Herein we report the structure-activity and structure-physicochemical property relationships of a series of class I selective ortho-aminoanilides targeting the “foot-pocket” in HDAC1&2. To balance the structural benefits and the physicochemical disadvantages of these substances, we started with a set of HDACi related to tacedinaline (CI-994) and evaluated their solubility, lipophilicity (log D7.4) and inhibition of selected HDAC isoforms. Subsequently, we selected the most promising “capless” HDACi and transferred its ZBG to our previously published scaffold featuring a peptoid-based cap group. The resulting hit compound 10c (LSH-A54) showed favorable physicochemical properties and is a potent, selective HDAC1/2 inhibitor. The following evaluation of its slow binding properties revealed that LSH-A54 binds tightly to HDAC1 in an induced-fit mechanism. The potent HDAC1/2 inhibitory properties were reflected by attenuated cell migration in a modified wound healing assay and reduced cell viability in a clonogenic survival assay in selected breast cancer cell lines.

No description available.

An important role of Pin1 is to catalyze the cis-trans isomerization of pSer/Thr-Pro bonds; as such, it plays an important role in many cellular events through the effects of conformational change on the function of its biological substrates, including Cdc25, c-Jun, and p53. The expression of Pin1 correlates with cyclin D1 levels, which contributes to cancer cell transformation. Overexpression of Pin1 promotes tumor growth, while its inhibition causes tumor cell apoptosis. Because Pin1 is overexpressed in many human cancer tissues, including breast, prostate, and lung cancer tissues, it plays an important role in oncogenesis, making its study vital for the development of anti-cancer agents. Many inhibitors have been discovered for Pin1, including 1) several classes of designed inhibitors such as alkene isosteres, non-peptidic, small molecular Pin1 inhibitors, and indanyl ketones, and 2) several natural products such as juglone, pepticinnamin E analogues, PiB and its derivatives obtained from a library screen. These Pin1 inhibitors show promise in the development of novel diagnostic and therapeutic anticancer drugs due to their ability to block cell cycle progression. In order to develop potent Pin1 inhibitors, the concept of transition-state analogues was used for the design of three classes of compounds: ketoamide, ketone, and reduced amide analogues. Specifically, a convergent synthesis of α-ketoamide inhibitors of Pin1 was developed. An α-hydroxyorthothioester derivative of Ser was reacted directly with an aminyl synthon. The reaction was catalyzed by HgO and HgCl2 to form an α-hydroxyamide. Hydrolysis and coupling were combined in one step in 80% yield. Two diastereomers of a phospho-Ser-Pro α-ketoamide analogue were synthesized. The resulting IC50 values of 100 µM and 200 µM were surprisingly weak for the Pin1 peptidyl-prolyl isomerase. Diastereomeric ketones were synthesized by coupling cyclohexenyl lithium to the serine Weinreb amide, via the Michael addition of a carboxylate synthon. The IC50 values of the two ketone diastereomers were determined to be 260 μM and 61 μM, respectively. Five reduced amide inhibitors for Pin1 were synthesized through a selective reduction using borane. The most potent inhibitor was found to be Fmocâ pSerâ Ψ[CH2N]-Proâ tryptamine, which had an IC50 value of 6.3 µM. This represents a 4.5-fold better inhibition for Pin1 than a comparable cis-amide alkene isostere. The co-crystal structure of Acâ pSerâ Ψ[CH2N]-Proâ tryptamine bound to Pin1 was determined to 1.76 Ã resolution. Towards understanding the two proposed mechanisms of Pin1 catalysis, nucleophilic-additition mechanism and twisted-amide mechanism, three classes of Pin1 inhibitors (ketoamide, ketone, and reduced amide analogues) involving a total of nine compounds were synthesized and evaluated. The weak inhibitory activities of ketoamide and ketone analogues do not support the nucleophilic-addition mechanism, while the twisted-amide mechanism of Pin1 catalysis is promising based on the reduced amide inhibitors with good potencies. / Ph. D.

No / Since the development of the first cytotoxic agents, synthetic organic chemistry has advanced enormously. The synthetic and medicinal chemists of today are at the centre of drug development and are involved in most, if not all, processes of drug discovery. Recent decreases in government funding and reformed educational policies could, however, seriously impact on drug discovery initiatives worldwide. Not only could these changes result in fewer scientific breakthroughs, but they could also negatively affect the training of our next generation of medicinal chemists.

Nucleic acids are macromolecules in cells for storing and transferring genetic information. Moreover, nucleic acids, especially RNAs, can fold into well-defined 3D structures and catalyze biochemical reactions. As ubiquitous biological molecules in all living systems, nucleic acids are important drug targets, and they can also be used in diagnostics and therapeutics. Structural information of nucleic acids provides the foundation for DNA and RNA function studies. X-ray crystallography has been a useful tool for structural studies of bio-macromolecules at atomic level. There are two major problems in macromolecular crystal structure determination: phasing and crystallization. Although selenium derivatization is routinely used for solving novel protein structures through the MAD phasing technique, the phase problem is still a critical issue in nucleic acid crystallography. The covalent selenium-derivatization of nucleic acids has been proven to be a useful strategy for solving the phase problem in nucleic acid X-ray crystallography. Besides the facilitation of nucleic acid crystallography, there is also a wide range of other applications for selenium-derivatized nucleic acids (SeNA). The investigation presented in this dissertation mainly focuses on the following research subjects (1) Synthesis and characterization of selenium-derivatized nucleic acids for X-ray crystallography, especially phosphoroselenoate RNAs. They are generated and used for crystallization. (2) Application of selenium-derivatized RNA for RNA interference. Phosphoroselenoate RNAs are tested for RNAi activities. (3) Synthesis and characterization of the uridine 5’-triphosphate modified with selenium at position 4. (4) Facile synthesis and antitumor activities of selenium modified deoxyribonucleosides. MeSe-thymidine nucleosides have shown antitumor activity in cell assays.

The mechanisms by which altered processing, distribution and secretion of proteolytic enzymes occur, facilitating degradation of the extracellular matrix in invasive and metastatic cells, are not fully understood. Studies on the MCF-10 A breast epithelial cell line and its premalignant, c-Ha-ras-transfected MCF-10AneoT counterpart have shown that the ras-transfected cell line has a more alkaline pH. The objective of this study was to determine which organelles of the endosome-lysosome route were alkalinized and shifted to the cell periphery after ras-transfection. Antibodies to the hapten 2,4-dinitrophenyl (DNP), required for pH studies, were raised in rabbits and chickens using DNP-ovalbumin (DNP-OVA) as immunogen. Cationised DNP-OVA (DNP-catOVA) was also inoculated to increase antibody titres. Anti-hapten and carrier antibody titres were assessed. In rabbits, cationisation seems useful to increase anti-DNP titres if a non-self carrier protein (OVA) is used. In chickens, cationisation of DNP-OVA seems necessary to produce a sustained anti-OVA (anti-self) response (implying a potential strategy for cancer immunotherapy). Oregon Green® 488 dextran pulse-chase uptake and fluorescent microscopy, and (2,4-dinitroanilino)-3'-amino-N-methyldipropylamine (DAMP) uptake, immunolabelling for DNP (a component of DAMP) and unique markers for the early endosome (early endosome antigen-I, EEAI), the late endosome (cation-independent mannose-6-phosphate receptor, CI-MPR) and the lysosome (small electron dense morphology and lysosome-associated membrane protein-2, LAMP-2) and electron mlcroscopy was performed. The pH of late endosomes and lysosomes in the ras-transfected MCF-10AneoT cell line were found to be relatively alkalinised and Iysosomes shifted toward the cell periphery. The acidic pH of late endosomes is required to release precursor cysteine and aspartic proteases from their receptors (e.g. CI-MPR), process the precursors to active proteases and to allow receptor recycling. The more alkaline pH observed potentially explains the altered processing of proteases in rastransfected cells. Alkalinisation ofthe cytosol may affect the cytoskeleton responsible for, among other things, the positioning and trafficking of various organelles, causing relocation of Iysosomes toward the cell periphery and actin depolymerisation. This may enable fusion of Iysosomes with the plasma membrane and the release of proteolytic enzymes, facilitating the observed invasive phenotype. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Philosophiae Doctor - PhD / Cancer is one of the leading causes of death worldwide. According to the WHO, cancer accounted for 7.4 million deaths world wide in 2004. The metallo-compound cisplatin has been used for years as an effective antitumor agent for treating solid tumours such as breast, bladder, lung, oesophageal, and head and neck carcinomas. However, the use of cisplatin as an antitumor agent has been limited because of its association with problems such as lack of selectivity for cancer cells over normal cells, development of resistance to cisplatin treatment, and side effects such as nephrotoxicity. Recent studies on anticancer drugs have focussed on alternative anticancer agents such as gold compounds in both Au(I) and (III) oxidation states, which have shown to be potential anticancer drug agents because of their ability to induce apoptosis in several human cancer cells. Some gold complexes have shown to be able to selectively kill cancer cells over normal cells.

