Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Radek Machan Supervisor: PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: Determination of permeability and active transport of selected butyrylcholinesterase inhibitors in vitro European Medicine Agency (EMA) and Food and Drug Administration agency (FDA) emphasise drug membrane permeability and drug-drug interactions on ABC transporters expressed in physiological barriers should be investigated for compounds in preclinical studies or for those already clinically used but evidence free. In this work we aimed to assess the capability of several experimental butyrylcholinesterase inhibitors that had been designed to treat dementia to permeate blood-brain barrier and to elucidate role of ATP-binding (ABC) cassette transporters in this transport. For this purpose, we employed in vitro bidirectional transport study across monolayers formed by polarized and highly differentiated Caco-2 cells. The permeability values gained from measurements were similar to values of several commonly used drugs for treatment of CNS disorders (e.g. antidepressants, antiepileptics). In addition, the compounds showed values of efflux ratio (basolateral- to-apical/apical-to-basolateral) approximately one...

Frequency of occurrence of selected single nucleotide polymorphisms of CYP2C8 and MDR1 in the Czech population and their influence on the effect of amiodarone Introduction: Variability in drug response is sometimes conditioned by genetic differences in the metabolism and the transport of drugs. Interindividual differences are often caused by polymorphisms affecting biotransformation activity of enzymes and expression of transporters. In the thesis we paid attention to the cytochrome P450 CYP2C8 and MDR1. First, we described the frequency of occurrence of selected variant alleles CYP2C8 * 2, CYP2C8 * 3 (2 substitution in exon 3 and 8, CYP2C8 and CYP2C8 * 3G416A * 3A1196G), CYP2C8 * 4, CYP2C8 P404A in the healthy Czech population and MDR1 variant alleles in these exons: 26 C3435T, 21 G2677A/T, 12 C1236T a 17 T-76A. Subsequently, we studied the influence of these polymorphisms on effects of amiodarone in the selected group of patients. Methods: We determined genotypes MDR1 a CYP2C8 by PCR-RFLP by using restriction enzymes and specific primers. We determined the frequency of MDR1 genotypes in 189 healthy volunteers and CYP2C8 in 161 healthy subjects. Further we included into the study 63 patients treated with amiodarone for longer than two months. Their treatment was assessed from medical records and...

ABSTRACT/SUMMARY Background: The clinical efficacy of tamoxifen therapy may be modified by the drug-metabolizing enzymes and transporting molecules involved into the pharmacokinetics of tamoxifen. The aim of this study was to evaluate the association of CYP2D6, ABCB1 polymorhisms and comedication with efficacy and safety of tamoxifen treatment. Methods: Totally 258 women with hormonal positive breast carcinoma were retrospectively evaluated in relation to CYP2D6, ABCB1 polymorphisms and comedication. Results: CYP2D6 polymorphisms or co-medication affecting CYP2D6 activity demonstrated no statistically significant effect on the efficacy of tamoxifen therapy or adverse event incidence; there was only a trend towards shortening the time to event (TTE) in CYP2D6 poor metabolizers. ABCB1 polymorphism rs2032582 was not associated with clinical outcomes, while a trend towards an increase of TTE in variant allele carriers was noted. The ABCB1 polymorphism rs1045642 demonstrated statistical significance in premenopausal patients (p = 0.0012, HR 0.69 (95% CI 0.21 to 2.31), and its significant association was noted with gynaecological /vasomotor adverse events (p = 0.0221, HR = 1.0588), with no evidence of the influence on the incidence and onset of venous complications. Conclusions: Although this work did not show...

This work is dedicated to thorough structural analysis of plant bifunctional nuclease TBN1, the representative of plant nuclease I group. TBN1 along with homologous nucleases from this family plays an important role in plant cell life cycle and also shows considerable anticancerogenic effects. Two variants of TBN1 (wild type and N211D mutant) were studied. Properties of both variants in different solutions were analyzed. Both were successfully crystallized. Structures of both types of TBN1 were solved using X-ray diffraction. The phase problem was solved by Multi-wavelength anomalous dispersion using Zn2+ ions natively present in TBN1. Structural properties of TBN1 such as fold, active site composition, effect of glycosylation and surface electrostatic potential distribution were analyzed. Reaction mechanism of TBN1 was proposed on the basis of structural properties and comparisons with similar structures.

