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Structure, function and importace of BRCA 1protein
Hojný, Jan ; Kleibl, Zdeněk (advisor) ; Falk, Martin (referee)
Studies of factors contributed to the development of hereditary breast and ovary cancers lead to the discovery of Breast Cancer 1 gene (BRCA1). The protein product of this tumor suppressor gene is nuclear phosphoprotein that plays a critical role in DNA repair and it is required for genome integrity control. The BRCA1 protein is the key component for correct assembly of reparation complexes formed in sites of DNA double strand breaks. Furthermore, BRCA1 protein is implicated in regulation of cell cycle checkpoints and it is also involved in regulation of gene expression in response to DNA damage. These activities suggest that BRCA1 protein plays a crucial role in orchestration of intracellular response to genotoxic DNA damage. Loss of BRCA1 functions leads to the DNA-damage repair mechanisms failure resulting in genomic instability and a tolerance of genomic alterations in affected cells. The genomic instability is the initial step toward early malignant transformation of cells lacking BRCA1 proteins. The aim of this work is to summarize the information about structure, functions known and the importance of BRCA1 protein with respect to the current discoveries enabling elucidation of versatile BRCA1-containing multiprotein complexes in which BRCA1 protein acts as the multiplatform interacting...
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Analysis of quantitative and qualitative genetic features in the pathogenesis of hereditary solid tumors.
Zemánková, Petra ; Kleibl, Zdeněk (advisor) ; Živný, Jan (referee) ; Tichý, Boris (referee)
Cancer the second most common causes of death in the Czech Republic. Carriers of mutations in genes predisposing to hereditary cancers represent a small but clinically significant group of high risk individuals. Today, dozens of predisposing genes for hereditary tumor syndromes are known and targeted next generation sequencing (NGS) has become a standard approach for their analysis. NGS allows rapid acceleration diagnostics of causal mutation in high-risk individuals. To identify mutations in genes predisposing to hereditary cancers, we designed a panel NGS analysis including subsequent bioinformatics analysis allowing a reliable identification of single nucleotide variants, insertions/deletions, and large intragenic rearrangements. The bioinformatics procedures described in this thesis were used for panel NGS validation, but also for identification of alterations associating with so far undescribed hereditary tumor types. Bioinformatics analyzes have become the basis for the unified processing of large datasets from the CZECANCA consortium and enable the construction of a population-specific database of genotypes that serve to improve clinical diagnostics of cancer predisposition in Czech patients. The versatility of NGS also allows its use for RNA (cDNA-based) analyzes of splicing variants in the...
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Analysis of cancer predisposition and functional analysis of variants of unknown significance
Stolařová, Lenka ; Kleibl, Zdeněk (advisor) ; Eckschlager, Tomáš (referee) ; Souček, Pavel (referee)
On average, 5-10% of all cancers occur in patients with hereditary tumors, who may have mutations in tens to hundreds of tumor predisposition genes. The phenotypes in mutation carriers overlap, and parallel analyses with sequencing panels is the method of choice in diagnostics. In our laboratory, we designed a universal panel and a targeted panel for a specific cancer, which allowed us to identify genetic alterations in patients with ovarian cancer, breast cancer, melanoma, and other cancers in the Czech Republic. The results of next generation sequencing (NGS) analyses show that the most frequent genetic alteration in ovarian cancers patients in the Czech Republic are hereditary mutations in BRCA1 (in 24% of unselected patients) and in malignant melanoma patients CDKN2A (in 2% of high risk patients). The presence of hereditary alterations is a clinically significant phenomenon affecting the prognosis and treatment of the disease. However, the interpretation of NGS findings is complicated by the presence of variants of unknown significance (VUS). We participate in the interpretation of VUS in the main predisposing genes BRCA1 and BRCA2 within the international consortium ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles). Our and international results of the most...
