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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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Plant alkaloids and their effects on enzymes metabolizing xenobiotics
Višněvská, Kateřina ; Stiborová, Marie (advisor) ; Černá, Věra (referee)
Sanguinarine and chelerythrine are quaternary benzo[c]phenanthridine alkaloids. The first step in sanguinarine metabolism is its reduction to dihydrosanguinarin. Antimicrobial and anti-inflammatory activities of these alkaloids are used in dentistry and as feed additives. Sanguinarine and chelerythrine induce apoptosis of cells. Fluorescence of these alkaloids and intercalation into DNA could be utilized to use the alkaloids as supravital DNA probe. Negative effect of sanguinarine and chelerythrine is their genotoxicity. Cytochrome P450 and peroxidase oxidize ellipticine to detoxication and activation metabolites. Ellipticine is a potent antineoplastic agent exhibiting the multimodal mechanism of its action. Ellipticine intercalates into DNA and inhibits topoisomerase II. Covalent DNA aducts are mediated by CYP or peroxidase oxidation of ellipticine. The anti-tumor activity of ellipticine and its derivatives is caused by a combination mechanism of cell cycle arrest and induction of the apoptotic pathway. Pharmacological efficiencies and geneotoxic side effects of ellipticine is dependent on levels and activities of cytochrome P450 or peroxidase in target tissues. Aristolactams are the major metabolites of biotransformation of aristolochic acid. Nitroreduction is the crucial step in formation of an...
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Carbohydrate dimers in tumor immunotherapy
Krupová, Monika ; Bezouška, Karel (advisor) ; Ryšlavá, Helena (referee)
Carbohydrate dimers in tumor immunotherapy Monika Krupová (Department of Biochemistry, Faculty of Science, Charles University in Prague) One possible approach to tumor immunotherapy is an activation of killer lymphocytes through specific ligands for their surface receptors. CD69 is a molecule greatly widespread among various cells of haematopoietic origin. Since the physiological ligand for this receptor is still unknown, ligand mimetics are used for modulation of its activity. The mimetics tested in this work are based on monomeric or oligomeric carbohydrated attached through two different chemical groups to the central linker of varying length, giving rise to thiourea and triazole series. The ability to precipitate soluble NKR-P1 and CD69 receptors was evaluated in precipitation assays and the optimal length of the linker for NKR-P1 receptor was found to be decyl. On the other hand, cross-linking of CD69 is not so dependent on the length of the linker. The aim of this work was to describe in vitro effect of the tested compounds on cellular signalization, natural killing of leukemic cell lines and activation-induced apoptosis. Compounds of triazole series containing two disaccharides (GalNAc β1→4 GlcNAc) linked by a linker were found to have the strongest effect on the production of...
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Úloha Mst1 / FoxO dráhy při indukci apoptosy
Lettlová, Sandra ; Bezouška, Karel (advisor) ; Liberda, Jiří (referee)
Vitamin E analogue -tocopheryl succinate (-TOS) from the group of mitocans, the drugs targeting mitochondria, is a selective inducer of apoptosis in various cancer cell types, which involves the accumulation of reactive oxygen species (ROS). It was found that ROS generation causes p53-independent upregulation of the pro-apoptotic protein Noxa that induces apoptosis by displacement of the BH3-only protein Bak from its inactive complex with the anti-apoptotic protein Mcl-1 to form a pore in outer mitochondrial membrane. Current research has demonstrated that generation of ROS causes activation of Mst1, a component of the Hippo pathway that presents a universal size-control mechanism in all metazoans, whose deregulation is linked to tumorigenesis. Treatment of Jurkat cells with - TOS revealed that activated Mst1 kinase phosphorylates the Forkhead box O1 (FoxO1) transcription factor that then translocates to the nucleus and activates transcription of genes important for apoptosis induction, including NOXA. This explains the p53 independent apoptosis induction and presents Mst1-FoxO1-Noxa as a new pathway involved in the process. Current research has also documented that activated Mst1 kinase controls the expression of the c-MYC oncogene and its target genes, whose products are involved in glucose...
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Effect of iron overload on the induction of apoptosis in mammalian cells
Kabíčková, Tereza ; Balušíková, Kamila (advisor) ; Klíma, Martin (referee)
Iron cations are an important metal ions required to number of essential cell functions. On the other hand, ferrous iron can be very toxic as well. When surplus iron is present in cells, it can catalyze the formation of reactive oxygen species (especially hydroxyl radicals) by Fenton reaction. Iron homeostasis is predominantly regulated by very strict mechanisms on the level of iron uptake into the body. Moreover, iron absorption, transport and storage within the body can be also regulated using complex mechanisms which differ on the level of individual cells and on the level of whole organism. Deregulation of iron homeostasis causing an iron overload and generation of reactive oxygen radicals can evoke serious cell damage leading up to apoptotic cell death. Excess iron storage and subsequent development of oxidative stress can affect lot of different tissues in the body. The organ damages such as fibrosis, cirrhosis, hepatocellular carcinoma, heart failure, loss of β cells and glucose intolerance or diabetes mellitus in patients with iron overload are very often seen. Nevertheless, the apoptosis induced by iron overload has not been well elucidated yet. There are no complex informations about the precise mechanism by which oxidative stress affects different cell types or whether there are other...
