Deletion on the short arm of chromosome 3 is one of the most important genetic abnormalities in the tumorigenesis of nasopharyngeal carcinoma (NPC). Both physical mapping and functional studies have targeted an NPC-related tumor suppressor gene(s) to chromosome 3p21.3. Our group has previously reported that the Ras Association Domain Family 1A (RASSF1A) gene, located within a 120-kb minimal deleted region on 3p21.3, was frequently inactivated by promoter hypermethylation in NPC. These findings suggest that RASSF1A may be a critical tumor suppressor gene in NPC. In this study, the functions of RASSF1A in NPC was characterized with the following specific aims: (1) the role of RASSF1A as a tumor suppressor in NPC cells; (2) the identification of novel RASSF1A-modulated genes and pathways in NPC; (3) the effect of RASSF1A knockdown in immortalized nasopharyngeal epithelial cells; (4) the aberrant transcription and epigenetic changes of other RASSF family of genes ( RASSFS/NORE1 and RASSF4/AD037) in NPC. / In summary, RASSF1A is a major tumor suppressor gene from 3p21.3 in NPC. RASSF1A may exert its tumor suppressor function through various biochemical pathways. The novel findings from this study revealed the role of RASSF1A in the tumorigenesis of NPC. It also led to the better understanding of the molecular pathogenesis of this endemic cancer. (Abstract shortened by UMI.) / RASSF1A is a member of the RASSF family of proteins characterized by a consensus Ras-association domain at the C-terminus. The expression and methylation status of two other members of RASSF gene family, RASSF4/AD037 and RASSF5/NORE1, were investigated in NPC. The study showed that RASSF1A, but not other members of the RASSF family, is the target tumor suppressor in this particular cancer type. / Restoration of wild-type RASSF1A, by means of transfection, in a RASSF1A-deficient NPC cell line (C666-1) led to marked growth inhibition in the NPC cells. Isolated stable clones expressing RASSF1A demonstrated retarded cell proliferation in vitro . Soft-agar assay showed decreased number and sizes of colonies formed by these clones. The expression of RASSF1A in NPC cells also led to a dramatic reduction in tumorigenic potential in nude mice. The findings provide functional evidence that RASSF1A is a target tumor suppressor gene on 3p21.3 in NPC. / Chow Shuk Nga Lillian. / "May 2005." / Adviser: Kwok Wai Lo. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3588. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 112-124). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

Os tumores odontogênicos compõem um grupo de lesões incomuns, porém interessantes, que se forma a partir dos tecidos que dão origem aos dentes. Esses tumores vêm sendo estudados há décadas por patologistas e cirurgiões que buscam entender seus mecanismos de formação e desenvolvimento, assim como desenvolver técnicas adequadas de tratamento. Inúmeras foram as tentativas realizadas até hoje para classificar esses tumores odontogênicos, sendo a última a nova Classificação de Tumores Odontogênicos da Organização Mundial da Saúde, publicada em 2005. Assim sendo, este trabalho teve por objetivo determinar a prevalência dos tumores odontogênicos diagnosticados nos Serviços de Anatomia Patológica das Faculdades de Odontologia de Bauru (USP) e de Araçatuba (UNESP) no Brasil, e das Faculdades de Odontologia da UNAM, da UAM-X e do Laboratório privado Peribact no México, compará-las e definir um perfil da ocorrência desses tumores nessas instituições e países seguindo essa nova classificação. Todos os casos diagnosticados como tumores e cistos odontogênicos passíveis de reanálise diagnóstica foram selecionados dos arquivos dessas instituições. Os dados demográficos e os aspectos clínicos de cada lesão foram obtidos a partir dos laudos e das fichas de requisição de exame anatomopatológico e as lâminas examinadas por um avaliador. Os resultados demonstraram que a inclusão do queratocisto no grupo de tumores provocou uma alteração significante na prevalência dessas lesões. O tumor odontogênico queratocístico foi a lesão mais prevalente, seguida pelo odontoma, ameloblastoma e mixoma no Brasil e no México. Quanto aos dados demográficos e localização, nossos achados corroboram com aqueles descritos na maior parte dos trabalhos realizados em todo o mundo, com diferenças pontuais em países como a China. Entretanto, a falta de maiores conhecimentos biomoleculares e genéticos dificulta a compreensão dessas diferenças. / Odontogenic tumors constitute a group of uncommon and particularly interesting lesions, arising from the odontogenic tissues. These tumors have been studied for decades by pathologists and surgeons seeking understand the mechanisms of formation and development, and trying to develop appropriate techniques of treatment. Many were the attempts made so far to classify these odontogenic tumors, the most recent being the new classification of odontogenic tumor of the World Health Organization, published in 2005. Therefore, this study aimed to determine the prevalence of odontogenic tumors diagnosed in five centers of diagnostic pathology: Laboratory of Oral Pathology, Faculty of Dentistry of Bauru USP; Laboratory of Oral Pathology, Faculty of Dentistry of Araçatuba UNESP, in Brazil; and Department of Oral Pathology, Faculty of Dentistry UNAM; Laboratory of Oral Pathology, Faculty of Dentistry of UAM-Xochimilco and Peribact Laboratory, a private laboratory of oral pathology, in Mexico; compare them and develop a profile of the occurrence of these tumors in these institutions and countries, following this new classification. All cases diagnosed as odontogenic cysts and tumors were selected for diagnostic review. The demographic and clinical features were obtained from the records when available. The cases were re-evaluated, and the diagnosis in each case was confirmed or modified when necessary. The results showed that the inclusion of keratocyst in the group of tumors caused a significant change in the prevalence of these lesions. The keratocyst odontogenic tumor was the most prevalent lesion, followed by odontoma, ameloblastoma and myxoma in Brazil and Mexico. Our findings corroborate with those reported arround the world, with occasional differences in countries, such as China. However, the lack of molecular and genetic knowledge precludes a better comprehension of these differences.

