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Marie Stiborová - One of the best experts on this subject based on the ideXlab platform.
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application of hepatic cytochrome b5 p450 reductase null hbrn mice to study the role of cytochrome b5 in the cytochrome p450 mediated bioactivation of the anticancer drug Ellipticine
Toxicology and Applied Pharmacology, 2019Co-Authors: Lindsay Reed, Michaela Moserová, Marie Stiborová, Radek Indra, David H Phillips, Iveta Mrizova, Heinz H Schmeiser, Colin J Henderson, Roland C Wolf, Volker M ArltAbstract:Abstract The anticancer drug Ellipticine exerts its genotoxic effects after metabolic activation by cytochrome P450 (CYP) enzymes. The present study has examined the role of cytochrome P450 oxidoreductase (POR) and cytochrome b5 (Cyb5), electron donors to P450 enzymes, in the CYP-mediated metabolism and disposition of Ellipticine in vivo. We used Hepatic Reductase Null (HRN) and Hepatic Cytochrome b5/P450 Reductase Null (HBRN) mice. HRN mice have POR deleted specifically in hepatocytes; HBRN mice also have Cyb5 deleted in the liver. Mice were treated once with 10 mg/kg body weight Ellipticine (n = 4/group) for 24 h. Ellipticine-DNA adduct levels measured by 32P-postlabelling were significantly lower in HRN and HBRN livers than in wild-type (WT) livers; however no significant difference was observed between HRN and HBRN livers. Ellipticine-DNA adduct formation in WT, HRN and HBRN livers correlated with Cyp1a and Cyp3a enzyme activities measured in hepatic microsomes in the presence of NADPH confirming the importance of P450 enzymes in the bioactivation of Ellipticine in vivo. Hepatic microsomal fractions were also utilised in incubations with Ellipticine and DNA in the presence of NADPH, cofactor for POR, and NADH, cofactor for Cyb5 reductase (Cyb5R), to examine Ellipticine-DNA adduct formation. With NADPH adduct formation decreased as electron donors were lost which correlated with the formation of the reactive metabolites 12- and 13-hydroxy-Ellipticine in hepatic microsomes. No difference in adduct formation was observed in the presence of NADH. Our study demonstrates that Cyb5 contributes to the P450-mediated bioactivation of Ellipticine in vitro, but not in vivo.
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tyrosine kinase inhibitors vandetanib lenvatinib and cabozantinib modulate oxidation of an anticancer agent Ellipticine catalyzed by cytochromes p450 in vitro
Neuro endocrinology letters, 2019Co-Authors: Matus Kolarik, Radek Indra, Volker M Arlt, Vojtech Adam, Zbynek Heger, Katerina Kopeckova, Marie StiborováAbstract:Objectives Vandetanib¸ lenvatinib, and cabozantinib are tyrosine kinase inhibitors (TKIs) targeting VEGFR subtypes 1 and 2, EGFR and the RET-tyrosine kinase, thus considered as multiple TKIs. These TKIs have already been approved for treating patients suffering from thyroid cancer and renal cell carcinoma. Ellipticine, a DNA-damaging drug, is another anticancer agent that is effective against certain tumors of the thyroid gland, ovarian carcinoma, breast cancer and osteolytic breast cancer metastasis. Its anticancer efficiency is dictated by its oxidation with cytochrome P450 (CYP) and peroxidase enzymes. A number of studies testing the effectiveness of individual anticancer drugs, the pharmacological efficiencies of which are affected by their metabolism, alone or in a combination with other cytostatics demonstrated that such combination can have both positive and negative effects on treatment regimen. The aim of this study was to study the effect of vandetanib, lenvatinib and cabozantinib on oxidation of Ellipticine which dictates its pharmacological efficiency. Methods Ellipticine oxidation catalyzed by hepatic microsomes, recombinant CYP enzymes and peroxidases (horseradish peroxidase, lactoperoxidase and myeloperoxidase) and the effect of TKIs (vandetanib, lenvatinib and cabozantinib) on this oxidation were analyzed by HPLC used for separation of Ellipticine metabolites and quantification of their amounts formed during oxidation. Results The CYP enzymatic system oxidizes Ellipticine up to five metabolites (9-hydroxy-, 12-hydroxy-, 13-hydroxy-, 7-hydroxyEllipticine, and Ellipticine N2- oxide), while peroxidases form predominantly Ellipticine dimer. Ellipticine oxidation catalyzed by rat and human hepatic microsomes was inhibited by vandetanib and cabozantinib, but essentially no inhibition was caused by lenvatinib. Of individual CYP enzymes catalyzing oxidation of Ellipticine, TKIs inhibited oxidation of Ellipticine catalyzed by CYP2D6 > 2D1 > 2C9 > 3A1 > 3A4, the CYP enzymes participating in Ellipticine oxidation to metabolites increasing the Ellipticine anticancer efficiency. On the contrary, they have essentially no inhibition effect on Ellipticine oxidation catalyzed by CYP1A1 and 1A2, which are the enzymes that predominantly detoxify this drug. All tested TKIs had essentially no effect on oxidation of Ellipticine by used peroxidases. Conclusion The results found demonstrate that TKIs vandetanib, lenvatinib and cabozantinib cause a decrease in oxidative activation of DNA-damaging drug Ellipticine by several CYP enzymes in vitro which might lead to a decrease in its pharmacological efficiency. In contrast, they practically do not influence its detoxification catalyzed by CYP1A1, 1A2 and peroxidases. The present study indicates that tested TKIs seem not to have a potency to increase Ellipticine anticancer efficiency.
