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Cellular senescence and tumour immuno-surveillance
Včelková, Terézia ; Hodný, Zdeněk (advisor) ; Štěpánek, Ivan (referee)
Cellular senescence represents the antitumor mechanism that has been considered to be irreversible. However, it appears that under certain circumstances the cell is able to escape from senescent state, that led to increased risk of tumor transformation. Senescent cells secrete a plethora of substances including cytokines that modulate their surrounding environment. It turns out that they are able to induce senescence in neighboring cells and, paradoxically, they are the reason of tumor promoting effects of cellular senescence. According to the latest findings, senescent cells are subject to surveillance of the immune system, which is named as senescent surveillance. This event provide the ablation of these non- proliferating, damaged cells and protects the body from pathologies that are associated specifically with the phenomenon of cellular senescence. The aim of this bachelor thesis is to compile the current knowledge about the interactions of senescent cells with the immune system and to show their relevance in the war against cancer. Powered by TCPDF (www.tcpdf.org)
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Role of 5-azacytidine in therapy of myelodysplastic syndrome
Machalová, Veronika ; Hodný, Zdeněk (advisor) ; Indrová, Marie (referee)
The myelodysplastic syndrome (MDS) is a group of hematopoietic clonal disorders resulting in the inefficient production of myeloid lineage blood cells, with the prevalence of patients older than 65 years. One of the possible treatment options for MDS is 5- azacytidine and 5-aza-2'-deoxycytidine therapy. These compounds have been shown to cause the induction of cell-cycle arrest, cell differentiation and/or apoptosis. The in vitro experiments with 5-aza-2'-deoxycytidine indicated that this compound causes the premature cellular senescence, a state of the irreversible cell-cycle arrest. We have asked, whether 5-azacytidine, as a molecule with similar structure, is capable of causing the same effect. This treatment strategy could be beneficial in case that the negative pro- inflammatory effect of senescent cells on their surroundings can be nullified. In this thesis we have shown that 5-azacytidine induces DNA damage response, which is described as a fundamental event for the onset of the cell senescence. We tested 5- azacytidine treated HeLa cells for several markers of the cell senescence - the increase of the β-galactosidase activity, the PML and PML nuclear bodies and the formation of persistent DNA damage signaling lesions - albeit all these markers were positive, it was the very low increase in...
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Role of tumour suppressor PML in nucleolar functions
Kučerová, Alena ; Hodný, Zdeněk (advisor) ; Stejskalová, Eva (referee)
The cell nucleus is a complex structure composed of different parts, the nucleolus and PML nuclear bodies are important compartments of the nucleus. In the nucleolus, transcription of ribosomal DNA and biogenesis of ribosomes take place. The nucleolus may regulate the expression of proteins and thus the subsequent cell growth through regulating the amount of ribosomes. The nucleolus is also a sensor of stress. PML nuclear bodies play an important role in many cellular process - response to stress, virus infection or DNA damage. PML nuclear bodies consist of many proteins, the major protein is PML protein (Promyelotic leukemia protein). PML protein is coded by PML gene, it is spliced postrancriptionally and it has several isoforms. PML protein is an important cellular regulator and also a tumor suppressor. The nucleolus and PML protein cooperate together and have a functional relationship, which is not entirely clear. It was shown that PML protein changes its localization after exposure to stress and it goes near the nucleolus or into the nucleolus and this happens mainly in primary cells (the reason can be that the level of PML protein downregulates in tumour cells). The relationship between the nucleolus and PML nuclear bodies is important for cell response to stress. Keywords: nucleolus,...
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DNA damage and signalling pathways in cellular senescence
Hubáčková, Soňa ; Hodný, Zdeněk (advisor) ; Dvořák, Michal (referee) ; Růžičková, Šárka (referee)
Organisms such as mammals need tissue renewal as an important process for maintenance of their viability. Because proliferation is essential also for tumourigenesis, cells need tumour-suppressor mechanisms to protect organism against cancer. Cellular senescence, the permanent state of cell-cycle arrest, features one of these intrinsic barriers against tumourigenesis after DNA damage and understanding of this process may lead to finding of novel therapeutic targets and to optimization of chemotherapy for patients with cancer. In the first part of the PhD thesis, we investigated activation of JAK/STAT signalling pathway in drug-induced senescence. We used genotoxic drugs like aphidicolin, camptothecine, 5-bromo- 2'-doexyuridin, etoposide or thymidine to induce premature senescence in normal and cancer cells. All this chemicals were able to persistently activate JAK/STAT signalling in monitored cells. Activation of STATs was accompanied with up-regulation of expression of interferon-stimulated genes (ISGs), such as MX1, IRF1, IRF7 and PML. Since IRF1 and IRF7 can be directly involved in stimulation of the IFN genes, we show activated expression as well as secretion of IFNbeta and IFNgamma, but not IFNalpha in drug-induced senescent cells. Furthermore, an inhibition of JAK1 as a major kinase of STAT...