A podoplanina humana é uma glicoproteína que se expressa em várias células e tecidos normais e neoplásicos, inclusive aqueles de origem odontogênica. O objetivo deste estudo foi identificar a imunolocalização da podoplanina em tumores odontogênicos epiteliais com e sem ectomesênquima incluindo oito ameloblastomas, nove tumores odontogênicos adenomatóides, vinte tumores odontogênicos queratocísticos, cinco cistos odontogênicos ortoqueratinizados, um tumor odontogênico epitelial calcificante, dois fibromas ameloblásticos, quatro fibroodontomas ameloblásticos e cinco tumores odontogênicos císticos calcificantes. Todos os tumores odontogênicos foram submetidos a imuno-histoquímica para o anticorpo anti-podoplanina numa diluição de 1:100 e avaliados, microscopicamente, com base na distribuição tecidual e na intensidade da imunomarcação. Para os tumores odontogênicos queratocísticos e cistos odontogênicos ortoqueratinizados além da podoplanina foi determinado o índice de proliferação celular baseado na positividade nuclear das células do epitélio odontogênico imunomarcadas com o Ki-67 na diluição de 1:200 e comparados estatisticamente pelo coeficiente de correlação de Spearman. Os resultados mostraram uma forte expressão da podoplanina na membrana e no citoplasma do epitélio odontogênico da maioria dos tumores analisados, bem como, em células ectomesênquimais como os odontoblastos e suas extensões dentinárias. A ausência da podoplanina foi identificada nos ameloblastos completamente diferenciados, nas áreas de metaplasia escamosa, nas células fantasmas, nas áreas de calcificação e nos depósitos extracelulares de material eosinofílicos observados nos tumores odontogênicos. No tumor odontogênico queratocístico observou-se uma forte expressão da podoplanina na camada basal e suprabasal do epitélio, enquanto que, nos cistos odontogênicos ortoqueratinizados esta expressão estava ausente ou fracamente distribuída no epitélio. Houve uma correlação estatisticamente significativa (p=0,006) entre a expressão de podoplanina e o índice de proliferação celular dos tumores odontogênicos queratocísticos e cistos odontogênicos ortoqueratinizados. Estes resultados sugerem que a podoplanina participa dos processos de proliferação e diferenciação celular dos epitélios odontogênicos presentes nos tumores odontogênicos benignos dos ossos maxilares. / Human podoplanin is a glycoprotein expressed in various cells and normal and neoplastic tissues, including those of odontogenic origin. The aim of this study was to identify the immunolocalization of podoplanin in epithelial odontogenic tumors with and without ectomesenchyme, including eight ameloblastomas, nine adenomatoid odontogenic tumors, twenty keratocystic odontogenic tumors, five orthokeratinized odontogenic cysts, one calcifying epithelial odontogenic tumor, two ameloblastic fibromas, four ameloblastic fibro-odontomas and five calcifying cystic odontogenic tumors. All odontogenic tumors were submitted to immunohistochemistry using a podoplanin antibody at a dilution of 1:100 and evaluated microscopically, based on the tissue distribution and intensity of immunoreactivity. For keratocystic odontogenic tumors and orthokeratinized odontogenic cysts, in addition to podoplanin, the index of cell proliferation was determined based on the nuclear positivity of odontogenic epithelial cells immunostained with Ki-67 at a dilution of 1:200 and statistically compared by the Spearman correlation coefficient. The results showed strong expression of podoplanin in the membrane and cytoplasm of the odontogenic epithelium of most tumors analyzed, as well as in ectomesenchymal cells as odontoblasts and dentinal projections. Absence of podoplanin was observed in fully differentiated ameloblasts, in areas of squamous metaplasia, in ghost cells, in areas of calcification and extracellular deposits of eosinophilic material observed in odontogenic tumors. The keratocystic odontogenic tumor exhibited strong expression of podoplanin in basal and suprabasal epithelial layers, while in orthokeratinized odontogenic cysts this expression was absent or weakly distributed in the epithelium. There was statistically significant correlation (p=0,006) between the expression of podoplanin and the cellular proliferation index of odontogenic tumors and orthokeratinized odontogenic cysts. These results suggest that podoplanin participates in the processes of cell proliferation and differentiation of odontogenic epithelium present in benign odontogenic tumors of the jaws.

