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Study on the role of pharmacokinetic mechanisms of drug resistance in new anticancer drugs with focus on solid tumors
Vagiannis, Dimitrios ; Hofman, Jakub (advisor) ; Souček, Pavel (referee) ; Zendulka, Ondřej (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Candidate Mgr. Dimitrios Vagiannis Supervisor RNDr. Jakub Hofman, Ph.D. Title of Doctoral Thesis Study on the role of pharmacokinetic mechanisms of drug resistance in new anticancer drugs with focus on solid tumors Cancer chemotherapy is an important tool for the cure of cancer. Although the development of new anticancer drugs has been rapidly progressing, the phenomenon of multidrug resistance (MDR) continues to be a key issue leading to therapy failure in oncological patients. MDR is based on pharmacodynamic as well as pharmacokinetic mechanisms. Pharmacokinetic MDR includes drug efflux transporters and biotransformation enzymes that decrease the amount of (active form of) a drug in tumors. While the MDR role of transporters has been well understood, the participation of drug metabolizing enzymes is still unclear. This thesis investigates the role of cytochromes P450 (CYPs) in cytostatic resistance. Furthermore, it focuses on the modulation of pharmacokinetic MDR using pharmacokinetic drug-drug interactions of new targeted antitumor drugs. Finally, it aims to confirm the in vitro findings in ex vivo patient-derived tumor explants. In our latest publication, we demonstrate the significant role of...
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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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The role of genetic factors in the prognosis and prediction of effects of the chemotherapy of breast carcinoma
Hlaváč, Viktor ; Souček, Pavel (advisor) ; Hodek, Petr (referee) ; Liška, Václav (referee)
Breast carcinoma is the most common cancer among women in our country and worldwide. One of the obstacles to successful therapy is a multidrug resistance. It can be caused by different factors, such as overexpression of ABC transporters, or decreased expression of SLC transporters, deregulation of drug metabolizing enzymes, variability of the targets of anticancer drugs, failure of apoptosis or increased capacity of repair genes. The aim of this study was to search for associations of genes of drug transport and metabolism with the prognosis of patients or response to chemotherapy. From the view of preventive medicine, this aim constitutes an important part of both secondary and tertiary prevention of cancer, i.e., discovery of markers enabling optimal therapy selection for each patient, decreasing the risk of disease progression to advanced and resistant stage, and elimination of side effects of chemotherapy. The expression profile of ATP-binding cassette (ABC) transporters (49 genes), cytochromes P450 (CYPs, 10 genes), aldo-keto reductases (AKRs, 13 genes) and carbonyl reductase 1 was analyzed in the tumor and adjacent non- tumor control tissues in a cohort of neoadjuvantly treated patients. Genes deregulated in tumors compared with control tissues or genes associated with clinical data were assessed in...
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Role of genetic factors in the prognosis and prediction of efficacy of chemotherapy in breast carcinoma patients
Brynychová, Veronika ; Souček, Pavel (advisor) ; Macůrek, Libor (referee) ; Stružinská, Ivana (referee)
Changes in the regulation of apoptosis and cell cycle are involved in tumor development, progression, and resistance to antitumor therapy. The aim of this work was to evaluate the importance of apoptotic caspases and regulators of cytokineses as possible prognostic and predictive markers in breast carcinoma patients. In addition to determining the transcript levels of selected genes in tumor and control tissues obtained from breast carcinoma patients, we have also focused on the importance of alternative splice variants of caspases and their potential genetially determined regulation. We analysed the obtained data in relation to the clinical-pathological characteristics of the tumors, the progression-free survival of patients and to the response of the patients to the neoadjuvant chemotherapeutic treatment. Part of the work was determination of protein expression levels and verification of the importance of selected candidates for the effect of chemotherapy by functional study. The transcript levels of caspase 2, 3, 7, 8, 9, 10, the specifically detected splice variants caspase 2S, 2L, 3A and B, 3S, 9A, 9B, 8L, and the transcript levels of KIF14 and CIT in breast carcinomas were unrelated to the progression-free survival of patients, or to the response of patients to neoadjuvant treatment. The...
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The study of signaling pathways that modulate multidrug resistance
Dvořák, Pavel ; Souček, Pavel (advisor) ; Daum, Ondřej (referee) ; Benson, Veronika (referee)
The study of signaling pathways that modulate multidrug resistance The theme of cancer cell resistance to anti-cancer drugs including the common mechanisms of resistance development and the theory of cancer stem cells was introduced in the Introduction to the doctoral thesis. The theoretical part was focused more deeply on the two topics - the role of ATP-binding cassette (ABC) transport proteins and chromosomal abnormalities in the development of cancer chemoresistance. The possible therapeutic potential for the treatment of cancer was stressed for both topics. The Results were composed of the commentaries on the five published works, which the author of the thesis conducted as the main author. The first work brought the evidence supporting the hypothesis of the existence of ABC gene expression profiles (signatures), which are common to multiple types of tumors and are associated with significant clinical consequences. These general ABC gene expression profiles could possibly form a new hallmark of cancer. The second work studied more closely a group of acute myeloid leukemia patients, who did not achieve complete cytogenetic remission after two attempts to maintain remission of the malignant disease. The new entity, consisting of patients with the translocation t(2;11)(p21;q23) without the...
