|
|
Pathophysiological development and differentiation of cells during hematopoiesis
Moudrá, Alena ; Štěpánek, Ondřej (advisor) ; Černý, Jan (referee) ; Kalina, Tomáš (referee)
In recent years, a great effort has been deployed towards a better understanding of the molecular changes in cells and in the bone marrow (BM) environment that contribute to the development and progression of myelodysplastic syndrome (MDS) to acute myeloid leukemia (AML). Among others, the aberrant hematopoietic stem cells in MDS often display increase in DNA double strand breaks, genomic instability with common loss or rearrangement of chromosomes and an ineffective response to DNA damage, a phenomenon that has been linked to the onset of cellular senescence. Additionally, the BM microenvironment can become more pro-inflammatory. In our effort to better understand the contribution of the BM microenvironment on MDS progression, we analyzed the expression profiles of cytokines in the BM microenvironment in all stages of MDS/AML and found several proinflammatory cytokines that increase with disease progression. Also, by repeated sampling of patients over the course of 5-azacytidine therapy, we were able to assess the changes in the proinflammatory cytokine milieu with the progression of the disease. Additionally, we aimed to identify the candidate markers for the improvement of MDS prognosis. We focused on naturally occurring germline polymorphism of NAD(P)H dehydrogenase (quinone 1) gene (NQO1*2)...
|
|
|
Senolytics - current state
Sekáč, Dávid ; Hodný, Zdeněk (advisor) ; Zima, Michal (referee)
Cellular senescence is a state of the permanent cell cycle arrest caused by different stresses or cell to cell fusion. Senescent cells, unlike naturally aged cells, exhibit a specific phenotype, referred to as senescence associated phenotype (SASP). It is characterized by the production of biologically active substances such as interleukins, chemoattractants or proteases that affect their surroundings. Long-term survival of these cells in the body is the cause of age-related diseases. Under normal circumstances, number of senescent cells is maintained in the body by the immune system. However, the age-related abrogation of immune system function per se (immunosenescence) contributes to accumulation of senescent cells in tissues and aging of organism. This work describes origin, positive and negative effects of cell senescence, elimination of senescent cells by the immune system and current state of development of new substances causing specific lysis (killing) of senescent cells (senolytics).
|
|
|
Changes in oxidative phosphorylation during development of cellular senescence
Zima, Michal ; Hodný, Zdeněk (advisor) ; Kašparová, Dita (referee)
Cellular senescence represents a state of permanent cell cycle arrest. It is considered to be an active response of the cell to various extrinsic and intrinsic types of stress, which are damaged and/or uncapped telomeres, activation of certain oncogenes, DNA damage and effects of several cytokines. This thesis describes current mechanisms which may result in establishment of senescence phenotype, putting those facts in association with changes in oxidative phosphorylation. In thesis are also mentioned features of senescence cells and their impact on the neighborhood. Special attention is focused on the role of reactive oxygen species in promotion of cellular senescence, mechanisms of their elevation, the role of NADPH oxidases and the inhibition of mitochondrial oxidative phosphorylation complexes by activity of cytokine signaling pathways STAT3 and TGFbeta. Key words: cellular senescence, reactive oxygen species, cytokines, mitochondria, oxidative phosphorylation chain, NADPH oxidases, Signal Transducer and Activator of Transcription 3 (STAT3), TGF-β, DNA damage response (DDR)
|
|
|
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)
|
|
|
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...
|
|
|
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...
|
|
|
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.
|
|
|
DNA damage and signalling pathways in cellular senescence
Hubáčková, Soňa
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...
|
|
|
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
|
|
|
Role of the tumour suppressor PML in DNA damage response and cellular senescence after genotoxic stress
Knoblochová, Lucie ; Hodný, Zdeněk (advisor) ; Horníková, Lenka (referee)
The promyelocytic leukemia protein (PML) is a tumour suppressor. It has been reported that PML interaction with the p53 protein is involved in the activation of cell cycle checkpoints and, when persistent, may lead to the premature onset of cellular senescence. Cellular senescence is a state of permanent cell growth arrest that is associated with characteristic morphological and metabolic changes and persistent DNA damage signalling. Importantly, PML nuclear bodies coassociate with persistent DNA damage foci in senescent cells; however, the role of this interaction is still obscure. My goal was to characterize the role of PML in DNA damage response (DDR) and the induction of premature cellular senescence after genotoxic stress, namely X-radiation, using both siRNA-mediated PML knock down (PML KD) and complete PML knock out (PML KO) in human cells. The dynamics of DNA damage foci, levels of various proteins involved in DDR, and proliferation rate were measured in both PML KD and KO cells. No significant changes in the formation of DNA damage foci, activated DDR (p53 and Chk2), activated p21CIP1/WAF1 cyclin-dependent kinase inhibitor, senescent morphology, and SA-β-galactosidase activity in PML KO cells were observed. However, PML KO cells displayed higher levels of retinoblastoma protein (Rb) and...
|
guest ::
