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Immunoprotective character of polymer cytotoxic drugs
Šírová, Milada ; Říhová, Blanka (advisor) ; Turánek, Jaroslav (referee) ; Rabišková, Miloslava (referee)
18 I. INTRODUCTION Cancer is a serious health problem worldwide. In economically developed countries, it is a second most frequent cause of death after cardiovascular dis- eases, and the number of oncological patients continuously increases with the increasing age of population. The mainstay of cancer therapy is combination of surgery, radiation and chemotherapy. Whilst surgery and radiation are relatively precise and suitable to achieve a local control over the tumor, chemotherapy exerts a systemic ef- fect. These three modalities, when properly combined and sequenced, can cure a substantial number of hematological cancers and a smaller, but still significant subset of various solid tumors. Most cytostatic/cytotoxic drugs that are now in common use target the cells with high proliferation rate. The non-selective character of chemotherapy leads to increased toxicities towards normal rapidly proliferating cells. This means that the drugs have to be used at suboptimal doses, leading to development of (multi)drug resistance, metastatic disease and, eventually, to failure of the therapy. Innovative therapeutic strategies need to be developed in order to achieve better treatment outcome. For that purpose, several approaches are be- ing applied. First, sophisticated genomic and proteomic research could identify...
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Immunomodulatory effect of tumor targeted polymer drugs
Mervartová, Ivana ; Šírová, Milada (advisor) ; Palich Fučíková, Jitka (referee)
5 Abstract Myeloid-derived suppressor cells (MDSC) are a very heterogeneous population of immature, activated myeloid progenitors of neutrophils, monocytes/macrophages and dendritic cells that have not differentiated into mature forms. A common feature of these cells is the ability to suppress immune responses of T cells, NK cells, and dendritic cells. It is known that MDSC accumulate under various pathological conditions, such as chronic inflammation or cancer. In breast cancer patients, the highest MDSC counts correlate with the occurrence of metastatic foci in lung tissue. The suppressive effects of MDSCs are associated with resistance to chemotherapy, reduced effectiveness of immunotherapy and overall poor prognosis of the disease. Therefore, many studies focus on MDSC. One possibility is the differentiation of MDSC into mature populations that lose their suppressive phenotype. In this work, we focused on modulation of MDSC activity by all-trans retinoic acid (ATRA), bound to a polymer conjugate based on N-(2-hydroxypropyl)methacrylamide (HPMA). ATRA is used in clinical practice for the treatment of acute promyelocytic leukemia, where the mechanism of action is the differentiation of pathological cells into more mature forms and thus the cessation of their proliferation. The binding of ATRA to the...
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The importance of immunogenic cell death for modern tumor immunotherapy
Kubešová, Kateřina ; Šírová, Milada (advisor) ; Adkins, Irena (referee)
Immunogenic cell death is characterized by the release of molecules with damage-associated molecular patterns which can subsequently activate immune system. Only specific types of cell death can release these molecules. Classification of immunogenic cell death types and understanding of their initiation can be used for activation of the immune system against cancer cells. Simultaneously, it is necessary to understand different mechanisms, how the molecules with damage-associated molecular patterns work. Molecules with damage-associated molecular patterns which are studied the most, not only for their use in anticancer therapy, are type I interferons, calreticulin, high mobility group box 1 protein and heat shock proteins 70 and 90. Key words: immunogenic cell death, molecules with damage-associated molecular patterns, cancer, immunotherapy, type I interferons, calreticulin, high mobility group box 1 protein, ATP, heat shock protein 70, heat shock protein 90
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Possible applications of polymeric nitric oxide donors in treatment of murine experimental tumors
Horková, Veronika ; Šírová, Milada (advisor) ; Krulová, Magdaléna (referee)
Polymer-based drug delivery systems represent one of the promising strategies for successful tumor treatment. Conjugation of a low-molecular-weight drug to a syn- thetic polymer carrier enables targeted drug delivery to tumor tissue/cells and limited systemic toxicity of the drug. The conjugates show extended circulation time, and preferentially accumulate in tumor tissue due to the Enhanced Permeability and Re- tention (EPR) effect. The EPR effect depends on a structural anomaly in tumor neovasculature, and vasodilators were shown to enhance the EPR effect via an in- crease of blood supply in the tumor. Polymer drug carriers based on water-soluble N-(2-hydroxypropyl)methacrylamide (HPMA) benefit from variable architecture, drug loading and controlled release. HPMA-based conjugates with cancerostatics have al- ready proved high anti-tumor activity, inducing complete tumor regression followed by resistance to a second tumor challenge in experimental murine models. Three HPMA-based conjugates with organic nitrates (labeled 1, 2, and 3) were pre- pared as polymer donors of nitric oxide (NO) with the aim to intensify the EPR effect, thereby enhancing accumulation of co-administered macromolecular cancerostatics in the tumor. In this study, the conjugates were non-toxic to cancer cells and did not potentiate...
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Use of cucurbitacin D for cancer treatment
Malátová, Iva ; Šírová, Milada (advisor) ; Dibus, Michal (referee)
Cucurbitacins are highly oxidized triterpenoids commonly found in plants, especially in the family Cucurbitaceae. There are seventeen types of cucurbitacins and each of them has its derivatives. Cucurbitacins with the most prominent antitumor activity are B, D, E and I. Of these, cucurbitacin B and D are the most common in plants. This work focuses mainly on cucurbitacin D. Cucurbitacin D often induces apoptosis in tumor cells, cell cycle arrest and thereby stops cell proliferation. Indicators of these processes are reduced levels of Bcl-xL, Bcl-2, p21, p27 and cyclins A and B proteins. The main effect of cucurbitacin D on tumor cells is the inhibition of the STAT3 signaling pathway. Whether this pathway is affected at the level of phosphorylation, dimerization, or STAT3 translocation into the nukleus, the result is blocking transcription of genes, which are activated thanks to STAT3 pathway. These are primarily genes that affect tumor growth, angiogenesis, cell invasion, and immune escape. Cucurbitacin D also affects other cell components and processes, such as the NF-κB transcription factor, the enzyme complex of proteasome and inflammasome. However, current knowledge of cucurbitacin D and its mechanism of action is not yet sufficient for its use as an antitumor drug, although the results of its testing...
