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Charakterizace vlivu senescence na indukci a regulaci smrti nádorových buněk
Nováková, Gita ; Anděra, Ladislav (advisor) ; Truksa, Jaroslav (referee)
4 Abstract Senescence is a specific cell state distinquished by cessation of cell division and proliferation and changes in gene expression. Normal cells enter senescence after distinct number of cell divisions or in case of an unrepairable damage. Senescence in cancer cells can be induced by subliminal stress as sublethal treatment with certain drugs. Senescent cancer cells persist in the tissue and may secrete a number of factors and nutrients affecting surrounding cells. Senescence can thus change the response of cancer cells to various apoptogens during cancer therapy. In this study, we focused on the elucidation of presumed differences between normal proliferating and senescent cancer cells in their response to selected apoptogens. Implementing bromodeoxyuridine (BrdU)-mediated replication stress in cancer cells derived from pancreatic (PANC-1) or mesothelioma (H28) tumors, we efficiently forced these cells to acquire senescent phenotype. We document that these senescent cells gain higher resistance to combined TRAIL and homoharringtonine (HHT) treatment and enhance sensitivity to other apoptogens such as FasL, camptothecin and mVES. These cells also showed increased expression of anti-apoptotic protein c-FLIP in senescent cells and changes in the expression of some Bcl-2 family proteins....
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The relationship between circadian system and cell cycle
Vrtílková, Andrea ; Bendová, Zdeňka (advisor) ; Fárková, Eva (referee)
The circadian system is able to oscillate by itself owing to the transcriptional-translation feedback loop. Components of this loop do not affect just their own run, but they also have an impact on some other functions of the cell, for example cell cycle. This interaction is made by clock proteins (PER, CRY etc.) and by clock-controlled proteins (WEE1, TIM, XPA etc.). These proteins participate in the cell cycle run and have an impact on check-points. Disruption of the circadian clock can cause faults in cell cycle check-points, storing of DNA damages and increased cell apoptosis or tumor progression. Key words: circadian systém, cell cycle, WEE1, XPA, P21, C-Myc, TIM, PER
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A potential role of DAXX in cell cycle arrest and cellular senescence
Valášek, Ján ; Hanzlíková, Hana (advisor) ; Vopálenský, Václav (referee)
Death domain-associated protein 6 (DAXX) is a multifunctional protein involved in diverse cellular processes. It acts as a histone chaperone or regulator of transcription and apoptosis, in which is its role quite controversial. DAXX also participates in regulation of cell DNA damage response (DDR). DAXX co-creates and stabilizes complex with Mdm2, which negatively regulates the stability of p53, an important tumor suppressor, which is a part of signalling node in the DDR. If DNA damage is not lethal for the cell and unables it to proliferate, the irreversible state of cell cycle called cellular senescence takes place. Under physiological conditions, induction of senescence can prevent the development of tumorigenesis. Therefore, the description of mechanisms involved in the induction of senescence has potential clinical significance. In my thesis, I aimed to determine changes in the level of DAXX protein in senescent cells and to characterize the manner of its regulation. In tumor cells MCF-7 and primary BJ fibroblasts, I observed decrease in DAXX protein level and its regulation. I tested the hypothesis according to which an increase in DAXX level before DNA damage canprevent induction of cellular senescence, or increase in its expression during senescence can cause recovery of cell proliferation....
