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Investigation of the role of the KEAP1-NRF2 antioxidant pathway in the therapy of secondary acute myeloid leukaemia
Myšáková, Michaela ; Pimková, Kristýna (advisor) ; Suttnar, Jiří (referee)
The development of therapy resistance is a long-standing problem in treating cancer, particularly in the treatment of myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML), where the hypomethylating agent 5-azacytidine (AZA) is the first choice of treatment. To enhance therapeutic efficacy, AZA is often combined with other agents such as pevonedistat (Pevo), a NEDDylation inhibitor targeting the ubiquitin-proteasome system. While initial results showed a synergistic effect of the AZA and Pevo combination in treating MDS and AML, dual resistance has been described, underlining the importance of understanding the mechanisms behind the resistance development. Our previous data demonstrated an essential role of redox homeostasis and antioxidant system represented by Nuclear factor erythroid 2-related factor 2 (NRF2) in AZA resistance. The Kelch-like ECH-associated protein 1 (KEAP1)-NRF2 pathway is the master regulator of antioxidative defence in cells crucial for maintaining redox balance. However, hyperactivation of NRF2 has been implicated in therapy resistance and cancer progression. We hypothesised that NRF2 is crucial in MDS/AML therapy resistance, particularly in resistance to combined AZA and Pevo therapy. We worked with cells sensitive and resistant to AZA and Pevo and monitored...
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Epigenetic control of PU.1 gene transcription during development of 5-Azacytidine resistance in acute myeloid leukemia
Křtěnová, Petra ; Burda, Pavel (advisor) ; Čuřík, Nikola (referee)
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...
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The role of WT1 and its isoforms in normal haematopoiesis and leukaemogenesis
Kramarzová, Karolina ; Trka, Jan (advisor) ; Pospíšilová, Dagmar (referee) ; Živný, Jan (referee)
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...
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