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Regulation of Gene Expression in Tumour Tissue
Kulda, Vlastimil ; Černý, Radim (advisor) ; Vachtenheim, Jiří (referee) ; Kleibl, Zdeněk (referee)
Deregulation of gene expression caused by genetic or epigenetic changes plays an important role in pathogenesis of cancer. The thesis is a commented collection of ten publications dealing with the molecular biology of tumours. The author has significantly contributed to all of them. All the articles contained in the thesis are linked to the topic of assessment of molecules involved in gene expression regulation (microRNAs) or DNA alterations that affect gene expression (promoter methylation, presence of a fusion gene). MicroRNAs are short single-stranded RNA molecules involved in posttranscriptional regulation of gene expression by triggering mRNA degradation or inhibiting translation. It is a basic mechanism with an impact on all cellular processes including the pathogenesis of various diseases. MicroRNAs can either act as oncogenes by decreasing the expression of tumour-suppressor genes or as tumour-suppressor genes by decreasing the expression of oncogenes. However, the network of microRNA - RNA interactions is much more complex. Our published results that are part of this thesis are focused on colorectal carcinoma (CRC), prostate cancer, head and neck squamous cell carcinoma (HNSCC), gastric cancer and non-small cell lung cancer (NSCLC). In patients with CRC, we demonstrated the prognostic...
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The functional in vitro analysis of the BRCA1alternative splicing variants
Ševčík, Jan ; Kleibl, Zdeněk (advisor) ; Stopka, Tomáš (referee) ; Macůrek, Libor (referee)
BACKGROUND: The inactivation of the tumor suppressor gene BRCA1 is a predisposing factor for a breast/ovarian cancer development. Formation of cancer-specific alternative splicing variants with aberrant biological properties can represent additional mechanism decreasing the overall BRCA1 activity in DNA double strand break (DDSB) repair. In this study, we analyzed BRCA1 alternative splicing variants BRCA114-15 and 17-19 ascertained previously during the screening of high-risk breast cancer individuals. METHODS: We established a stable MCF-7 cell line-based model system for an in vitro analysis of BRCA1 variants. Using this system, we analyzed the impact of BRCA114-15 and 17-19 variants on DNA repair kinetics using comet assay and confocal immunomicroscopy. The capacity of DNA repair was assessed directly by an in vitro NHEJ assay and indirectly by a mitomycin C sensitivity test. The proliferation activities were determined by a clonogenic assay and growth curves. RESULTS: Overexpression of BRCA114-15 and 17-19 increases the endogenous level of DNA damage, slows down the DDSB repair, and decelerates the initial phase of radiation-induced foci formation and prolongs their persistence. Moreover, BRCA114-15 and 17-19 differentially influence the activity of HR and NHEJ and sensitivity of MCF-7 cells to ionizing...
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Transcription factor PU.1 is a target of 5-azacitidine during differentiation therapy of myelodysplastic syndrome
Čuřík, Nikola ; Stopka, Tomáš (advisor) ; Kleibl, Zdeněk (referee) ; Trka, Jan (referee)
PU.1 is a key hematopoietic transcription factor. Knock-out of PU.1 in mouse is embryonic lethal due to complete depletion or several disruption of differentiation of multiple blood cell lineages. Low level of PU.1 and the disruption of its regulation are associated in vivo with acute myeloid leukemia and other hematologic malignancies. Myelodysplastic syndrome (MDS) is hematopoietic stem cell disorder with extremely heterogeneous features and outcome. It is characterized by improper differentiation of blood cells resulting in loss of function, dysplasia and blasts accumulation in bone marrow. About one third of MDS cases transforms into AML. MDS is also characterized by silencing of gene expression caused by aberrant DNA hypermethylation. Using DNA Methyltransferase inhibitors (DNMTi) such as 5-azacitidine (AZA) has good clinical results for the MDS patients with higher risk of disease. Indeed, AZA became standard therapy of high risk MDS in recent years. Nonetheless, our understanding of molecular mechanisms of AZA remains incomplete. This PhD thesis reports about the role of transcription factor PU.1 in MDS. We found that significant subset of high risk MDS patients express low level of PU.1 due to DNA hypermethylation of PU.1 upstream regulatory element (URE). We also found significant...
