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Non-Hodgkin’s lymphoma is the fifth most common cancer in the UK, accounting for 4% of all new cases. The control of lymphomagenesis still remains a challenge. Early growth response gene (Egr) 2 and 3 are zinc finger transcription factors. Egr2 plays an important role in the development of both central nervous system and lymphocytes. However the mechanism of action in lymphocytes is still unknown. In order to fully understand the function of Egr2, in lymphocytes, we developed Egr2 and 3 double knockout mice (Egr2-/-Egr3-/-) by crossbreeding lymphocyte specific Egr2 knockout mice (CD2-Egr2-/-) with Egr3 knockout mice (Egr3-/-), as previous reports suggested that Egr3 compensates for the role of Egr2. In the absence of Egr2 and 3, the homeostasis of T cells is dysregulated with hyper-homeostatic proliferation of effector like phenotype cells. More importantly the development of spontaneous B and T cell lymphoma was found in more than 70% of Egr2-/-Egr3-/- mice. The lymphoma cells from Egr2-/-Egr3-/- mice were highly proliferative and metastatically spread into other non-lymphoid organs, such as lung, liver and kidney. In additional to this lymphoma development the Egr2-/-Egr3-/- mice showed signs of chronic inflammatory disorder. This inflammatory disorder was characterised by glomerulonephritis and an increase in serum cytokines, which may provide the microenvironment for the lymphoma development. To explore the molecular mechanism of tumour development in Egr2-/-Egr3-/- mice, the transcriptional profile of Egr2 was studied by microarray and ChIP-on-chip. We found firstly that Egr2 directly binds to the promoter regions of Ikaros and FOXO3. The deletion of Egr2 and 3 in lymphocytes led to the downregulation of Ikaros, Aiolos and FOXO3 expression. The impaired expression was found to be associated with proliferative disorder and the development of T and B cell lymphoma. Secondly Egr2 strongly inhibits STAT3 transcriptional activity by regulating SOCS3, which is a known inhibitor of STAT3. The breakdown of this regulation could be an important mechanism in lymphomagenesis. A model is proposed which defines Egr2 and Egr3 as the backbone of important tumour suppressor genes that control cell fate decision and regulates homeostasis in the lymphoid system. Thus, our results suggest that Egr2 and 3 are important regulators of lymphocyte function by their involvement in multiple cell signalling pathways, which could potentially be key genes for future cancer therapy.

Made available in DSpace on 2014-06-11T19:25:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-22Bitstream added on 2014-06-13T19:12:37Z : No. of bitstreams: 1 legnaro_cc_me_botfm.pdf: 1219324 bytes, checksum: 89e33a96cd65e36401b20581892cd1d1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O câncer de mama é o tipo de câncer mais comum entre as mulheres, correspondendo a 22% de todos os casos. Foram estimados mais de 1.050.000 casos novos de câncer de mama em todo o mundo no ano 2000. Mecanismos epigenéticos como a ativação e desativação de genes por meio da hipometilação e hipermetilação, respectivamente, da região promotora dos genes estão associados ao surgimento de diversos tipos de cânceres. Embora os fatores que resultam na metilação aberrante ainda não sejam bem conhecidos, a deficiência de folato têm sido associada a esse mecanismo no desenvolvimento de cânceres como de colo uterino, pulmão, mama, cólon e cérebro. Neste trabalho, foi avaliado se os polimorfismos em genes de enzimas chaves no metabolismo do folato como a timidilato sintase (TS) e metilenotetrahidrofolato redutase (MTHFR) influenciam o padrão de metilação da região promotora dos genes CDH1, BRCA1 e hMLH1 em amostras de câncer de mama. A metilação foi avaliada através da MS-PCR e os polimorfismos por PCR e PCR-RFLP. Não houve diferença