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Effects of valproic acid and its combinations with cytostatic agents on tumor cells in vitro
Hinďoš Hřebačková, Jana ; Dyr, Jan (advisor) ; Vávrová, Jiřina (referee) ; Entlicher, Gustav (referee)
Cancer is one of the most challenging problems the modern medicine is facing today. An increasing incidence and a great variability of tumor cells are the main reasons those drive the research to develop better diagnostics and therapeutic protocols. Histone deacetylase inhibitors, a group of epigenetic chemotherapeutics, are able to improve the performance of currently used anticancer agents. Vaplroic acid that is commonly used as antiepileptic drug exhibits a remarkable anticancer activity by itself as well as it is capable of therapy potentiation based on other therapeutic agents. Its effect to inhibit growth of tumor cells and induce apoptotic cell death seems to be even greater under hypoxic conditions (<1% O2). This study is focused on effect of valproic acid on neuroblastoma cell lines in vitro under normoxic and hypoxic conditions. We observed significantly greater efficacy of valproic acid in hypoxia compared to normoxia. The mechanism of induction of apoptotic cell death is based on disruption of the balance between pro- and antiapoptoic proteins. Intrinsic apoptotic pathway is probably initiated by the action of 19 kDa variant of proapoptotic protein Bax on mitochondrial membrane. Moreover, we examined the efficiency of a combined treatment of neuroblastoma cells with valproic acid and...
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Effects of valproic acid and its combinations with cytostatic agents on tumor cells in vitro
Hinďoš Hřebačková, Jana ; Dyr, Jan (advisor) ; Vávrová, Jiřina (referee) ; Entlicher, Gustav (referee)
Cancer is one of the most challenging problems the modern medicine is facing today. An increasing incidence and a great variability of tumor cells are the main reasons those drive the research to develop better diagnostics and therapeutic protocols. Histone deacetylase inhibitors, a group of epigenetic chemotherapeutics, are able to improve the performance of currently used anticancer agents. Vaplroic acid that is commonly used as antiepileptic drug exhibits a remarkable anticancer activity by itself as well as it is capable of therapy potentiation based on other therapeutic agents. Its effect to inhibit growth of tumor cells and induce apoptotic cell death seems to be even greater under hypoxic conditions (<1% O2). This study is focused on effect of valproic acid on neuroblastoma cell lines in vitro under normoxic and hypoxic conditions. We observed significantly greater efficacy of valproic acid in hypoxia compared to normoxia. The mechanism of induction of apoptotic cell death is based on disruption of the balance between pro- and antiapoptoic proteins. Intrinsic apoptotic pathway is probably initiated by the action of 19 kDa variant of proapoptotic protein Bax on mitochondrial membrane. Moreover, we examined the efficiency of a combined treatment of neuroblastoma cells with valproic acid and...
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Epigenetic modification of DNA of tumor cell lines in normoxia and hypoxia
Omaňa Gudiňo, Žaneta ; Poljaková, Jitka (advisor) ; Hinďoš Hřebačková, Jana (referee)
5 Abstract Neuroblastoma is one of the most common cancer diseases diagnosed in children. This rapidly growing solid tumor is usually formed by hypoxic areas which arise as a consequence of inefficient and disorganized neovascularization. The cells stressed by hypoxia triggers transcription of many genes necessary for their survival, and conversely stop the production of proteins which are not necessarily needed for the survival in these severe conditions. The adaptation of cells to hypoxic conditions may appear due to the epigenetic regulation of metabolism associated with chromatin remodeling which involves the DNA methylation and also the posttranslational modifications of histones. Among the most important of these, there is the acetylation of lysine residues of histones associated with the DNA strands loosening, facilitated binding of transcription factors and the activation of gene expression. Thus, the first part of this study is concerned with changes in the acetylation of histones H3 and H4 of human neuroblastoma cell lines UKF-NB-3, UKF-NB-4, SH-SY5Y and SK-N-AS, cultured in parallel under standard culture conditions and in the absence of oxygen (hypoxia, 1% O2) for 24 hours, which are studied by Western blot analysis. Thereupon, the activity of histone deacetylases and histonacetyltransferases,...
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Study of gene expression profile of ellipticine - resistant neuroblastoma cell line UKF-NB-4
Pinkas, Michael ; Poljaková, Jitka (advisor) ; Hinďoš Hřebačková, Jana (referee)
Neuroblastoma (NB) is a malignant embryonal tumor of the peripheral sympathetic nervous system derived from neural crest and is the most common tumor in infants. If the protooncogen MYCN is amplified in the case of high risk neuroblastoma, the current therapy fails. The biggest issue is the development of resistance. Ellipticine (ELLI) is a potential antineoplastic drug, whose cytotoxic effect is mainly based on the inhibition of topoisomerase II, its intercalation into the double helix structure of DNA and formation of adducts with DNA after enzymatic activation by cytochromes P450, peroxidases, sulfotransferases and N,O-acetyltransferases. Long-term cultivation of NB cell line UKF-NB-4 with ELLI leads to resistance, which is multifactorial. (i) It appears that ELLI is not effluxed from cells of the line UKF-NB-4ELLI as in the case of doxorubicin resistance in UKF-NB-4, but is transported from the nucleus and sequestrated in intracellular compartments. Cytotoxicity of ELLI is reduced also by (ii) low intracellular pH and (iii) decreased expression of topoisomerase II. (iv) Expression of enzymes activating ELLI is unchanged on the mRNA level detected by DNA microarray. However, enhanced expression of enzymes activating ELLI (cytochrome P450 3A4 and cyclooxygenase-1) is detected by qRT-PCR. Moreover...
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