Regensburg, Univ., Diss., 2009.

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Jakub Poráč Supervisor: doc. PharmDr. Martina Čečková, Ph.D. Title of diploma thesis: Effect of CDK and FLT3 inhibitors on activity of ABC efflux transporters in vitro, relation to multidrug resistance P-gp and BCRP are transmembrane proteins that form part of a large family of ABC transporters. These are ATP-driven transporters, which main task is to eliminate exogenous and endogenous substances and their metabolites from cells of both, healthy and tumour tissues. This activity is often associated with the expulsion of administered therapeutics and multiple drug resistance (MDR) in tumour cells. A promising therapy of cancer represents a newer class of drugs target the tyrosine kinase (TK), and cyclin-dependent kinases (CDK), which are cell enzymes responsible for the processes of proliferation, apoptosis and differentiation. Cyclin- dependent kinase inhibitors (CDKI) are used in the treatment of breast cancer, but at the same time they form a new group of drugs with the potential for use in hematological malignancies. In the treatment of AML, a new successful approach is TK inhibitors (TKI), which target the mutated FLT3 receptor, specifically the recently approved drugs midostaurin and...

Sphingosine 1-phosphate (S1P) is a lipid chemoattractant molecule. Once formed, S1P can be transported extracellularly by S1P transporters spinster homolog 2 (Spns2) or major facilitator domain containing 2B (mfsd2b). In the extracellular space, S1P can bind to S1P-specific G-protein coupled receptors (S1PR), which initiate many signaling pathways. A critical role of extracellular S1P is its ability to cause lymphocyte egress, which can have implications for inflammatory and autoimmune diseases. For this reason, there has been a growing interest in exploring potential spns2 inhibitors to further elucidate their therapeutic potential. Initial screenings confirmed that fused heterocycles, including phthalimide and benzoxazoles, demonstrated moderate inhibition of Spns2 using a HeLa cell assay. An extensive structure-activity relationship (SAR) study of these scaffolds was performed to analyze the impact of various amine head groups, regioisomers, and alkyl tails on performance. It was determined that 2-aminobenzoxazoles with secondary amines were potent inhibitors of the transporter. Additionally, the position of the lipophilic tail moiety played a large role in activity. From these modifications, SLB1122168 (2.44p) was found to be our lead compound. It was determined that (2.44p) had an IC50 of 94 ± 6 nM and was shown to be efficacious in decreasing lymphocyte count by 55% in a dose-dependent manner in both rat and mice models. The discovery of (2.44p) can serve as a novel chemical tool to investigate Spns2 biology and use it as a probe to determine the potential of Spns2 as a drug target. Organoboron compounds are useful synthetic intermediates in forming C-X, C-C, and C-H bonds. One way to synthesize these compounds is through copper catalysis. Copper is favorable to other transition metals because it is an Earth-abundant, low-cost metal that can be utilized in regio- and stereoselective reactions. Conjugated 1,3-enynes are important functional groups that iii are found in active natural products, organic synthetic intermediates, and materials. Previous methods used rare transition metals, designer ligands, or harsh acidic conditions to synthesize such compounds. In this dissertation, we developed a stereoselective one-pot copper-catalyzed semi-reduction of 1,3-diynes to produce (Z)-1,3-enynes. This method uses Cu(OAc)2, HBpin and Xantphos to successfully synthesize (Z)-1,3-enynes that were tolerated well over a broad substrate scope, including heterocyclic, alkyl, and aryl substituents. It was determined that this reaction went through a 2-boryl intermediate which was facilitated by a CuH species. / Doctor of Philosophy / Autoimmune diseases are caused by immune cells attacking healthy cells. The signaling lipid sphingosine-1-phosphate (S1P) plays a major role in trafficking immune cells, in which immune cells follow the S1P gradient from low concentrations (secondary lymphoid tissues) to high concentrations (lymph). In the case of multiple sclerosis, immune cells can attack healthy neurons that cause a myriad of symptoms. Currently, there are four drugs approved by the Food and Drug Administration (FDA) targeting the S1P pathway for multiple sclerosis. In all cases, these drugs act as S1P-receptor (S1PR) functional antagonists, which decreases the amount of extracellular S1P, which in turn decreases the immune cells in the lymph that can attack healthy cells. Unfortunately, all four drugs exhibit on-target cardiovascular side effects. To circumvent the on-target side effects seen in current FDA-approved drugs, other nodes of the S1P pathway have been assessed for multiple sclerosis. One node of interest is spinster homolog 2 (Spns2), a transporter of S1P, whose inhibition has also been shown to decrease extracellular S1P. In this dissertation, we will be assessing various inhibitors for their in vitro and in vivo properties. 1,3-Enynes are a functional group found in medicinally relevant compounds and can be used as intermediates to make more complex compounds. Current methods to make this functional group use expensive rare metals or harsh acidic conditions. We developed new methods that utilized copper, an abundant metal, and boron, an atom whose empty p orbital allows for unique reactivity. Utilizing a copper-hydride species allowed us to semi-reduce 1,3-diynes to (Z)-1,3-enynes, where water was used instead of acid to allow for the semi-reduction to occur. This reaction was shown to tolerate a wide range of substrates and gave good to excellent yield.