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the impact of chemotherapeutic drugs on the cyp1a1 catalysed metabolism of the environmental carcinogen benzo a pyrene effects in human colorectal hct116 tp53 tp53 and tp53 cells
Toxicology, 2018Co-Authors: Alexandra J Willis, Marie Stiborová, Radek Indra, David H Phillips, Laura E Wohak, Osman Sozeri, Kerstin Feser, Iveta Mrizova, Volker M ArltAbstract:Abstract Polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) can induce cytochrome P450 1A1 (CYP1A1) via a p53-dependent mechanism. The effect of different p53-activating chemotherapeutic drugs on CYP1A1 expression, and the resultant effect on BaP metabolism, was investigated in a panel of isogenic human colorectal HCT116 cells with differing TP53 status. Cells that were TP53(+/+), TP53(+/–) or TP53(–/–) were treated for up to 48 h with 60 μM cisplatin, 50 μM etoposide or 5 μM Ellipticine, each of which caused high p53 induction at moderate cytotoxicity (60–80% cell viability). We found that etoposide and Ellipticine induced CYP1A1 in TP53(+/+) cells but not in TP53(–/–) cells, demonstrating that the mechanism of CYP1A1 induction is p53-dependent; cisplatin had no such effect. Co-incubation experiments with the drugs and 2.5 μM BaP showed that: (i) etoposide increased CYP1A1 expression in TP53(+/+) cells, and to a lesser extent in TP53(–/–) cells, compared to cells treated with BaP alone; (ii) Ellipticine decreased CYP1A1 expression in TP53(+/+) cells in BaP co-incubations; and (iii) cisplatin did not affect BaP-mediated CYP1A1 expression. Further, whereas cisplatin and etoposide had virtually no influence on CYP1A1-catalysed BaP metabolism, Ellipticine treatment strongly inhibited BaP bioactivation. Our results indicate that the underlying mechanisms whereby etoposide and Ellipticine regulate CYP1A1 expression must be different and may not be linked to p53 activation alone. These results could be relevant for smokers, who are exposed to increased levels of BaP, when prescribing chemotherapeutic drugs. Beside gene-environment interactions, more considerations should be given to potential drug-environment interactions during chemotherapy.
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the histone deacetylase inhibitor valproic acid exerts a synergistic cytotoxicity with the dna damaging drug Ellipticine in neuroblastoma cells
International Journal of Molecular Sciences, 2018Co-Authors: Tereza Cerna, Eva Frei, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Jan Hrabeta, Marie StiborováAbstract:Neuroblastoma (NBL) originates from undifferentiated cells of the sympathetic nervous system. Chemotherapy is judged to be suitable for successful treatment of this disease. Here, the influence of histone deacetylase (HDAC) inhibitor valproate (VPA) combined with DNA-damaging chemotherapeutic, Ellipticine, on UKF-NB-4 and SH-SY5Y neuroblastoma cells was investigated. Treatment of these cells with Ellipticine in combination with VPA led to the synergism of their anticancer efficacy. The effect is more pronounced in the UKF-NB-4 cell line, the line with N-myc amplification, than in SH-SY5Y cells. This was associated with caspase-3-dependent induction of apoptosis in UKF-NB-4 cells. The increase in cytotoxicity of Ellipticine in UKF-NB-4 by VPA is dictated by the sequence of drug administration; the increased cytotoxicity was seen only after either simultaneous exposure to these drugs or after pretreatment of cells with Ellipticine before their treatment with VPA. The synergism of treatment of cells with VPA and Ellipticine seems to be connected with increased acetylation of histones H3 and H4. Further, co-treatment of cells with Ellipticine and VPA increased the formation of Ellipticine-derived DNA adducts, which indicates an easier accessibility of Ellipticine to DNA in cells by its co-treatment with VPA and also resulted in higher Ellipticine cytotoxicity. The results are promising for in vivo studies and perhaps later for clinical studies of combined treatment of children suffering from high-risk NBL.
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cytochrome b5 plays a dual role in the reaction cycle of cytochrome p450 3a4 during oxidation of the anticancer drug Ellipticine
Monatshefte Fur Chemie, 2017Co-Authors: Marie Stiborová, Eva Frei, Radek Indra, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Zbyněk Heger, Vojtěch Adam, Kateřina Kopeckova, Vaclav MartinekAbstract:Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important Ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b 5 reductase and/or cytochrome b 5 in Supersomes™ to oxidize this drug. We also evaluated the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b 5 reductase, to mediate Ellipticine oxidation in these enzyme systems. Using HPLC analysis we detected up to five Ellipticine metabolites, which were formed by human hepatic microsomes and human CYP3A4 in the presence of NADPH or NADH. Among Ellipticine metabolites, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine were formed by hepatic microsomes as the major metabolites, while 7-hydroxyEllipticine and the Ellipticine N 2-oxide were the minor ones. Human CYP3A4 in Supersomes™ generated only three metabolic products, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine. Using the 32P-postlabeling method two Ellipticine-derived DNA adducts were generated by microsomes and the CYP3A4-Supersome system, both in the presence of NADPH and NADH. These adducts were derived from the reaction of 13-hydroxy- and 12-hydroxyEllipticine with deoxyguanosine in DNA. In the presence of NADPH or NADH, cytochrome b 5 stimulated the CYP3A4-mediated oxidation of Ellipticine, but the stimulation effect differed for individual Ellipticine metabolites. This heme protein also stimulated the formation of both Ellipticine-DNA adducts. The results demonstrate that cytochrome b 5 plays a dual role in the CYP3A4-catalyzed oxidation of Ellipticine: (1) cytochrome b 5 mediates CYP3A4 catalytic activities by donating the first and second electron to this enzyme in its catalytic cycle, indicating that NADH:cytochrome b 5 reductase can substitute NADPH-dependent POR in this enzymatic reaction and (2) cytochrome b 5 can act as an allosteric modifier of the CYP3A4 oxygenase.
Eva Frei - One of the best experts on this subject based on the ideXlab platform.
