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Mechanism of tumor development and its influencing by ellipticine
Parisová, Martina ; Stiborová, Marie (advisor) ; Moserová, Michaela (referee)
Ellipticine (5.11-dimethyl-6H-pyridate [4,3-b] carbazole) is a powerful anti-cancer agent, exhibiting multiple mechanisms of action. This work describes the causes of cancer processes and summarizes the main pharmacological mechanisms and cytotoxic effects of ellipticine together with the results found in our laboratory indicating, a new mechanism of ellipticine action. Cytotoxic and mutagenic activity of ellipticine is attributed to its two mechanisms of activity ellipticine intercalation into DNA and its effectivity to inhibit topoisomerase II. Ellipticine also forms covalent DNA adducts after its oxidation with cytochromes P450 and peroxidases. Cytochromes P450 oxidize ellipticine up to five metabolites, of which 13- hydroxyellipticin, 12-hydroxyellipticin and N(2)-oxide of ellipticine are responsible for formation of two major DNA adducts. In the case of peroxidases, ellipticine is oxidized to a radical producing the ellipticine dimer and a minor ellipticine metabolite, the N(2)-oxide of ellipticine. Because of the high efficiency of ellipticine and its derivatives against various types of cancer, this coumpound is studied in detail. Its utilization for drug tangeting is a challenge for further study.
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Preparation of the constructs for analysis of expression of nuclear receptor nhr-97 by using transgenic techniques in the model system Caenorhabditis elegans
Boušová, Kristýna ; Stiborová, Marie (advisor) ; Hudeček, Jiří (referee)
The aim of this work was to prepare two constructs of the promoter of a gene coding for nuclear hormone receptor nhr-97 in C. elegans. Nuclear receptors belong to a large group of genes sharing homologous sequences in some vertebrate nuclear receptors. The first part of the work describes the structure of nuclear hormone receptors, their function and significance in the nematodes C. elegans. The model organism C. elegans, its anatomy, life cycle and genome were also described. The work also discusses the structure and use of green fluorescent protein (GFP), which serves to localize the expression of the nhr-97 gene in C. elegans. In the practical part of the work, the preparation of two constructs of the promoter is described. Isolation of genomic DNA of C. elegans, PCR amplification of the promoters and their subsequent cloning into vector pPD95.67 containing a gene coding for green fluorescent protein were performed. To verify the successful cloning of the promoter constructs, sequencing DNA was performed. Cloned promoters of nhr-97 will be used for microinjetions to C. elegans gonads and the expression of this gene regulated from particular promoters will be subsequently monitored using expression of green fluorescent protein in progeny.
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Role of selected ABC transporters in breast cancer development
Perglerová, Karolína ; Souček, Pavel (advisor) ; Stiborová, Marie (referee)
Breast cancer is a leading cause of death among women in many countries. In the treatment of the breast cancer cytotoxic drugs (chemotherapy) are often used. Interindividual differences of drug response are an important cause of treatment failures. Bioavailability also depends on a major extent from the expression and activity of drug transport across biomembranes. In particular efflux transporters of the ATP-binding cassette family such as ABCB1, ABCC1 and ABCC2 have been identified as major determinants of chemoresistance in tumor cells. It was hypothesized that variance in the gene expression of membrane transporters and their genetic variance could explain at least in part interindividual differences of pharmacokinetics and clinical outcome of a variety of drugs. This thesis focuses on the functional significance of gene expression of ABCB1, ABCC1 and ABCC2 and single nucleotide polymorphisms in ABCC1 gene.
