Made available in DSpace on 2014-06-11T19:22:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2006Bitstream added on 2014-06-13T20:48:33Z : No. of bitstreams: 1 garcia_vcl_me_botfm_prot.pdf: 957486 bytes, checksum: f860c8e0d2f9c1906e798f8bcd79542f (MD5) / o paciente com câncer de esôfago tem a desnutrição protéico-energética como principal fator de risco. A taurina é um composto sulfurado que participa de funções fisiológicas importantes, como a manutenção do sistema de defesa do organismo. O objetivo deste trabalho foi estudar o metabolismo da taurina e seus precursores e a associação destes, com os indicadores nuíricionais de pacientes com câncer de esôfago. Para tanto, realizou-se estudo prospectivo com corte vertical e grupo controle, em 18 pacientes (43-73 anos) portadores de neoplasia maligna de esôfago, e 20 voluntários (27-65 anos) controles sadios. Em todos foram realizadas dosagens plasmáticas de taurina, cisteína e homocisteína e avaliação do estado nutricional antropométrico e bioquímico. Paralelamente, foram coletados dados referentes à história e ao diagnóstico clínico e período de sobrevivência dos pacientes. Os dados foram analisados por meio do teste t de Sfudenf e correlação de Pearson. O câncer de esôfago foi mais predominante no sexo masculino e na raça branca. Houve maior freqüência do carcinoma espino celular e localização no terço superior. A maioria dos pacientes. no momento do diagnóstico, apresentou estágio avançado da doença (estadio IV). A perda de peso nos pacientes foi de 14,9%, entretanto, variáveis CMB e %GC não apresentaram diferença estatística com o controle. Adicionalmente, no grupo de estudo, foram observadas hipoalbuminemia e elevação da PCR (55,5% e 50% dos pacientes, respectivamente). Os níveis de Hb, Ht, Colesterol total, HOL e cisteína foram menores, e os de TGO, TGP, taurina e homocisteína maiores significativamente do que o grupo controle (p<0,05). A taurina se correlacionou positivamente com CTL (r=0,49 e p=O,03) e a sobrevida... / The main risk factor of the esophagus' cancer patient is pratein-energetic malnourishment. Taurine is a sulphur-containing amino acid which takes part in important physiological functions such as organíc defense system maintenance. The objective of this work was to study the metabolism of taurine and its precursors and their association with nutritional indicators in patients with esophagus cancer whose main risk factor is protein-energy undemutrition. This was a prospective study with a vertical cut and control group with 18 malignant esophageal neoplasia (4373yrs) and 20 healthy volunteers (27-65yrs). Ali individuais were scrutinized with respect to their plasma levels of taurine, cysteine, and homocysteine and underwent nutritional, anthropometrical, and biomedical state evaluation. Also data were collected on patient history, clínical diagnosis, and survival time. Data were analyzed by Student t and Pearson Correlatíon tests. Esophagus cancer was more predominant in white males. Squamous cel! carcinoma and superior third location were frequent Most patients were in the advanced stage when diagnosed (Stage IV). Patient weight loss was 14.9%, however, AMC and %BF were not statistically different to contrais. Additionally hypoalbuminemia and elevaíed PCR (in 55.5% & 50% of patients, respectively). Hb, Ht, total cholesterol, HDL, and cysteine were significantly lower, and GOT, GPT, taurine, and homocysteine significantly higher than controls (p<0.05). Taurine positively correlated with CTL... (Complete abstract click eletronic address below)

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Esophageal squamous cell carcinoma (ESCC) is the predominant type of esophageal cancer in Asia. Cisplatin is commonly used as an agent for treating ESCC patients undergoing chemotherapy. However establishment of resistance over the course of treatment diminishes the clinical usefulness and is one reason explaining poor prognosis of ESCC patients. In order to gain insights into the mechanism of cisplatin resistance in ESCC, HPLC/nESI-MS/MS proteomic profiling was employed to examine the global protein alterations of cisplatin-resistant ESCC cell line HKESC2/CDDP comparing with its parental cisplatin-sensitive cell line HKESC2. Stable over-expression and knocked-down cell lines were established for pathway analysis and functional studies. Seventeen proteins were identified with more than 2-fold difference in expression levels. These proteins are involved in endoplasmic reticulum stress response, metabolic processes, DNA replication and repair, nucleotide binding and cell cycle control, while some of them are components of cytoskeletal proteins. Among them, 14-3-3σ was one of the most significantly upregulated proteins found in HKESC2/CDDP cells and its differential expression levels were validated using western blotting and real-time quantitative polymerase chain reaction. Pathway analysis revealed that ectopic overexpression of 14-3-3σ caused a general upregulation in DNA repairing genes. Furthermore, functional validation showed that elevated 14-3-3σ expression contributed considerably to the observed cisplatin resistance in HKESC2/CDDP cells. While knocking down 14-3-3σ expression reversed the above situations in SLMT1 cells. I conclude that up-regulation in 14-3-3σ, together with DNA repairing genes, contributes to the establishment of cisplatin resistance in HKESC2/CDDP cells. Knocking down 14-3-3σ expression sensitized ESCC cells to cisplatin treatment, and hence, opens a therapeutic opportunity for ESCC cisplatin resistance. / published_or_final_version / Surgery / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Medicine / Master / Master of Philosophy

published_or_final_version / abstract / toc / Anatomy / Master / Master of Philosophy

This thesis explores attitudes to the body, illness and healing in contemporary rural China through the prism of Pierre Bourdieu's notion of habitus. It is divided in two parts. Part 1 aims to situate attitudes to the body in the specific social, cultural and political economic settings which have engendered them. I show that bodily dispositions articulate ways of engaging with one's surroundings and claims to authority and status. Past experiences equip different generations with different habitus (Bourdieu, 1977; 1990). At the same time, habitus is revised in light of engagements with new environments. As such, this section shows that habitus is made through daily practices, and that attitudes to the body are contingent and contested. Hierarchies with regard to what constitutes a desirable body or a healthy diet are not stable but always disputed. Negotiations surrounding them are informative of wider social processes and serve to reproduce or challenge social relations and values. Part 2 examines bodily practices at times of illness through the case of oesophagus cancer, an illness prevalent in the area, and with specific reference to one case and brief comparisons to others (including some discussion of stomach cancer). This section aims to show that family relationships are produced and contested through various practices of care, and that such relations engender particular bodily attitudes. These practices are not enactments of an already given reality or relationship, but rather vital to producing them. Closer attention to practices during illness are therefore important for understanding how illness is experienced by all involved, but also how it intersects with family relations, attitudes to resources, strategies to secure them and invest them, and perceptions of the state and welfare provision. It shows that a study of social change and reproduction is central to understanding cancer. Conversely, practices surrounding cancer, such as decisions not to undergo surgery, also present ways in which social reproduction and change take place. Employing habitus allows a closer grasp of the intricate processes through which family relations are formed, why families opt for particular forms of treatment and how the effectiveness of therapy is produced.

M.Sc. / Statistics provided by the World Health Organization state that cancer accounted for 7.9 million deaths worldwide in 2007, with numbers expected to increase to over 12 million by the year 2030. The transformation of a normal cell to a malignant tumour is known to be the result of a set of several key mutations in the genome of a normal cell, resulting in several unique properties including the evasion of programmed cell death, or apoptosis. Exacerbation of this cell death evasion can occur by overexpression of cell survival effectors such as heat shock proteins (Hsps), which are a family of highly conserved proteins that are rapidly induced in response to a variety of stresses in order to protect the cell from death. These proteins perform this function both by assisting in protein folding and therefore acting as molecular chaperones and also by directly interacting with the apoptotic machinery to prevent the initiation of cellular death. Various Hsps interfere at a range of sites in the intrinsic apoptotic pathway, both upstream of the mitochondria, and downstream at the sites of caspase activation. Similarly, Hsps also interfere at various sites in the extrinsic pathway, the caspase-independent pathways, and also function to promote the activity of survival pathways. Nonsteroidal anti-inflammatory drugs (NSAIDs) are well known for their anti-inflammatory properties via inhibition of cyclooxygenase (COX) enzymes. These drugs have also been shown to induce apoptosis in a variety of cancer cell lines as well as decrease the risk of the development of various cancers. Interestingly, NSAIDs have additionally been shown to have the curious property of activating the heat shock transcription factor (HSF1) at concentrations much higher than that required for inhibition of COX activity. The combination of NSAIDs and hyperthermia has resulted in seemingly contradictory evidence, where some studies show that this combination leads to thermotolerance and resistance to further treatments, whilst other studies have shown that this combination directly leads to cell death or indirectly sensitizes cells to subsequent stress.

Le glioblastome qui correspond au stade de malignité le plus élevé des gliomes est associé à un très mauvais pronostic car il envahit le parenchyme cérébral de manière diffuse, ce qui rend son exérèse complète généralement impossible, et il résiste aux traitements conventionnels en raison de sa résistance intrinsèque aux stimuli pro-apoptotiques. Le cancer de l’œsophage est également un cancer très agressif car invasif et résistant également aux stimuli pro-apoptotiques. <p>Les chémokines sont des cytokines chémotactiques responsables de la migration des leucocytes et exprimées en réponse à des cytokines inflammatoires, à des facteurs de croissance et à des stimuli pathogènes. De nombreux cancers possèdent un réseau complexe de ces chémokines. Les chémokines de type CXCL et plus particulièrement CXCL8 et CXCL12 sont impliquées dans la biologie des gliomes et du cancer de l’oesophage. Au cours de mon travail de thèse de doctorat, nous avons étudié l’expression des 15 chémokines CXCL et des 9 récepteurs aux chémokines CXCL dans divers modèles de gliomes et de cancers de l’œsophage. Cette étude menée par RT-PCR nous a permis de mettre en évidence la présence d’un patron d’expression complexe de ces chémokines CXCL dans les divers modèles analysés. Nous avons observé une expression plus importante des chémokines CXCL pro-angiogéniques par rapport aux chémokines anti-angiogéniques dans ces deux types de cancers. Nous avons également pu mettre en évidence une implication potentielle des chémokines CXCL2, CXCL3 et CXCL8 dans l’acquisition de la résistance au traitement par témozolomide des gliomes d’origine astrogliale. <p>Les glioblastomes et les cancers de l’œsophage étant deux types de cancers résistants aux stimuli pro-apoptotiques, et le témozolomide étant la seule molécule dotée de bénéfices thérapeutiques réels dans le cas du glioblastome, nous avons également testé le témozolomide dans nos modèles de cancer de l’œsophage in vitro et in vivo. Nous avons pu ainsi montrer un bénéfice thérapeutique réel apporté par cette molécule in vivo sur des animaux immunodéficients greffés avec des cellules humaines de carcinome épidermoïde de l’œsophage. Ce bénéfice thérapeutique peut être expliqué en partie par différents mécanismes d’action tels que l’induction de processus soutenus d’autophagie suivis par de l’apoptose mais également par des effets anti-angiogéniques. Enfin, nous avons pu montrer que la diminution d’expression même transitoire de la chémokine CXCL2 dans nos modèles in vitro de glioblastome et de carcinome épidermoïde de l’œsophage entraîne une diminution de la croissance de ces populations cellulaires cancéreuses, suggérant un rôle important de cette chémokine dans la biologie de ces deux types de cancers. Enfin, nous avons démontré un effet anti-angiogénique in vivo pour le témozolomide dans un modèle de xénogreffes de cancers oesophagiens humains chez la souris immunodéficiente.<p><p>En conclusion, l’ensemble de nos résultats suggèrent que le témozolomide, bien qu’il devienne bientôt un générique sous sa forme d’administration i.v. (la forme orale étant déjà générique), pourrait représenter une molécule d’intérêt pour combattre le cancer de l’œsophage, comme on le sait déjà depuis 2005 en ce qui concerne les glioblastomes. Nos résultats montrent ensuite l’importance du patron d’expression des chémokines CXCL dans la biologie des cellules gliales tumorales et des cellules cancéreuses de l’œsophage. Enfin, nos résultats montrent que le témozolomide détruit en partie ce réseau de chémokines CXCL au sein de ces deux types de cancers.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

Chromatin regulation is a major aspect of cancer development, progression, and treatment. Several small molecule inhibitors of chromatin regulators are currently used for treatment of certain hematological malignancies. However, there is still opportunity for many more patients to benefit from therapeutic approaches that target chromatin regulation, especially in the context of solid tumors. A critical unmet need is the identification of robust biomarkers that can guide the application of epigenetic inhibitors in a precise and personalized manner. In my dissertation, I aim to address this important knowledge gap by studying how perturbation of chromatin can target metabolic and lineage abnormalities in solid tumors for therapeutic benefit. To do this, I have focused on genetic and pharmacological perturbations of chromatin pathways in two cancer models: (1) lung adenocarcinoma (LUAD) with NRF2 activation and (2) neuroendocrine esophageal carcinoma (NEC). In the study on NRF2-active LUAD, we found that histone deacetylase (HDAC) inhibitors can be repurposed to reprogram the epigenomic and metabolic landscape, which leads to specific and potent anti-tumor effects in the context of NRF2 activation. Specifically, we employed a chromatin-focused genetic screen to identify dependencies on chromatin regulators. The screen revealed an NRF2-specific dependency on class I histone deacetylases. Experiments in mouse and human LUAD cell lines in vitro and in vivo indicated an NRF2-specific sensitivity to the class I HDAC inhibitor Romidepsin. Mechanistically, profiling of histone acetylation and gene expression upon Romidepsin treatment revealed a relative loss of histone H4 acetylation at promoters which was associated with reduced gene expression. Many downregulated genes were more essential for the survival of NRF2 hyperactive cancer cells, including genes involved in glutamine and serine metabolism, c-Myc and several of its targets involved in purine and pyrimidine synthesis. These transcriptional changes had corresponding effects on altering the metabolic pathways that NRF2-active cells selectively require for survival. In the study on neuroendocrine esophageal carcinoma (NEC), we identified a crucial role for epigenetic regulation of lineage fate through transcriptional control of the key epidermal transcription factor p63. This project originated from data from my collaborators that indicates a role for p63 in the suppression of basal-to-neuroendocrine identity transition in the developing esophagus. Consistently, I found that p63 is silenced in NEC through a non-genetic mechanism. Reintroducing p63 isoforms in a human NEC cell line showed that ΔNp63α was sufficient to restore squamous marker expression. An epigenetic drug screen assessing p63 gene expression and subsequent validation experiments revealed that inhibition of EZH2, a histone methyltransferase, induced expression of ΔNp63α and genes related to the squamous identity. Analysis of the chromatin state in the TP63 locus showed that EZH2 inhibition led to a loss histone H3 methylation and a gain of histone H3 acetylation and its reader BRD4. These results support the hypothesis that the squamous identity can be reactivated epigenetically in NEC through de-repression of ΔNp63α as a potential therapeutic strategy. Together, these studies contribute to our understanding of the transcriptional response to chromatin perturbation and show that this can be leveraged to modulate cell metabolism and identity, as well as to achieve therapeutic benefit in new contexts of cancer.

Thesis (PhD (Pathology. Anatomical Pathology))--University of Stellenbosch, 2006. / Patients with chronic gastro-oesophageal reflux disease are predisposed to Barrett’s metaplasia and oesophageal adenocarcinoma. The availability of molecular markers that can objectively identify patients with Barrett’s oesophagus at increased risk of carcinoma is highly desirable. A literature search was conducted to identify potentially useful biomarkers for genotype-phenotype correlation studies in South African patients with Barrett’s oesophagus. The COX-2, c-myb and c-myc genes selected for mRNA expression analysis were analysed in 26 patients with Barrett’s metaplasia (BM) without dysplasia; 14 with Barrett’s oesophagus and dysplasia (BD); 2 patients with Barrett’s adenocarcinoma (BAC); 19 with erosive oesophagitis (ERD); 25 with non-erosive oesophagitis (NERD) and 19 control individuals with a normal gastroscopy and no gastro-oesophageal reflux disease (GORD) symptoms. In the BD/BAC group, 69% (11/16) showed increased c-myb mRNA expression compared with 35% (9/26) in the BM group (p = 0.03). A statistically significant difference (p = 0.002) in c-myb expression was also observed between Barrett’s patients (20/42, 48%) and the control groups (9/63, 14%). In the BD patients, 21% (3/14) had increased c-myc mRNA expression compared with none in those with BM (p < 0.05) and BAC. No significant differences in mRNA expression levels were observed between ethnic groups for the genes analysed. In an attempt to determine whether the low expression level of c-myc in the study cohort may be related to possible gene-gene interaction, DNA samples of 199 individuals were subjected to genotyping of the functional GT-repeat polymorphism in the promoter region of the NRAMP1/SLC11A1 gene. Both these genes are involved in iron metabolism and c-myc is known to repress NRAMP1/SLC11A1. Genotype and allele frequencies were similar in all the groups studied with the 3/3 genotype being the most common. However, none of the three above-mentioned BD patients with increased c-myc mRNA expression had the 3/3 genotype. Therefore, although small in number, c-myc-NRAMP1/SLC11A1 interaction may be of adverse significance in patients with allele 2. TP53 mutation analysis was performed on 68 Barrett’s patients, and TP53 immuno-staining on oesophageal biopsy specimens of 55 subjects. Sporadic TP53 mutations were not identified in any of the patients with BM or dysplasia without BAC. Immuno-histochemistry staining of 2+ and 3+ intensity was similar in patients with metaplasia and dysplasia (58%). The low mutation frequency and relative non-specificity of TP53 immunostaining observed in Barrett’s patients seem to preclude its widespread use as a screening tool. TP53 mutation detection may however be useful for risk stratification once dysplasia has been diagnosed, as mutations G245R and D281Y were identified in two patients with BAC. Of the genes studied in the South African population, c-myb represents the most useful marker for early detection of an increased cancer risk in Barrett’s patients. In future, patients with Barrett’s oesophagus may benefit from genetic assessment to complement existing cancer surveillance and treatment strategies.