O objetivo do presente trabalho foi investigar as repercussões de uma relação social estável sobre diferentes parâmetros de comportamento, neuroquímica e atividade imune de camundongos dominantes e submissos. Machos adultos (com aproximadamente 90 dias de idade) mantidos em duplas desde o desmame, foram determinados como dominantes ou submissos, após três avaliações consecutivas do comportamento, onde foram observadas a presença ou ausência de ataques ou fugas e posturas de submissão. Em alguns experimentos, grupos de cinco animais mantidos em uma mesma caixa foram utilizados para comparação com resultados obtidos de animais que conviveram em duplas. Foram utilizadas apenas as duplas de camundongos onde a hierarquia social foi claramente observada. Os resultados mostraram que os animais submissos apresentaram em relação aos dominantes: 1) diminuição no tempo gasto na zona central do campo aberto; 2) diminuição no número de entradas nos braços abertos e diminuição no tempo gasto na exploração dos braços abertos do labirinto em cruz elevado; 3) aumento no tempo gasto na exploração dos braços fechados do labirinto em cruz elevado; 4) diminuição no número de entradas e no tempo gasto na exploração do terço final dos braços fechados do labirinto em cruz elevado; 5) aumento na taxa de renovação de dopamina no hipotálamo; 6) diminuição da taxa de renovação de dopamina no corpo estriado; 7) maior número de metástases induzidas pelo melanoma murino experimental B16F10; 8) aumento do percentual de células T CD8+ no timo após 14 dias de inoculação do mesmo melanoma; 9) diminuição no burst oxidativo basal de neutrófilos e monócitos sangüíneos, mas não naquele induzido por bactérias; 10) menor atividade de células NK presentes no baço e no sangue. Em relação aos animais mantidos em número de cinco, os animais submissos apresentaram: menor percentual de células NK no sangue. Já os animais dominantes, apresentaram em relação aos animais mantidos em grupos: 1) aumento da taxa de renovação de noradrenalina no hipotálamo; 2) aumento na taxa de renovação de dopamina no corpo estriado; 3) menor percentual de células NK no sangue. O status social, no entanto, não provocou diferenças: 1) nos níveis absolutos de dopamina, noradrenalina e serotonina; 2); nos metabólitos de serotonina; 3) nos níveis séricos basais de corticosterona; 4) no peso e número de células do baço e timo; 5) no percentual de células T CD4+ e CD8+ no baço e 6) no percentual de linfócitos, neutrófilos e monócitos sangüíneos. Em conjunto, os presentes resultados mostraram que animais dominantes e submissos mantidos por 90 dias em uma hierarquia social estável, apresentaram diferenças comportamentais e neuroquímicas, e responderam de forma diferente a um mesmo estímulo imune, no caso, o desenvolvimento de metástases induzida nos pulmões pela administração do melanoma experimental murino B16F10. Estes resultados sugerem que diferentes mecanismos, que não a ativação do eixo HPA, estejam envolvidos com o aumento de susceptibilidade ao desenvolvimento do tumor observado nos indivíduos submissos / The objective of the present work was to investigate the repercussions of a stable social relationship on different parameters of the behavior, neurochemical and immune activity of dominant and submissives mice. Adult males (with approximately 90 days of age) kept in pairs since wean it, had been determined as dominant or submissives, after three consecutive evaluations of the behavior, where presences or absences of attacks or escapes and positions of submission had been observed. In some experiments, groups of five animals kept in one same box had been used to compare the results gotten between these and the animals coexisting in pairs. The pairs had been used only where the social hierarchy clearly was observed. The results had shown that the submissives animals in relation to the dominant ones had presented: 1) reduction in the time spent in the central zone of the open field; 2) reduction in the number of entrances in the open arms and reduction in the time spent in the exploration of the open arms of the plus maze; 3) increase in the time spent in the exploration of the closed arms of the plus maze; 4) reduction in the number of entrances and time spent in the exploration of the final third of the closed