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The influence of xenobiotic metabolizing enzymes and transporters on the incidence of colorectal cancer and chemotherapy outcome
Krus, Ivona ; Souček, Pavel (advisor) ; Králíčková, Milena (referee) ; Hodis, Jiří (referee)
Introduction: Colorectal cancer (CRC) is one of the most frequent malignancies and affects approximately 5% of worldwide population. More than 75% of CRC cases represent sporadic forms. Susceptibility to nonhereditary CRC is significantly influenced by polymorphisms and mutations in low-penetrance genes. Variations in biotransformation and DNA repair genes may result in acumulation of toxins and DNA damage in cells leading to the development of cancer. Furthermore, different gene expression profiles of membrane transporters affecting the accumulation of anticancer drugs in tumour cells, e.g. ABC drug transporters, may largely influence inter-individual variability in drug response and chemotherapy outcome. The aim of this study was to evaluate the role of genetic and lifestyle factors in the risk of onset and progression of colorectal cancer. This study followed selected genetic alterations in xenobiotic-metabolizing enzymes (CYP1B1, GSTM1, GSTT1, GSTP1, NQO1 and EPHX1) and genes involved in response to DNA damage (CHEK2 and NBN), as potential CRC susceptibility factors. Another aim of this study was to investigate expression profile of all human ABC transporter genes to follow their prognostic and predictive potential in colorectal carcinoma. Materials and methods: The polymorphisms and other...
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Influence of biotransformation and transport to the effects of chemotherapy and prognosis of breast cancer
Hubáčková, Miluše ; Souček, Pavel (advisor) ; Pávek, Petr (referee) ; Janatová, Markéta (referee)
Influence of biotransformation and transport to the effects of chemotherapy and prognosis of breast cancer Abstract: Introduction: The aim of this study was to evaluate the influence of biotransformation enzymes and enzymes of multidrug resistance for the prognosis and effects of chemotherapy of breast cancer patients. The first part dealed with the genetic factors and the influence of genetic polymorphisms in selected biotransformation genes and in ABCB1 gene and their influence in the formation and prognosis of breast cancer. In the second part, the expression profiles of these genes were analyzed as potential prognostic and predictive properties of a treatment's outcome. Materials and methods: Polymorphisms of biotransformation genes were determined using real-time PCR and polymorphisms of ABCB1 gene were determined using NanoChip Assay, which was performed in our cooperated department. In both cases, the polymorphisms were detected in DNA obtained from the blood of patients. The expression of genes was determined using quantitative real-time PCR in paired tumor and adjacent non-tumor tissue of breast cancer samples. The expression of NQO1 and p53 protein was assesed by immunohistochemistry in the tumor breast tissues. Results: The frequencies of the studied SNPs did not differ from the previous...
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Study on the role of pharmacokinetic mechanisms of drug resistance in new anticancer drugs with focus on solid tumors
Vagiannis, Dimitrios ; Hofman, Jakub (advisor) ; Souček, Pavel (referee) ; Zendulka, Ondřej (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Candidate Mgr. Dimitrios Vagiannis Supervisor RNDr. Jakub Hofman, Ph.D. Title of Doctoral Thesis Study on the role of pharmacokinetic mechanisms of drug resistance in new anticancer drugs with focus on solid tumors Cancer chemotherapy is an important tool for the cure of cancer. Although the development of new anticancer drugs has been rapidly progressing, the phenomenon of multidrug resistance (MDR) continues to be a key issue leading to therapy failure in oncological patients. MDR is based on pharmacodynamic as well as pharmacokinetic mechanisms. Pharmacokinetic MDR includes drug efflux transporters and biotransformation enzymes that decrease the amount of (active form of) a drug in tumors. While the MDR role of transporters has been well understood, the participation of drug metabolizing enzymes is still unclear. This thesis investigates the role of cytochromes P450 (CYPs) in cytostatic resistance. Furthermore, it focuses on the modulation of pharmacokinetic MDR using pharmacokinetic drug-drug interactions of new targeted antitumor drugs. Finally, it aims to confirm the in vitro findings in ex vivo patient-derived tumor explants. In our latest publication, we demonstrate the significant role of...
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Study of genetic factors modifying the risk of onset and progression of colorectal and pancreatic cancer
Mohelníková Duchoňová, Beatrice ; Souček, Pavel (advisor) ; Skálová, Lenka (referee) ; Macek, Milan (referee)
Introduction: The aim of this study was to evaluate the role of genetic and lifestyle factors in the risk of onset and progression of colorectal and pancreatic cancer. The first part deals with the etiological factors and the importance of polymorphisms in biotransformation enzymes and genetic alterations in the gene CHEK2 in the origin of these malignancies. In the second part, the ABC transporter genes were analyzed as potential prognostic and predictive markers of a treatment's outcome. Materials and methods: The polymorphisms and other genetic alterations were detected using real-time PCR, allelespecific PCR and PCR-RFLP methods in DNA which was extracted from the blood of patients. The frequency of polymorphisms was evaluated and their importance was assessed with regard to the available epidemiological data. Gene expressions were determined by qPCR in paired samples of tumor tissue and adjacent non-tumorous parenchyma. Results: A majority of the observed polymorphisms failed to show a relationship between their presence and the risk of any of these malignancies. CYP2A13 variant allele*7 coding inactive enzyme was found in 7 of 265 controls and in none of 235 pancreatic carcinoma patients. In contrast, GSTP1-codon 105 Val variant allele and GSTT1-null genotype were associated with an elevated...
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Dynamic impact wear and impact resistance of W-B-C coatings
Daniel, Josef ; Grossman, Jan ; Buršíková, V. ; Zábranský, L. ; Souček, P. ; Mirzaei, S. ; Vašina, P.
Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings.
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