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the histone deacetylase inhibitor valproic acid exerts a synergistic cytotoxicity with the dna damaging drug Ellipticine in neuroblastoma cells
International Journal of Molecular Sciences, 2018Co-Authors: Tereza Cerna, Eva Frei, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Jan Hrabeta, Marie StiborováAbstract:Neuroblastoma (NBL) originates from undifferentiated cells of the sympathetic nervous system. Chemotherapy is judged to be suitable for successful treatment of this disease. Here, the influence of histone deacetylase (HDAC) inhibitor valproate (VPA) combined with DNA-damaging chemotherapeutic, Ellipticine, on UKF-NB-4 and SH-SY5Y neuroblastoma cells was investigated. Treatment of these cells with Ellipticine in combination with VPA led to the synergism of their anticancer efficacy. The effect is more pronounced in the UKF-NB-4 cell line, the line with N-myc amplification, than in SH-SY5Y cells. This was associated with caspase-3-dependent induction of apoptosis in UKF-NB-4 cells. The increase in cytotoxicity of Ellipticine in UKF-NB-4 by VPA is dictated by the sequence of drug administration; the increased cytotoxicity was seen only after either simultaneous exposure to these drugs or after pretreatment of cells with Ellipticine before their treatment with VPA. The synergism of treatment of cells with VPA and Ellipticine seems to be connected with increased acetylation of histones H3 and H4. Further, co-treatment of cells with Ellipticine and VPA increased the formation of Ellipticine-derived DNA adducts, which indicates an easier accessibility of Ellipticine to DNA in cells by its co-treatment with VPA and also resulted in higher Ellipticine cytotoxicity. The results are promising for in vivo studies and perhaps later for clinical studies of combined treatment of children suffering from high-risk NBL.
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cytochrome b5 plays a dual role in the reaction cycle of cytochrome p450 3a4 during oxidation of the anticancer drug Ellipticine
Monatshefte Fur Chemie, 2017Co-Authors: Marie Stiborová, Eva Frei, Radek Indra, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Zbyněk Heger, Vojtěch Adam, Kateřina Kopeckova, Vaclav MartinekAbstract:Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important Ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b 5 reductase and/or cytochrome b 5 in Supersomes™ to oxidize this drug. We also evaluated the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b 5 reductase, to mediate Ellipticine oxidation in these enzyme systems. Using HPLC analysis we detected up to five Ellipticine metabolites, which were formed by human hepatic microsomes and human CYP3A4 in the presence of NADPH or NADH. Among Ellipticine metabolites, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine were formed by hepatic microsomes as the major metabolites, while 7-hydroxyEllipticine and the Ellipticine N 2-oxide were the minor ones. Human CYP3A4 in Supersomes™ generated only three metabolic products, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine. Using the 32P-postlabeling method two Ellipticine-derived DNA adducts were generated by microsomes and the CYP3A4-Supersome system, both in the presence of NADPH and NADH. These adducts were derived from the reaction of 13-hydroxy- and 12-hydroxyEllipticine with deoxyguanosine in DNA. In the presence of NADPH or NADH, cytochrome b 5 stimulated the CYP3A4-mediated oxidation of Ellipticine, but the stimulation effect differed for individual Ellipticine metabolites. This heme protein also stimulated the formation of both Ellipticine-DNA adducts. The results demonstrate that cytochrome b 5 plays a dual role in the CYP3A4-catalyzed oxidation of Ellipticine: (1) cytochrome b 5 mediates CYP3A4 catalytic activities by donating the first and second electron to this enzyme in its catalytic cycle, indicating that NADH:cytochrome b 5 reductase can substitute NADPH-dependent POR in this enzymatic reaction and (2) cytochrome b 5 can act as an allosteric modifier of the CYP3A4 oxygenase.
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The Anticancer Drug Ellipticine Induces Cytochromes P450 1A1, 1A2 and 3A, Cytochrome b5 and NADPH:Cytochrome
2015Co-Authors: P Oxidoreductase, Rat Liver, Iveta Vranová, Michaela Moserová, Petr Hodek, Rene Kizek, Eva Frei, Marie StiborováAbstract:The antineoplastic alkaloid Ellipticine is a prodrug, the pharmacological efficiency of which is dependent on its cytochrome P450 (CYP)- and/or peroxidase-mediated activation in target tissues. Using the Western blotting, we found that this compound increases protein expression of cytochrome b5, CYP1A1, 1A2, 3A and NADPH:CYP oxidoreductase (POR) in livers, lungs and kidneys of rats treated (i.p.) with Ellipticine. The Ellipticine-mediated induction of these enzymes resulted in an increase in their enzymatic activities and Ellipticine oxidation to 7-hydroxy-, 9-hydroxy-, 12-hydroxy-and 13-hydroxyEllipticine, the metabolites that are both detoxication products (7-hydroxy-, 9-hydroxyEllipticine) and metabolites responsible for generation Ellipticine-derived DNA adducts (12-hydroxy- and 13-hydroxyEllipticine). The results demonstrate that by inducing CYP1A1/2, 3A, POR and cytochrome b5, Ellipticine increases its own metabolism in rats, thereby modulating its own pharmacological and/or genotoxic potential
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Electrochemical Determination of Enzymes Metabolizing Ellipticine in Thyroid Cancer Cells- a Tool to Explain the Mechanism of Ellipticine Toxicity to these Cells
2015Co-Authors: Jitka Poljaková, Rene Kizek, Eva Frei, Tomas Eckschlager, Jindřich Činátl, Marie StiborováAbstract:The antineoplastic alkaloid Ellipticine is a prodrug, the pharmacological efficiency of which is dependent on its cytochrome P450 (CYP)- and/or peroxidase-mediated activation to species forming DNA adducts in target tissues. Here, we found that this compound is cytotoxic to human BHT-101, B-CPAP and 8505-C thyroid cancer cells and blocks one or more phases of cell cycle in these cancer cells. Ellipticine toxicity to the thyroid cancer cells corresponded to levels of DNA adducts generated by the CYP- and/or peroxidase-mediated Ellipticine metabolites, 12-hydroxy- and 13-hydroxyEllipticine, in these cells. Cultivation of all tested cells under hypoxic conditions (1 % oxygen) led to a decrease in Ellipticine toxicity. Such a lower sensitivity of cells to Ellipticine correlates with a decrease in the formation of Ellipticine-derived DNA adducts in these cells. Using Western blotting, the expression of CYP1A1, 1B1, 3A4, thyroid peroxidase (TPO), cyclooxygenase-1 (COX-1) an
