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The role of DNA repair mechanisms in the pathogenesis of myelodysplastic syndrome.
Válka, Jan ; Čermák, Jaroslav (advisor) ; Pospíšilová, Dagmar (referee) ; Penka, Miroslav (referee)
Background: The high incidence of mutations and cytogenetic abnormalities in patients with myelodysplastic syndrome (MDS) suggests the involvement of DNA repair mechanism defects in the pathogenesis of this disorder. The first part of this work was focused on monitoring of gene expression of DNA repair genes in MDS patients and on their alterations during disease progression. In the second part, next generation sequencing was used to detect single nucleotide polymorphisms (SNPs) and mutations in DNA repair genes and their possible association with MDS development was evaluated. Methods: Expression profiling of 84 DNA repair genes was performed on bone marrow CD34+ cells of patients with MDS. Screening cohort consisted of 28 patients and expression of selected genes was further validated on larger cohort of 122 patients with all subtypes of MDS. Paired samples were used for monitoring of RAD51 and XRCC2 gene expression during disease progression. Immunohistochemical staining for RAD51 recombinase protein was done on samples acquired by trephine-biopsy. Targeted enrichment resequencing of exonic parts of 84 DNA repair genes was performed on the screening cohort of MDS patients. Real-time PCR was used for genotyping of selected SNPs in the population study. Results: RAD51 and XRCC2 genes showed...
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Epigenetic factors CTCF a SMARCA5 control expression of hematopoietic transcription factor SPI1 in cells of acute myeloid leukemia and myelodysplastic syndrome.
Dluhošová, Martina ; Stopka, Tomáš (advisor) ; Machová Poláková, Kateřina (referee) ; Kozák, Tomáš (referee)
CCCTC-binding factor (CTCF) can both activate as well as inhibit transcription by forming chromatin loops between regulatory regions and promoters. In this regard, Ctcf binding on the non-methylated DNA and its interaction with the Cohesin complex results in differential regulation of the H19/Igf2 locus. Similarly, a role for CTCF has been established in normal hematopoietic development; however its involvement, despite mutations in CTCF and Cohesin complex were identified in leukemia, remains elusive. CTCF regulates transcription dependently on DNA methylation status and can if bound block interactions of enhancers and promoters. Here, we show that in hematopietic cells CTCF binds to the imprinting control region of H19/Igf2 and found that chromatin remodeller Smarca5, which also associates with the Cohesin complex, facilitates Ctcf binding and regulatory effects. Furthermore, Smarca5 supports CTCF functionally and is needed for enhancer-blocking effect at imprinting control region. We identified new CTCF-recognized locus near hematopoietic regulator SPI1 (PU.1) in normally differentiating myeloid cells together with members of the Cohesin complex. Due to DNA methylation, CTCF binding to the SPI1 gene is reduced in AML blasts and this effect was reversible by DNA methylation inhibitor 5-azacitidine.
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Myelodysplastic syndromes - search for the molecular basis]
Beličková, Monika
Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic stem cell disorders with ineffective hematopoiesis. It is characterized by morphological dysplasia, peripheral cytopenias affecting one or more cell lineages and an increased risk of transformation into acute myeloid leukemia (AML). The early stages of MDS can be considered a premalignant disease. The pathogenesis of MDS has not been fully explained yet, but due to the development of molecular genetic and cytogenetic methods, the origin and development of the disease is gradually being elucidated. In addition to the cytogenetic changes that are part of the prognostic system (IPSS-R), the somatic mutations found in different genes come to the forefront of interest. However, they are not routinely used in clinical practice. One of the objectives of this study was monitoring of mutations in TP53 gene in lower-risk MDS patients who generally have a good prognosis and for whom these findings have a particularly relevant prognostic significance. We investigated a total of 154 patients with lower-risk MDS, and 13% of them had a mutation. After dividing patients according to the presence of del(5q), we observed significant differences in the incidence of the mutations. The mutations were detected in 23.6% of patients with...
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Myelodysplastic syndromes - search for the molecular basis]
Beličková, Monika ; Čermák, Jaroslav (advisor) ; Divoký, Vladimír (referee) ; Pospíšilová, Dagmar (referee)
Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic stem cell disorders with ineffective hematopoiesis. It is characterized by morphological dysplasia, peripheral cytopenias affecting one or more cell lineages and an increased risk of transformation into acute myeloid leukemia (AML). The early stages of MDS can be considered a premalignant disease. The pathogenesis of MDS has not been fully explained yet, but due to the development of molecular genetic and cytogenetic methods, the origin and development of the disease is gradually being elucidated. In addition to the cytogenetic changes that are part of the prognostic system (IPSS-R), the somatic mutations found in different genes come to the forefront of interest. However, they are not routinely used in clinical practice. One of the objectives of this study was monitoring of mutations in TP53 gene in lower-risk MDS patients who generally have a good prognosis and for whom these findings have a particularly relevant prognostic significance. We investigated a total of 154 patients with lower-risk MDS, and 13% of them had a mutation. After dividing patients according to the presence of del(5q), we observed significant differences in the incidence of the mutations. The mutations were detected in 23.6% of patients with...