Syncytin-1 is an endogenous retroviral envelope glycoprotein specifically expressed in human placenta, where the protein was adopted for its physiological function. After interaction with specific receptors, transmembrane proteins ASCT1 and ASCT2, Syncytin-1 initiates cell-cell fusion leading to formation of multinucleated syncytiotrophoblast, which is essential for feto-maternal nutrients exchange. In this diploma thesis a new cell-cell fusion quantification assay was implemented for characterisation of Syncytin-1 fusion determinants. The assay uses Syncytin-1 and ASCT2 expressed separately with fragments of luciferase in heterologous cell-culture system. The assay enables to specifically quantify cell-cell fusions based on activity of reconstituted luciferase reporter. This study discovered new facts about the role of intracytoplasmic tail of Syncytin-1 in the process of the cell- cell fusion. This specific part of protein contains a tandem motif sensitive to changes in amino acid sequence that led to loss of fusogenic potential of Syncytin-1. It was further confirmed, that the protein Suppressyn works as an inhibitor of cell-cell fusions initiated by Syncytin-1. Suppressyn however does not bind to receptors of Syncytin-1 and the mechanism of its inhibition remains unsolved. Finally, it was demonstrated...

Background: Bernard-Soulier syndrome (BSS) is a severe congenital bleeding disorder characterized by thrombocytopenia, thrombocytopathy and decreased platelet adhesion. BSS results from genetic alterations of the glycoprotein (GP) Ib/IX/V complex. Methods: We report on a patient demonstrating typical BSS phenotype (thrombocytopenia with giant platelets, bleeding symptoms). However, BSS was not diagnosed until he reached the age of 39 years. Results: Flow cytometry of the patient’s platelets revealed absence of GPIb/IX/V receptor surface expression. In addition, immunofluorescence analysis of patient’s platelets demonstrated very faint staining of GPIX. A novel homozygous deletion comprising 11 nucleotides starting at position 1644 of the GPIX gene was identified using molecular genetic analysis. Conclusions: The novel 11-nucleotide deletion (g.1644_1654del11) was identified as causing the bleeding disorder in the BSS patient. This homozygous deletion includes the last 4 nucleotides of the Kozak sequence as well as the start codon and the following 4 nucleotides of the coding sequence. The Kozak sequence is a region indispensable for the initiation of the protein translation process, thus preventing synthesis of functional GPIX protein in the case of deletion. / Hintergrund: Das Bernard-Soulier-Syndrom (BSS) ist eine angeborene Blutungsstörung, die mit Thrombozytopenie, Thrombozytopathie und verminderter Thrombozytenadhäsion assoziiert ist. BSS wird durch genetische Veränderungen des Glykoprotein(GP)-Ib/IX/V-Komplexes verursacht. Methoden: Wir berichten über einen Patienten mit typischem BSS-Phänotyp (Thrombozytopenie mit Riesenthrombozyten, Blutungssymptome). Dennoch wurde die Diagnose BSS erst im Alter von 39 Jahren gestellt. Ergebnisse: Die Durchflusszytometrie der Thrombozyten des Patienten ergab eine fehlende Oberflächenexpression des GPIb/IX/V-Rezeptors. Zusätzlich zeigten Immunfluoreszenz-Analysen der Thrombozyten eine nur sehr schwache Anfärbung von GPIX. In der molekulargenetischen Analyse wurde eine noch nicht bekannte homozygote Deletion von 11 Nukleotiden (beginnend an Position 1644 im GPIX-Gen) identifiziert. Schlussfolgerungen: Diese neue Deletion von 11 Nukleotiden (g.1644_1654del11) wurde als Ursache für die vermehrte Blutungsneigung bei dem BSS-Patienten identifiziert. Von der homozygoten Deletion betroffen sind die letzten 4 Nukleotide der Kozak-Sequenz sowie das Startkodon und weitere 4 Nukleotide des kodierenden Bereichs. Die Kozak-Sequenz ist unerlässlich für die Initiation der Translation in der Proteinbiosynthese, so dass die bei dem Patienten nachgewiesene Deletion die Synthese des funktionellen GPIX-Proteins verhindert. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Veronika Křečková Supervisor: PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: Role of drug transporters in placental transfer of entecavir Entecavir (ETV), an analogue of guanosine, is a highly efficient anti-hepatitis B antiviral drug. It is the first-line therapy for both adults and children. Its use in pregnancy is limited due to a number of factors, including lack of data on placental pharmacokinetics. The placental transition of drugs is frequently controlled by drug transporters. ATP-binding (ABC) transporters, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) or multidrug resistance-associated protein 2 (MRP2) localized in the apical membrane of syncytiotrophoblast and pumping their substrates in the feto-maternal direction belong to most significant determinants of placental pharmacokinetics. Moreover placental transport of nucleoside-derived drugs can be affected by the activity of nucleoside transporters (NTs); equilibrative nucleoside transporters (ENTs) mediate facilitated diffussion, while the concentrative nucleoside transporters (CNTs) control active influx of their substrates. The aim of the diploma thesis was to describe the role of P-gp, BCRP, MRP2 and NTs (ENTs and...

