National Repository of Grey Literature 56 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Proximity proteome of intramembrane serine protease RHBDL4
Boháčová, Šárka ; Stříšovský, Kvido (advisor) ; Brábek, Jan (referee)
Regulated intramembrane proteolysis is an interesting process involved in a multitude of cellular pathways. Enzymes which catalyse this are termed intramembrane proteases (IMPRs), cleaving proteins passing through the membrane within their transmembrane domain. Rhomboid proteases are serine IMPRs. They are widely distributed among organisms and evolutionarily conserved, but despite many efforts, their physiological roles are largely unexplored. RHBDL4 is a mammalian rhomboid protease localised to the endoplasmic reticulum. It is involved in the development of colorectal cancer, which makes it an important focus of research, but its physiological function is not well understood. In order to explore it, I established and employed a proximity proteomics approach, termed APEX2. It is based on biotinylation of proteins in the spatial proximity of the target in the physiological environment of intact living cells. Labelled proteins are subsequently purified, identified and quantified by mass spectrometry. Exploring the physiological vicinity of RHBDL4, its interaction partners and substrates can be revealed and the detailed subcellular compartment, where RHBDL4 resides, can thus be inferred. During three independent experiments in HCT116 cell line, three proteins emerged repeatedly in the RHBDL4...
Molecular bases of sensitivity to electron transport chain inhibition-induced cell death
Blecha, Jan ; Rohlena, Jakub (advisor) ; Brábek, Jan (referee) ; Pecinová, Alena (referee)
1 Abstract in English Mitochondrial electron transport chain (ETC) targeting shows a great promise in cancer therapy. However, why modern ETC-targeted compounds are tolerated on the organismal level and what are the molecular reasons for this tolerance remains unclear. Most somatic cells are in a non-proliferative state, and features associated with the ETC in quiescence might therefore contribute to specificity. Thus, we investigated the ETC status and the role of two major consequences of ETC blockade, reactive oxygen species (ROS) generation and inhibition of ATP production, in cell death induction in breast cancer cells and in proliferating and quiescent non-transformed cells. First, we characterised the effect of a newly developed ETC inhibitor mitochondria- targeted tamoxifen (MitoTam) in in vitro and in vivo tumour models of breast cancer with varying status of the Her2 oncogene. We document that Her2high cells and tumours have increased assembly of respiratory supercomplexes (SCs) and increased complex I-driven respiration in vitro and in vivo. They are also highly sensitive to MitoTam. Unlike the parental compound tamoxifen, MitoTam efficiently suppressed experimental Her2high tumours without systemic toxicity. Mechanistically, MitoTam inhibits complex I- driven respiration and disrupts respiratory...
Modification of murine tumor cell lines with CRISPR/Cas9 system and their characterization
Lhotáková, Karolína ; Poláková, Ingrid (advisor) ; Brábek, Jan (referee)
MHCI molecules are constitutively expressed in all nucleated cells and play a key role in antigen presentation to CD8+ T lymphocytes. One of the tumor immune evasion strategies is MHCI expression downregulation. This leads to an impaired recognition of tumor antigens by CD8+ T lymphocytes that are unable to start the immune response. Since the MHCI expression downregulation occurs in up to 90 % of some tumors it is neccesary to have a clinical relevant tumor model without a MHCI surface expression that would be used for testing of immunotherapeutic approaches. This thesis describes a production of new model cell lines of TC-1 tumor cells with irreversibly downregulated MHCI. That was achieved by an inactivation of B2m, which is a part of MHCI, by gene editing using CRISR/Cas9. The B2m inactivation was confirmed by flow cytometry, western blot and sanger sequencing of single alleles. The inactivation slowed down the cell growth for both in vitro and in vivo. The cell metastatic activity was not affected. The tumors established by cells without the B2m expression are not sensitive to DNA vaccine against HPV16 E7 oncoprotein by a pBSC/PADRE.E7GGG vaccine. The main effector function against these tumors possess the NK1.1+ cells. In a therapeutic vaccination experiment it was repeatedly achieved of...
