Recent Advances in the Development of Catalytic Inhibitors of Human DNA Topoisomerase IIα As Novel Anticancer Agents (original) (raw)
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Recent Developments of DNA Poisons - Human DNA Topoisomerase IIα Inhibitors - as Anticancer Agents
Current Pharmaceutical Design, 2013
DNA topoisomerases are an important family of enzymes that catalyze the induction of topological changes in the DNA molecule. Their ability to modulate the topology of the DNA makes DNA topoisomerases a key player in several vital cell processes such as replication, transcription, chromosome separation and segregation. Consequently, they already represent an important collection of macromolecular targets for some of the established anticancer drugs on the market as well as serve as templates in the development of novel anticancer drugs especially supported by recent structural advances in the field.
DNA Topoisomerases: As target for anti-cancer drugs
Indian Journal of Pharmacy and Pharmacology
Topoisomerase inhibitors are agents designed to interfere with the action of topoisomerase enzymes I and II. Topoisomerases are enzymes that control the changes in DNA tridimensional structure by catalyzing the breaking and rejoining of the phosphodiester backbone of DNA strands during the normal cell cycle. DNA Topoisomerases control the conformational changes in DNA topology by breaking and resealing DNA strands during normal cellular growth, that’s why these are essential enzymes. A major class of anticancer drugs acts as inhibitors of DNA Topoisomerases. This paper gives a brief review on Topoisomerase targeting drugs which shows anticancer activities. The mechanism of action of these drugs by inhibiting type I and type II DNA Topoisomerases are discussed. DNA topoisomerases, especially type II A topoisomerases, are proved therapeutic targets of anticancer and antibacterial drugs. Clinically successful topoisomerase-targeting anticancer drugs act through topoisomerase poisoning,...
Synthesis and cytotoxic activity of a new series of topoisomerase I inhibitors
Bioorganic & Medicinal Chemistry Letters, 2008
A series of structurally simple analogues of natural topopyrone C were synthesized and tested for cytotoxic and topoisomerase I inhibitory activities. The removal of the hydroxyl groups at the 5 and 9 positions resulted in an increased cytotoxic potency and ability to stabilize topoisomerase-mediated cleavage. In addition, the results suggest that some structural features, such as the pyrone ring and a polar group in position 11, are fundamental for topoisomerase I inhibitory effect. These structural requirements are also consistent with the cytotoxic activity.
ACS Medicinal Chemistry Letters, 2015
A study of structure-based modulation of known ligands of hTopoIIα, an important enzyme involved in DNA processes, coupled with synthesis and in vitro assays led to the establishment of a strategy of rational switch in mode of inhibition of the enzyme's catalytic cycle. 6-Arylated derivatives of known imidazopyridine ligands were found to be selective inhibitors of hTopoIIα, while not showing TopoI inhibition and DNA binding. Interestingly, while the parent imidazopyridines acted as ATP-competitive inhibitors, arylated derivatives inhibited DNA cleavage similar to merbarone, indicating a switch in mode of inhibition from ATP-hydrolysis to the DNA-cleavage stage of catalytic cycle of the enzyme. The 6-aryl-imidazopyridines were relatively more cytotoxic than etoposide in cancer cells and less toxic to normal cells. Such unprecedented strategy will encourage research on "choicebased change" in target-specific mode of action for rapid drug discovery.