P-Glykoprotein als Produkt des MDR1-Gens stellt einen gut untersuchten Mediator der Multidrugresistenz (MDR) in humanen Malignomen dar. Die Überexpression dieses ABC-Transporters steht in Korrelation zu einer erniedrigten Tumorremission und einer kürzeren Überlebensrate der Patienten. Bisherige Versuche, das Protein über niedermolekulare Substanzen (MDR-Modulatoren) zu inhibieren, vermochten in allen bisherigen klinischen Studien nicht zu überzeugen, so daß diese bis heute keinen Eingang in Standardtherapieschemata gefunden haben. Ziel dieser Arbeit war es, mittels RNA-Interferenz Strategien die Expression von MDR1 zu hemmen und eine Reversion der zellulären Chemoresistenz sowohl im Zellkultur- als auch im Tiermodell zu erreichen. Für die in vitro Untersuchungen an drei humanen multidrug-resistenten Karzinomzellinien wurden verschiedene siRNA (short interfering) Duplexe und shRNA (short hairpin)-exprimierende Vektoren gegen die MDR1 mRNA entwickelt. Die Behandlung der Zellen mit siRNAs führte zu einer bis zu 91 %igen Inhibition der MDR1 mRNA-Expression und zu einer Sensitivierung der Zellen gegenüber dem Anthrazyklin um 89 %. Diese Effekte konnte über einen Zeitraum von drei bis fünf Tagen aufrechterhalten werden. Die stabile Expression von anti-MDR1 shRNAs führte in zwei der untersuchten Zellmodelle zu einer dauerhaften und kompletten Überwindung des MDR1-abhängigen Resistenzphänotyps. Im Mausmodell konnte durch intratumorale Applikation des anti-MDR1 shRNA-kodierenden Vektors mittels low-volume Jet-Injektion eine komplette Reversion der MDR1-Überexpression sowie eine Wiederherstellung der Chemosensitivität gegenüber Doxorubicin in dem resistenten Tumormodell erreicht werden. Die Effizienz der kombinierten Gen- und Chemotherapie wird durch die Verminderung des in vivo Tumorwachstums auf das Volumen des von der sensiblen Zellinien-abgeleiteten Tumors reflektiert. / Multidrug resistance (MDR) is the major cause of failure of effective chemotherapeutic treatment of disseminated neoplasms. The "classical" MDR phenotype of human malignancies is mediated by drug extrusion by the adenosine triphosphate binding cassette (ABC)-transporter P-glycoprotein (MDR1/P-gp). For stable reversal of "classical" MDR in three human cancer cell lines by RNA interference (RNAi) technology, two small interfering RNA (siRNA) constructs and four H1-RNA gene promoter-driven expression vectors encoding anti-MDR1/P-gp short hairpin RNA (shRNA) molecules were constructed. In all cellular systems, siRNAs could specifically inhibit MDR1 expression up to 91% at the mRNA and protein levels. Resistance against daunorubicin was decreased to a maximum of 89%. The introduction of anti-MDR1/P-gp shRNA expression vectors leads in two of the three human cancer cell lines to a complete reversion of the MDR phenotype. The reversal of MDR was accompanied by a complete suppression of MDR1/P-gp expression on mRNA and protein level, and by a considerable increased intracellular anthracyline accumulation in the anti-MDR1/P-gp shRNA-treated cells. In a mouse xenograft model a complete in vivo restoration of MDR1 overexpression and chemosensitivity to doxorubicin could be obtained by intratumorally jet-injected anti-MDR1 shRNA in a multidrug resistant human cancer tumor model.

