Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Pouco se conhece a respeito da incidência ou prevalência da infecção pelo vírus da raiva em morcegos, ou ainda sobre a distribuição do vírus em tecidos e órgãos não nervosos. Os objetivos deste trabalho foram: i) verificar as espécies de morcegos mais freqüentemente envolvidas com a raiva no Estado de São Paulo, Sudeste do Brasil; ii) estudar a distribuição do vírus da raiva em tecidos e órgãos não nervosos de morcegos; iii) estudar os períodos de mortalidade das amostras de vírus da raiva encontradas nos cérebros e glândulas salivares de morcegos, após inoculação intracerebral em camundongos, e iv) comparação do isolamento do vírus da raiva no sistema camundongo e cultura de células de neuroblastoma (N2A). Entre abril de 2002 a novembro de 2003, 4.393 morcegos capturados de diferentes municípios do Estado de São Paulo foram enviados à Seção de Diagnóstico da Raiva do Instituto Pasteur de São Paulo. Destes, 82 (1,87%) foram positivos para raiva pela técnica de imunofluorescência aplicada aos materiais do cérebro e 33 morcegos pertenciam ao gênero Artibeus sp; 15 Myotis sp; 10 Epitesicus sp; 5 Lasiurus sp; 4 Nyctinomops sp; 4 Tadarida sp; 3 Histiotus sp; 1 Molossus sp; 1 Eumops sp e 6 vampiros Desmodus rotundus. A distribuição do vírus em diferentes órgãos foi examinada pela inoculação de camundongos e células N2A com suspensões a 20% preparadas a partir de fragmentos do cérebro, glândula salivar submandibular, pulmão, língua, coração, bexiga urinária, rins, gordura interescapular, músculo peitoral, trato genital (testículos ou ovários e útero) e estômago. O vírus foi prontamente recuperado de tecidos e órgãos não nervosos com diferentes graus de sensibilidade, tanto em camundongos como em células N2A, e os órgãos mais apropriados para o isolamento viral foram os cérebros e glândulas salivares. Os períodos máximos de mortalidade observados para os vírus presentes nos cérebros usualmente foram mais curtos que os das glândulas salivares, a média do período máximo &plusmn; desvio padrão calculado para os cérebros de morcegos hematófagos foi de 15,33 &plusmn; 2,08 dias e para as glândulas salivares, 11,33 &plusmn; 2,30 dias; para os morcegos insetívoros, 16,45 &plusmn; 4,48 dias para os cérebros e para as glândulas salivares, 18,91 &plusmn; 6,12 dias; e para os morcegos frugívoros, as suspensões cerebrais apresentaram período máximo médio 12,60 &plusmn; 2,13 dias e para as glândulas salivares, 15,67 &plusmn; 4,82 dias. O teste de ANOVA indicou existir diferenças significantes entre os períodos de mortalidade correspondentes às suspensões preparadas a partir dos cérebros de morcegos insetívoros (período mínimo) e glândulas salivares de morcegos insetívoros (período máximo) e entre glândulas salivares de morcegos insetívoros (período máximo) e cérebros de morcegos frugívoros (período mínimo), com p<0.001. O uso de células N2A para o primo-isolamento do vírus da raiva a partir de tecidos e órgãos não nervosos de morcegos, diferente de cérebros, não mostraram resultados consistentes, especialmente devido à contaminação bacteriana e fator toxicidade / Little is known about the incidence of infection or the prevalence rate of rabies in bats, or the distribution of virus in non-nervous tissues and organs. The aim of this work was to study: i) the most frequent species of bats involved with rabies virus infection in the State of São Paulo, Southeast Brazil; ii) the distribution of rabies virus in tissues and non-nervous organs of bats; iii) the mortality periods of virus found in brains and salivary glands of bats after intracerebral inoculation of mice, and iv) comparison of virus isolation in mice and N2A neuroblastoma cell culture. From April 2002 to November 2003, 4,393 bats captured from different municipalities of the State of São Paulo were sent to Rabies Diagnostic Section of the Instituto Pasteur de São Paulo - SP. Among these, 82 (1.87%) were found positive by the immunofluorescence technique applied to brain specimens and 33 bats were of the genus Artibeus sp; 15 Myotis sp; 10 Epitesicus sp, 5 Lasiurus sp, 4 Nyctinomops sp, 4 Tadarida sp, 3 Histiotus sp; 1 Molossus sp, 1 Eumops sp, and 6 vampires Desmodus rotundus. The distribution of virus in the organs was examined by inoculating mice and N2A cells with the 20% suspensions prepared from brain, submaxillary salivary gland, lungs, tongue, heart, urinary bladder, kidneys, brown fat, pectoral muscle, genital tract (testicles or ovaries and uterus), and stomach. The virus was promptly recovered from tissues and non-nervous organs at different degrees of sensitivity in both mice and N2A cells, and the most appropriate organs for the virus isolation were the brains and salivary glands. The maximum mortality periods found for the brain specimens usually were shorter than the salivary glands, the maximum mean perio &plusmn; standard deviation calculated for the brains taken from the vampire bats was 15.33 &plusmn; 2.08 days and for salivary glands, 11.33 &plusmn; 2.30 days; for the insectivorous bats the maximum for the brain suspensions was 16.45 &plusmn; 4.48 days and for the salivary glands, 18.91 &plusmn; 6.12; and for the frugivorous bats, the brain suspensions showed the maximum of 12.60 &plusmn; 2.13 days and the salivary glands, the mean maximum period of 15.67 &plusmn; 4.82 days. The ANOVA test indicated that the most significant differences in the mortality periods were between the suspensions prepared by the brains of insectivorous bats (minimum period) and salivary glands of insectivorous bats (maximum period); salivary glands of insectivorous bats (minimum period) and brains of frugivorous bats (minimum period) with p<0.001. The use of N2A cells for the prime isolation of rabies virus from tissues and non-nervous organs other than brains of bats did not show consistent results, especially due to bacterial contamination and toxicity factor

O neuroblastoma é o tumor sólido extra-cranial mais comum e mortal da infância, sendo o tempo de sobrevida nos casos mais agressivos ainda muito curto. Uma das esperanças nesses casos é que os estudos moleculares possam fornecer informações sobre os genes ou as vias moleculares que governam a patogênese dos neuroblastomas. Pois, há poucos genes como o MYCN, que foi descrito por estar diretamente ligado ao neuroblastoma. A amplificação deste oncogene ocorre em pouco mais de 25% dos neuroblastomas e é considerada como o mais importante marcador de prognóstico nestes tumores, sendo fortemente relacionada aos estádios avançados da doença e falha no tratamento. Outros genes do amplicon do MYCN, incluindo o DDX1 \"DEAD box polypeptide 1 gene\" e o NAG \"neuroblastoma-amplified gene\", estão sendo observados por se apresentarem co-amplificados com o MYCN. Entretanto, a importância deste fenômeno no prognóstico ainda é desconhecida. Os objetivos deste trabalho foram determinar qual o melhor método para estudar a amplificação dos genes MYCN, DDX1 e NAG, além de esclarecer a importância da coamplificação dos genes DDX1 e NAG no prognóstico. Procedimento: O número de cópias dos genes MYCN, DDX1 e NAG foi determinado por PCR em Tempo Real e PCR convencional em 100 neuroblastomas primários. Os dados da PCR em Tempo Real foram analisados por quantificação absoluta e relativa. Os resultados da PCR convencional foram analisados por eletroforese em gel de agarose, medindo a intensidade das bandas formadas no gel no sistema Kodak. A relevância da amplificação gênica como marcador de prognóstico foi avaliada em 74 pacientes, dos quais nós obtivemos o acompanhamento clínico. Resultados: Nos 74 casos estudados, ambos os métodos demonstraram que a amplificação do MYCN estava associada com os estádios mais avançados da doença. A análise das curvas de sobrevida livre de progressão confirmou que pacientes com ausência de amplificação do MYCN apresentavam maior tempo de sobrevida. Nós também analisamos a amplificação do DDX1 nas mesmas amostras incluindo aquelas com ausência de amplificação de MYCN. Não foi encontrada nenhuma relação entre a co-amplificação com idade ao diagnóstico ou tempo de sobrevida. Conclusões: Os métodos aplicados para calcular o número de cópias dos genes na PCR em Tempo Real mostraram-se equivalentes. A PCR em Tempo Real apresentou maior acurácia nos resultados quando comparada à PCR convencional. A análise da sobrevida não demonstrou relação entre a amplificação dos genes DDX1 e/ou NAG com piora no prognóstico. / Neuroblastoma is the most common and deadly extra-cranial solid childhood tumor. Survival rates for aggressive neuroblastomas are still disappointingly low. One of the hopes is that molecular studies will provide insights into the genes and molecular pathways that govern neuroblastoma pathogenesis. However, at present only a few genes as MYCN have been directly linked to neuroblastoma. MYCN oncogene amplification, occurring in up to 25% of neuroblastomas, has been considered the most important prognostic factor, strongly correlating to advanced stage disease and treatment failure. Another genes in the MYCN amplicon, including the DEAD box polypeptide 1 (DDX1) gene, and neuroblastoma-amplified gene (NAG gene), have been found to be frequently co-amplified with MYCN in NB. But the prognostic significance of the coamplification remains unclear. The aims of this study were to evaluate which is the best method to study the gene amplification of those three genes MYCN, DDX1 and NAG, as well