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Charakterizace vlivu senescence na indukci a regulaci smrti nádorových buněk
Nováková, Gita ; Anděra, Ladislav (advisor) ; Truksa, Jaroslav (referee)
4 Abstract Senescence is a specific cell state distinquished by cessation of cell division and proliferation and changes in gene expression. Normal cells enter senescence after distinct number of cell divisions or in case of an unrepairable damage. Senescence in cancer cells can be induced by subliminal stress as sublethal treatment with certain drugs. Senescent cancer cells persist in the tissue and may secrete a number of factors and nutrients affecting surrounding cells. Senescence can thus change the response of cancer cells to various apoptogens during cancer therapy. In this study, we focused on the elucidation of presumed differences between normal proliferating and senescent cancer cells in their response to selected apoptogens. Implementing bromodeoxyuridine (BrdU)-mediated replication stress in cancer cells derived from pancreatic (PANC-1) or mesothelioma (H28) tumors, we efficiently forced these cells to acquire senescent phenotype. We document that these senescent cells gain higher resistance to combined TRAIL and homoharringtonine (HHT) treatment and enhance sensitivity to other apoptogens such as FasL, camptothecin and mVES. These cells also showed increased expression of anti-apoptotic protein c-FLIP in senescent cells and changes in the expression of some Bcl-2 family proteins....
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Vztah mezi genetickými polymorfismy DNA reparačních genů a jejich expresí u zdravé populace (s výhledem na stanovení u onkologických pacientů).
Hánová, Monika ; Vodička, Pavel (advisor) ; Bencko, Vladimír (referee) ; Černá, Marie (referee)
DNA damage response is a complex system responsible for protection of a cell against internal and external DNA damaging agents and in maintaining genome integrity. Many of genes participating in DNA damage response pathways are polymorphic. Genetic polymorphisms in coding and regulatory regions may have impact on the function of proteins encoded by the genes. Phenotypic effect of single nucleotide polymorphisms (SNPs) is subject of investigation in connection with the ability of a cell to manage genotoxic stress and subsequently, in relation to cancer susceptibility. The aim of this thesis was to evaluate the association between SNPs in DNA repair genes (hOGG1, XRCC1, XPC) and cell cycle genes (TP53, p21CDKN1A , BCL2 and BAX) and their mRNA expression in peripheral blood lymphocytes from individuals occupationally exposed to styrene and control individuals. The aim was extended to analyses of relationships between mRNA expression levels of the above-mentioned genes and markers of exposure to styrene (concentration of styrene in blood and in air), markers of DNA damage (single strand breaks - SSBs, and endonuclease III specific sites - Endo III sites) and the base excision repair (BER) capacity, by means of γ-irradiation specific DNA repair rates and oxidative repair. Study on the group of healthy...
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Role of DNA damage response signalling in induction and maintenance of cellular senescence
Pešina, František ; Hodný, Zdeněk (advisor) ; Janoštiak, Radoslav (referee)
Cellular senescence is a state of permanent growth arrest. It is induced by many stimuli, including telomere shortening, DNA damage, oncogene hyperstimulation, chromatin perturbation and various stresses by which are cells affected. Researches showed central role of two pathways in induction and maintenance of this state. These are the p53/21 and p16/RB. The extent and dynamics of their activation by various stimuli is different. Slightly different is also their function in induction and maintenance of senescence. These differences are depicted and compared in this work.
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Dynamics of selected DNA damage response proteins
Benada, Jan ; Hodný, Zdeněk (advisor) ; Kuthan, Martin (referee)
DNA damage response (DDR) represents a vital signaling network that protects genome integrity and prevents development of cancer. Therefore the study of DDR is of a crucial clinical importance and DDR proteins are promising therapeu- tic targets. Although the great advances have been made mapping out interac- tions between individual DDR proteins, better understanding of complex behav- ior of this network is still needed. One approach, which might help us in this task, is to describe the dynamics of key proteins under different conditions. The first objective of this study was to investigate whether the temporal dynamics of selected DDR proteins differ upon different genotoxic insults, particularly upon γ- irradiation and UV-C irradiation. We showed that under certain insult some DDR proteins exhibit a monotone continuous activation pulse, while the activation of others triggers a series of pulses. We observed a previously described pulsative dynamics of p53 after γ-irradiation in MCF7 cells. Interestingly, we detected a monotone increase of p53 in U2OS after γ-irradiation and similar dynamics upon UV-C irradiation. We suggest that p53 dynamics depends on the presence or ab- sence of effective negative feedback loops between the upstream p53-activating kinases and Wip1 phosphatase. In the second...
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