Chronic myeloid leukemia is a clonal haematopoietic disease, with characteristic BCR-ABL1 fusion gene. Despite the significant improvement in patient treated with tyrosine kinase inhibitors (TKI), 20-30 % of patients develop resistance. One of the main causes of treatment failure are mutations in the BCR-ABL1 kinase domain (KD). The aim of this work was to elucidate the molecular mechanisms of resistance and mutagenesis development in CML using an in vitro CML model KCL-22. The main part of this work was focused on the identification of genes involved in DNA damage response and repair, that could play a role in the process of mutagenesis of BCR-ABL1. We used the RT2 Profiler PCR Arrays method for the group of selected genes regulating DNA damage response and repair. We identified the genes XRCC6 and PARP1 whose gene expression was significantly and specifically decreased during KD BCR-ABL1 mutagenesis. Products of these genes are involved in repairing DNA double-strand breaks through non-homologous end joining (NHEJ). During study of the KD BCR-ABL1 mutagenesis we also found that clones, which developed mutations, did not show the increased BCR-ABL1 expression in the beginning of the culture compared to the clones in which mutations have not evolved. Key words: myeloid leukemia, mutation,...

The heterogeneous nature of acute myeloid leukemia (AML) worsens the results of patients treated with standard therapy. Understanding the processes of leukemogenesis can contribute to identification of more appropriate treatment. Family of DLX genes (Distal-less homeobox), belonging to the homeobox genes, are associated with haematological malignancies and solid tumors. In the analysis of expression data, the low level of the DLX1 gene was associated with a worse prognosis of patients with AML. In this work we studied phenotypic changes of cell lines with different expression of the DLX1 gene. We silenced the DLX1 gene in AML cell line (sh cells) and compared it to the parental line with higher expression of DLX1 (NSC cells). By cell cycle analysis and apoptosis assays in vitro and in vivo, we have observed the arrest of sh cells in the G0 phase and a lower number of apoptotic cells. Differences were found when measuring the absolute number of cells in time. In in vitro conditions there were less sh cells, in in vivo environment there was significantly higher number of sh cells engrafted in comparison to NSC cells. Further results have shown that sh cells have lower levels of pro-apoptotic proteins and exhibit a higher level of TGF-β targeting PAI-1 gene that activates replicative senescence. We...

Accurate localization of breakpoints and deleted regions on chromosome 7 in bone marrow cells of patients is an essential step in identifying genes involved in tumor transformation of a cell. In case of hematological malignancies usually oncogenes and tumor suppressor genes are activated or deleted by a change in the arrangement of genetic material. Aberration of chromosome 7, total or partial loss of chromosome, especially long arms 7q, are among the recurrent cytogenetic abnormalities in patients with myeloid diseases such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Aberrations of chromosome 7 are an important prognostic marker occurring in 8-10% de novo MDS and AML and in 40-50% treated MDS / AML. For a detailed analysis of chromosome 7 breakpoints and aberrations, samples of 51 adult patients diagnosed with AML / MDS were examined using conventional and molecular cytogenomic methods. In our testing group we demonstrated a separate 7q deletion in one patient (2%) and an isolated monosomy of chromosome 7 in six patients (12%). Aberration of chromosome 7 detected in combination with another change was found in 17 cases (33%) and 27 patients (53%) had complex karyotype changes including chromosome 7. The most frequent breakpoint was 7q22. In 26 patients we proved a deletion...

Klasické schéma vývoje hematopoetických buněk předpokládá časné oddělení lymfoidního a myeloidního prekurzoru. V poslední době jsou navrhovány složitější modely, které předpokládají větší flexibilitu hematopoezy a navrhují existenci progenitorů s lymfoidním i myeloidním potenciálem. Akutní hybridní leukémie jsou malignity, které podle různých kritérií nelze jednoznačně zařadit k lymfoidní nebo k myeloidní linii a jejichž chování spíše dává za pravdu novým modelům hematopoezy. Předkládaná práce se zabývala především výzkumem dětských leukémií s přesmykem z lymfoidní do myeloidní linie během indukční léčby. Jedná se o rozsáhlý projekt, v jehož rámci si diplomová práce si kladla za úkol určit liniové zařazení leukemických blastů pomocí detekce přestaveb genů pro imunoglobuliny a T-buněčné receptory (TCR). Potvrdili jsme, že myeloidní buňky derivované v průběhu léčby pochází u všech pacientů z původního lymfoidního klonu. Dále jsme u těchto případů zkoumali expresi vytipovaných genů ve srovnání s běžnými druhy leukémií. Třetí částí práce byl výzkum prognostického významu přítomnosti přestaveb TCR (a tedy příslušnosti k lymfoidní linii) u leukémií z T-lymfoidní řady.