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vacuolar atpase mediated intracellular sequestration of Ellipticine contributes to drug resistance in neuroblastoma cells
International Journal of Oncology, 2015Co-Authors: Jan Hrabeta, Rene Kizek, Jitka Poljaková, Tomas Groh, Mohamed Ashraf Khalil, Vojtech Adam, Jiri Uhlik, Helena Doktorova, Tereza Cerna, Eva FreiAbstract:Neuroblastoma is the most common cancer in infants and the fourth most common cancer in children. Aggressive cell growth and chemoresistance are notorious obstacles in neuroblastoma therapy. Exposure to the anticancer drug Ellipticine inhibits efficiently growth of neuroblastoma cells and induces apoptosis in these cells. However, Ellipticine induced resistance in these cells. The upregulation of a vacuolar (V)-ATPase gene is one of the factors associated with resistance development. In accordance with this finding, we found that levels of V-ATPase protein expression are higher in the Ellipticine-resistant UKF-NB-4ELLI line than in the parental Ellipticine-sensitive UKF-NB-4 cell line. Treatment of Ellipticine-sensitive UKF-NB-4 and Ellipticine-resistant UKF-NB-4ELLI cells with Ellipticine-induced cytoplasmic vacuolization and Ellipticine is concentrated in these vacuoles. Confocal microscopy and staining of the cells with a lysosomal marker suggested these vacuoles as lysosomes. Transmission electron microscopy and no effect of an autophagy inhibitor wortmannin ruled out autophagy. Pretreatment with a V-ATPase inhibitor bafilomycin A and/or the lysosomotropic drug chloroquine prior to Ellipticine enhanced the Ellipticine‑mediated apoptosis and decreased Ellipticine-resistance in UKF-NB-4ELLI cells. Moreover, pretreatment with these inhibitors increased formation of Ellipticine-derived DNA adducts, one of the most important DNA-damaging mechanisms responsible for Ellipticine cytotoxicity. In conclusion, resistance to Ellipticine in the tested neuroblastoma cells is associated with V-ATPase-mediated vacuolar trapping of this drug, which may be decreased by bafilomycin A and/or chloroquine.
Tomas Eckschlager - One of the best experts on this subject based on the ideXlab platform.
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Ellipticine loaded apoferritin nanocarrier retains dna adduct based cytochrome p450 facilitated toxicity in neuroblastoma cells
Toxicology, 2019Co-Authors: Radek Indra, Tereza Cerna, Jan Hraběta, Zbyněk Heger, Marek Wilhelm, Simona Dostalova, Alžběta Lengalova, Marketa Martinkova, Vojtěch Adam, Tomas EckschlagerAbstract:Although Ellipticine (Elli) is an efficient anticancer agent, it exerts several adverse effects. One approach to decrease the adverse effects of drugs is their encapsulation inside a suitable nanocarrier, allowing targeted delivery to tumour tissue whereas avoiding healthy cells. We constructed a nanocarrier from apoferritin (Apo) bearing Ellipticine, ApoElli, and subsequently characterized. The nanocarrier exhibits a narrow size distribution suggesting its suitability for entrapping the hydrophobic Ellipticine molecule. Ellipticine was released from ApoElli into the water environment under pH 6.5, but only less than 20% was released at pH 7.4. The interaction of ApoElli with microsomal membrane particles containing cytochrome P450 (CYP) biotransformation enzymes accelerated the release of Ellipticine from this nanocarrier making it possible to be transferred into this membrane system even at pH 7.4 and facilitating CYP-mediated metabolism. Reactive metabolites were formed not only from free Ellipticine, but also from ApoElli, and both generated covalent DNA adducts. ApoElli was toxic in UKF-NB-4 neuroblastoma cells, but showed significantly lower cytotoxicity in non-malignant fibroblast HDFn cells. Ellipticine either free or released from ApoElli was concentrated in the nuclei of neuroblastoma cells, concentrations of which being significantly higher in nuclei of UKF-NB-4 than in HDFn cells. In HDFn the higher amounts of Ellipticine were sequestrated in lysosomes. The extent of ApoElli entering the nuclei in UKF-NB-4 cells was lower than that of free Ellipticine and correlated with the formation of Ellipticine-derived DNA adducts. Our study indicates that the ApoElli form of Ellipticine seems to be a promising tool for neuroblastoma treatment.
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the histone deacetylase inhibitor valproic acid exerts a synergistic cytotoxicity with the dna damaging drug Ellipticine in neuroblastoma cells
International Journal of Molecular Sciences, 2018Co-Authors: Tereza Cerna, Eva Frei, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Jan Hrabeta, Marie StiborováAbstract:Neuroblastoma (NBL) originates from undifferentiated cells of the sympathetic nervous system. Chemotherapy is judged to be suitable for successful treatment of this disease. Here, the influence of histone deacetylase (HDAC) inhibitor valproate (VPA) combined with DNA-damaging chemotherapeutic, Ellipticine, on UKF-NB-4 and SH-SY5Y neuroblastoma cells was investigated. Treatment of these cells with Ellipticine in combination with VPA led to the synergism of their anticancer efficacy. The effect is more pronounced in the UKF-NB-4 cell line, the line with N-myc amplification, than in SH-SY5Y cells. This was associated with caspase-3-dependent induction of apoptosis in UKF-NB-4 cells. The increase in cytotoxicity of Ellipticine in UKF-NB-4 by VPA is dictated by the sequence of drug administration; the increased cytotoxicity was seen only after either simultaneous exposure to these drugs or after pretreatment of cells with Ellipticine before their treatment with VPA. The synergism of treatment of cells with VPA and Ellipticine seems to be connected with increased acetylation of histones H3 and H4. Further, co-treatment of cells with Ellipticine and VPA increased the formation of Ellipticine-derived DNA adducts, which indicates an easier accessibility of Ellipticine to DNA in cells by its co-treatment with VPA and also resulted in higher Ellipticine cytotoxicity. The results are promising for in vivo studies and perhaps later for clinical studies of combined treatment of children suffering from high-risk NBL.
