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.

• MeSH
• antibiotika antitumorózní toxicita   MeSH
• antracykliny * toxicita   terapeutické užití   MeSH
• chinoxaliny * MeSH
• daunomycin toxicita   terapeutické užití   MeSH
• DNA-topoisomerasy typu II metabolismus   terapeutické užití   MeSH
• doxorubicin toxicita   MeSH
• inhibitory topoisomerasy II * toxicita   terapeutické užití   MeSH
• kardiotoxicita MeSH
• králíci MeSH
• krysa rodu rattus MeSH
• poškození DNA MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Anthracycline-induced heart failure has been traditionally attributed to direct iron-catalyzed oxidative damage. Dexrazoxane (DEX)-the only drug approved for its prevention-has been believed to protect the heart via its iron-chelating metabolite ADR-925. However, direct evidence is lacking, and recently proposed TOP2B (topoisomerase II beta) hypothesis challenged the original concept. METHODS: Pharmacokinetically guided study of the cardioprotective effects of clinically used DEX and its chelating metabolite ADR-925 (administered exogenously) was performed together with mechanistic experiments. The cardiotoxicity was induced by daunorubicin in neonatal ventricular cardiomyocytes in vitro and in a chronic rabbit model in vivo (n=50). RESULTS: Intracellular concentrations of ADR-925 in neonatal ventricular cardiomyocytes and rabbit hearts after treatment with exogenous ADR-925 were similar or exceeded those observed after treatment with the parent DEX. However, ADR-925 did not protect neonatal ventricular cardiomyocytes against anthracycline toxicity, whereas DEX exhibited significant protective effects (10-100 µmol/L; P<0.001). Unlike DEX, ADR-925 also had no significant impact on daunorubicin-induced mortality, blood congestion, and biochemical and functional markers of cardiac dysfunction in vivo (eg, end point left ventricular fractional shortening was 32.3±14.7%, 33.5±4.8%, 42.7±1.0%, and 41.5±1.1% for the daunorubicin, ADR-925 [120 mg/kg]+daunorubicin, DEX [60 mg/kg]+daunorubicin, and control groups, respectively; P<0.05). DEX, but not ADR-925, inhibited and depleted TOP2B and prevented daunorubicin-induced genotoxic damage. TOP2B dependency of the cardioprotective effects was probed and supported by experiments with diastereomers of a new DEX derivative. CONCLUSIONS: This study strongly supports a new mechanistic paradigm that attributes clinically effective cardioprotection against anthracycline cardiotoxicity to interactions with TOP2B but not metal chelation and protection against direct oxidative damage.

• MeSH
• antibiotika antitumorózní škodlivé účinky   farmakologie   MeSH
• antracykliny škodlivé účinky   farmakologie   MeSH
• daunomycin metabolismus   farmakologie   MeSH
• dexrazoxan škodlivé účinky   farmakologie   MeSH
• DNA-topoisomerasy typu II škodlivé účinky   metabolismus   MeSH
• inhibitory topoisomerasy II metabolismus   MeSH
• kardiomyocyty účinky léků   metabolismus   MeSH
• kardiotoxicita farmakoterapie   metabolismus   prevence a kontrola   MeSH
• lidé MeSH
• nemoci srdce farmakoterapie   MeSH
• oxidační stres účinky léků   MeSH
• srdeční selhání farmakoterapie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Cardioprotective activity of dexrazoxane (ICRF-187), the only clinically approved drug against anthracycline-induced cardiotoxicity, has traditionally been attributed to its iron-chelating metabolite. However, recent experimental evidence suggested that the inhibition and/or depletion of topoisomerase IIβ (TOP2B) by dexrazoxane could be cardioprotective. Hence, we evaluated a series of dexrazoxane analogues and found that their cardioprotective activity strongly correlated with their interaction with TOP2B in cardiomyocytes, but was independent of their iron chelation ability. Very tight structure-activity relationships were demonstrated on stereoisomeric forms of 4,4'-(butane-2,3-diyl)bis(piperazine-2,6-dione). In contrast to its rac-form 12, meso-derivative 11 (ICRF-193) showed a favorable binding mode to topoisomerase II in silico, inhibited and depleted TOP2B in cardiomyocytes more efficiently than dexrazoxane, and showed the highest cardioprotective efficiency. Importantly, the observed ICRF-193 cardioprotection did not interfere with the antiproliferative activity of anthracycline. Hence, this study identifies ICRF-193 as the new lead compound in the development of efficient cardioprotective agents.

