Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 135-142). Also available in electronic version. Access restricted to campus users.

Therapeutic inefficacy of conventional cancer treatment is a particular dilemma associated with metastatic triple negative breast cancer (TNBC), with patients still facing poor prognosis. The design and development of novel anticancer agents specifically targeted to cancer-associated pathways is of therapeutic interest. The rationale is twofold: firstly, targeted therapy overcomes widespread toxicity and adverse effects of conventional chemotherapy due to the selectivity of the treatment modality. Secondly, synergistic combinations of different classes of highly targeted therapies could hold therapeutic promise to overcome resistance by simultaneously circumventing multiple cancer hallmarks. This study evaluates the in vitro antiproliferative activity of six compounds using breast cancer cell lines as experimental model. Five of these compounds are novel, agents designed in silico to selectively target cancer hallmarks via inhibition of specific cancer-associated proteins. The compounds include an antimitotic (STX1972), three variants of bromodomain 4 (BRD4) inhibitors (Bzt-W41, Bzt-W49 and Bzt-W52), an inhibitor of both sirtuin (SIRT) 1 and 2 (W137) and an inhibitor of janus kinases 1 and 2 (Ruxolitinib). The synergism between paired combinations was also explored. Two breast cancer cell lines, MDA-MB-231 and MCF-7 were used as experimental models. The MDA-MB-231 cell line is oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) negative and is therefore commonly used to model triple negative breast cancer with invasive and metastatic properties. MCF-7 cells are ER and PR positive and represent the hormone-dependent breast cancer model. The endothelial EA.hy926 cell line was used to represent non-cancerous cells. A crystal violet assay was used to determine the half maximal inhibitory concentration (IC50) of the six compounds on the tested cell lines after 48 h exposure. Drug combination studies based on the Chou-Talalay method of paired drug combinations were performed. Effects of treatment on cell morphology was assessed by means of confocal-microscopy. Flow cytometry was used to study the effects on cell cycle progression, apoptosis, autophagy/lysosomal activity, reactive oxygen species (ROS) production, changes in mitochondrial membrane potential (ΔΨm) and the serine 70 phosphorylation status of Bcl-2. Real-time quantitative PCR was used to analyse the effects of the compounds on the mRNA expression levels of p53, c-myc and bcl-2. Quantitative protein expression of c-MYC was analysed by means of enzyme-linked immunosorbent assay. In vitro screening for antiproliferative activity revealed that the compounds showed cancer-selective cytotoxic effects when compared to the EA.hy926 control cell line. The initial screening identified three compounds for further investigative inclusion, namely the antimitotic (STX1972), the BRD4i (Bzt-W41) and the SIRTi (W137). STX1972 was found to inhibit cell growth in the nanomolar concentration range, whilst the rest of the compounds showed growth inhibition in micromolar concentration ranges. Bzt-W41 showed significant preferential selectivity for the TNBC MDA-MB-231 cell line versus the hormone-dependent MCF-7 cell line, while STX1972 and W137 exhibited only slight differential selectivity. Two combinations (STX + Bzt-W41 and Bzt-W41 + W137) exhibited synergism, whilst the STX + W137 combination exhibited antagonistic interaction. Cell cycle and apoptosis analysis revealed that STX1972 and Bzt-W41, alone and in combination, selectively induced cell cycle arrest and apoptosis in cancer cells. However, the W137 +Bzt-W137 combination did not show preferential targeting of breast cancer cell lines, with apoptosis induced equally or even more so in the control EA.hy926 cell line. STX1972 and Bzt-W41, as well as their paired combination, was further probed in aim of deciphering their individual and combined mode of action. STX1972, Bzt-W41 as well as the paired combination proved to selectively inhibit cancer targets resulting in several molecular changes, leading to downstream pathway activation which culminates in both apoptotic and autophagy-related cellular demise. The study contributed towards deducing possible hypotheses regarding the mechanistic behaviours of the individual compounds and elucidated their combined effect during dual treatment. Results warrant future studies to further probe the intricate interaction of pathways involved in the synergistic combination of antimitotics and epigenetic regulators as a novel anticancer therapeutic modality. / Thesis (PhD)--University of Pretoria, 2020. / Physiology / PhD / Unrestricted