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The expression of TP53 gene at the mRNA level in patients with myelodysplastic syndrome
Šeborová, Karolína ; Beličková, Monika (advisor) ; Španielová, Hana (referee)
Myelodysplastic syndrome (MDS) is a heterogeneous group of diseases characterized by ineffective hematopoiesis which is caused by damage of differentiation of pluripotent haematopoietic stem cells. TP53 gene mutations are identified approximately in 10% of MDS and represent a negative prognostic factor. Altered TP53 gene expression may have similar effect as the mutation. Mutations or deregulated expression of this gene have an impact on many cellular processes including apoptosis, DNA repair, cell growth and angiogenesis. In this work, the expression mRNA levels of genes involved in p53 signalling pathway were studied in CD34+ pluripotent haematopoietic cells from bone marrow of patients with low- risk MDS. MDS patients showed increased expression of genes involved in apoptosis induction, regulation of cell cycle and DNA repair (BAX, BBC3, CCNE1, CDC25A, CDKN1A, FAS, GADD45A) as compared to healthy subjects. The patients with TP53 mutation had decreased expression of apoptotic genes (BAX, PIDD, TRAF2) and increased gene expression of apoptotic inhibitor (BCL2A1), indicating a reduced activity of apoptotic pathways and that way the pathological cell clone may gain a growth advantage. Deregulation of 21 genes (BAX, BBC3, EGR1, KAT2B, MDM2 etc.) was observed in patients with del (5q) compared to...
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Monitoring of blood counts parameters during the therapy in patients with myelodysplastic syndrome
Sochorová, Lenka ; Fátorová, Ilona (advisor) ; Vrbacký, Filip (referee)
Blood counts belongs among basic examination methods in hematology laboratory. It is used to determine the basic parameters of leukocytes, erythrocytes, hemoglobin, hematocrit and platelets. The goal of study was to determine which blood counts have changed during the treatment of patients with myelodysplastic syndrome using immunomodulatory drug lenalidomide. Analysis of blood samples were performed on the Sysmex XE-5000. The selected blood counts parameters were evaluated in two periods - before the beginning of the treatment and during the treatment. The final blood counts showed increasing concentrations of hemoglobin and decreasing platelet values; other blood count parameters have not changed significantly. The evaluated blood counts changes could be used to determine the efficiency of the treatment and the transfusion therapy could be stopped based on these results.
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DNA methylation in haematological malignancies
Šeborová, Karolína ; Beličková, Monika (advisor) ; Vopálenský, Václav (referee)
DNA methylation is one of the most common epigenetics modifications, during which a methyl group from the donor molecule S-adenosyl-L-methionine is transferred to the 5'position of the cytosine ring to create 5-methylcytosine. This reaction is catalyzed by DNA methyltransferases. Epigenetics modification plays an important role in the regulation of the transcription, genomic imprinting, X-chromosome inactivation and the development of the organism. This role in the regulation of transcription is important for the cancer. Especially the aberrant forms, like hypermethylation, which leads to transcriptional silencing of the tumor suppressing genes leading to the tumor progression, or hypomethylation causing genomic instability. Key words: DNA methylation, demethylating drugs, haematological malignancies, methods of detection, myelodysplastic syndrome
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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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Pathophysiologic aspects of myelodysplastics syndromes in relation to the effect of targeted imunomodulation and demetylation therapy
Jonášová, Anna ; Stopka, Tomáš (advisor) ; Maisnar, Vladimír (referee) ; Faber, Edgar (referee)
Myelodysplastic syndromes (MDS) represent a group of clonal stem cell disorders characterized by ineffective hematopoiesis, peripheral cytopenia, morphological dysplasia and the risk of transformation to acute myeloid leukemia (AML). MDS belongs to one of the most common hematological diseases in patients over 60 years old. MDS incidence is still increasing. Appropriate therapy of MDS remains challenging. There is no curative approach besides peripheral stem cells transplantation, which is regretfully appropriate only for a small group of patients due to a higher median age of the MDS population. This is why the search for therapeutic alternatives remains paramount. MDS treatment was rather frustrating until the recent introduction of two new therapeutic approaches: immunomodulation therapy with lenalidomide and epigenetic or demethylating therapy with 5-azacytidine. Both new drugs have significantly higher effect than standard therapy. However, the precise mechanism of this effect remains unknown. As a result, we decided to initiate several research projects while introducing this promising treatment to our patients. Our aim is to investigate the mechanism of both agents in relation to disease pathogenesis by examining changes of certain occurrences and factors prior to and during the course of...
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Proteomic analysis of selected oncohematological diseases
Pimková, Kristýna ; Dyr, Jan (advisor) ; Kodíček, Milan (referee) ; Petrák, Jiří (referee)
Oxidative stress is an important factor in carcinogenesis of oncohematological diseases. However its role in the pathogenesis of myelodysplastic syndromes (MDS) remains unclear. In this study, we have determined the oxidative status and evaluated proteomic changes in plasma of MDS patients as a consequence of oxidative dysbalance (oxidative modifications, protein-protein interaction and complex forming). We measured the levels of total cysteine, homocysteine, cysteinyglycine, glutathione, nitrites and nitrates in the plasma from 61 MDS patients and 23 healthy donors using high performance liquid chromatography. Glutathione and nitrites levels reduced significantly while other aminothiols levels increased significantly in plasma of MDS patients. This association with oxidative stress did not correlate with iron overload. We also found enhanced levels of asymmetric dimethylarginine in serums of middle aged patients with MDS that correlate to posttranslational modifications of proteins arginyl residues. Furthermore, carbonylated proteins level was significantly elevated in MDS patients compared to healthy donors. Using mass spectrometry, 5 S-nitrosylated blood platelets proteins were identified in plasma and blood platelets of MDS patients and set of 16 plasma proteins with high probability of...
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