Philadelphia (Ph) chromosome, as a result of reciprocal translocation, is in majority of cases connected to two types of leukaemia - chronic myelogenous (CML) and acute lymphoblastic (ALL). The translocation occurs within large intronic sequences of BCR and ABL genes. The breakpoints are specific for individual patient and may be used as a target for monitoring of leukemic burden (MRD, minimal residual disease) during the treatment. In general, MRD is an important prognostic factor, which influences the treatment intensity. Two standardized methods are currently used for its monitoring. The first one is based on the detection of clonal specific Immunoglobulin and/or T-cell receptor genes rearrangements (and thus cannot be used for CML cases) at the DNA level, the second one utilizes detection of the BCR/ABL fusion gene at the mRNA level. Our aim was to optimize and standardize the process to find individual patient breakpoints on Ph chromosome and to use it for MRD quantification. We found the breakpoint in 80 % cases. The MRD data from 15 patients obtained by our method were compared to the levels obtained by standard methods (Ig/TCR and BCR/ABL transcript quantification). In all but 1 patient we found significant discrepancies, raising the questions about leukemic origin and the most accurate method for...

Hematopoiesis is a highly orchestrated process, in which a single hematopoietic stem cell (HSC) gives a rise to all blood cellular components. For myeloid and lymphoid development precise controlled expression of the PU.1 transcription factor is needed. Deletion of PU.1 gene in mouse is lethal and its dysregulation during hematopoietic differentiation is associated with blood malignancies including acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). MDS and AML are serious blood disorders characterized by expansion of immature blood cells and lack of differentiated functional cells. Not only genetic but also epigenetic aberrations represent a very important field for studying pathophysiology of leukemia genesis and dysregulation of the PU.1 gene represents intensively studied candidate mechanism. Modern therapy of selected MDS and subset of AML patients is based on treatment with DNA hypomethylating agent Azacytidine (AZA) interfering in PU.1 gene regulatory mechanism. However, poor response or resistance to this therapy often occurs. In this thesis we present data obtained from AZA-resistant clones of MDS/AML cell line OCI-M2. We analysed DNA methylation and DNA hydroxymethylation at the key regulatory element of the PU.1 gene (URE). We found that these epigenetic modifications at URE...

61 Summary Wilms' tumor gene 1 (WT1) is highly expressed in acute leukemia and other hematological malignancies. It has been therefore suggested as a potential universal marker of minimal residual disease (MRD), particularly in patients with acute myeloid leukemia (AML). Due to controversial results of some of the studies, the role of WT1 in MRD follow-up and WT1 prognostic significance remain unclear. WT1 protein is produced in more than 36 different isoforms. These variants have distinct, partially overlapping functions and their ratio is supposed to influence the final effect of WT1. However, despite the increasing number of studies, the clinical impact of WT1 and its isoforms in acute leukemia have not yet been elucidated. We established a unique qPCR method to assess the expression pattern of the main 4 WT1 isoforms. Using this method, we determined the ratio of WT1 variants in the samples of patients with AML, myelodysplastic syndrome (MDS) and healthy controls. Our data showed that this pattern can distinguish among particular hematological malignancies, but lacks a prognostic significance. Within our international study group we determined the prognostic significance of total WT1 expression in childhood AML. Based on our results of a large cohort of patients we can conclude that WT1 expression at...

Hematooncological diseases are often accompanied by dietary restriction, especially in cytotoxic therapy. The main purpose of the work was to assess the effect of high-dose chemotherapy on the change of nutritional status in two groups of hematooncological patients. A total of 16 patients were enrolled. Changes of the body composition were evaluated using bioelectrical impedance analysis supplemented by monitoring of biochemical nutritional indicators. Observations showed that in both groups the majority lost weight. In the first group of eight patients with acute myeloid leukemia observed during three consecutive hospitalizations, the median of change of body weight was -3.7 kg (-4.3%). Loss of lean body mass with a median value of -4.8 kg (-7.2%) was detected at all patients. Body fat was reduced at half of the patients. In some cases, with length of observation, there was an increase in fat mass along with visceral fat. In the second group, which included eight patients (after autologous hematopoietic stem cell transplantation) at whom one hospitalization was evaluated, body weight was reduced at six patients. The medianof change of body weight was -2.1 kg (-2.3%). At five patients, the treatment representeda loss of active metabolic mass. The change of the weight of the lean body mass was shown...

This work presents the results ofour research of cell-free nucleic acids (cfNA). The first part shows changes in methylation patterns of immune response genes promoters that are detectable in plasma during the hemodialysis sessions and also differences in methylation between patients and healthy subjects. Alterations include genes that play their role in the regulation of hematopoiesis and these changes are in close relation with the need of anemia therapy. In the other plasma cfNA study we detected miRNA signatures in patients with acute myeloid leukemia at diagnosis (6 highly abundant miRNAs found) and in remission achieved after standard chemotherapy (trend to n01malization, lower levels ofthese miRNAs). Another part of work presents data from the study of potential non-invasive biomarker of bladder cancer. The amounts of cfDNA in urine are higher in patients than in healthy subjects and there were found 5 down-regulated miRNAs. Simultaneously it was established set of 30 miRNAs that are constantly present in urine supematants independently on sex, age and healthy status of subjects. The last part presents analysis ofcell-free fetal DNA. We analyzed differences between a new quantification method - droplet digital PCR and real-time PCR which is used routinely nowadays. Slightly more precise was...