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cytochrome b5 plays a dual role in the reaction cycle of cytochrome p450 3a4 during oxidation of the anticancer drug Ellipticine
Monatshefte Fur Chemie, 2017Co-Authors: Marie Stiborová, Eva Frei, Radek Indra, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Zbyněk Heger, Vojtěch Adam, Kateřina Kopeckova, Vaclav MartinekAbstract:Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important Ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b 5 reductase and/or cytochrome b 5 in Supersomes™ to oxidize this drug. We also evaluated the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b 5 reductase, to mediate Ellipticine oxidation in these enzyme systems. Using HPLC analysis we detected up to five Ellipticine metabolites, which were formed by human hepatic microsomes and human CYP3A4 in the presence of NADPH or NADH. Among Ellipticine metabolites, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine were formed by hepatic microsomes as the major metabolites, while 7-hydroxyEllipticine and the Ellipticine N 2-oxide were the minor ones. Human CYP3A4 in Supersomes™ generated only three metabolic products, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine. Using the 32P-postlabeling method two Ellipticine-derived DNA adducts were generated by microsomes and the CYP3A4-Supersome system, both in the presence of NADPH and NADH. These adducts were derived from the reaction of 13-hydroxy- and 12-hydroxyEllipticine with deoxyguanosine in DNA. In the presence of NADPH or NADH, cytochrome b 5 stimulated the CYP3A4-mediated oxidation of Ellipticine, but the stimulation effect differed for individual Ellipticine metabolites. This heme protein also stimulated the formation of both Ellipticine-DNA adducts. The results demonstrate that cytochrome b 5 plays a dual role in the CYP3A4-catalyzed oxidation of Ellipticine: (1) cytochrome b 5 mediates CYP3A4 catalytic activities by donating the first and second electron to this enzyme in its catalytic cycle, indicating that NADH:cytochrome b 5 reductase can substitute NADPH-dependent POR in this enzymatic reaction and (2) cytochrome b 5 can act as an allosteric modifier of the CYP3A4 oxygenase.
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Electrochemical Determination of Enzymes Metabolizing Ellipticine in Thyroid Cancer Cells- a Tool to Explain the Mechanism of Ellipticine Toxicity to these Cells
2015Co-Authors: Jitka Poljaková, Rene Kizek, Eva Frei, Tomas Eckschlager, Jindřich Činátl, Marie StiborováAbstract:The antineoplastic alkaloid Ellipticine is a prodrug, the pharmacological efficiency of which is dependent on its cytochrome P450 (CYP)- and/or peroxidase-mediated activation to species forming DNA adducts in target tissues. Here, we found that this compound is cytotoxic to human BHT-101, B-CPAP and 8505-C thyroid cancer cells and blocks one or more phases of cell cycle in these cancer cells. Ellipticine toxicity to the thyroid cancer cells corresponded to levels of DNA adducts generated by the CYP- and/or peroxidase-mediated Ellipticine metabolites, 12-hydroxy- and 13-hydroxyEllipticine, in these cells. Cultivation of all tested cells under hypoxic conditions (1 % oxygen) led to a decrease in Ellipticine toxicity. Such a lower sensitivity of cells to Ellipticine correlates with a decrease in the formation of Ellipticine-derived DNA adducts in these cells. Using Western blotting, the expression of CYP1A1, 1B1, 3A4, thyroid peroxidase (TPO), cyclooxygenase-1 (COX-1) an
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electrochemical study of Ellipticine interaction with single and double stranded oligonucleotides
Anti-cancer Agents in Medicinal Chemistry, 2014Co-Authors: Katerina Tmejova, Marie Stiborová, Tomas Eckschlager, Vojtech Adam, Ludmila Krejcova, David Hynek, Petr Babula, Libuse Trnkova, Rene KizekAbstract:Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is an alkaloid that has been isolated from plants of an Apocynaceae family. It is one of the simplest naturally occurring alkaloids with a planar structure. Over the past decades, Ellipticine became a very promising antitumor agent. Interaction with DNA is one of the most studied Ellipticine effects on cell division. This phenomenon is not clearly explained so far. In our experiments we studied interaction of Ellipticine with single-stranded and double-stranded oligonucleotides by electrochemical methods on mercury electrode. Differential pulse voltammetry was applied for Ellipticine (Elli) and CA peak detection. Square wave voltammetry was applied for G peak detection. The effect of the interaction time and Ellipticine concentrations on interactions of Ellipticine with single- and double-stranded oligonucleotides was tested too.
Volker M Arlt - One of the best experts on this subject based on the ideXlab platform.
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application of hepatic cytochrome b5 p450 reductase null hbrn mice to study the role of cytochrome b5 in the cytochrome p450 mediated bioactivation of the anticancer drug Ellipticine
Toxicology and Applied Pharmacology, 2019Co-Authors: Lindsay Reed, Michaela Moserová, Marie Stiborová, Radek Indra, David H Phillips, Iveta Mrizova, Heinz H Schmeiser, Colin J Henderson, Roland C Wolf, Volker M ArltAbstract:Abstract The anticancer drug Ellipticine exerts its genotoxic effects after metabolic activation by cytochrome P450 (CYP) enzymes. The present study has examined the role of cytochrome P450 oxidoreductase (POR) and cytochrome b5 (Cyb5), electron donors to P450 enzymes, in the CYP-mediated metabolism and disposition of Ellipticine in vivo. We used Hepatic Reductase Null (HRN) and Hepatic Cytochrome b5/P450 Reductase Null (HBRN) mice. HRN mice have POR deleted specifically in hepatocytes; HBRN mice also have Cyb5 deleted in the liver. Mice were treated once with 10 mg/kg body weight Ellipticine (n = 4/group) for 24 h. Ellipticine-DNA adduct levels measured by 32P-postlabelling were significantly lower in HRN and HBRN livers than in wild-type (WT) livers; however no significant difference was observed between HRN and HBRN livers. Ellipticine-DNA adduct formation in WT, HRN and HBRN livers correlated with Cyp1a and Cyp3a enzyme activities measured in hepatic microsomes in the presence of NADPH confirming the importance of P450 enzymes in the bioactivation of Ellipticine in vivo. Hepatic microsomal fractions were also utilised in incubations with Ellipticine and DNA in the presence of NADPH, cofactor for POR, and NADH, cofactor for Cyb5 reductase (Cyb5R), to examine Ellipticine-DNA adduct formation. With NADPH adduct formation decreased as electron donors were lost which correlated with the formation of the reactive metabolites 12- and 13-hydroxy-Ellipticine in hepatic microsomes. No difference in adduct formation was observed in the presence of NADH. Our study demonstrates that Cyb5 contributes to the P450-mediated bioactivation of Ellipticine in vitro, but not in vivo.