estatisticamente significante (p<0.05, teste exato de Fisher) do padrão de metilação dos genes quando comparado com estádio, grau histológico, idade e freqüência dos polimorfismos. Os polimorfismos 5´UTR TS, C677T e A1298C MTHFR não influenciam no padrão de metilação da região promotora dos genes CDH1, BRCA1 e hMLH1 em amostras de câncer de mama / The breast cancer is the most frequent cancer in women equivalent to 22% of all cases. It were estimated more than 1.050.000 new cases of breast cancer in all the world in the year 2000. Epigenetic mechanisms like ativation and desativation of genes by hypomethylation and hipermethylation, respectivelly, of genes promoter regions are associated to the appearance of several types of cancer. Although the factors that result in aberrant methylation are not well known, the lack of folate has been associated to this mechanism in the development of cancers like cervical uterine, lungs, breast, colon and brain. In this research it was evaluated if the polymorphisms in genes of folate metabolism enzymes like the thymidilate syntase (TS) and methylenetetrahydrofolate reductase (MTHFR) influence the methylation pattern of the promoter of genes CDH1, BRCA1 and hMLH1 in samples the tissue of breast cancer. The methylation was evaluated through the MS-PCR and the polymorphisms through PCR and PCR-RFLP. We observed no statistically significant associations (p<0.05, exact test of Fisher) of the patterns of methylation of genes when compared to stage, histologic grade, age and frequency of polymorphisms. The polymorphisms 5´UTR TS, C677T AND A1298C MTHFR did not influence in the pattern of methylation of the promoter region of genes CDH1, BRCA1 e hMLH1 in samples the tissue of breast cancer

Formação de tumores deve-se a combinações de fatores. A via de p53 tem um papel fundamental no controle de proliferação e apoptose. O interferon-beta (IFNb) é importante na modulação da resposta imunológica, no efeito antitumoral e no impacto apoptótico em células tumorais. Segundo a literatura, IFNb ativa a transcrição de p53 e componentes do sistema IFN efetuam sua função pela via p53/p14arf. Neste projeto, foi construída uma série de ferramentas para explorar interações entre p53 e IFNb. A primeira ferramenta, uma linhagem celular derivada de B16 com expressão de p53 reduzida por miRNA. Também construímos vetores plasmidiais e adenovirais portadores dos cDNAs para eGFP, Luciferase, p53 ou IFNb. Os vetores são utilizados para introduzir estes fatores, sozinho ou combinados, na célula alvo. Mesmo confirmando a atividade de p53 ou IFNb sozinho, não foi observado um efeito aditivo destes fatores em conjunto com este tipo de ensaio. Futuros estudos das possíveis interações entre as vias de p53 e IFNb terão o benefício das ferramentas construídas neste projeto. / Formation of tumors it must to combinations of factors. The p53 pathway has an essential role in proliferation control and apoptosis. The interferon-beta (IFNb) is important in modulation of the immunologic response, in the antitumoral effect and in the apoptotic impact in tumor cells. According to literature, IFNb activate the p53 transcription and components of IFN system effect its function to p53/p14arf pathway. In this project, a series of tools was constructed to explore interactions between p53 and IFNb. The first tool, a cellular lineage derivative of B16 with expression of p53 reduced by miRNA. We also construct plasmidial and adenoviral vectors carriers of cDNAs for eGFP, Luciferase, p53 or IFNb. The vectors are used to introduce these factors, alone or agreed, in the target cell. Even confirming the activity of p53 or IFNb alone, an additive effect of these factors combined was not observed with this type of assay. Future studies of the possible interactions between p53 and IFNb pathways will have the benefit of the tools constructed in this project.