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Gold nanoparticles as a tool of targeted therapy of cancer
Knoblochová, Lucie ; Hodný, Zdeněk (advisor) ; Brábek, Jan (referee)
Nanomaterials have caught the interest of biomedical science because of their size (which enables them to interact with cellular structures), high surface area, and unique physical properties. Gold nanoparticles (GNPs) can be synthesised in various shapes. Their common property is surface plasmon resonance, which makes it possible to detect these particles with high resolution using dark field microscopy. GNPs can be efficiently modified with various ligands such as drugs, antibodies, or aptamers; this can be utilized to selectively bind GNPs to tissues, e.g. for drug delivery. Conjugated GNPs can also be used in diagnostics of tumor cells as well. Photothermal therapy consists of GNPs selectively binding to the tumor tissue, where they transform light into heat upon irradiation by near-infrared (NIR) light, thereby damaging nearby cells. The toxicity of GNPs is currently unclear. Research into modified gold nanoparticles is of great interest for targeted tumor therapy, as it may yield a tool for the selective destruction of tumor cells.
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Cellular senescence escape mechanisms - anti-cancer barrier
Davidová, Eliška ; Hodný, Zdeněk (advisor) ; Horníková, Daniela (referee)
Cancer is one of the most dangerous diseases of the modern world. Therefore, many world laboratories engaged in research into the causes leading to the outbreak of this insidious disease. In this context, it has already been found that the normal animal cells do not divide indefinitely, but have a finite replicative life span. After this period, cells undergo either apoptotic processes or enter into so-called senescence, typical for proliferation arrest, but preserved metabolic processes. Further research has revealed that senescence serves as an effective anticancer program and currently is shed light on its significance in relation to various physiological or pathological processes associated with aging. In this work, the focus is on the role of senescence as a barrier for cancer development, and effectiveness. It can be assumed, that if the senescent cycle arrest functioned perfectly, the incidence of cancer among people would be recorded in much lower extent. The aim of this thesis is the current knowledge about the physiological and pathological roles of senescence and possible causes of overcoming this barrier, the result may be the uncontrolled cell division and tumorigenicity.
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Odpověď metastatických buněčných linií karcinomu prostaty na genotoxický stres
Imrichová, Terezie ; Hodný, Zdeněk (advisor) ; Rösel, Daniel (referee)
Prostate cancer is the fourth most frequent cause of cancer-related deaths in men worldwide. One of current successful approaches to treat prostate cancer is radical prostatectomy followed by radiotherapy. However, this treatment is not 100% successful, as 53% patients develop secondary tumors. Our hypothesis is, that ionizing radiation itself contributes to the development of metastases by inducing changes in cell phenotype, particularly in terms of epithelial-to-mesenchymal transition and stemness. To test this hypothesis, we irradiated the cells of metastatic prostate cancer cell line DU145 by fractionated radiation 2 x 10 Gy and we compared the expression of selected epithelial, mesenchymal and stem-cell markers prior to and after irradiation. Besides we focused on a subpopulation of so called floating cells which arise during irradiation. These cells can survive the radiation treatment and after some time they are able to reattach and give rise to readherent population. We wanted to asses what is the cell cycle profile of these cells and whether and how fast they proliferate. In this thesis we have shown that radiation causes only minor changes in epithelial/mesenchymal and stem-like character of adherent fraction of the DU145 cell line. However, we have also described that small population of...
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Cytoskeletal organization of senescent cell
Kolářová, Věra ; Hodný, Zdeněk (advisor) ; Hock, Miroslav (referee)
This bachelor thesis discusses the phenomenon of cellular senescence in the context of cytoskeleton organization. Differences in the organization of cytoskeleton be- tween normal proliferative cells and senescent cells are being compared. Cellular cytoskele- ton is a very dynamic structure and influences the function of the cell within a tissue. This thesis gathers current evidence about senescence and cytoskeleton and indicates possible directions for future research. Keywords: cellular senescence, antitumour barrier, cell migration, cytoskeleton, microtubules, cancer 1
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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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