Most cancer cells rely on aerobic glycolysis to support the mitochondrial oxidative phosphorylation system (OXPHOS). The persistent oxic-anoxic cycle exerts selection pressures which lead to constitutive activation of glycolysis even in the presence of abundant oxygen. Expression of hypoxia-inducible factor 1 (HIF1) increases following hypoxia in neoplastic cells. This leads to the induction of pyruvate dehydrogenase kinase 1 (PDK1). The latter inactivates pyruvate dehydrogenase (PDH) that converts pyruvate to acetyl-coenzyme A for delivery to the tricarboxylic acid cycle (TAC). Dichloroacetic acid (DCA) is an inhibitor of PDK that forces cells into oxidative phosphorylation thereby suppressing cancer growth. 2-Ethyl-3-O-sulphamoyl-estra-1,3,5(10),15-tetraen-3-ol-17-one (C9), along with a few other 17β-estradiol analogs, are a novel class of in silico-designed inhibitors of microtubule dynamics. These newly designed and synthesized antimitotic compounds induce G2/M arrest and apoptosis by docking to colchicine binding site between α- and β-tubulin. These compounds are 5 to 20 times more potent than their source molecule, 2-methoxyestradiol (2ME). To improve bioavailability C9 has been in silico-modified at carbon positions C2, C3 and C17 compared to 2ME. The approach to investigate the anticancer potential of the in silico-designed antimitotic C9 in combination with the glycolytic inhibitor DCA in vitro is novel. Human breast carcinoma cell line MCF-7 and non-tumorigenic breast cells MCF-12A were used as an experimental model system. The present study demonstrated that DCA (7.5 mM) in combination with C9 (130 nM) selectively inhibited half of MCF-7 cells‘ population (50.8%). Under the same treatment conditions, MCF-12A cells displayed high number of cell survival (70% cell growth). Qualitative morphological studies revealed decreased cell density in both cell lines, as well as hallmarks of apoptosis and autophagic processes including formation of apoptotic bodies, DNA fragmentation and autophagic vacuoles. Cell cycle- and apoptosis quantification analyses revealed C9+DCA treatment induced apoptosis in both cell lines and exhibited selectivity towards tumorigenic cells. Presence of autophagosome was observed and microtubule-associated protein 1 light chain 3 (II) (LC3-II) expression was elevated. Reduction of mitochondrial membrane potential depolarization in tumorigenic MCF-7 cells was demonstrated, but not in MCF-12A cells. Oxidative stress tests suggested the combination treatment C9+DCA is able to induce lysosomal rupture and/or mitochondrial damage in tumorigenic MCF-7 cells. Kinase inhibition studies revealed that transient activation of c-Jun N-terminal kinase (JNK) plays an important role in cell proliferation. However, C9+DCA stimulated prolonged JNK activation and, in turn, promoted Bcl-2 phosphorylation, thereby facilitating autophagic and apoptotic cell death. C9+DCA induced expression of a number of genes related to stress in MCF-7 treated cells including TP53BP1, MDM2 and BBC3/PUMA. Genes related to cell motility and maintenance of the cytoskeleton such as ACTG1, MAP7, TUBA1, TUBA6, TUBA8 and TUBB2A genes were down-regulated. In MCF-12A cells, treatment of C9+DCA induced expression of multidrug resistance gene ABCB1. Moreover, genes involved in reactive oxygen species metabolism FTH1, GSTA2, NOS2A, SMOX, SOD1 and SOD2 were also up-regulated. In conclusion, the novel 17β-estradiol derivative, C9, in combination with DCA is a potent antiproliferative treatment. This study addressed the mechanisms of combination treatment at the basis of molecular and cellular level, warranting further research projects to develop viable and functional combination treatment as clinically useable anticancer agents. / Thesis (PhD)--University of Pretoria, 2014. / lk2014 / Physiology / PhD / Unrestricted

Thesis (Ph.D.)--University of Western Australia, 2005.

