and species-specific manner and is required for proper centromere/kinetochore structure.

1996 ◽  
Vol 134 (5) ◽  
pp. 1097-1107 ◽  
Author(s):  
J B Rattner ◽  
M J Hendzel ◽  
C S Furbee ◽  
M T Muller ◽  
D P Bazett-Jones
Keyword(s):  
Cell Cycle ◽  
Topoisomerase Ii ◽  
Chromatin Condensation ◽  
Culture Cell ◽  
Centromeric Heterochromatin ◽  
Tissue Culture Cell ◽  
Topoisomerase Ii Alpha ◽  
A Cell ◽  
Topo Ii ◽  
Species Specific

A study of the distribution of Topoisomerase II alpha (Topo II) in cells of six tissue culture cell lines, human (HeLa), mouse (L929), rat, Indian muntjac, rat kangaroo (PTK-2), and wallaby revealed the following features: (1) There is a cell cycle association of a specific population of Topo II with the centromere. (2) The centromere is distinguished from the remainder of the chromosome by the intensity of its Topo II reactivity. (3) The first appearance of a detectable population of Topo II at the centromere varies between species but is correlated with the onset of centromeric heterochromatin condensation. (4) Detectable centromeric Topo II declines at the completion of cell division. (5) The distribution pattern of Topo II within the centromere is species- and stage-specific and is conserved only within the kinetochore domain. In addition, we report that the Topo II inhibitor ICRF-193 can prevent the normal accumulation of Topo II at the centromere. This results in the disruption of chromatin condensation sub-adjacent to the kinetochore as well as the perturbation of kinetochore structure. Taken together, our studies indicate that the distribution of Topo II at the centromere is unlike that reported for the remainder of the chromosome and is essential for proper formation of centromere/kinetochore structure.

scholarly journals Transfection of human topoisomerase IIα into etoposide-resistant cells: transient increase in sensitivity followed by down-regulation of the endogenous gene

1996 ◽  
Vol 319 (1) ◽  
pp. 307-313 ◽  
Author(s):  
Takeshi ASANO ◽  
Taeha AN ◽  
Janice MAYES ◽  
Leonard A. ZWELLING ◽  
Eugenie S. KLEINERMAN
Keyword(s):  
Topoisomerase Ii ◽  
Dexamethasone Treatment ◽  
Down Regulation ◽  
Topoisomerase Iiα ◽  
Endogenous Gene ◽  
Protein Levels ◽  
Mammalian Expression ◽  
Protein Complex Formation ◽  
Mmtv Promoter ◽  
Topo Ii

We have investigated the possibility of overcoming the resistance of human brain tumour cells (HBT20) to etoposide by transferring the normal human topoisomerase IIα (H-topo II) gene into these cells. H-topo II in a mammalian expression vector containing a glucocorticoid-inducible mouse mammary tumour virus (MMTV) promoter was transfected into etoposide-resistant HBT20 cells (HBT20-hTOP2MAM). HBT20 cells transfected with pMAMneo vector alone served as control cells (HBT20-MAM). These were stable transfections. Following a 2 h dexamethasone treatment, H-topo II mRNA expression, protein production, etoposide-induced DNA-protein complex formation and sensitivity to etoposide were increased in HBT20-hTOP2MAM cells compared with control HBT20-MAM cells and with HBT20-hTOP2MAM cells not treated with dexamethasone. However, mRNA and protein levels and cell sensitivity returned to baseline when incubation with dexamethasone was continued for 24 h. This decrease from the 2 h values could not be explained by a loss of the MMTV promoter response to dexamethasone. (H-topo IIα promoter)-(chloramphenicol acetyltransferase) constructs containing regions -559–0 and -2400–0 were significantly down-regulated in HBT20-hTOP2MAM cells treated for 24 h with dexamethasone compared with dexamethasone-treated control cells. H-topo II mRNA stability after 24 h of dexamethasone treatment was not altered compared with that in control cells. Our data indicate that the exogenously produced H-topo II may have a negative-feedback effect on the endogenous topoisomerase II promoter, causing down-regulation of the endogenous gene.

Monascin and monascinol, azaphilonoid pigments from Mortierella polycephala AM1: in silico and in vitro targeting of the angiogenic VEGFR2 kinase

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohamed Shaaban ◽  
Mohammad Magdy El-Metwally ◽  
Amal A. I. Mekawey ◽  
Ahmed B. Abdelwahab ◽  
Maha M. Soltan
Keyword(s):  
In Silico ◽  
Topoisomerase Ii ◽  
Potent Inhibitor ◽  
Bioactive Metabolites ◽  
Cytotoxic Activities ◽  
Feather Waste ◽  
Biological Target ◽  
Topo Ii ◽  
Poultry Feather

Abstract The fungus, Mortierella polycephala is one of the most productive sources of anticancer bioactive compounds namely those of pigment nature. During our investigation of the produced bioactive metabolites by the terrestrial M. polycephala AM1 isolated from Egyptian poultry feather waste, two main azaphilonoid pigments, monascin (1) and monascinol (2) were obtained as major products; their structures were identified by 1D (1H&13C) and 2D (1H–1H COSY, HMBC) NMR and HRESI-MS spectroscopic data. Biologically, cytotoxic activities of these compounds were broadly studied compared with the fungal extract. To predict the biological target for the presumed antitumor activity, an in silico study was run toward three proteins, topoisomerase IIα, topoisomerase IIβ, and VEGFR2 kinase. Monascinol (2) was expected to be moderately active against VEGFR2 kinase without any anticipated inhibition toward topo II isoforms. The in vitro study confirmed the docked investigation consistently and introduced monascinol (2) rather than its counterpart (1) as a potent inhibitor to the tested VEGFR2 kinase. Taxonomically, the fungus was identified using morphological and genetic assessments.

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