Exploring DNA Topoisomerase I Ligand Space in Search of Novel Anticancer Agents
PLOS One, 2011
DNA topoisomerase I (Top1) is over-expressed in tumour cells and is an important target in cancer chemotherapy. It relaxes DNA torsional strain generated during DNA processing by introducing transient single-strand breaks and allowing the broken strand to rotate around the intermediate Top1 -DNA covalent complex. This complex can be trapped by a group of anticancer agents interacting with the DNA bases and the enzyme at the cleavage site, preventing further topoisomerase activity. Here we have identified novel Top1 inhibitors as potential anticancer agents by using a combination of structureand ligand-based molecular modelling methods. Pharmacophore models have been developed based on the molecular characteristics of derivatives of the alkaloid camptothecin (CPT), which represent potent antitumour agents and the main group of Top1 inhibitors. The models generated were used for in silico screening of the National Cancer Institute (NCI, USA) compound database, leading to the identification of a set of structurally diverse molecules. The strategy is validated by the observation that amongst these molecules are several known Top1 inhibitors and agents cytotoxic against human tumour cell lines. The potential of the untested hits to inhibit Top1 activity was further evaluated by docking into the binding site of a Top1 -DNA complex, resulting in a selection of 10 compounds for biological testing. Limited by the compound availability, 7 compounds have been tested in vitro for their Top1 inhibitory activity, 5 of which display mild to moderate Top1 inhibition. A further compound, found by similarity search to the active compounds, also shows mild activity. Although the tested compounds display only low in vitro antitumour activity, our approach has been successful in the identification of structurally novel Top1 inhibitors worthy of further investigation as potential anticancer agents.
Eukaryotic topoisomerases is widely used in anticancer drug development that they are essential for several cellular processes such as replication, transcription, and chromosome condensation. Their antitumor activity is related to the formation of protein-concealed DNA strand breaks, resulting in the stabilization by the drug of an intermediary complex of the Topo II reaction.1 In this study, a new series of benzazoles, has been investigated for their inhibitory activity on eukaryotic DNA topoisomerase II in cell free system.2 The goal of this research was that predictions from the structure activity relationships of these tested compounds possibly will lead to design more active new DNA topoisomerase II inhibitors. For the structure–activity relationship studies pharmacophore analysis was performed using Catalyst among a set of some Topo II inhibitor compounds which the general Formula given below.
Novel DNA Topoisomerase IIα Inhibitors from Combined Ligand- and Structure-Based Virtual Screening
PLoS ONE, 2014
DNA topoisomerases are enzymes responsible for the relaxation of DNA torsional strain, as well as for the untangling of DNA duplexes after replication, and are important cancer drug targets. One class of topoisomerase inhibitors, "poisons", binds to the transient enzyme-DNA complex which occurs during the mechanism of action, and inhibits the religation of DNA. This ultimately leads to the accumulation of DNA double strand breaks and cell death. Different types of topoisomerases occur in human cells and several poisons of topoisomerase I and II are widely used clinically. However, their use is compromised by a variety of side effects. Recent studies confirm that the inhibition of the α-isoform of topoisomerase II is responsible for the cytotoxic effect, whereas the inhibition of the β-isoform leads to development of adverse drug reactions. Thus, the discovery of agents selective for topoisomerase IIα is an important strategy for the development of topoisomerase II poisons with improved clinical profiles. Here, we present a computer-aided drug design study leading to the identification of structurally novel topoisomerase IIα poisons. The study combines ligand- and structure-based drug design methods including pharmacophore models, homology modelling, docking, and virtual screening of the National Cancer Institute compound database. From the 8 compounds identified from the computational work, 6 were tested for their capacity to poison topoisomerase II in vitro: 4 showed selective inhibitory activity for the α- over the β-isoform and 3 of these exhibited cytotoxic activity. Thus, our study confirms the applicability of computer-aided methods for the discovery of novel topoisomerase II poisons, and presents compounds which could be investigated further as selective topoisomerase IIα inhibitors.
Mechanism of action of eukaryotic DNA topoisomerase I and drugs targeted to the enzyme
Biochimica Et Biophysica Acta-gene Structure and Expression, 1998
DNA topoisomerase I is essential for cellular metabolism and survival. It is also the target of a novel class of anticancer drugs active against previously refractory solid tumors, the camptothecins. The present review describes the topoisomerase I catalytic mechanisms with particular emphasis on the cleavage complex that represents the enzyme's catalytic intermediate and the site of action for camptothecins. Roles of topoisomerase I in DNA replication, transcription and recombination are also reviewed. Because of the importance of topoisomerase I as a chemotherapeutic target, we review the mechanisms of action of camptothecins and the other topoisomerase I inhibitors identified to date. 0167-4781 / 98 / $^see front matter ß