arms of the plus maze; 5) increase in the turnover of dopamine in the hypothalamus; 6) reduction in the turnover of dopamine in the corpus striatum; 7) increased number of metastasis in the lungs induced by murino melanoma experimental B16F10; 8) increase of the percentage of cells T CD8+ in the thymus after 14 days of inoculation of the same melanoma; 9) reduction in the basal oxidative burst of neutrophil and monocytes sanguine, but not in the induced by bacteria; 10) decreased NK cells activity measured in the blood and spleen. In relation to the animals kept in number of five, the submissives animals had presented: 11) reduction in the percentile of NK cells in the blood. While the dominant animals had presented in relation to the animals kept in groups: 1) increase in the turnover of norepinephrine in hypothalamus; 2) increase in the turnover of dopamine in the fluted body; 3) reduction in the percentile of NK cells in the blood. The social status, however, did not provoke differences: 1) in the absolute levels of dopamine, norepinephrine and serotonin; 2) in the metabolites of serotonin; 3) in the serum levels of corticosterone; 4) in the weight and number of cells of the spleen and thymus; 5) in the percentage of cells T CD4+ and CD8+ in the spleen and 6) in the percentage of lymphocytes, neutrophil and monocytes in the blood. Together, the results obtained had shown that dominants and submissives animals kept 90 days living in a stable social hierarchy had presented behavior and neurochemical differences, and had answered of different form to one same immune stimulation, in this case, the induced development of metastasis in the lungs for experimental melanoma murino B16F10, where the submissives had been more susceptible than the dominant ones. This results suggest that other mechanisms, different of HPA activation, may be involved with the decreased resistance of submissive mice to B16F10 tumor dissemination

Receptores para somatostatina são amplamente expressos por vários tumores, especialmente os de origem neuroendócrina. Imagens in vivo destes tumores usando análogos da somatostatina radiomarcados tornaram-se uma ferramenta clínica útil em oncologia. O radiofármaco de uso consagrado para este método diagnóstico é o octreotídeo-[D-Phe1-DTPA-111In]. Entretanto, o uso do índio-111 (111In) sofre limitações devido à produção no ciclotron ser limitada, a meia-vida física longa e alta energia gama, resultando em alta dose de radiação ao paciente e características de imagem subótimas. O tecnécio-99m (99mTc), produzido por um gerador de radioisótopo e viabilidade diária, com meia-vida de seis horas e emissão de raios gama de 140 keV, possui características ideais para procedimentos de imagens em medicina nuclear. O objetivo deste trabalho foi desenvolver um radiofármaco de tecnécio-99m baseado em peptídeo derivado da somatostatina, o octreotídeo, destinado ao diagnóstico de tumores neuroendócrinos em medicina nuclear. A marcação pelo método indireto envolveu a adição de 20 g do peptídeo OCT-HYNIC (octreotídeo-[Tyr3]-HYNIC), 10 mg do coligante EDDA, 20 mg do coligante tricina, aproximadamente 1110 MBq (30 mCi) de pertecnetato de sódio e 15 g do agente redutor SnCl2.2H2O em pH final 6,5, incubando-se em banho de água em ebulição por 10 minutos. O controle de qualidade radioquímico para determinar a pureza radioquímica da marcação foi realizado 30 minutos e 5 horas após marcação pelo método de cromatografia em camada delgada ascendente, utilizando como fases móveis metanol:acetato de amônio (1:1), metiletilcetona e tampão citrato de sódio 0,1 N pH 5,0, e como fases estacionárias as fitas de sílica gel (TLC-SG e ITLC-SG). Esta marcação tida como padrão, resultou numa pureza radioquímica de marcação de 89,91 4,82 % aos 30 minutos e 91,37 6,14 % em 5 horas. Estudando-se os parâmetros de marcação: massa dos coligantes, agente redutor e peptídeo, tempo e temperatura de reação, pH final de marcação e atividade, o melhor resultado obtido foi de 92,14 0,30 % aos 30 minutos e 90,60 0,35 % em 5 horas para uma massa de 80 g de octreotídeo-HYNIC, 10 mg de EDDA, 20 mg de tricina, 150 g de SnCl2.2H2O em pH final de marcação 8,0, numa atividade de até 3700 MBq (100 mCi). Essa formulação seria uma alternativa para a administração de mais de um paciente por