Doctor of Philosophy / In healthy individuals, the autoimmune system is the body's natural defense against foreign materials and organisms. The main tools utilized for this defense mechanism are immune cells. However, in patients suffering from autoimmune diseases, the autoimmune system is overactive resulting in its attack on healthy cells, which leads to reduced or eliminated function of the targeted organs. To suppress these overreactive immune responses, pharmaceutical intervention is needed. An integral part of autoimmune response is the lipid sphingosine-1-phosphate (S1P). Interactions of S1P with its response-inducing receptors prompts the release of immune cells, lymphocytes in particular, from lymph tissue to migrate and participate in the invoked immune response. The pharmaceutical industry has produced five FDA approved drugs that disrupt this S1P-receptor interaction by blocking the receptor to reduce the autoimmune response in patients suffering from autoimmune diseases such as multiple sclerosis and ulcerative colitis. However, these treatments had adverse side effects on the cardiovascular system due to the presence of S1P receptors in the heart. Due to this, there is attraction to target a different node of the S1P signaling pathway to avoid these side effects while still suppressing the immune response. A node that is a viable target for therapeutic target that has recently become the focus of medicinal chemistry campaigns is the transporter protein spinster homolog 2 (Spns2). This protein is responsible for the transport of S1P from intracellular space to extracellular space to interact with its receptors and induce the immune response. Recently, our group has developed several effective inhibitors of Spns2. In this dissertation, several improvements of previously reported inhibitors are revealed. The pinnacle of this work is the development of 4.22v that is optimized to have drug-like properties for testing in mice. Administration of 4.22v to mice resulted in reduced circulating lymphocytes and without showing signs of toxicity following chronic dosing for 14 days. These results suggest that 4.22v is a potential drug candidate and is currently undergoing further biological evaluation.

Overexpression of monocarboxylate transporters (MCTs) has been shown for a variety of human cancers (e.g., colon, brain, breast, and kidney) and inhibition resulted in intracellular lactate accumulation, acidosis, and cell death. Thus, MCTs are promising targets to investigate tumor cancer metabolism with positron emission tomography (PET). Here, the organ doses (ODs) and the effective dose (ED) of the first 18F-labeled MCT1/MCT4 inhibitor were estimated in juvenile pigs. Whole-body dosimetry was performed in three piglets (age: ~6 weeks, weight: ~13–15 kg). The animals were anesthetized and subjected to sequential hybrid Positron Emission Tomography and Computed Tomography (PET/CT) up to 5 h after an intravenous (iv) injection of 156 ± 54 MBq [18F]FACH. All relevant organs were defined by volumes of interest. Exponential curves were fitted to the time–activity data. Time and mass scales were adapted to the human order of magnitude and the ODs calculated using the ICRP 89 adult male phantom with OLINDA 2.1. The ED was calculated using tissue weighting factors as published in Publication 103 of the International Commission of Radiation Protection (ICRP103). The highest organ dose was received by the urinary bladder (62.6 ± 28.9 µSv/MBq), followed by the gall bladder (50.4 ± 37.5 µSv/MBq) and the pancreas (30.5 ± 27.3 µSv/MBq). The highest contribution to the ED was by the urinary bladder (2.5 ± 1.1 µSv/MBq), followed by the red marrow (1.7 ± 0.3 µSv/MBq) and the stomach (1.3 ± 0.4 µSv/MBq). According to this preclinical analysis, the ED to humans is 12.4 µSv/MBq when applying the ICRP103 tissue weighting factors. Taking into account that preclinical dosimetry underestimates the dose to humans by up to 40%, the conversion factor applied for estimation of the ED to humans would rise to 20.6 µSv/MBq. In this case, the ED to humans upon an iv application of ~300 MBq [18F]FACH would be about 6.2 mSv. This risk assessment encourages the translation of [18F]FACH into clinical study phases and the further investigation of its potential as a clinical tool for cancer imaging with PET.

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