as clarify the prognostic significance of the co-amplification or DDX1 and NAG with MYCN. Procedure: The gene copy numbers of MYCN, DDX1, and NAG were determined by the real-time quantitative polymerase chain reaction and conventional polymerase chain reaction in 100 primary NBs. Real-Time data were analyzed by absolute and relative quantification. For conventional PCR, samples were electrophoresed on a 2% agarose gel and the intensity of each band evaluated by Kodak image software. To evaluate of the prognostic significance of the gene amplification we had only 74 cases in witch we could analyze the follow-up. Results: In all 74 cases, both methods demonstrated that MYCN amplification was associated mainly with advanced cancer stages, and the analysis of overall survival confirmed that patients without MYCN amplification had a cumulative survival significantly higher than patients with oncogene amplification. We also studied DDX1 and NAG amplification for all NB samples even that without MYCN amplification. No relationship between any gene co-amplification status and disease stage, age at diagnosis, or overall survival was found. Conclusions: The two methods used to calculate gene copy number for Real Time PCR assay shown to be equivalent. Real Time PCR assay shown to be more accurate to study gene amplification than conventional PCR assay. Survival analysis pointed out that DDX1 and/or NAG amplification has no additional adverse effect on prognosis.

Neuroblastoma as a pediatric tumor develops in the sympathetic nervous system. DLG2 is a gene that encodes a member of the membrane-associated guanylate kinase (MAGUK) family and it resides in the chromosome region 11q. SK-N-AS is a neuroblastoma cell line with 11q deletion and consequently only one copy of the potential tumor suppressor gene DLG2. This study investigated synergistic effect by a combination treatment with 1,25(OH)2D3 and the vitamin A metabolite, retinoic acid.  Separately, SK-N-AS cells was transfected with expression vector pcDNA3.1+‐DYK that contained the DLG2-gene, followed by monitoring cell proliferation and qPCR, investigating the expression of the genes DLG2, DLG3, DLG4, VDR and PDIA3. Simultaneously, effects of knocked-down of DLG2, by siRNA transfection was monitored.  Transfection of expression plasmid with the DLG2 gene increased significantly gene expression in SK-N-AS cells with significant inhibition of the proliferation rate. Furthermore, silencing of DLG2 gene had no effect on the cell growth as well. Slower cell growth showed in combination treatment with 1,25(OH)2D3 (1nM) and 9-cis RA after 48 hours of treatment. Down-regulated VDR and possible missing RARRES3 could be the reason why SK-N-AS cell line showed resistance to the combination treatment with vitamin metabolites. All these results raised the question if another vitamin D synthetic analog could be a better choice for the future study of SK-N-AS cells. Moreover, overexpression of NAIP, large amounts of IGF-II, or not responsive RXR-VDR heterodimer to 1,25(OH)2D3 could be a potential explanation for the SK-N-AS cell unresponsiveness to the treatment.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Surgery / Master / Master of Philosophy

published_or_final_version / abstract / Surgery / Doctoral / Doctor of Philosophy

Dans les neuroblastomes, le gène N-MYC est amplifié dans 20-25 % des cas,associé à un mauvais pronostic. Au laboratoire, nous avions préalablement montré que la dérégulation de l’expression du gène TWIST1 était corrélée à celle de N-MYC dans les neuroblastomes agressifs de stade IV avec une amplification de N-MYC (Valsesia-Wittmann et al., 2004). Au cours de ma thèse, j’ai pu mettre en évidence que les gènes TWIST1 et TWIST2 étaient régulés positivement ou négativement de façon dose dépendante par les oncoprotéines Myc. De façon intéressante, le maintien de l’expression de TWIST1 est dépendant de l’expression des protéines Myc. Ces résultats suggèrent que la dérégulation et l’amplification des oncoprotéines Myc dans les neuroblastomes N-MYC Amplifiés pourraient permettre l’induction sélective et le maintien de l’expression de l’oncogène TWIST, agissant comme facteur de survie. / The N-MYC gene is amplified in 20-25 % of human neuroblastoma, and this amplification is associated with poor clinical outcome. We previously reported aconstant deregulation of TWIST1 in synergy with N-MYC in aggressive stage IVneuroblastoma harboring N-MYC amplification (Valsesia-Wittmann et al., 2004). We demonstrated here that specifically in neuroblastoma cells, TWIST1 and TWIST2 are negatively or positively regulated depending on Myc oncoproteins dosage, thus being a putative Myc transcriptional target. We confirmed by EMSA that Myc proteins could bind TWIST1 promoter. We further highlighted TWIST1 maintenance of expression strictly Myc dependant. Therefore, we propose that deregulation and amplification of Myc oncoproteins in aggressive neuroblastoma tumors induce selective expression and maintenance of TWIST1 oncogene, responsible forapoptosis resistance

Les neuroblastomes, même de haut risque répondent bien à la chimiothérapie initiale mais deviendront fréquemment résistants au traitement. Les inhibiteurs de topoisomérase I représentent un outil thérapeutique important dans la prise en charge des neuroblastomes réfractaires. Pour étudier la résistance aux inhibiteurs de topoisomérase I acquise dans un contexte thérapeutique, un modèle murin de neuroblastome résistant au CPT-11 a été développé. La chimiorésistance est connue comme un phénomène multifacoriel. Nous avons donc utilisé plusieurs approches pour mieux caractériser les mécanismes à l'origine de la résistance dans notre modèle. Une approche génomique a permis d'identifier la dérégulation de la voie de signalisation formée du récepteur ALK et de deux ligands PTN et MDK. Alors que ALK est décrit comme gène majeur de prédisposition au neuroblastome, principalement par le biais de mutations activatrices, nous avons démontré que l'activation du récepteur survenait par des mécanismes alternatifs aux mutations dans une large majorité de cas et participerait à l'initiation de la maladie. En revanche, nous n'avons pas pu prouver l'implication de ce récepteur dans la progression de la maladie ou dans sa réponse au traitement. Il semble que la régulation de ALK soit complexe et le rôle exact de ce récepteur dans la progression du neuroblastome reste à établir. En revanche, nous avons démontré l'importance du ligand MDK dans la régulation de l'expression et de l'activation de ALK ainsi que dans le contrôle de la survie des cellules neuroblastiques. Inhiber cette cytokine représente une stratégie thérapeutique intéressante, complémentaire des thérapies anti-ALK, actuellement en développement clinique dans le neuroblastome. D’autre part, la caractérisation phénotypique du modèle a permis de mettre en évidence une signalisation altérée des dommages à l'ADN associée à une instabilité génétique accrue dans les tumeurs résistantes. Celles-ci présentent également une modification de progression dans le cycle cellulaire et une proportion plus importante de cellules quiescentes. Au final, ce travail a permis d'identifier différents mécanismes de résistance qui représentent des marqueurs de réponse au traitement et des cibles thérapeutiques intéressantes dans le neuroblastome. / Neuroblastoma, including high-risk cases, show a good initial response to chemotherapy but will frequently become resistant to treatment. Topoisomerase I inhibitors represent an important therapeutic option for refractory neuroblastoma. To study the reisitance to topoisomerase I inhibitors acquired in a therapeutic setting, we developed in vivo a resistant model to irinotecan (CPT-11). Chemoresistance is known as a multifactorial phenomenon. We have therefore used several approaches to better characterize mechanisms leading to resistance in our model. A genomic approach enabled us to identify the deregulation of a signaling pathway, constituted with a receptor (ALK) and two lignads (PTN and MDK). While ALK is decsribed as a major neuroblastoma predisposition gene, mainly through activating mutations, we demonstrated that the activation of ALK occurs via mechanisms others than mutation in a large majority of cases. Moreover ALK activation is an important event in the initiation of the disease. However, we couldn’t prouve the implication of the receptor in the progression of the disease or in its response to treatment. It seems that the regulation of ALK is complex and its precise role in the progression of neuroblastoma remains to be precisely defined. Nevertheless, we have demonstrated the importance of MDK, one of ALK ligands in the regulation of the expression and activation of ALK as well as in the control of the neuroblastoma cells survival. The inhibition of the cytokine, MDK represents an interesting therapeutic strategy, complementary to anti-ALK therapies, currently in clinical development in neuroblastoma. On another hand, the phenotypic characterization of the model, showed an alteration of the signaling of DNA damage and an increased genomic instability in the resistant tumors. Those tumors also harbor a modification in the cell cycle progression, particularly an increased proportion of quiescent cells. Finally, this work enables us to identify several resistance mechanism that represent markers of response to chemotherapy and relevant therapeutic targets in neuroblastoma.