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<p> The objective of this study was to synthesize and biologically evaluate a series of novel nucleoside derivatives of the naturally occurring lignans, podophyllotoxin and 4'-demethylepipodophyllotoxin. Epipodophyllotoxin derivatives display two types of biological activity: while the naturally occurring compounds are potent inhibitors of microtubule polymerization, two semi-synthetic glycoside derivatives, viz VP16-213 (etoposide) and VM26 (teniposide), are specific inhibitors of mammalian DNA topoisomerase II. The latter two compounds have proven to be very useful in the treatment of many different types of cancer. In this study, the glycoside moiety of VP16-213/VM26 was replaced with either a thymidine or a 2'-deoxyadenosine group. The synthetic approach involved protective group chemistry, where functional groups on the nucleosides and DMEP were selectively blocked prior to their condensation in the presence of boron trifluoride etherate catalyst. These compounds are of interest because they involve substitution of the glucoside moiety with a nucleoside residue, whose effect on the biological activity of epipodophyllotoxin derivatives has not been examined. The biological activity of these compounds was assessed by examining their cross-resistance patterns towards a set of Chinese hamster ovary mutants resistant to podophyllotoxin VP16-213/VM26, mitotic index, and by a competition assay. From the cross resistance assay, all of the thymidine derivatives were found to be considerably less active than the parent podophyllotoxin and 4'-demethylepipodophyllotoxin molecules, while the 2'-deoxyadenosine derivatives were found to be completely inactive. The cross-resistance patterns of the thymidine derivatives suggests that these compounds display podophyllotoxin-like activity in vivo and show no VP16-213/VM26-like activity. Treatment of wild type cells with the active thymidine derivatives (compounds 1.2, 2.2, 2.3, and 2.4) increased the mitotic indices approximately ten-fold in a dose-dependent manner, which parallels the results of the dose-response curves in the initial cross-resistance assay. Furthermore, there was a marked increase in the levels of drug required to elevate the mitotic index in second-step mutants resistant to podophyllotoxin, again lending support to the initial results indicating that the cellular target of these compounds is tubulin. Only one compound (1.2), was found to out compete the binding of radiolabelled podophyllotoxin to purified calf brain tubulin. However, due to their low activity relative to podophyllotoxin, most of these compounds were insoluble at concentrations required to out compete the binding of radiolabelled podophyllotoxin. Molecular modelling studies have provided useful insights regarding the structure/activity relationships among the active and inactive nucleoside derivatives showing podophyllotoxin-like antimitotic activity. There appears to be steric limits for substituents attached at the C4 moiety that maintain the antimitotic activities of the parent molecules. The electrostatic potential and hydrophobic properties of these groups also seem to play a role in the degree of activity these compounds show, but remain unclear at this point. By simple comparison of the three-dimensional structures of these compounds there appears to be a very limited spacial and electrostatic requirement for the bulky glycosidic moiety attached to C4 which is essential for targeting VP16-213 and VM26 to DNA topoisomerase II. Thus, several important structural features which may distinguish the selectivity POD derivatives show for either tubulin or DNA topoisomerase II are described.</p> / Thesis / Master of Science (MSc)

Submitted by Vasti Diniz (vastijpa@hotmail.com) on 2017-09-08T12:30:20Z No. of bitstreams: 1 arquivototal.pdf: 3898148 bytes, checksum: 4bd5b276470027c8968ec023cab6d4fd (MD5) / Made available in DSpace on 2017-09-08T12:30:20Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3898148 bytes, checksum: 4bd5b276470027c8968ec023cab6d4fd (MD5) Previous issue date: 2015-05-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Cancer is characterized by uncontrolled cell growth of a particular tissue, which invades and impairs healthy cells functions. Chemotherapy is the main cancer treatment, and consists of drug administration that interferes in several metabolic pathways, leading to cancer cell death. Among the main chemotherapy drugs, antimitotics directly affect cell division. This study aimed to investigate the effect of a pyrimidinone derivative (4-4-chloro-phenyl)-2-(-4-methoxy-phenyl)-6-oxo-1,6-dihydropyrimidine- 5-carbonitrile, Py-09) on embryonic development of the sea urchin Echinometra lucunter. Adult animals were collected at João Pessoa coast, Paraíba, Brazil and kept in filtered sea water under constant air flow. Gametes or embryos were treated with Py-09 and the effects of the compound were analyzed on fertilization, embryonic development, mitochondrial membrane potential (ΔΨm), production of reactive oxygen species (ROS) and ABC transporters activity. Py-09 (12.5 μM) inhibited around 60% fertilization of pretreated eggs. However, treatment of sperm with Py-09 did not affect fertilization rate. Treatment of zygotes with Py-09 inhibited the early embryonic development in a time and dose-dependent pattern, with the maximum effect at 50 μM (EC50 = 12.5 μM). Morphological