Este trabalho descreve a remediação simultânea de dois genes supressores de tumor, CDKN2A e p53, em três linhagens celulares derivadas de glioblastoma multiforme: U87 (CDKN2A-/-, p53wt/wt), U251 (CDKN2A-/-, p53mut/mut) e T98G (CDKN2A-/-, p53mut/mut). A entrega gênica foi mediada por vetor adenoviral bicistrônico contendo o cassete CDKN2AIRESp53, capaz de expressar as duas proteínas simultaneamente. Vetores monocistrônicos também foram testados (AdCDKN2A e Adp53). Visando detectar apoptose, as linhagens receberam o sensor de atividade de caspase-3/7 GFP-DEVD-ssGLUC por transdução lentiviral. Este possui Gaussia luciferase (GLUC) C-terminal, que é secretada após ativação de caspases e pode ser dosada no sobrenadante. Após a marcação, realizaram-se ensaios de viabilidade celular, proliferação, formação de colônias, senescência, ciclo celular e dosagem de GLUC após remediação dos genes supressores de tumor nas linhagens GBMDEVD-GLUC. Com ensaio de viabilidade, observou-se efeito citotóxico do vetor bicistrônico AdCDKN2AIRESp53 maior que a soma dos obtidos com cada tratamento monocistrônico. No ensaio de senescência, o vetor AdCDKN2A resultou na maior indução do fenótipo senescente em todas as linhagens, seguido por Adp53, enquanto AdCDKN2AIRESp53 produziu resultados similares a um desses dois perfis em cada linhagem. Dosagem de GLUC no sobrenadante foi usada como indicador para atividade de caspase-3/7 após tratamento com os vetores supressores de tumor. O controle AdLacZ resultou em atividade de GLUC maior que nas amostras sem vírus (mock), enquanto tratamento com AdCDKN2A obteve resultados maiores que o controle em 72 h nas três linhagens. O vetor AdCDKN2AIRESp53 alcançou, inesperadamente, resultados variados em 72 h. Os dados obtidos neste trabalho indicam que a remediação simultânea de CDKN2A e p53 possui notável ação antiproliferativa tumoral, podendo levar à morte ou à senescência celular. Também é apontado que o sensor de caspase-3/7 GFP-DEVD-ssGLUC é robusto, mas detecta não apenas a indução de apoptose, mas a combinação de todos os processos ativadores de caspases em uma amostra. / This thesis describes the simultaneous remedy of two tumor suppressor genes, CDKN2A and p53, in three glioblastoma multiforme (GBM)-derived cell lines: U87 (CDKN2A-/-, p53wt/wt), U251 (CDKN2A-/-, p53mut/mut) and T98G (CDKN2A-/-, p53mut/mut). Gene delivery was mediated by a bicistronic adenoviral vector bearing the sequence CDKN2AIRESp53, which simultaneously expresses both proteins. Monocistronic vectors were also tested (AdCDKN2A and Adp53). To detect apoptosis, the GBM cell lines received caspase-3/7 sensor GFP-DEVD-ssGLUC via lentiviral transduction. This sensor has a C-terminal Gaussia luciferase (GLUC), which is secreted by the cell after caspase activation and can be measured in the supernatant. After sensorization, functional assays were carried out, including cell viability, proliferation, colony formation, cell senescence, cell cycle and GLUC measure after treatment with the tumor suppressor vectors in GBMDEVD-GLUC lineages. Viability assay with the AdCDKN2AIRESp53 vector resulted in a remarkable cytotoxic effect, greater than the sum of the effects with each monocistronic treatment. In the senescence assay, vector AdCDKN2A yielded the highest induction of cell senescence in all lineages, followed by Adp53, while AdCDKN2AIRESp53 induced results that followed one of these two profiles in each cell line. GLUC measure was an indicator of intracellular caspase-3/7 activity after treatment with the tumor supressor vectors. Control vector AdLacZ resulted in higher GLUC activity than mock treatment in all three cell lines, while AdCDKN2A treatment showed results bigger than control at 72 h in all cell lines. Bicistronic vector AdCDKN2AIRESp53 reached, unexpectedly, varied results at 72 h in all cell lines. Data obtained in this study indicate that simultaneous remedy of CDKN2A and p53 has remarkable antiproliferative activity in GBM cells, resulting in cell death or cell senescence. It is also shown that caspase-3/7 sensor GFP-DEVD-ssGLUC is a robust tool, but its results detect not only a single cellular process, such as apoptosis, but the combination of all caspase-activating processes in a cell population.