marcação a partir da elaboração de um reagente liofilizado. A biodistribuição realizada por método invasivo nos intervalos de 1,5 e 4 horas após administração intravenosa do radiofármaco em camundongos Swiss avaliou a porcentagem da atividade administrada presente no sangue e nos diversos órgãos. Os dados de biodistribuição em camundongos Swiss e Nude com tumor de células AR42J (adenocarcinoma de pâncreas de rato) foram compatíveis com a distribuição do peptídeo marcado: rápido clareamento sangüíneo, alta captação nos rins devido à eliminação do peptídeo pelo trato urinário e alta captação em órgãos com alta densidade de receptores para somatostatina como pulmão, estômago, pâncreas e tumor no caso dos camundongos Nude. A captação do peptídeo radiomarcado na região abdominal não foi significativa, o que representa uma vantagem relativa ao diagnóstico de tumores neuroendócrinos, comuns nesta região. Os resultados de marcação e biodistribuição descritos neste estudo determinaram o potencial do peptídeo marcado com 99mTc para uso em diagnóstico em medicina nuclear. / Somatostatine receptors are widely expressed by several tumors, especially of the neuroendocrine origin. In vivo images of these tumors using radiolabeled somatostatine analogues became a useful clinical tool in oncology. The radiopharmaceutical currently applied is [111In-DTPA-Phe1-D]-octreotide. However, the use of indium-111 (111In) is limited by the production in cyclotron as well as the long physical half-life and high gamma energy, resulting in high dose of radiation to the patient and suboptimal characteristics of image. The technetium-99m (99mTc), produced by a radioisotope generator and daily viability, with half-life of six hours and gamma rays emission of 140 keV, is ideal for imaging procedures in nuclear medicine. The objective of this work was the development of a technetium-99m radiopharmaceutical based on a peptide somatostatine derivatived, the octreotide, to be applied in the diagnosis of neuroendocrine tumors in nuclear medicine. The labeling by indirect method was based in the addition of 20 g of the peptide TOC-HYNIC (octreotide-[Tyr3]-HYNIC), 10 mg of EDDA and 20 mg of tricine coligands, approximately 1110 MBq (30 mCi) of sodium pertecnetate and 15 g of the reducing agent SnCl2.2H2O in final pH 6.5, followed by the incubation for 10 minutes in water boiling bath. The radiochemical purity was determined 30 minutes and 5 hours after labeling by thin layer chromatography, using as mobile phase methanol:ammonium acetate (1:1), methilethilketone and sodium citrate buffer 0.1 N pH 5.0, and as stationary phases the silica gel plates (TLC-SG and ITLC-SG). This labeling referred as standard condition resulted in radiochemical purity of 89.91 4.82 % at 30 minutes and 91.37 6.14 % at 5 hours. Studying the labeling parameters: mass of the coligands, reducing agent and peptide, time and temperature of reaction, pH and activity, the best results obtained were 92.14 0.30 % at 30 minutes and 90.60 0.35 % at 5 hours using 80 g octreotide-HYNIC, 10 mg of EDDA, 20 mg of tricine, 150 g of SnCl2.2H2O in a final pH 8.0, and activity up to 3700 MBq (100 mCi). This formulation can be an alternative for the administration of more than one patient per labeling procedure, using a lyophilized reagent. The biodistribution performed by invasive method in the intervals of 1.5 and 4 hours after intravenous administration of the radiopharmaceutical in Swiss mice determined the percentage of the activity administered in the blood and the various organs. The biodistribution data in Swiss and Nude mice bearing AR42J tumor (rat pancreatic adenocarcinoma) were compatible with the distribution of the labeled peptide: fast blood clearance, high uptake in the kidneys due to the elimination by the urinary tract, and high uptake in organs with high density of somatostatine receptors like lung, stomach, pancreas and tumor in the case of Nude mice. The uptake of the radiolabeled peptide in the abdominal region was not significant and represents an advantage related to the diagnosis of neuroendocrine tumors, frequently found in this region. The labeling and biodistribution results described in this study showed the potential of the 99mTc-labeled peptide to be applied in diagnostic procedures in nuclear medicine.