• MeSH
• daunomycin toxicita   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• inhibitory topoisomerasy II chemická syntéza   metabolismus   terapeutické užití   MeSH
• kardiomyocyty účinky léků   MeSH
• kardiotonika chemická syntéza   metabolismus   terapeutické užití   MeSH
• kardiotoxicita farmakoterapie   MeSH
• lidé MeSH
• molekulární struktura MeSH
• nádorové buněčné linie MeSH
• novorozená zvířata MeSH
• piperaziny chemická syntéza   metabolismus   terapeutické užití   MeSH
• potkani Wistar MeSH
• proliferace buněk účinky léků   MeSH
• Saccharomyces cerevisiae - proteiny metabolismus   MeSH
• Saccharomyces cerevisiae chemie   MeSH
• simulace molekulární dynamiky MeSH
• simulace molekulového dockingu MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The bisdioxopiperazine topoisomerase IIβ inhibitor ICRF-193 has been previously identified as a more potent analog of dexrazoxane (ICRF-187), a drug used in clinical practice against anthracycline cardiotoxicity. However, the poor aqueous solubility of ICRF-193 has precluded its further in vivo development as a cardioprotective agent. To overcome this issue, water-soluble prodrugs of ICRF-193 were prepared, their abilities to release ICRF-193 were investigated using a novel UHPLC-MS/MS assay, and their cytoprotective effects against anthracycline cardiotoxicity were tested in vitro in neonatal ventricular cardiomyocytes (NVCMs). Based on the obtained results, the bis(2-aminoacetoxymethyl)-type prodrug GK-667 was selected for advanced investigations due to its straightforward synthesis, sufficient solubility, low cytotoxicity and favorable ICRF-193 release. Upon administration of GK-667 to NVCMs, the released ICRF-193 penetrated well into the cells, reached sufficient intracellular concentrations and provided effective cytoprotection against anthracycline toxicity. The pharmacokinetics of the prodrug, ICRF-193 and its rings-opened metabolite was estimated in vivo after administration of GK-667 to rabbits. The plasma concentrations of ICRF-193 reached were found to be adequate to achieve cardioprotective effects in vivo. Hence, GK-667 was demonstrated to be a pharmaceutically acceptable prodrug of ICRF-193 and a promising drug candidate for further evaluation as a potential cardioprotectant against chronic anthracycline toxicity.

• MeSH
• antracykliny škodlivé účinky   MeSH
• dexrazoxan chemie   farmakologie   MeSH
• diketopiperaziny chemie   farmakologie   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• inhibitory topoisomerasy II chemie   farmakologie   MeSH
• kardiomyocyty účinky léků   metabolismus   MeSH
• kardiotonika chemie   farmakologie   MeSH
• kardiotoxicita farmakoterapie   metabolismus   MeSH
• králíci MeSH
• piperazin chemie   farmakologie   MeSH
• prekurzory léčiv chemie   farmakologie   MeSH
• razoxan chemie   farmakologie   MeSH
• voda chemie   MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A549 human lung carcinoma cell lines were treated with a series of new drugs with both tacrine and coumarin pharmacophores (derivatives 1a-2c) in order to test the compounds' ability to inhibit both cancer cell growth and topoisomerase I and II activity. The ability of human topoisomerase I (hTOPI) and II to relax supercoiled plasmid DNA in the presence of various concentrations of the tacrine-coumarin hybrid molecules was studied with agarose gel electrophoresis. The biological activities of the derivatives were studied using MTT assays, clonogenic assays, cell cycle analysis and quantification of cell number and viability. The content and localization of the derivatives in the cells were analysed using flow cytometry and confocal microscopy. All of the studied compounds were found to have inhibited topoisomerase I activity completely. The effect of the tacrine-coumarin hybrid compounds on cancer cells is likely to be dependent on the length of the chain between the tacrine and coumarin moieties (1c, 1d = tacrine-(CH2)8-9-coumarin). The most active of the tested compounds, derivatives 1c and 1d, both display longer chains.