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Synthesis of ellipticine and its pharmacologically more efficient derivative 13-hydroxyellipticine
Hájek, Jan ; Stiborová, Marie (advisor) ; Černá, Věra (referee)
Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is plant alcaloid isolated from Ochrosia elliptica1) (Apocyanaceae). Ellipticine's anticancer effect is mainly caused by its intercalation into DNA, formation of covalent adduct with DNA and inhibition of topoisomerase II. Known syntheses of ellipticine are based on chemicals containing two or three aromatic cycles that are used in cyklisation and/or addition reaction to get ellipticine or ellipticine derivates. 13- hydroxyellipticine can be prepared de novo as a product of casual ellipticine synthesis, or as a modification of already synthetised ellipticine. Keywords: ellipticine; synthesis; derivates of ellipticine
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Nephropathy and tumour development caused by plant alkaloids aristolochic acid
Bárta, František ; Stiborová, Marie (advisor) ; Šácha, Pavel (referee)
Aristolochic acids (AA) are alkaloids contained in plant species of the family Aristolochiaceae. These plants are used since antiquity in traditional medicine to treatment of many varied diseases. There are known anti-inflammatory effects of these compounds, however these alkaloids exhibit mutagenic and carcinogenic properties. Despite of this fact, plant extracts AA are still used in traditional medicine, e.g. in China, India, Taiwan. Aristolochic acids are proven to be the cause of disease designated Aristolochic Acid Nephropathy (AAN, theretofore known as Chinese Herbs Nephropathy (CHN). This unusual nephropathy leads to a total renal failure. The late complication of this disease is the development of tumours in urothelial tissue of patients. AA can form persistent stable covalent DNA adducts. Formation of these DNA adducts lead to AT→TA transversion, the unique mutation in tumour suppressor gene p53 responsible for tumour formation. Balkan Endemic Nephropathy (BEN) is associated with AA, too. In this instance is supported also influence of another factors, e.g. mycotoxins (ochratoxin A). However, in all probability AA contribute to a development of this disease particularly. This hypothesis is supported by finding of AA-DNA adducts in tissues of patients suffering from AAN and BEN and that of...
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Synthesis and biochemical characterization of hybrid analogues of human insulin and IGF-2
Povalová, Anna ; Stiborová, Marie (advisor) ; Koberová, Monika (referee)
The ever-increasing occurrence of diabetes mellitus brings about the need for development of new therapeutic agents to provide adequate treatment for patients. An important element in this research area is elucidation how insulin works, mainly in connection with insulin-like growth factors (IGF-1 and IGF-2), which show significant structural homology to each other. In addition, their respective receptors - insulin receptor (IR) and receptor for IGF-1 and IGF-2 (IGF-1R) - exhibit very high similarity. As a result, IGF-1 and IGF-2 can bind to IR and insulin can bind to IGF-1R. Of a particular importance is the high affinity binding of IGF-2 to the isoform A of IR. Unlike insulin, which predominantly mediates glucose entry into cells, IGFs induce growth or mitogenic effects. The finding which structural determinants in insulin and IGFs are responsible for the differences in the activation of their cognate receptors could provide an explanation for different functional responses upon binding of these hormones to different target cells. Understanding of this mechanism could also help in the development of functionally selective analogues of these hormones. The aim of this study was the synthesis and characterization of analogues of human insulin extended at the C terminus of the B chain with the amino...
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Enzymes metabolizing drugs
Škodová, Petra ; Stiborová, Marie (advisor) ; Kubíčková, Božena (referee)
Mixed function oxidase system (MFO) is one of the most effective systems of enzymes of the first phase of biotransformation of xenobiotics. Cytochromes P450 seem to be the most important part of the MFO system, which also contains other components such as NADPH:CYP reductase and membrane lipids. Cytochromes P450 function as a terminal oxidase of the mixed function oxidase (MFO) system. Many xenobiotics, including drugs, are the substrates of these enzymes. Endogenous substances can serve as the substrates of these enzymes as well. Peroxidases are a group of enzymes which are able to metabolize drugs. The function of cytochromes P450 can be substituted by peroxidases. Both groups of enzymes are able to potentiate the effect of the drugs by activating them or they form deactivated metabolites, which are excreted from the organism. The action of cytochromes P450 and peroxidases is shown on the metabolism of the drug ellipticine. Ellipticine has anticancer effects. The advantage of this drug is its low number of side-effects. The oxidation of ellipticine by cytochromes P450 and peroxidases leads to its metabolic activation or detoxification. Carbenium ions are generated by spontaneous cleavage of two active metabolites, 12-hydroxyellipticine and 13-hydroxyellipticine. Carbenium ions then form adducts...
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