Mechanisms of resistance and iron metabolism in cancer stem cells
Lettlová, Sandra ; Truksa, Jaroslav (advisor) ; Kovář, Jan (referee) ; Brábek, Jan (referee)
(EN) Analogously to normal stem cells within the tissues, cancer stem cells (CSCs) have been proposed to be responsible for maintenance and growth of tumours. CSCs represent a small fraction of cells within the tumour, which is characterised by self-renewal capacity and ability to give rise to a tumour when grafted into immunocompromised mice. Cells with increased stemness properties are believed to be responsible for tumour resistance, metastases formation and relapse after tumour treatment. The first part of this work concentrates on resistance of the tumours, which is often associated with increased expression of ATP-binding cassete (ABC) transporters pumping chemotherapeutics out of the cells. For the purposes of this study, we utilized an in vitro model of CSCs, based on cultivation of cells as 3D "spheres". Expression profiling demonstrates that our model of CSCs derived from breast and prostate cancer cell lines express higher mRNA level of ABC transporters, particularly ABCA1, ABCA3, ABCA5, ABCA12, ABCA13, ABCB7, ABCB9, ABCB10, ABCC1, ABCC2, ABCC3, ABCC5, ABCC8, ABCC10, ABCC11 and ABCG2 among the cell lines tested. The protein level of ABC transporters tested in breast CSCs showed higher expression of ABCB8, ABCC1, ABCC2, ABCC10 and ABCG2 but downregulation of ABCB10 and ABCF2 proteins....
Molecular mechanisms of apoptosis induction by taxanes in breast cancer cells
Jelínek, Michael ; Kovář, Jan (advisor) ; Brábek, Jan (referee) ; Reiniš, Milan (referee)
Taxanes are cytostatic routinely used for the treatment of solid breast, ovarian, prostate, head and neck tumors and other types of tumors. Resistance of tumor cells to the effect of taxanes represents serious obstacle for the employment of taxanes in the treatment of tumors. This resistance can be associated, among other things, with lower rate of apoptosis induction in cancer cells or also with increased level of transporters transporting taxanes out of the cell. In this PhD thesis we tried: (1) to contribute to elucidation of the role of molecular mechanisms of apoptosis induction by taxanes in cells of human breast cancer. Specifically, it meant to contribute to elucidation of the role of initiator caspase -8 a - 9 and mainly of initiator caspase-2. Next, to contribute to elucidation of the role of executioner caspase -3 - 6, and -7 and selected proteins of the Bcl-2 family. (2) To contribute to elucidation of molecular mechanisms of resistance of human breast cancer cells to taxanes. Specifically, it meant to describe the role of selected functional groups in taxane structure in bringing about and overcoming resistance to taxane and next to contribute to elucidation of the role of P-glycoprotein (ABCB1 transporter) in the resistance to individual taxanes. 1) We found that caspase-2 represents...
Regulation of Epithelial-Mesenchymal transition by the ERK pathway.
Čáslavský, Josef ; Vomastek, Tomáš (advisor) ; Brábek, Jan (referee) ; Gregor, Martin (referee)
Typical epithelium is uniformly polarized solid structure defined by the presence of cell-cell contacts that are connected to well-organized network of actin cytoskeleton. While epithelium is considered to be rather static, during embryogenesis or cancer development epithelial tissues undergo considerable dynamic changes in their integrity that are characterized by loss of epithelial polarity, disruption of cell-cell adhesions and gaining mesenchymal or mesenchymal-like migratory phenotype. These changes, collectively termed as epithelial-mesenchymal transition (EMT), allow cells to effectively invade surrounding tissues and are considered to be a main factor underlying the formation of metastatic cancer. The MAPK/ERK cascade, comprised of protein kinases Raf, MEK and ERK, induces the breakdown of epithelial integrity and cell autonomous migration in various cell lines. In the ERK pathway, ERK is an effector protein kinase which, depending on the cellular context, phosphorylates a number of different substrates. Spatiotemporal phosphorylation of specific constellation of ERK substrates drives specific biologic outcome. The question arises whether, during conversion of multicellular epithelium to autonomously migrating cells, ERK regulates a "master" controller or whether the ERK regulatory function...