changes were observed in the pattern of embryos cleavage (unequal cleavage) and at larval stages (irregular distribution and cracks of spicules and pigment cells leakage). Py-09 induced the loss of ΔΨm without altering ROS intracellular levels. The assays with ABCB1 and ABCC1 transporters inhibitors (Reversin 205 and MK571, respectively) showed that Py-09 is not ABC proteins substrate. The intracellular calcein accumulation assay and PY-09/vinblastine association demonstrated Py-09 was not able to increase intracellular calcein fluorescence levels and that the compound did not reverse MXR phenomenon. In summary, this study demonstrated that the Py-09 features a remarkable antimitotic activity, producing changes both in morphology and cell physiology. Further studies are needed for a better understanding of the mechanism of action of the compound, and research on the potential of Py-09 as pharmacological tool for in vitro studies, as well as its therapeutic use. / O câncer é caracterizado pelo crescimento descontrolado de células de um determinado tecido, que invadem e comprometem, funcionalmente, células sãs do organismo. A quimioterapia é o principal tratamento do câncer, consistindo na administração de drogas que interferem em diversas vias metabólicas, ocasionando a morte celular. Dentre os principais quimioterápicos, os antimitóticos são drogas que afetam, diretamente, a divisão celular.O presente trabalho teve como objetivo investigar a atividade antimitótica de um derivado de pirimidinona (Py-09) no desenvolvimento embrionário do ouriço-do-mar Echinometra lucunter. Animais adultos foram coletados na costa João Pessoa, Paraíba, Brasil, mantidos em água do mar filtrada sob fluxo de ar constante. Os gametas foram coletados por injeção intracelomática de KCl. Os gametas ou embriões foram tratados com Py-09 e foi analisada a atividade do composto sobre a fertilização, o desenvolvimento embrionário, o potencial de membrana mitocondrial interna (ΔΨm), a produção de espécies reativas de oxigênio (ROS) e a atividade de transportadores ABC. O Py-09 (12,5 μM) inibiu, em cerca de 60%, a fertilização de óvulos previamente tratados com o composto. No entanto, o tratamento dos espermatozoides com o Py-09 não afetou a taxa de fertilização. O tratamento dos zigotos com o Py-09 inibiu o desenvolvimento embrionário inicial, apresentando um efeito antimitótico dose e tempo-dependente, atingindo um efeito máximo na concentração de 50 μM (CE50 = 12,5 μM). Foram observadas alterações morfológicas no padrão de clivagem dos embriões (clivagem desigual) e em estágios larvais (distribuição irregular e fissuras das espículas e extravasamento de células pigmentares).O tratamento com Py-09 promoveu a perda do ΔΨm, sem, entretanto, alterar os níveis intracelulares de ROS. O ensaio com os inibidores dos transportadores ABCB1 e ABCC1 (Reversina 205 e MK571, respectivamente) mostrou que o Py-09 não é substrato de proteínas ABC. Por outro lado, o ensaio de acúmulo intracelular de calceína e os ensaios de associação do Py-09 com a vimblastina demonstraram que o mesmo não reverte o fenômeno MXR, uma vez que o composto não foi capaz de aumentar os níveis de fluorescência intracelular da calceína, e a associação Py-09 (12,5 μM)/vimblastina (100 e 400 nM) apresentou o mesmo efeito inibitório da vimblastina per se.Em suma, o presente trabalho demonstrou que o Py-09 apresenta uma marcante atividade antimitótica, acarretando alterações tanto na morfologia quanto na fisiologia celular.Estudos adicionais são necessários para um maior entendimento do mecanismo de ação do composto, e para a investigação acerca do potencial do Py- 09 como ferramenta farmacológica para estudos in vitro, assim como para o seu uso terapêutico.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T14:21:17Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T14:21:17Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T14:21:17Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T14:21:17Z (GMT). No. of bitstreams: 0 / Compostos farmacêuticos são identificados em matrizes ambientais em ordens de grandeza de ng.L-1 a &mu;g.L-1. Dentre os fármacos, os antibióticos têm recebido atenção especial devido aos problemas que podem causar à biota aquática. O objetivo do presente estudo foi avaliar a citotoxicidade de Amoxicilina e Clavulanato de Potássio isolados e em associação para mexilhões Perna perna utilizando o ensaio do tempo de retenção do corante vermelho neutro, que avalia a estabilidade da membrana lisossômica de hemócitos dos organismos teste. A Amoxicilina causou citotoxicidade aos mexilhões nas concentrações de: CEO: 1 ng.L-1, CI25-24h: 0,44 ng.L-1, CI25-48h: 1,19 ng.L-1 e CI25-72h: 0,85 ng.L-1, o Clavulanato de Potássio foi citotóxico nas concentrações de: 10 ng.L-1 em 24h e 50 ng.L-1 e 100 ng.L-1 em 48h e 72h. Os valores de concentração inibitória foram de CI25-24h: 3,11 ng.L-1, CI25-48h: 3,45 ng.L-1 e CI25-72h: 3,43 ng.L-1. No ensaio realizado com a associação dos fármacos todas as concentrações foram citotóxicas aos mexilhões em 48h e em 72h apenas 40 ng.L-1 de Amoxicilina + 10 ng.L-1 de Clavulanato de Potássio e 200 ng.L-1 de Amoxicilina + 50 ng.L-1 de Clavulanato de Potássio. As concentrações inibitórias foram: CI25-48h: 1,67 ng.L-1 e CI25-72h: 1,36 ng.L-1 a partir dos dados de Amoxicilina e CI25-48h: 0,42 ng.L-1 e CI25-72h: 0,34 ng.L-1 a partir dos dados de Clavulanato de Potássio. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP