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.
- MeSH
- chromozomy genetika MeSH
- DNA vazebné proteiny chemie genetika MeSH
- DNA-topoisomerasy typu II chemie genetika MeSH
- DNA chemie genetika MeSH
- dvouřetězcové zlomy DNA * MeSH
- etoposid chemie MeSH
- genetická transkripce MeSH
- genová konverze genetika MeSH
- HCT116 buňky MeSH
- inhibitory topoisomerasy II chemie farmakologie MeSH
- kinetika MeSH
- lidé MeSH
- multiproteinové komplexy chemie genetika MeSH
- oprava DNA genetika MeSH
- proteiny vázající poly-ADP-ribosu chemie genetika MeSH
- torze mechanická MeSH
- translokace genetická genetika MeSH
- zlomy chromozomů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Intramural MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
In this study, enhancement of the electrochemical signals of etoposide (ETO) measured by differential pulse voltammetry (DPV) by modifying a glassy carbon electrode (GCE) with carbon quantum dots (CQDs) is demonstrated. In comparison with a bare GCE, the modified GCE exhibited a higher sensitivity towards electrochemical detection of ETO. The lowest limit of detection was observed to be 5 nM ETO. Furthermore, scanning electron microscopy (SEM), fluorescence microscopy (FM), and electrochemical impedance spectroscopy (EIS) were employed for the further study of the working electrode surface after the modification with CQDs. Finally, the GCE modified with CQDs under optimized conditions was used to analyse real samples of ETO in the prostate cancer cell line PC3. After different incubation times (1, 3, 6, 9, 12, 18 and 24 h), these samples were then prepared prior to electrochemical detection by the GCE modified with CQDs. High performance liquid chromatography with an electrochemical detection method was employed to verify the results from the GCE modified with CQDs.
- MeSH
- elektrochemie přístrojové vybavení metody MeSH
- elektrody MeSH
- etoposid analýza chemie farmakologie MeSH
- kvantové tečky chemie MeSH
- lidé MeSH
- limita detekce MeSH
- nádorové buněčné linie MeSH
- povidon chemie MeSH
- sklo chemie MeSH
- uhlík chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Liposome-based drug delivery systems hold great potential for cancer therapy. The aim of this study was to design a nanodevice for targeted anchoring of liposomes (with and without cholesterol) with encapsulated anticancer drugs and antisense N-myc gene oligonucleotide attached to its surface. To meet this main aim, liposomes with encapsulated doxorubicin, ellipticine and etoposide were prepared. They were further characterized by measuring their fluorescence intensity, whereas the encapsulation efficiency was estimated to be 16%. The hybridization process of individual oligonucleotides forming the nanoconstruct was investigated spectrophotometrically and electrochemically. The concentrations of ellipticine, doxorubicin and etoposide attached to the nanoconstruct in gold nanoparticle-modified liposomes were found to be 14, 5 and 2 µg·mL(-1), respectively. The study succeeded in demonstrating that liposomes are suitable for the transport of anticancer drugs and the antisense oligonucleotide, which can block the expression of the N-myc gene.
- MeSH
- antisense DNA chemie terapeutické užití MeSH
- doxorubicin chemie terapeutické užití MeSH
- elipticiny chemie terapeutické užití MeSH
- etoposid chemie terapeutické užití MeSH
- fluorescence MeSH
- lidé MeSH
- liposomy chemie terapeutické užití MeSH
- magnetické nanočástice chemie terapeutické užití MeSH
- nádory farmakoterapie MeSH
- protoonkogen n-myc antagonisté a inhibitory genetika MeSH
- systémy cílené aplikace léků * MeSH
- zlato chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- akutní myeloidní leukemie farmakoterapie MeSH
- antitumorózní látky farmakologie škodlivé účinky terapeutické užití MeSH
- etoposid farmakologie chemie terapeutické užití MeSH
- lidé MeSH
- nádory plic farmakoterapie MeSH
- nádory žaludku farmakoterapie MeSH
- nehodgkinský lymfom farmakoterapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- klinické zkoušky MeSH
- přehledy MeSH