• MeSH
• antitumorózní látky chemie   farmakologie   MeSH
• buňky A549 MeSH
• DNA-topoisomerasy I metabolismus   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• inhibitory topoisomerasy I chemie   farmakologie   MeSH
• inhibitory topoisomerasy II chemie   farmakologie   MeSH
• kumariny chemie   farmakologie   MeSH
• léky antitumorózní - screeningové testy MeSH
• lidé MeSH
• molekulární struktura MeSH
• nádorové buňky kultivované MeSH
• proliferace buněk účinky léků   MeSH
• proteiny vázající poly-ADP-ribosu antagonisté a inhibitory   metabolismus   MeSH
• takrin chemie   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The importance of fluorescence light microscopy for understanding cellular and sub-cellular structures and functions is undeniable. However, the resolution is limited by light diffraction (~200-250 nm laterally, ~500-700 nm axially). Meanwhile, super-resolution microscopy, such as structured illumination microscopy (SIM), is being applied more and more to overcome this restriction. Instead, super-resolution by stimulated emission depletion (STED) microscopy achieving a resolution of ~50 nm laterally and ~130 nm axially has not yet frequently been applied in plant cell research due to the required specific sample preparation and stable dye staining. Single-molecule localization microscopy (SMLM) including photoactivated localization microscopy (PALM) has not yet been widely used, although this nanoscopic technique allows even the detection of single molecules. In this study, we compared protein imaging within metaphase chromosomes of barley via conventional wide-field and confocal microscopy, and the sub-diffraction methods SIM, STED, and SMLM. The chromosomes were labeled by DAPI (4',6-diamidino-2-phenylindol), a DNA-specific dye, and with antibodies against topoisomerase IIα (Topo II), a protein important for correct chromatin condensation. Compared to the diffraction-limited methods, the combination of the three different super-resolution imaging techniques delivered tremendous additional insights into the plant chromosome architecture through the achieved increased resolution.

• MeSH
• chromozomy rostlin chemie   genetika   metabolismus   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• fluorescenční barviva chemie   MeSH
• fluorescenční mikroskopie metody   MeSH
• indoly chemie   MeSH
• ječmen (rod) cytologie   genetika   MeSH
• konfokální mikroskopie metody   MeSH
• metafáze genetika   MeSH
• reprodukovatelnost výsledků MeSH
• zobrazení jednotlivé molekuly metody   MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

A series of new 3,6,9-trisubstituted acridine derivatives with fluorine substituents on phenyl ring were synthesized and their interaction with calf thymus DNA was investigated. Analysis using UV-Vis absorbance spectra provided valuable information about the formation of the acridine-DNA complex. In addition, compounds 8b and 8d were found to display an increased binding affinity (K = 2.32 and 2.28 × 106 M-1, respectively). Topo I/II inhibition mode assays were also performed, and the results verify that the novel compounds display topoisomerase I and II inhibitory activity; compounds 8a, 8b and 8c completely inhibited topoisomerase I activity at a concentration of 60 × 10-6 M, but only compound 8d showed partial ability to inhibit topoisomerase II at concentrations of 30 and 50 × 10-6 M. The ability of the derivatives to impair cell proliferation was tested through an analysis of cell cycle distribution, quantification of cell number, viability studies, metabolic activity measurement and clonogenic assay. The content and localization of the derivatives in cells were analyzed using flow cytometry and fluorescence microscopy. The compounds 8b and 8d altered the physiochemical properties and improved antiproliferative activity in A549 human lung carcinoma cells (compound 8d displayed the highest level of activity, 4.25 × 10-6 M, after 48 h).