No description available.

No description available.

No / Objectives Previous studies have demonstrated that intravesical administration of apaziquone (EOquin) has ablative activity against superficial bladder cancer marker lesions with 8 out of 12 complete responses recorded. We present a comparison between the rates of tumor recurrence before and after treatment with apaziquone. Methods The rate of tumor recurrence after treatment with apaziquone was compared with each patient's historical record of recurrences obtained from a retrospective analysis of the patients' case notes. The time to each recurrence event before apaziquone treatment and the time to the first recurrence after apaziquone treatment were recorded, and the data were analyzed using a population-averaged linear regression model using Stata Release, version 9.2, software. Results Of the eight complete responses obtained in the Phase I study, tumor recurrence occurred in 4 patients and the remaining 4 patients remained disease free after a median follow-up of 31 months. The time to the first recurrence after apaziquone treatment was significantly longer (P <0.001) compared with the historical pattern and recurrence interval before apaziquone. Before apaziquone instillation, the mean ± SE recurrence rate and tumor rate per year was 1.5 ± 0.2 and 4.8 ± 1.2, respectively, and these decreased to 0.6 ± 0.25 and 1.5 ± 0.8, respectively, after apaziquone treatment (P <0.05). Conclusions The results of this study indicate that early recurrences after treatment with apaziquone are infrequent and the interval to recurrence is significantly greater compared with the historical recurrence times for these patients. Larger prospective randomised trials are warranted to confirm these results. Aapaziquone (EOquin, USAN, E09, 3-hydroxy-5-aziridinyl-1-methyl-2[indole-4,7-dione]¿prop-¿-en-¿-ol) belongs to a class of anticancer agents known as bioreductive drugs that require metabolism by cellular reductases to generate a cytotoxic species.1 Although it is chemically related to mitomycin C, apaziquone has a distinctly different mechanism of action and preclinical activity profile.1 and 2 The initial optimism generated by its preclinical activity profile rapidly evaporated after the demonstration that intravenously administered apaziquone was clinically inactive against a range of solid tumors in Phase II clinical trials.3 and 4 Several possible explanations were considered for its lack of efficacy, but poor drug delivery to the tumor because of the rapid pharmacokinetic elimination of apaziquone in conjunction with relatively poor penetration through avascular tissue was considered to be the principal reason.5 On the basis of the rationale that intravesical administration would circumvent the problem of drug delivery and any apaziquone absorbed into the blood stream would be rapidly cleared,6 a Phase I-II clinical pilot study of intravesical administration of apaziquone to superficial bladder tumors was established.7 The results of that trial demonstrated that intravesically administered apaziquone has ablative activity against superficial bladder transitional cell carcinoma (TCC) marker lesions.7 These results were confirmed and extended in a Phase II clinical trial of 47 patients with superficial bladder TCC, in which complete responses were obtained in 67% of patients.8 Because all the enrolled patients in the original trial7 had had multiple recurrences after previous intravesical chemotherapy and/or immunotherapy, the purpose of the present study was, first, to report the recurrences that occurred after apaziquone treatment and, second, to study the effect of apaziquone instillation on the recurrence rate by statistically comparing these results with the historical pattern of recurrences for each patient before treatment with apaziquone.