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Interference of selected DNA viruses with apoptotic processes
Sauerová, Pavla ; Forstová, Jitka (advisor) ; Štěpánek, Luděk (referee)
This work is focused on selected DNA viruses and some of their mechanisms used for inhibition or induction of the apoptotic processes. The selected DNA viruses are Hepatitis B virus, polyomaviruses, papillomaviruses and herpesviruses. Viruses developed different strategies for fighting the host defense mechanism during their evolution. One of the host defense mechanisms that reacts against virus infection is apoptosis. In case of viruses we can observe the phenomenon of inhibition or induction of apoptosis (which both depend on the life cycle phase of the virus). The purpose of these "fighting" strategies is to ensure successful replication, virus releasing from the cell and finally to let it spread in an organism or among them. Some "fighting" strategies are similar e.g. targeting and manipulation on p53 oncosupresor level or production of Bcl-2 homologs; other strategies are very specific. Certain viruses have mechanisms which allow them to survive in a host organism for a long time.
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The influence of acyclic nucleotide phosphonates PMEG and PMEDAP on p38 kinase signaling in human leukemic cells
Nejedlá, Michaela ; Entlicher, Gustav (advisor) ; Slaninová, Jiřina (referee)
PMEG [9-(2-phosphonomethoxyethyl)guanine] and PMEDAP [9-phosphonomethoxy- ethyl)-2,6-diaminopurine] are acyclic nucleoside phosphonates possessing cytotoxic properties. Antiproliferative effect of PMEG was demonstrated in various tumor cell lines in vitro. PMEG also represents an active component of some experimental prodrugs with enhanced selectivity and efficacy (such as GS-9219). PMEDAP seems to have weaker effect in vitro compared to PMEG, however it exhibited pronounced antitumor effect in SD-rats with spontaneous lymphoma. Therefore it was included in the present study as well. The aim of this study was to describe the interactions of PMEG and PMEDAP with p38 MAP kinase signaling and its relationship to the apoptosis. We investigated the influence of these compounds on the expression of four genes encoding p38 MAPK isoforms and whether this change is translated into the protein. It was found that PMEG up-regulates p38β and γ mRNA in CCRF-CEM cells and p38 β and δ in HL-60 cells. The effect of PMEDAP was less pronounced than that of PMEG. However, total p38 protein level remained unaffected by PMEG and PMEDAP. Activation of p38 MAPK cascade was also measured in the cells exposed to these agents using phospho-specific antibodies. We found that neither PMEG nor PMEDAP activated p38 kinase...
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IGFBP3 expressing rekombinant vaccinia virus used for tumor therapy
Musil, Jan ; Němečková, Šárka (advisor) ; Forstová, Jitka (referee)
IGFBP-3 expressing rekombinant vaccinia viruses used for tumor therapy Insulin-like growth factor-binding protein-3 (IGFBP-3) is a major regulator of endocrine effects of IGF and is capable to suppress the growth of variety of cancer. Several studies have shown that IGFBP-3 can induce the apoptosis of cancer cells via IGF-dependent and IGF-independent mechanisms. In our study, we have constructed recombinant vaccinia viruses (VACV) expressing IGFBP-3 under the control of the early H5 and synthetic early/late (E/L) promoter to investigate the potential effect on cancer growth in our cervical cancer model. We have shown that the expression of IGFBP-3 alone had no effect on tumor growth. On the other hand, the co-expression of IGFBP-3 enhanced the anti-cancer effect of immunization with the fusion protein SigE7LAMP, which gave rise to the anti-cancer immunity directed against HPV16 induced tumors. We have shown that the double-recombinant P13-SigE7LAMP-H5-IGFBP-3 can enhance the protective immune responses against MK16/ABC induced tumors. Furthermore, we have show that both double-recombinant viruses P13-SigE7LAMP-H5- IGFBP-3 and P13-SigE7LAMP-E/L-IGFBP-3 can increase the anti-cancer effect of SigE7LAMP expression in the therapy of TC-1 induced tumors. Key words: IGFBP-3, IGF, VACV, HPV16, E7 oncoprotein,...
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Role of DD- and DED-containing adaptor proteins in apoptotic signaling
Čaja, Fabián ; Janštová, Vanda (referee) ; Anděra, Ladislav (advisor)
Proteins containing a bundle of six anti-paralel α-helices in so-called "death domain" (DD) and similar structures (DED, CARD) represent important players in apoptotic signaling. To DD/DED/CARD domains-containing proteins belong pro- apoptotic membrane receptors from the TNFR superfamily, then adaptor proteins and enzymes as proteases or kinases. These pro-apoptotic "death receptors" interact with adaptor proteins and initiator caspases containing DDs or DEDs and activate apoptotic signaling cascade. DEDs and DDs are in addition found in many proteins participating in activation of caspases or other non-apoptotic signaling. Many experimental models document that defects in and deregulations of proteins containing DDs and DEDs can have severe if not lethal consequences for an organism. Abberations in these proteins in many cases could lead to cancerogenesis, immunodeficiencies or developmental defects.
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The role of fatty acids in apoptosis induction in pancreatic beta cells
Žigová, Ivana ; Libusová, Lenka (referee) ; Němcová, Vlasta (advisor)
Type 2 diabetes belongs to lifestyle diseases. To its development contributes also the decrease in functional cell mass caused particularly by long-term action of increased blood levels of fatty acids and glucose. Experiments from recent years demonstrated that apoptosis of pancreatic cells is induced especially by saturated fatty acids, in contrast to unsaturated fatty acids which do not exert significant cytotoxic effect and they are even able to inhibit the proapoptotic effect of saturated fatty acids. Despite intensive research, the mechanisms of fatty acid-induced apoptosis of pancreatic cells are not convincingly explained. Understanding of the processes that lead to destruction of functional cells could enable development of new therapies for type 2 diabetes treatment that would be targeted directly at one of the causes of this disease. The aim of this work is to summarize the recent knowledge about mechanisms by which fatty acids induce and regulate apoptosis of pancreatic cells.
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