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tyrosine kinase inhibitors vandetanib lenvatinib and cabozantinib modulate oxidation of an anticancer agent Ellipticine catalyzed by cytochromes p450 in vitro
Neuro endocrinology letters, 2019Co-Authors: Matus Kolarik, Radek Indra, Volker M Arlt, Vojtech Adam, Zbynek Heger, Katerina Kopeckova, Marie StiborováAbstract:Objectives Vandetanib¸ lenvatinib, and cabozantinib are tyrosine kinase inhibitors (TKIs) targeting VEGFR subtypes 1 and 2, EGFR and the RET-tyrosine kinase, thus considered as multiple TKIs. These TKIs have already been approved for treating patients suffering from thyroid cancer and renal cell carcinoma. Ellipticine, a DNA-damaging drug, is another anticancer agent that is effective against certain tumors of the thyroid gland, ovarian carcinoma, breast cancer and osteolytic breast cancer metastasis. Its anticancer efficiency is dictated by its oxidation with cytochrome P450 (CYP) and peroxidase enzymes. A number of studies testing the effectiveness of individual anticancer drugs, the pharmacological efficiencies of which are affected by their metabolism, alone or in a combination with other cytostatics demonstrated that such combination can have both positive and negative effects on treatment regimen. The aim of this study was to study the effect of vandetanib, lenvatinib and cabozantinib on oxidation of Ellipticine which dictates its pharmacological efficiency. Methods Ellipticine oxidation catalyzed by hepatic microsomes, recombinant CYP enzymes and peroxidases (horseradish peroxidase, lactoperoxidase and myeloperoxidase) and the effect of TKIs (vandetanib, lenvatinib and cabozantinib) on this oxidation were analyzed by HPLC used for separation of Ellipticine metabolites and quantification of their amounts formed during oxidation. Results The CYP enzymatic system oxidizes Ellipticine up to five metabolites (9-hydroxy-, 12-hydroxy-, 13-hydroxy-, 7-hydroxyEllipticine, and Ellipticine N2- oxide), while peroxidases form predominantly Ellipticine dimer. Ellipticine oxidation catalyzed by rat and human hepatic microsomes was inhibited by vandetanib and cabozantinib, but essentially no inhibition was caused by lenvatinib. Of individual CYP enzymes catalyzing oxidation of Ellipticine, TKIs inhibited oxidation of Ellipticine catalyzed by CYP2D6 > 2D1 > 2C9 > 3A1 > 3A4, the CYP enzymes participating in Ellipticine oxidation to metabolites increasing the Ellipticine anticancer efficiency. On the contrary, they have essentially no inhibition effect on Ellipticine oxidation catalyzed by CYP1A1 and 1A2, which are the enzymes that predominantly detoxify this drug. All tested TKIs had essentially no effect on oxidation of Ellipticine by used peroxidases. Conclusion The results found demonstrate that TKIs vandetanib, lenvatinib and cabozantinib cause a decrease in oxidative activation of DNA-damaging drug Ellipticine by several CYP enzymes in vitro which might lead to a decrease in its pharmacological efficiency. In contrast, they practically do not influence its detoxification catalyzed by CYP1A1, 1A2 and peroxidases. The present study indicates that tested TKIs seem not to have a potency to increase Ellipticine anticancer efficiency.
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the impact of chemotherapeutic drugs on the cyp1a1 catalysed metabolism of the environmental carcinogen benzo a pyrene effects in human colorectal hct116 tp53 tp53 and tp53 cells
Toxicology, 2018Co-Authors: Alexandra J Willis, Marie Stiborová, Radek Indra, David H Phillips, Laura E Wohak, Osman Sozeri, Kerstin Feser, Iveta Mrizova, Volker M ArltAbstract:Abstract Polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) can induce cytochrome P450 1A1 (CYP1A1) via a p53-dependent mechanism. The effect of different p53-activating chemotherapeutic drugs on CYP1A1 expression, and the resultant effect on BaP metabolism, was investigated in a panel of isogenic human colorectal HCT116 cells with differing TP53 status. Cells that were TP53(+/+), TP53(+/–) or TP53(–/–) were treated for up to 48 h with 60 μM cisplatin, 50 μM etoposide or 5 μM Ellipticine, each of which caused high p53 induction at moderate cytotoxicity (60–80% cell viability). We found that etoposide and Ellipticine induced CYP1A1 in TP53(+/+) cells but not in TP53(–/–) cells, demonstrating that the mechanism of CYP1A1 induction is p53-dependent; cisplatin had no such effect. Co-incubation experiments with the drugs and 2.5 μM BaP showed that: (i) etoposide increased CYP1A1 expression in TP53(+/+) cells, and to a lesser extent in TP53(–/–) cells, compared to cells treated with BaP alone; (ii) Ellipticine decreased CYP1A1 expression in TP53(+/+) cells in BaP co-incubations; and (iii) cisplatin did not affect BaP-mediated CYP1A1 expression. Further, whereas cisplatin and etoposide had virtually no influence on CYP1A1-catalysed BaP metabolism, Ellipticine treatment strongly inhibited BaP bioactivation. Our results indicate that the underlying mechanisms whereby etoposide and Ellipticine regulate CYP1A1 expression must be different and may not be linked to p53 activation alone. These results could be relevant for smokers, who are exposed to increased levels of BaP, when prescribing chemotherapeutic drugs. Beside gene-environment interactions, more considerations should be given to potential drug-environment interactions during chemotherapy.