Development and use of a polymer-based antibody mimetic for specific targeting of fibroblast activation protein
Dvořáková, Petra ; Konvalinka, Jan (advisor) ; Brábek, Jan (referee)
Fibroblast activation protein (FAP) is a serine protease which is associated with cancer and recently also with other diseases such as rheumatoid arthritis or liver cirrhosis. Increased expression of FAP was observed in more than 90 % of epithelial cancers in contrast to its minimal expression levels in healthy tissues. FAP therefore represents a potential target for anti-cancer treatment as well as a diagnostic marker for various other diseases. In order to accomplish inhibition of FAP, a series of inhibitors was developed. The essential property of the inhibitors is their selectivity against dipeptidyl peptidase IV (DPP-IV), a homologue of FAP, which is expressed in majority of healthy tissues. This diploma thesis describes a novel research tool for characterization of FAP - a polymer conjugate containing FAP inhibitor as a targeting ligand, fluorophore for the visualization of the conjugate and biotin for its immobilization. The polymer conjugate functions as an antibody mimetic, which can be used in a variety of biochemical methods for detection, visualization and specific targeting of FAP. This study shows that the polymer conjugate selectively and effectively inhibits FAP with more than three orders of magnitude difference of the inhibition constant in comparison to DPP-IV. At the same time,...
Adhesion structures of leukemia cells and their regulation by Src family kinases
Obr, Adam ; Kuželová, Kateřina (advisor) ; Brdička, Tomáš (referee) ; Brábek, Jan (referee)
Adhesion signaling is a field of cell biology studied mostly on adherent cell types. However, hematopoietic cells grow in suspension, and use adhesion to the extracellular matrix (ECM) only in their early development, or - in case of differentiated cells - to perform the tasks they are specialized for. Peripheral leukemic cells are derived from more or less immature hematopoietic precursors that have, among other alterations, defects in adhesion to the bone marrow microenvironment. On the other hand, leukemic stem cells (LSC) use adhesion to the bone marrow ECM as a mean to evade chemotherapy, and are a source of the minimal residual disease, and of the disease relapses. Kinases of the Src family (SFK) are known regulators of adhesion signaling in adherent cell types, and their overexpression and/or hyperactivation is often seen in malignant diseases. They are also involved in hematooncologic disease progression and resistance to therapy, particularly in several types of leukemias. In the present work, we used a variety of methods including microimpedance measurement, fluorimetric measurement of adhered cell fraction, immunoblotting, confocal microscopy, and interference reflection microscopy. Our results indicate that active Lyn kinase, a hematopoietic SFK, is present in adhesion structures of...
The role of galectins in cancer cell invasiveness
Remišová, Michaela ; Brábek, Jan (advisor) ; Kovář, Marek (referee)
Galectins are family of β-galactosidase binding proteins that serve many functions in all kind of mammalian cells. In the past years galectins, namely galectin-1 and galectin-3, have been revealed to play a major role in various cancer processes including cancer cell invasiveness, a process indispensable for the formation of metastasis. Both extracellular and intracellular forms of galectins modify the process of invasiveness in various ways, through interacting with different components of the cell or of the cell signalling pathways. The aim of this bachelor's thesis is to summarize mechanisms by which galectins promote cancer cell invasiveness. Keywords: galectins, galectin-1, galectin-3, invasiveness, cancer, metastasis
Organic codes and memories
Švorcová, Jana ; Markoš, Anton (advisor) ; Brábek, Jan (referee)
5 Abstract The backgrounds of Marcello Barbieri's semantic biology and the semiotic biology are confronted in the issue of autonomy of living systems. In the place of an interpreter in Pierce's triad, in Barbieri's case there stands a code. Although both concepts attribute important status to the meaning in biology (which is left out outside the scope of semiotic tradition), both concepts are by definition different in the way of apprehension the nature of living systems and of basic biological ideas. Codes are considered to have fundamental status in Barbieri's concept. From this point of view the analysis of histone code hypothesis seems to be appropriate. Can we say (according to our today's scientific knowledge) that histone code truly fulfills demands of Barbieri's concept of codes? Another Barbieri's idea of epigenesis functioning on the basis of biological memory can be unfolded not only thanks to analysis of the phylotypic stage's role, but also by similar analysis of the homeotic genes' role in morphogenesis of vertebrates, because even these genes can be regarded as biological memory of species. These analyses will lead us step by step to the negation of the thesis "cultura contra natura".

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