No description available.

Background: Bernard-Soulier syndrome (BSS) is a severe congenital bleeding disorder characterized by thrombocytopenia, thrombocytopathy and decreased platelet adhesion. BSS results from genetic alterations of the glycoprotein (GP) Ib/IX/V complex. Methods: We report on a patient demonstrating typical BSS phenotype (thrombocytopenia with giant platelets, bleeding symptoms). However, BSS was not diagnosed until he reached the age of 39 years. Results: Flow cytometry of the patient’s platelets revealed absence of GPIb/IX/V receptor surface expression. In addition, immunofluorescence analysis of patient’s platelets demonstrated very faint staining of GPIX. A novel homozygous deletion comprising 11 nucleotides starting at position 1644 of the GPIX gene was identified using molecular genetic analysis. Conclusions: The novel 11-nucleotide deletion (g.1644_1654del11) was identified as causing the bleeding disorder in the BSS patient. This homozygous deletion includes the last 4 nucleotides of the Kozak sequence as well as the start codon and the following 4 nucleotides of the coding sequence. The Kozak sequence is a region indispensable for the initiation of the protein translation process, thus preventing synthesis of functional GPIX protein in the case of deletion. / Hintergrund: Das Bernard-Soulier-Syndrom (BSS) ist eine angeborene Blutungsstörung, die mit Thrombozytopenie, Thrombozytopathie und verminderter Thrombozytenadhäsion assoziiert ist. BSS wird durch genetische Veränderungen des Glykoprotein(GP)-Ib/IX/V-Komplexes verursacht. Methoden: Wir berichten über einen Patienten mit typischem BSS-Phänotyp (Thrombozytopenie mit Riesenthrombozyten, Blutungssymptome). Dennoch wurde die Diagnose BSS erst im Alter von 39 Jahren gestellt. Ergebnisse: Die Durchflusszytometrie der Thrombozyten des Patienten ergab eine fehlende Oberflächenexpression des GPIb/IX/V-Rezeptors. Zusätzlich zeigten Immunfluoreszenz-Analysen der Thrombozyten eine nur sehr schwache Anfärbung von GPIX. In der molekulargenetischen Analyse wurde eine noch nicht bekannte homozygote Deletion von 11 Nukleotiden (beginnend an Position 1644 im GPIX-Gen) identifiziert. Schlussfolgerungen: Diese neue Deletion von 11 Nukleotiden (g.1644_1654del11) wurde als Ursache für die vermehrte Blutungsneigung bei dem BSS-Patienten identifiziert. Von der homozygoten Deletion betroffen sind die letzten 4 Nukleotide der Kozak-Sequenz sowie das Startkodon und weitere 4 Nukleotide des kodierenden Bereichs. Die Kozak-Sequenz ist unerlässlich für die Initiation der Translation in der Proteinbiosynthese, so dass die bei dem Patienten nachgewiesene Deletion die Synthese des funktionellen GPIX-Proteins verhindert. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.