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the histone deacetylase inhibitor valproic acid exerts a synergistic cytotoxicity with the dna damaging drug Ellipticine in neuroblastoma cells
International Journal of Molecular Sciences, 2018Co-Authors: Tereza Cerna, Eva Frei, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Jan Hrabeta, Marie StiborováAbstract:Neuroblastoma (NBL) originates from undifferentiated cells of the sympathetic nervous system. Chemotherapy is judged to be suitable for successful treatment of this disease. Here, the influence of histone deacetylase (HDAC) inhibitor valproate (VPA) combined with DNA-damaging chemotherapeutic, Ellipticine, on UKF-NB-4 and SH-SY5Y neuroblastoma cells was investigated. Treatment of these cells with Ellipticine in combination with VPA led to the synergism of their anticancer efficacy. The effect is more pronounced in the UKF-NB-4 cell line, the line with N-myc amplification, than in SH-SY5Y cells. This was associated with caspase-3-dependent induction of apoptosis in UKF-NB-4 cells. The increase in cytotoxicity of Ellipticine in UKF-NB-4 by VPA is dictated by the sequence of drug administration; the increased cytotoxicity was seen only after either simultaneous exposure to these drugs or after pretreatment of cells with Ellipticine before their treatment with VPA. The synergism of treatment of cells with VPA and Ellipticine seems to be connected with increased acetylation of histones H3 and H4. Further, co-treatment of cells with Ellipticine and VPA increased the formation of Ellipticine-derived DNA adducts, which indicates an easier accessibility of Ellipticine to DNA in cells by its co-treatment with VPA and also resulted in higher Ellipticine cytotoxicity. The results are promising for in vivo studies and perhaps later for clinical studies of combined treatment of children suffering from high-risk NBL.
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cytochrome b5 plays a dual role in the reaction cycle of cytochrome p450 3a4 during oxidation of the anticancer drug Ellipticine
Monatshefte Fur Chemie, 2017Co-Authors: Marie Stiborová, Eva Frei, Radek Indra, Tomas Eckschlager, Volker M Arlt, Heinz H Schmeiser, Zbyněk Heger, Vojtěch Adam, Kateřina Kopeckova, Vaclav MartinekAbstract:Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important Ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b 5 reductase and/or cytochrome b 5 in Supersomes™ to oxidize this drug. We also evaluated the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b 5 reductase, to mediate Ellipticine oxidation in these enzyme systems. Using HPLC analysis we detected up to five Ellipticine metabolites, which were formed by human hepatic microsomes and human CYP3A4 in the presence of NADPH or NADH. Among Ellipticine metabolites, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine were formed by hepatic microsomes as the major metabolites, while 7-hydroxyEllipticine and the Ellipticine N 2-oxide were the minor ones. Human CYP3A4 in Supersomes™ generated only three metabolic products, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyEllipticine. Using the 32P-postlabeling method two Ellipticine-derived DNA adducts were generated by microsomes and the CYP3A4-Supersome system, both in the presence of NADPH and NADH. These adducts were derived from the reaction of 13-hydroxy- and 12-hydroxyEllipticine with deoxyguanosine in DNA. In the presence of NADPH or NADH, cytochrome b 5 stimulated the CYP3A4-mediated oxidation of Ellipticine, but the stimulation effect differed for individual Ellipticine metabolites. This heme protein also stimulated the formation of both Ellipticine-DNA adducts. The results demonstrate that cytochrome b 5 plays a dual role in the CYP3A4-catalyzed oxidation of Ellipticine: (1) cytochrome b 5 mediates CYP3A4 catalytic activities by donating the first and second electron to this enzyme in its catalytic cycle, indicating that NADH:cytochrome b 5 reductase can substitute NADPH-dependent POR in this enzymatic reaction and (2) cytochrome b 5 can act as an allosteric modifier of the CYP3A4 oxygenase.
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heterologous expression of human cytochrome p450 2s1 in escherichia coli and investigation of its role in metabolism of benzo a pyrene and Ellipticine
Monatshefte Fur Chemie, 2016Co-Authors: Iveta Mrizova, Michaela Moserová, Rene Kizek, Volker M Arlt, Jan Milichovský, Miroslav Sulc, Kateřina Kubackova, Marie StiborováAbstract:Cytochrome P450 (CYP) 2S1 is "orphan" CYP that is overexpressed in several epithelial tissues and many human tumors. The pure enzyme is required for better understanding of its biological functions. Therefore, human CYP2S1 was considered to be prepared by the gene manipulations and heterologous expression in Escherichia coli. Here, the conditions suitable for efficient expression of human CYP2S1 protein from plasmid pCW containing the human CYP2S1 gene were optimized and the enzyme purified to homogeneity. The identity of CYP2S1 as the product of heterologous expression was confirmed by dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and mass spectrometry. To confirm the presence of the enzymatically active CYP2S1, the CO spectrum of purified CYP2S1 was recorded. Since CYP2S1 was shown to catalyze oxidation of compounds having polycyclic aromatic structures, the prepared enzyme has been tested to metabolize the compounds having this structural character; namely, the human carcinogen benzo[a]pyrene (BaP), its 7,8-dihydrodiol derivative, and an anticancer drug Ellipticine. Reaction mixtures contained besides the test compounds the CYP2S1 enzyme reconstituted with NADPH:CYP reductase (POR) in liposomes, and/or this CYP in the presence of cumene hydroperoxide or hydrogen peroxide. High performance liquid chromatography was employed for separation of BaP, BaP-7,8-dihydrodiol, and Ellipticine metabolites. The results found in this study demonstrate that CYP2S1 in the presence of cumene hydroperoxide or hydrogen peroxide catalyzes oxidation of two of the test xenobiotics, a metabolite of BaP, BaP-7,8-dihydrodiol, and Ellipticine. Whereas BaP-7,8,9,10-tetrahydrotetrol was formed as a product of BaP-7,8-dihydrodiol oxidation, Ellipticine was oxidized to 12-hydroxyEllipticine, 13-hydroxyEllipticine, and the Ellipticine N (2)-oxide.