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Current methods of genome analysis and their use in identification of genetic determinants of human diseases
Stránecký, Viktor ; Kmoch, Stanislav (advisor) ; Kleibl, Zdeněk (referee) ; Pačes, Jan (referee)
The study of rare genetic diseases presents unique opportunity to uncover the genetic and molecular basis of human traits and greatly helped to the identification of genes, to the elucidation of their function and to the characterization of metabolic pathways and cellular processes. Over the past decades, linkage analysis has been appropriate approach to search for the genes causing Mendelian diseases and contributed to the identification of many genes, but the genetic cause of many diseases remains unknown. New methods of studying the human genome, microarray technology and massively parallel sequencing (next generation sequencing), represent a way to efficiently identify the cause of genetically determined diseases, based on direct observation of mutations in the genome of affected individuals. These techniques replaced the traditional method of disease gene identification represented by linkage analysis and sequencing of candidate genes and have become the standard approach to elucidate the molecular basis of diseases. In this work, i describe the the results achieved by using these methods - identification of the genes underlying mucopolysacharidosis type IIIC, isolated defect of ATP synthase, Rotor syndrome, autosomal dominat ANCL and GAPO syndrome.
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Analysis of quantitative and qualitative genetic features in the pathogenesis of hereditary solid tumors.
Zemánková, Petra ; Kleibl, Zdeněk (advisor) ; Živný, Jan (referee) ; Tichý, Boris (referee)
Cancer the second most common causes of death in the Czech Republic. Carriers of mutations in genes predisposing to hereditary cancers represent a small but clinically significant group of high risk individuals. Today, dozens of predisposing genes for hereditary tumor syndromes are known and targeted next generation sequencing (NGS) has become a standard approach for their analysis. NGS allows rapid acceleration diagnostics of causal mutation in high-risk individuals. To identify mutations in genes predisposing to hereditary cancers, we designed a panel NGS analysis including subsequent bioinformatics analysis allowing a reliable identification of single nucleotide variants, insertions/deletions, and large intragenic rearrangements. The bioinformatics procedures described in this thesis were used for panel NGS validation, but also for identification of alterations associating with so far undescribed hereditary tumor types. Bioinformatics analyzes have become the basis for the unified processing of large datasets from the CZECANCA consortium and enable the construction of a population-specific database of genotypes that serve to improve clinical diagnostics of cancer predisposition in Czech patients. The versatility of NGS also allows its use for RNA (cDNA-based) analyzes of splicing variants in the...
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Identification of hereditary alterations predisposing to breast cancer development using "next-gen" sequencing
Lhota, Filip ; Kleibl, Zdeněk (advisor) ; Zikán, Michal (referee) ; Mohelníková Duchoňová, Beatrice (referee)
Summary: Breast cancer (BC) is the most frequent cancer type in female population of Europe. Approximately 5 - 10 % accounts for its hereditary form which is characterized by high penetrance, early onset, risen recurrence risk and development of other cancers. Mutational analyses of high risk patients identify a predisposing mutation in one of the most studied genes (BRCA1, BRCA2, TP53, ATM, CHEK2, NBS1, PALB2) only in less than one third of tested breast cancer patients. Lately, with the use of new methods of next-generation sequencing, a number of other susceptibility or candidate genes were characterized, but the incidence of their pathogenic alteration is often geographically different. A notable proportion of high risk patients from families with hereditary BC can represent carriers of population-specific, or private mutations. Most of the to date identified BC susceptibility genes codes for proteins involved in DNA repair, especially repair of double strand break DNA repair. Nevertheless the mutation analysis was conducted only on a small fraction of these DNA repair genes. We can expect that in the group of yet nontested genes coding for DNA repair proteins a rare, but clinically important genetic alterations predisposing to BC in affected families can be discovered. This work describes a...
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