• MeSH
• akridiny chemická syntéza   chemie   farmakologie   MeSH
• antitumorózní látky chemická syntéza   chemie   farmakologie   MeSH
• buňky A549 MeSH
• DNA-topoisomerasy I metabolismus   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• DNA účinky léků   MeSH
• halogenace MeSH
• inhibitory topoisomerasy I chemická syntéza   chemie   farmakologie   MeSH
• inhibitory topoisomerasy II chemická syntéza   chemie   farmakologie   MeSH
• léky antitumorózní - screeningové testy MeSH
• lidé MeSH
• molekulární struktura MeSH
• proliferace buněk účinky léků   MeSH
• skot MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Bisdioxopiperazine agent dexrazoxane (ICRF-187) has been the only effective and approved drug for prevention of chronic anthracycline cardiotoxicity. However, the structure-activity relationships (SARs) of its cardioprotective effects remain obscure owing to limited investigation of its derivatives/analogs and uncertainties about its mechanism of action. To fill these knowledge gaps, we tested the hypothesis that dexrazoxane derivatives exert cardioprotection via metal chelation and/or modulation of topoisomerase IIβ (Top2B) activity in chronic anthracycline cardiotoxicity. Dexrazoxane was alkylated in positions that should not interfere with the metal-chelating mechanism of cardioprotective action; that is, on dioxopiperazine imides or directly on the dioxopiperazine ring. The protective effects of these agents were assessed in vitro in neonatal cardiomyocytes. All studied modifications of dexrazoxane molecule, including simple methylation, were found to abolish the cardioprotective effects. Because this challenged the prevailing mechanistic concept and previously reported data, the two closest derivatives [(±)-4,4'-(propane-1,2-diyl)bis(1-methylpiperazine-2,6-dione) and 4-(2-(3,5-dioxopiperazin-1-yl)ethyl)-3-methylpiperazine-2,6-dione] were thoroughly scrutinized in vivo using a rabbit model of chronic anthracycline cardiotoxicity. In contrast to dexrazoxane, both compounds failed to protect the heart, as demonstrated by mortality, cardiac dysfunction, and myocardial damage parameters, although the pharmacokinetics and metal-chelating properties of their metabolites were comparable to those of dexrazoxane. The loss of cardiac protection was shown to correlate with their abated potential to inhibit and deplete Top2B both in vitro and in vivo. These findings suggest a very tight SAR between bisdioxopiperazine derivatives and their cardioprotective effects and support Top2B as a pivotal upstream druggable target for effective cardioprotection against anthracycline cardiotoxicity. SIGNIFICANCE STATEMENT: This study has revealed the previously unexpected tight structure-activity relationships of cardioprotective effects in derivatives of dexrazoxane, which is the only drug approved for the prevention of cardiomyopathy and heart failure induced by anthracycline anticancer drugs. The data presented in this study also strongly argue against the importance of metal-chelating mechanisms for the induction of this effect and support the viability of topoisomerase IIβ as an upstream druggable target for effective and clinically translatable cardioprotection.