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The therapeutic potential of mesenchymal stem cells in a mouse experimental model
Hájková, Michaela ; Krulová, Magdaléna (advisor) ; Hrdý, Jiří (referee) ; Šírová, Milada (referee)
Due to their immunomodulatory and regenerative potential, mesenchymal stem cells (MSCs) represent a promising therapeutic tool for cell-based therapy, organ transplantation or tissue engineering. To improve clinical applicability of MSCs, new methods to increase their delivery and efficacy have been tested in the latest years but the mechanism of observed alterations has not yet been described. In the present project we focused on studying the effect of several factors that can significantly affect the therapeutic success of MSC-based treatment. Initially, we analysed the therapeutic effect of MSCs applied locally on nanofiber scaffold with incorporated cyclosporine A (CsA) in a mouse model of allogeneic skin transplantation. Our results indicate that application of MSCs in the presence of CsA direct M1/M2 macrophage polarization towards regulatory phenotype. This phenotype switching is accompanied by decreased production of nitric oxide (NO) and interferon (IFN-) and increase production of interleukin 10 (IL-10), and may result in suppression of the local inflammatory reaction. The next goal of proposed study was to analyse the effect of the treatment based on MSCs combined with immunosuppressive drugs with different mechanism of action on the balance among distinct T cell subpopulations. We...
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Myeloid - Derived Suppressor Cell in the Context of Tumor Microenvironment
Košťálová, Monika ; Šírová, Milada (advisor) ; Indrová, Marie (referee)
Today, tumors are considered not only as a complex of genetically mutated cells with pathological function of excessive proliferation, invasiveness and increased viability, but increased attention is paid for the tumor microenvironment created by the tumor itself. This microenvironment generates conditions, which differ from the normal tissues - for example local hypoxia, lactic acidosis and tumor- induced immunosupression - all these abnormalities lead to increased viability of the tumor tissue. Myeloid-derived suppressor cells (MDSCs) seem to be one of the main mediators of the escape from immunosurveillance. MDSCs represent a heterogenous cell population of myeloid origin. In active state, MDSCs produce enhanced amount of reactive oxygen species, nitrogen compounds and arginase, which represent the mechanisms of the suppression of the anti-tumor immune response. That makes MDSCs a promising therapeutic target. However, recent studies also point out the physiological role of MDSCs, which seems to be essential to consider for succesfull MDSCs targeting. Key words: Tumor microenvironment, immunosurveillance theory, immunoediting, myeloid-derived suppressor cells, immunosuppresion in tumors, therapeutic targeting of MDSCs, physiological role of MDSCs Powered by TCPDF (www.tcpdf.org)
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Experimental murine leishmaniasis and its application for drug discovery and study of host-pathogen interactions
Grekov, Igor ; Lipoldová, Marie (advisor) ; Krulová, Magdaléna (referee) ; Šírová, Milada (referee)
Leishmania spp. have a great clinical significance, being a causative agent of leishmaniasis. Leishmania is transmitted to its vertebrate hosts by phlebotomine sand flies. In vertebrates, the parasites infect professional phagocytes (neutrophils, monocytes and macrophages) and a variety of other cells. Clinical symptoms of leishmaniasis range from lesions, local or disseminated, to mucosal and visceral pathology. Twelve million people are infected with Leishmania and 350 million people are under risk of infection in 88 countries. Yet, no vaccine has been developed and the treatment needs significant improvement. In this regard, animal models of leishmaniasis play a key role in understanding the mechanisms of the disease and in finding ways to treat and prevent it. This thesis summarizes the results of my Ph.D. project devoted to refinement of procedures relevant to Leishmania studies and to the use of the optimized protocols for gene mapping and search for antileishmanial drugs. Large-scale cultivation of infective Leishmania parasites is important in a wide range of experimental setups. We adapted a biphasic SNB-9 medium for the large-scale cultivation of Leishmania and compared it with a common liquid medium. We also modified and optimised detection and quantification of Leishmania with PCR-ELISA by using...
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Use of polymer prodrugs containing cucurbitacin D for the treatment of experimental tumors
Hrabánková, Klára ; Šírová, Milada (advisor) ; Grobárová, Valéria (referee)
Chemotherapy is still the most widely used anti-cancer treatment. The majority of chemotherapeutics inhibit proliferating cells generally, not selectively cancer cells. The side effects associated with chemotherapy can be partly limited by conjugating a cytotoxic drug with a polymer nanocarrier. Such binding facilitates solubility in aqueous solutions, reduces systemic toxicity; and passively targets the drug directly into the tumour through the enhanced permeability and retention (EPR) effect. This thesis focuses on testing polymer conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA) carrying cucurbitacin D (CuD), a naturally occurring compound with potential anti-cancer activity. The mechanism of action is not elucidated yet, but several studies have depicted the inhibitory effect on signal transducer and activator of transcription 3 (STAT3) transcription factor. A STAT3 signalling pathway is overexpressed in several cancer cell lines and is also involved in the differentiation of myeloid- derived suppressor cells (MDSCs). We examined the therapeutic effect of the HPMA copolymers based on CuD in combined therapy with other polymer chemotherapeutics. CuD conjugates have shown in vitro cytotoxic effect on several model cancer cell lines. The combination with conjugates carrying doxorubicin...
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