Receptores para somatostatina são amplamente expressos por vários tumores, especialmente os de origem neuroendócrina. Imagens in vivo destes tumores usando análogos da somatostatina radiomarcados tornaram-se uma ferramenta clínica útil em oncologia. O radiofármaco de uso consagrado para este método diagnóstico é o octreotídeo-[D-Phe1-DTPA-111In]. Entretanto, o uso do índio-111 (111In) sofre limitações devido à produção no ciclotron ser limitada, a meia-vida física longa e alta energia gama, resultando em alta dose de radiação ao paciente e características de imagem subótimas. O tecnécio-99m (99mTc), produzido por um gerador de radioisótopo e viabilidade diária, com meia-vida de seis horas e emissão de raios gama de 140 keV, possui características ideais para procedimentos de imagens em medicina nuclear. O objetivo deste trabalho foi desenvolver um radiofármaco de tecnécio-99m baseado em peptídeo derivado da somatostatina, o octreotídeo, destinado ao diagnóstico de tumores neuroendócrinos em medicina nuclear. A marcação pelo método indireto envolveu a adição de 20 g do peptídeo OCT-HYNIC (octreotídeo-[Tyr3]-HYNIC), 10 mg do coligante EDDA, 20 mg do coligante tricina, aproximadamente 1110 MBq (30 mCi) de pertecnetato de sódio e 15 g do agente redutor SnCl2.2H2O em pH final 6,5, incubando-se em banho de água em ebulição por 10 minutos. O controle de qualidade radioquímico para determinar a pureza radioquímica da marcação foi realizado 30 minutos e 5 horas após marcação pelo método de cromatografia em camada delgada ascendente, utilizando como fases móveis metanol:acetato de amônio (1:1), metiletilcetona e tampão citrato de sódio 0,1 N pH 5,0, e como fases estacionárias as fitas de sílica gel (TLC-SG e ITLC-SG). Esta marcação tida como padrão, resultou numa pureza radioquímica de marcação de 89,91 4,82 % aos 30 minutos e 91,37 6,14 % em 5 horas. Estudando-se os parâmetros de marcação: massa dos coligantes, agente redutor e peptídeo, tempo e temperatura de reação, pH final de marcação e atividade, o melhor resultado obtido foi de 92,14 0,30 % aos 30 minutos e 90,60 0,35 % em 5 horas para uma massa de 80 g de octreotídeo-HYNIC, 10 mg de EDDA, 20 mg de tricina, 150 g de SnCl2.2H2O em pH final de marcação 8,0, numa atividade de até 3700 MBq (100 mCi). Essa formulação seria uma alternativa para a administração de mais de um paciente por marcação a partir da elaboração de um reagente liofilizado. A biodistribuição realizada por método invasivo nos intervalos de 1,5 e 4 horas após administração intravenosa do radiofármaco em camundongos Swiss avaliou a porcentagem da atividade administrada presente no sangue e nos diversos órgãos. Os dados de biodistribuição em camundongos Swiss e Nude com tumor de células AR42J (adenocarcinoma de pâncreas de rato) foram compatíveis com a distribuição do peptídeo marcado: rápido clareamento sangüíneo, alta captação nos rins devido à eliminação do peptídeo pelo trato urinário e alta captação em órgãos com alta densidade de receptores para somatostatina como pulmão, estômago, pâncreas e tumor no caso dos camundongos Nude. A captação do peptídeo radiomarcado na região abdominal não foi significativa, o que representa uma vantagem relativa ao diagnóstico de tumores neuroendócrinos, comuns nesta região. Os resultados de marcação e biodistribuição descritos neste estudo determinaram o potencial do peptídeo marcado com 99mTc para uso em diagnóstico em medicina nuclear. / Somatostatine receptors are widely expressed by several tumors, especially of the neuroendocrine origin. In vivo images of these tumors using radiolabeled somatostatine analogues became a useful clinical tool in oncology. The radiopharmaceutical currently applied is [111In-DTPA-Phe1-D]-octreotide. However, the use of indium-111 (111In) is limited by the production in cyclotron as well as the long physical half-life and high gamma energy, resulting in high dose of radiation to the patient and suboptimal characteristics of image. The technetium-99m (99mTc), produced by a radioisotope generator and daily viability, with half-life of six hours and gamma rays emission of 140 keV, is ideal for imaging procedures in nuclear medicine. The objective of this work was the development of a technetium-99m radiopharmaceutical based on a peptide somatostatine derivatived, the octreotide, to be applied in the diagnosis of neuroendocrine tumors in nuclear medicine. The labeling by indirect method was based in the addition of 20 g of the peptide TOC-HYNIC (octreotide-[Tyr3]-HYNIC), 10 mg of EDDA and 20 mg of tricine coligands, approximately 1110 MBq (30 mCi) of sodium pertecnetate and 15 g of the reducing agent SnCl2.2H2O in final pH 6.5, followed by the incubation for 10 minutes in water boiling bath. The radiochemical purity was determined 30 minutes and 5 hours after labeling by thin layer chromatography, using as mobile phase methanol:ammonium acetate (1:1), methilethilketone and sodium citrate buffer 0.1 N pH 5.0, and as stationary phases the silica gel plates (TLC-SG and ITLC-SG). This labeling referred as standard condition resulted in radiochemical purity of 89.91 4.82 % at 30 minutes and 91.37 6.14 % at 5 hours. Studying the labeling parameters: mass of the coligands, reducing agent and peptide, time and temperature of reaction, pH and activity, the best results obtained were 92.14 0.30 % at 30 minutes and 90.60 0.35 % at 5 hours using 80 g octreotide-HYNIC, 10 mg of EDDA, 20 mg of tricine, 150 g of SnCl2.2H2O in a final pH 8.0, and activity up to 3700 MBq (100 mCi). This formulation can be an alternative for the administration of more than one patient per labeling procedure, using a lyophilized reagent. The biodistribution performed by invasive method in the intervals of 1.5 and 4 hours after intravenous administration of the radiopharmaceutical in Swiss mice determined the percentage of the activity administered in the blood and the various organs. The biodistribution data in Swiss and Nude mice bearing AR42J tumor (rat pancreatic adenocarcinoma) were compatible with the distribution of the labeled peptide: fast blood clearance, high uptake in the kidneys due to the elimination by the urinary tract, and high uptake in organs with high density of somatostatine receptors like lung, stomach, pancreas and tumor in the case of Nude mice. The uptake of the radiolabeled peptide in the abdominal region was not significant and represents an advantage related to the diagnosis of neuroendocrine tumors, frequently found in this region. The labeling and biodistribution results described in this study showed the potential of the 99mTc-labeled peptide to be applied in diagnostic procedures in nuclear medicine.