• MeSH
• antracykliny škodlivé účinky   MeSH
• dexrazoxan farmakologie   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• HL-60 buňky MeSH
• inhibitory topoisomerasy II farmakologie   MeSH
• kardiomyocyty účinky léků   metabolismus   MeSH
• kardiomyopatie farmakoterapie   metabolismus   MeSH
• kardiotoxicita farmakoterapie   MeSH
• králíci MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• modely u zvířat MeSH
• myokard metabolismus   MeSH
• nádorové buněčné linie MeSH
• ochranné látky farmakologie   MeSH
• potkani Wistar MeSH
• srdce účinky léků   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Background: Iron oxide nanoparticles (IONs) have been increasingly utilized in a wide spectrum of biomedical applications. Surface coatings of IONs can bestow a number of exceptional properties, including enhanced stability of IONs, increased loading of drugs or their controlled release. Methods: Using two-step sonochemical protocol, IONs were surface-coated with polyoxyethylene stearate, polyvinylpyrrolidone or chitosan for a loading of two distinct topo II poisons (doxorubicin and ellipticine). The cytotoxic behavior was tested in vitro against breast cancer (MDA-MB-231) and healthy epithelial cells (HEK-293 and HBL-100). In addition, biocompatibility studies (hemotoxicity, protein corona formation, binding of third complement component) were performed. Results: Notably, despite surface-coated IONs exhibited only negligible cytotoxicity, upon tethering with topo II poisons, synergistic or additional enhancement of cytotoxicity was found in MDA-MB-231 cells. Pronounced anti-migratory activity, DNA fragmentation, decrease in expression of procaspase-3 and enhancement of p53 expression were further identified upon exposure to surface-coated IONs with tethered doxorubicin and ellipticine. Moreover, surface-coated IONs nanoformulations of topo II poisons exhibited exceptional stability in human plasma with no protein corona and complement 3 binding, and only a mild induction of hemolysis in human red blood cells. Conclusion: The results imply a high potential of an efficient ultrasound-mediated surface functionalization of IONs as delivery vehicles to improve therapeutic efficiency of topo II poisons.

• MeSH
• biokompatibilní potahované materiály chemie   MeSH
• buněčná smrt účinky léků   MeSH
• buněčné linie MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• doxorubicin farmakologie   MeSH
• hojení ran účinky léků   MeSH
• inhibitory topoisomerasy II farmakologie   MeSH
• kinetika MeSH
• lidé MeSH
• nanočástice chemie   MeSH
• pohyb buněk účinky léků   MeSH
• povrchové vlastnosti MeSH
• statická elektřina MeSH
• uvolňování léčiv * MeSH
• vibrace ultrazvukové metody   MeSH
• železité sloučeniny chemie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Novel dexrazoxane derivative JR-311 was prepared to investigate structure-activity relationships and mechanism(s) of protection against anthracycline cardiotoxicity. Its cardioprotective, antiproliferative, iron (Fe) chelation and inhibitory and/or depletory activities on topoisomerase IIbeta (TOP2B) were examined and compared with dexrazoxane. While in standard assay, JR-311 failed in both cardioprotection and depletion of TOP2B, its repeated administration to cell culture media led to depletion of TOP2B and significant protection of isolated rat neonatal ventricular cardiomyocytes from daunorubicin-induced damage. This effect was explained by a focused analytical investigation that revealed rapid JR-311 decomposition, resulting in negligible intracellular concentrations of the parent compound but high exposure of cells to the decomposition products, including Fe-chelating JR-H2. Although chemical instability is an obstacle for the development of JR-311, this study identified a novel dexrazoxane analogue with preserved pharmacodynamic properties, contributed to the investigation of structure-activity relationships and suggested that the cardioprotection of bis-dioxopiperazines is likely attributed to TOP2B activity of the parent compound rather than Fe chelation of their hydrolytic metabolites/degradation products. Moreover, this study highlights the importance of early stability testing during future development of novel dexrazoxane analogues.

• MeSH
• antracykliny toxicita   MeSH
• chelátory železa farmakologie   MeSH
• daunomycin toxicita   MeSH
• dexrazoxan analogy a deriváty   farmakologie   MeSH
• diketopiperaziny farmakologie   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• kardiomyocyty účinky léků   MeSH
• kardiotonika farmakologie   MeSH
• kardiotoxicita farmakoterapie   etiologie   MeSH
• krysa rodu rattus MeSH
• kultivované buňky MeSH
• novorozená zvířata MeSH
• potkani Wistar MeSH
• proliferace buněk účinky léků   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• železo metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH