Thesis--University of Oklahoma. / Bibliography: leaves 90-93.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 126-139).

Orientador: Carmen Silvia Passos Lima, Fernando Ferreira Costa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T11:53:50Z (GMT). No. of bitstreams: 1 Nascimento_Helvia_D.pdf: 1845231 bytes, checksum: 16f227072d706aacb01f06165bd8a553 (MD5) Previous issue date: 2007 / Resumo: Os mecanismos moleculares envolvidos na origem do adenocarcinoma de cólon esporádico (ACE) ainda não estão completamente elucidados. Recentemente, o método da análise seriada da expressão gênica (SAGE) foi descrito como eficaz para identificar a expressão total de genes de tipos celulares diversos, mas esta análise não foi realizada em células epiteliais purificadas do ACE moderadamente diferenciado. Nós caracterizamos pelo método SAGE a expressão gênica total de células epiteliais neoplásicas do cólon de um paciente com ACE moderadamente diferenciado (SAGE CC) e de células epiteliais normais do cólon de um paciente com megacólon chagásico (SAGE CN). Foram geradas, após o seqüenciamento automático, 44.004 e 43.570 tags totais das bibliotecas SAGE CC e SAGE CN, representando 16.484 e 13.479 tags únicas, respectivamente. Na comparação entre as bibliotecas, 171 transcritos diferencialmente expressos foram identificados (P< 0,001; expressão diferencial = 5), incluindo 10% de transcritos que podem representar genes não descritos. As expressões de 10 genes diferencialmente expressos foram quantificadas pela reação em cadeia da polimerase em tempo real (qPCR) na amostra de células epiteliais neoplásicas (SAGE CC), com o intuito de validar os resultados obtidos pelo SAGE, e, posteriormente, em amostras de células epiteliais de outros cinco pacientes com o mesmo tipo de doença. As expressões foram concordantes em 80% dos genes (CEACAM6, KLK6, LYZ, PFN1, S100A8, S100A9, VIL2 e ZFHX1B) e discordantes nos demais 20% (PLA1A e ZNF277). As expressões dos genes de interesse, quantificadas pelos dois métodos, foram similares na amostra SAGE CC e nas amostras dos demais pacientes com a doença. Foram observadas expressões anormais de genes envolvidos com a proliferação e diferenciação celular e com a resposta ao stress em células epiteliais neoplásicas. Foram também visualizadas expressões anormais de genes não relacionados com a doença e de genes ainda não identificados. Em conjunto, os nossos resultados podem contribuir para a identificação de genes relacionados com a origem ou a progressão do ACE moderadamente diferenciado e, ainda, para a descoberta de agentes terapêuticos específicos que controlem a proliferação anormal das células neoplásicas. / Abstract: The molecular mechanisms involved in sporadic colon adenocarcinoma (SCA) are still not completely elucidated. Recently, the serial analysis of gene expression (SAGE) method has allowed the global analysis of genes expressed in diverse cellular types but there are no studies in purified epithelial cells of SCA moderately differenciated. We have characterized through SAGE the global gene expression of neoplastic epithelial cells from a SCA moderately differenciated patient (SAGE CC) and normal epithelial cells from a megacolon patient (SAGE CN). After automatic sequencing, a total of 44.004 tags from SAGE CC and 43.570 tags from SAGE CN profiles were generated, representing 16.484 and 13.479 unique tags, respectively. Comparing both profiles, 171 differentially expressed transcripts were identified (P< 0.001; fold = 5), including 10.0% that may represent novel transcripts. The expression of 10 selected genes was further investigated by realtime polymerase chain reaction (qPCR) in the SCA moderately differenciated epithelial cells sample (SAGE CC), with the purpose of to validate the results obtained by the SAGE method, and also in five epithelial cells samples from the same type of SCA patients. Similar expressions were seen in 80% (CEACAM6, KLK6, LYZ, PFN1, S100A8, S100A9, VIL2 e ZFHX1B) and discordant expressions were seen in 20% (PLA1A e ZNF277) of analysed genes. On SAGE CC sample and samples of the SCA patients, all genes presented similar expressions measured by both methods. We observed abnormal expression of genes involved with cell proliferation and differentiation, and with response to stress in neoplastic epithelial cells. Also, were found abnormal expressions of genes not related with the disease and not identified genes. Together, our results may contribute for the identification of genes involved in the origin or progression of SCA moderately differenciated, as well as for the discovery of new therapeutical agents, with specific action on abnormal proliferation of the neoplastic cells. / Doutorado / Ciencias Basicas / Doutor em Clínica Médica

Coral reef biodiversity is threatened by rapidly changing anthropogenic activities and natural perturbations, leading to massive ecological and economic consequences ranging from the loss of fisheries to coastal erosion. It is necessary to understand corals responses to environmental changes in order to determine management programs on appropriate spatial and temporal scales to address these issues. Coral larvae are the product of sexual reproduction, have the potential to recruit to new areas, and are fundamental in maintaining genetic diversity. These larvae are subjected to variations in local environmental conditions until they settle, inducing specific larval molecular response patterns. One factor that influences coral health is salinity. Low salinities can alter cell homeostasis creating stress in cells. In the natural environment larvae may be exposed to low salinities due to heavy rainfall or run-off. This study investigated larvae responses to low salinity and characterized gene expression in the reef-building coral Porites astreoides using a coral stress-focused microarray. Nine batches of 250+ larvae from three different colonies were collected and immediately exposed in an acute hyposalinity experiment. Samples from two treatments of 25 and 30 ppt, and a control at 35 ppt were used in this study. After experimental exposure these samples were stored in RNAlater® and molecular analysis was performed. The RNA from the samples was extracted, purified and hybridized to a coral stress-focused microarray. Statistical analysis indicates 72 genes were differentially expressed across treatments (p<0.003, analysis of variance). The hierarchical cluster analysis groups together the larvae exposed to salinities of 30 and 35 ppt indicating both treatments induced similar patterns of gene expression. Larvae responses to 30 ppt are minimal, suggesting larvae can tolerate acute exposures to 30 ppt salinity levels. In contrast, the lower salinity (25 ppt) induced a strong response in both the coral and zooxanthellae. The coral larvae up-regulated stress response genes and down-regulated genes associated with normal cell functioning. Additionally, the zooxanthellae down-regulated genes associated with photosynthesis. These results suggest larvae may be vulnerable to bleaching, which may affect the ability of larvae to successfully undergo metamorphosis and survive at low salinities. However, this has yet to be confirmed with complementary techniques. Long-term studies are recommended to examine the effects of hyposalinity on larvae at different time scales and life history stages.

Le lymphome folliculaire (LF) représente le 2ème lymphome par ordre de fréquence et reste considéré à l’heure actuelle comme incurable. De nombreuses questions sur le processus de lymphomagénèse sont encore non résolues et il n’existe aucun marqueur génomique ou moléculaire unanimement reconnu permettant de prédire l’évolution des patients. Nos travaux de recherche s’inscrivent dans l’objectif de mieux comprendre l’impact des altérations moléculaires identifiées dans ces tumeurs, grâce à une approche intégrative visant à combiner des données génomiques, transcriptomiques et mutationnelles. Ce travail a permis de construire un score, basé sur l’expression d’un panel de gènes, prédictif du risque de progression de la maladie. Ce score a été confirmé sur une seconde cohorte de patients, validant son utilité potentielle en pratique clinique. Par ailleurs, nos résultats suggèrent que les cellules tumorales peuvent acquérir des propriétés évocatrices d’un profil de cellules souches et associées à un pronostic particulièrement défavorable. Une 2ème partie de notre travail a porté sur les altérations touchant le gène EZH2, muté chez 25% des patients. Nous avons démontré qu’un gain génomique au niveau du locus EZH2 pouvait également avoir des conséquences sur le profil transcriptomique et un impact pronostique, soulignant l’importance de prendre en compte l’ensemble des anomalies touchant ce gène. Enfin, nous rapportons qu’un polymorphisme constitutionnel situé dans ce gène est associé au risque de progression des patients traités par un anticorps anti-CD20. L’ensemble de ces résultats apporte un éclairage nouveau sur la biologie du LF et peut contribuer à améliorer la prise en charge des patients / Follicular Lymphoma (FL) is the 2nd most frequent lymphoma subtype and is usually considered incurable with current strategies. Several questions regarding the lymphomagenesis process are still pending, and no molecular or genomic marker has been unanimously recognized yet to predict outcome. We performed an integrative analysis combining genomic, transcriptomic and mutational data in the view to bringing new highlights in the molecular alterations acting in FL. Based on gene-expression profiling data we developed a model able to predict progression-free survival in FL patients. We confirmed its predictive value in another cohort of patients, thereby allowing its potential use in clinical practice. Furthermore, our results highlight that some tumors show a stem-cell-like gene-expression profile that was associated with highly unfavorable outcome. In the second part of our work, we focused on alterations of the gene EZH2. Although mutations have been reported in 25% of FL patients, we questioned whether genomic gains at EZH2 locus could also contribute to lymphomagenesis. We showed that such gain may impact the transcriptional profile and have a prognostic significance, thus highlighting the crucial interest of determining both kinds of alterations. Finally, we report that a germ-line polyporphism in the EZH2 gene was significantly associated with progression-free survival in patients treated by anti-CD20 therapy. Taken together, these results bring new highlights on FL biology and may help to improve the clinical management of FL patients

Ribosome profiling (RP) is a novel technique that exploits RNA sequencing and ribosome immobilization to quantify transcription and translation at different cell growth stages. Therefore, RP provides invaluable information for expression dynamics studies. Quantitative –omics studies are of crucial importance for identification of potential biomarkers of infection. An ideal parasite detection system should definitely establish the presence or absence of infection; determine the species involved; be detectable even in low concentrations; be proportional to parasite density; and determine the presence of antibiotic resistance. Here, we propose a simple workflow that attempts to identify a set of biomarkers that fulfill some of the above criteria for the ideal detection system. RP expression profiles were ranked for abundance, crosschecked with PlasmoDB for homogeneity along infection cycles and probed for availability of structural stability. The latter is of fundamental importance for the development of molecular biosensors to be give birth to rapid diagnostic kits. In addition, a simple biochemistry workflow was developed for easy production of the selected biomarkers in E. coli. Altogether, the present work provides two complementary and novel workflows that shall aid researchers to rapidly produce molecular biomarkers and develop biosensors based on antibodies or aptamers. / Tesis

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The lymphocyte-specific transcription factor Interferon (IFN) Regulatory Factor 4 (IRF4) is implicated in certain types of lymphoid and myeloid malignancies. However, the molecular mechanisms underlying its interactions with these malignancies are largely unknown. In this study, we have first profiled molecular signatures associated with IRF4 expression in associated cancers, by analyzing existing gene expression profiling datasets. Our results show that IRF4 is overexpressed in melanoma, in addition to previously reported contexts including leukemia, myeloma, and lymphoma, and that IRF4 is associated with a unique gene expression pattern in each context. A pool of important genes involved in B-cell development, oncogenesis, cell cycle regulation, and cell death including BATF, LIMD1, CFLAR, PIM2, and CCND2 are common signatures associated with IRF4 in non-Hodgkin B cell lymphomas. We confirmed the correlation of IRF4 with LIMD1 and CFLAR in a panel of cell lines derived from lymphomas. Moreover, we profiled the IRF4 transcriptome in the context of EBV latent infection, and confirmed several genes including IFI27, IFI44, GBP1, and ARHGAP18, as well as CFLAR as novel targets for IRF4. These results provide valuable information for understanding the IRF4 regulatory network, and improve our knowledge of the unique roles of IRF4 in different hematological malignancies.