Tumors need the development of new vessels from the pre-existing vasculature to bring nutrients and oxygen to the whole tumor mass. The tumor vascular network is known to be poorly functional due to architectural and functional abnormalities. The end result is an inadequate and heterogeneous tumor perfusion leading to the development of tumor hypoxia. From a therapeutic perspective, hypoxia is a source of radioresistance and the dysfunctional perfusion hampers drug delivery. Historically, tumor hypoxia refers to chronic hypoxia (or diffusion-limited hypoxia) that results from the increasing distance between O2-consuming cells and blood vessels due to the high metabolic rate of tumor cells. Many studies have demonstrated the impact of chronic hypoxia on the clonal selection of tumor cells resistant to conventional anti-cancer therapies. Growing evidence for the existence of another form of hypoxia caused by heterogeneities in tumor perfusion, namely acute or perfusion-limited hypoxia, plead however for a non-genetic source of phenotype conversion reaching not only tumor cells but also the tumor vasculature and in particular endothelial cells. In the cardiovascular field, the cyclic exposure to different pO2 levels is known to precondition cardiac myocytes to resist more prolonged ischemic insults. We hypothesized that this concept of myocardium preconditionning to promote the resistance vs pro-apoptotic stresses could be translated in tumors. Indeed, intermittent hypoxia in tumors is nothing else than cyclic changes in pO2 and radio- and chemotherapy can be viewed as pro-apoptotic stresses that the tumor can face. In particular, in the case of the tumor vasculature, the resistance could be a capacity to re-initiate angiogenesis after treatment. Radioresistance would be further potentiated since low pO2 is per se associated to reversibility of the damages. Also, since intermittent hypoxia is thought to be due in part to fluctuations in tumor blood flow (TBF), access of chemotherapy to the tumor could also further participate to chemoresistance. To address the above hypotheses, we first aimed to explore the extent and the origin of TBF fluctuations in tumor mouse models and to determine whether therapeutic modulation of such potential TBF heterogeneities could improve the efficacy of chemotherapy. We then more directly examined whether and how intermittent hypoxia could influence endothelial cell survival and modulate resistance to radiotherapy. We also took advantage of this study to dissect the molecular mechanisms driving the phenotype conversion of endothelial cells exposed to intermittent hypoxia. Finally, because VEGF plays a major role in hypoxia-mediated angiogenesis but also regulates major pro-survival pathways in endothelial cells, we evaluated the potential role of caveolin as a new therapeutic target to tackle EC resistance. Caveolin is, indeed, a key structural protein recently documented to interact with many downstream targets of VEGF. 1. To explore the extent and the origin of TBF fluctuations in tumor mouse models and to determine whether therapeutic modulation of such potential TBF heterogeneities could improve chemotherapy. We focused this part of the work on the vascular tone modulator endothelin-1. Indeed, this peptide is over-expressed in many mouse and human tumors where it is documented to act as a mitogenic factor in both para- and autocrine manners. Endothelin-1 is also a potent vasoconstrictor acting through the ETA receptors located on VSMCs. In our lab, we previously showed that over-expression of endothelin-1 in tumors accounted for the development of a myogenic tone within the tumor vasculature. We have now documented that an ETA receptor antagonist induces the relaxation of microdissected tumor arterioles and selectively and quantitatively increases tumor blood flow in experimental tumor models. We also combined dye staining of functional vessels, fluorescent microsphere-based mapping, and magnetic resonance imaging to identify heterogeneities in tumor blood flow and to examine the reversibility of such phenomena. We showed that administration of an ETA receptor antagonist reduces the extent of underperfused tumor areas, proving the key role of vessel tone variations in tumor blood flow heterogeneity. We also provided evidence that ETA antagonist could improve the access of cyclophosphamide to the tumor compartment and thereby induces a significant tumor growth delay. 