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The Anticancer Drug Ellipticine Induces Cytochromes P450 1A1, 1A2 and 3A, Cytochrome b5 and NADPH:Cytochrome
2015Co-Authors: P Oxidoreductase, Rat Liver, Iveta Vranová, Michaela Moserová, Petr Hodek, Rene Kizek, Eva Frei, Marie StiborováAbstract:The antineoplastic alkaloid Ellipticine is a prodrug, the pharmacological efficiency of which is dependent on its cytochrome P450 (CYP)- and/or peroxidase-mediated activation in target tissues. Using the Western blotting, we found that this compound increases protein expression of cytochrome b5, CYP1A1, 1A2, 3A and NADPH:CYP oxidoreductase (POR) in livers, lungs and kidneys of rats treated (i.p.) with Ellipticine. The Ellipticine-mediated induction of these enzymes resulted in an increase in their enzymatic activities and Ellipticine oxidation to 7-hydroxy-, 9-hydroxy-, 12-hydroxy-and 13-hydroxyEllipticine, the metabolites that are both detoxication products (7-hydroxy-, 9-hydroxyEllipticine) and metabolites responsible for generation Ellipticine-derived DNA adducts (12-hydroxy- and 13-hydroxyEllipticine). The results demonstrate that by inducing CYP1A1/2, 3A, POR and cytochrome b5, Ellipticine increases its own metabolism in rats, thereby modulating its own pharmacological and/or genotoxic potential
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Electrochemical Determination of Enzymes Metabolizing Ellipticine in Thyroid Cancer Cells- a Tool to Explain the Mechanism of Ellipticine Toxicity to these Cells
2015Co-Authors: Jitka Poljaková, Rene Kizek, Eva Frei, Tomas Eckschlager, Jindřich Činátl, Marie StiborováAbstract:The antineoplastic alkaloid Ellipticine is a prodrug, the pharmacological efficiency of which is dependent on its cytochrome P450 (CYP)- and/or peroxidase-mediated activation to species forming DNA adducts in target tissues. Here, we found that this compound is cytotoxic to human BHT-101, B-CPAP and 8505-C thyroid cancer cells and blocks one or more phases of cell cycle in these cancer cells. Ellipticine toxicity to the thyroid cancer cells corresponded to levels of DNA adducts generated by the CYP- and/or peroxidase-mediated Ellipticine metabolites, 12-hydroxy- and 13-hydroxyEllipticine, in these cells. Cultivation of all tested cells under hypoxic conditions (1 % oxygen) led to a decrease in Ellipticine toxicity. Such a lower sensitivity of cells to Ellipticine correlates with a decrease in the formation of Ellipticine-derived DNA adducts in these cells. Using Western blotting, the expression of CYP1A1, 1B1, 3A4, thyroid peroxidase (TPO), cyclooxygenase-1 (COX-1) an
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vacuolar atpase mediated intracellular sequestration of Ellipticine contributes to drug resistance in neuroblastoma cells
International Journal of Oncology, 2015Co-Authors: Jan Hrabeta, Rene Kizek, Jitka Poljaková, Tomas Groh, Mohamed Ashraf Khalil, Vojtech Adam, Jiri Uhlik, Helena Doktorova, Tereza Cerna, Eva FreiAbstract:Neuroblastoma is the most common cancer in infants and the fourth most common cancer in children. Aggressive cell growth and chemoresistance are notorious obstacles in neuroblastoma therapy. Exposure to the anticancer drug Ellipticine inhibits efficiently growth of neuroblastoma cells and induces apoptosis in these cells. However, Ellipticine induced resistance in these cells. The upregulation of a vacuolar (V)-ATPase gene is one of the factors associated with resistance development. In accordance with this finding, we found that levels of V-ATPase protein expression are higher in the Ellipticine-resistant UKF-NB-4ELLI line than in the parental Ellipticine-sensitive UKF-NB-4 cell line. Treatment of Ellipticine-sensitive UKF-NB-4 and Ellipticine-resistant UKF-NB-4ELLI cells with Ellipticine-induced cytoplasmic vacuolization and Ellipticine is concentrated in these vacuoles. Confocal microscopy and staining of the cells with a lysosomal marker suggested these vacuoles as lysosomes. Transmission electron microscopy and no effect of an autophagy inhibitor wortmannin ruled out autophagy. Pretreatment with a V-ATPase inhibitor bafilomycin A and/or the lysosomotropic drug chloroquine prior to Ellipticine enhanced the Ellipticine‑mediated apoptosis and decreased Ellipticine-resistance in UKF-NB-4ELLI cells. Moreover, pretreatment with these inhibitors increased formation of Ellipticine-derived DNA adducts, one of the most important DNA-damaging mechanisms responsible for Ellipticine cytotoxicity. In conclusion, resistance to Ellipticine in the tested neuroblastoma cells is associated with V-ATPase-mediated vacuolar trapping of this drug, which may be decreased by bafilomycin A and/or chloroquine.
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electrochemical study of Ellipticine interaction with single and double stranded oligonucleotides
Anti-cancer Agents in Medicinal Chemistry, 2014Co-Authors: Katerina Tmejova, Marie Stiborová, Tomas Eckschlager, Vojtech Adam, Ludmila Krejcova, David Hynek, Petr Babula, Libuse Trnkova, Rene KizekAbstract:Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is an alkaloid that has been isolated from plants of an Apocynaceae family. It is one of the simplest naturally occurring alkaloids with a planar structure. Over the past decades, Ellipticine became a very promising antitumor agent. Interaction with DNA is one of the most studied Ellipticine effects on cell division. This phenomenon is not clearly explained so far. In our experiments we studied interaction of Ellipticine with single-stranded and double-stranded oligonucleotides by electrochemical methods on mercury electrode. Differential pulse voltammetry was applied for Ellipticine (Elli) and CA peak detection. Square wave voltammetry was applied for G peak detection. The effect of the interaction time and Ellipticine concentrations on interactions of Ellipticine with single- and double-stranded oligonucleotides was tested too.