2. To examine whether and how intermittent hypoxia could influence endothelial cell survival and modulate resistance to radiotherapy. To dissect the mechanisms driving the phenotype conversion of endothelial cells exposed to intermittent hypoxia. This second part of our work, is a comprehensive investigation of the consequences of intermittent hypoxia, as caused by TBF heterogeneities, on the endothelial cell phenotype. First, we postulated that intermittent hypoxia (IH) favors endothelial cell (EC) survival, thereby extending the concept of hypoxia-driven resistance to the tumor vasculature. We showed that exposing EC to cycles of hypoxia/re-oxygenation reduces radiation-induced cell death and promotes angiogenesis. In contrast, prolonged hypoxia failed to achieve such protection and even appeared deleterious. We also observed that although HIF-1£ is completely degraded during each re-oxygenation, its abundance is paradoxically found higher at each new hypoxic challenge. Moreover, the use of siRNA targeting HIF-1£ pointed out that HIF-1ƓÑ accumulation account for the increased resistance of EC to radiotherapy. Finally, we extended this concept in vivo by forcing IH in tumor-bearing mice and found that it is associated with less radiation-induced apoptosis within both the vascular and the tumor cell compartments (vs normoxia or prolonged hypoxia). Next, we focused our work on the underlying mechanisms of EC phenotype conversion exposed to IH and particularly on potential actors that may favor HIF-1£ accumulation during IH. Prolylhydroxylases (PHD), MAPK and PI3K/Akt pathways as well as eNOS are known to regulate HIF-1£ abundance and transcriptional activity. We documented that PHD2 and PHD3 abundance are slightly decreased during IH, whereas prolonged hypoxia increases PHD3 expression in EC. We then showed that, ERK, Akt as well as eNOS were phosphorylated during reoxygenation periods of the IH protocol. We also used specific inhibitors of these cascades (i.e. PD98059, LY294002 and L-NAME, respectively), to evaluate their specific impact on HIF-1£ abundance and performed clonogenic assays to evaluate their consequences on EC survival. We showed that although, PD98059 and LY294002 sensitizes EC to pro-apoptotic stresses, only the PI3K/Akt inhibitor abrogates the HIF-1£ signal during IH. Conversely, L-NAME, a non-specific NOS-inhibitor, appears to potentiate the expression of HIF-1£ and to favor the EC survival. 3. To identify new therapeutic targets to prevent endothelial cell resistance by studying VEGF signaling, the major pro-survival and pro-angiogenic growth factor in endothelial cells. Because VEGF plays a central role in hypoxia-mediated angiogenesis and cell survival, the VEGF signaling cascade is a an obvious therapeutic target. To more specifically identify the pathways leading to cell survival and the resistance phenomena that we observed in response to intermittent hypoxia, a careful dissection of the downstream VEGF signaling cascades was performed. In this part of the work, we focused our attention on caveolin since it modulates the activity of eNOS, ERK and Akt that are major effectors acting downstream VEGF stimulation. We demonstrated the paradoxical role of caveolin-1 preventing signaling in basal conditions and ensuring the coupling between VEGFR2 and the downstream cascades upon VEGF stimulation. We used mice deficient for the caveolin-1 gene (Cav-/-) to examine the impact of caveolae suppression in a model of adaptive angiogenesis obtained after femoral artery resection. Evaluation of the ischemic tissue perfusion and histochemical analyses revealed that contrary to Cav+/+ mice, Cav-/- mice fails to recover a functional vasculature and actually loose part of the ligated limbs. We also isolated endothelial cells (ECs) from Cav-/- aorta and showed that on VEGF stimulation, endothelial tube formation is dramatically abrogated when compared with Cav +/+ ECs. The Ser1177 eNOS phosphorylation and Thr495 dephosphorylation but also the ERK phosphorylation were similarly altered in VEGF-treated Cav-/- ECs. Interestingly, caveolin transfection in Cav-/- ECs redirected the VEGFR-2 in caveolar membranes and restored the VEGF-induced ERK and eNOS activation. However, when high levels of recombinant caveolin are reached, VEGF exposure fails to activate ERK and eNOS. Altogether, these data identify caveolin as a new therapeutic target to alter VEGF signaling, in particular the cascades leading to angiogenesis and resistance to stresses.

Thesis (Ph. D.)--University of Chicago, Dept. of Pathology, December 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--Flinders University, School of Medicine, Dept. of Medicine. / Typescript bound. Includes bibliographical references (leaves 308-361). Also available electronically via the World Wide Web.

Thesis (Ph. D.)--East Tennessee State University, 2002. / Includes bibliographical references. Also available via Internet at the UMI web site.