Indiana University-Purdue University Indianapolis (IUPUI)

Orientadores: Edgard Graner, Dirce Maria Carraro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-09T00:12:11Z (GMT). No. of bitstreams: 1 Silva_SabrinaDanielada_D.pdf: 3843644 bytes, checksum: 5f28aadd1eaaa2a9069f84e9bccd7d5f (MD5) Previous issue date: 2007 / Resumo: O sistema ubiquitina (Ub)-proteassomo degrada proteínas intracelulares marcadas com etiquetas de Ub, controlando a disponibilidade destas para a célula. Graner et al. (2004) clonaram recentemente USP2a, uma enzima desubiquitinante que interage com ácido graxo sintase (FAS), provocando sua estabilização e protegendo-a da degradação proteassômica, o que aumenta a meia vida desta enzima metabólica. FAS é a principal enzima envolvida na síntese endógena de ácidos graxos saturados de cadeia longa. Nos tecidos normais a síntese é mínima, pois a maior parte dos ácidos graxos utilizados pelas células é proveniente da dieta. Vários trabalhos recentes têm demonstrado que a expressão de FAS está elevada em diversas neoplasias malignas humanas e, em alguns tumores, sua alta expressão foi associada com pior prognóstico. Há poucos estudos sobre a expressão de FAS em carcinomas espinocelulares (CEC) bucais e todos sugerem a sua participação nas etapas iniciais de transformação maligna. Foi demonstrado que FAS é essencial para a proliferação de linhagens celulares de CECs bucais, tumores estes que expressam maior quantidade desta enzima que o epitélio normal adjacente. Entretanto, pouco se sabe sobre os mecanismos básicos envolvidos no aumento da expressão de FAS em células malignas e seu controle pós-traducional. Recentemente foi demonstrado que ErbB2, um receptor da família ErbB, é capaz de aumentar a expressão de FAS em uma linhagem celular de mama, a qual se torna sensível ao tratamento com bloqueadores da atividade de FAS, entrando em apoptose. Considerando-se o relevante papel biológico de USP2a de proteger FAS da destruição pelo proteassomo e o fato da superexpressão de ErbB2 estar ligada a FAS, o objetivo deste projeto foi estudar a quantidade de RNAs mensageiros provenientes de amostras microdissecadas a laser e suas proteínas em CECs bucais. Nas amostras avaliadas, ErbB2 exibiu dois padrões bastante distintos de marcação, um localizado na membrana plasmática e o outro intra-citoplasmático. Uma alta porcentagem (97,06%) das células fortemente positivas para FAS foi também intensamente marcada para ErbB2 em membrana plasmática, com correlação positiva estatisticamente significante (p = 0,001) e ambos tiveram associação com o marcador de proliferação celular Ki-67. A positividade para ErbB2 e FAS foi correlacionada com os tumores que apresentaram maior espessura de lesão e comprometimento microscópico dos linfonodos. A intensa expressão de ErbB2 na membrana celular ocorreu em áreas de maior diferenciação celular, enquanto que áreas menos diferenciadas e com maior pleomorfismo celular, a expressão citoplasmática de ErbB2 foi mais evidente. As análises realizadas, por meio de qRT-PCR indicaram que os transcritos USP2a, FAS e ErbB2 estão diferencialmente expressos entre as amostras tumorais de CEC bucal quando comparado ao tecido pareado morfologicamente normal das margens adjacentes e ambos estão estatisticamente correlacionadas entre si. Estes resultados mostram que a maioria dos CECs bucais analisados expressa concomitantemente FAS e ErbB2, sugerindo a participação desta última molécula na regulação da expressão gênica de FAS, a qual pode ter um papel biológico na patogênese destas lesões. Além do mais, as proteínas analisadas mostraram ser marcadores moleculares para o prognóstico nestas lesões / Abstract: The ubiquitin (Ub)-proteasome pathway controls cellular protein turnover by degrading targeted intracellular proteins tagged with Ub. Graner et al. (2004) demonstrated that the deubiquitinating enzyme USP2a stabilizes and rescues fatty acid synthase (FAS) from proteassomal degradation. FAS plays a central role in de novo lipogenesis and is down-regulated in most of the tissues, because cells preferentially use circulating dietary fatty acids for the synthesis of new structural lipids. On the other hand, it has been demonstrated that FAS is highly expressed in several human cancers and in some of them its expression is correlated with poor outcome. Few studies describe FAS expression in oral squamous cell carcinoma (SCC), however, all of them suggest that the it is increased at the early stages of malignant transformation. It has been shown that FAS is over-expressed in human oral SCC cell lines and plays an essential role in their proliferation. However, the basic mechanism underlying the control of FAS expression in malignant cells is not known at the moment. It was recently demonstrated that the overexpression of the transmembrane tyrosine kinase receptor ErbB2 is able to increase the expression of FAS in a breast epithelial cell line, which in turn becomes susceptible to apoptosis by FAS inhibition. Considering that USP2a prevents the destruction of FAS through deubiquitination and that ErbB2 overexpression is associated with FAS production, the purpose of the present study was to investigate their mRNA levels by real time PCR in SCC samples and morphologically normal tissue after laser capture microdissection. We also evaluated ErbB2 and FAS protein levels by immunohistochemistry. Two distinct patterns of ErbB2 positivity were identified, a sharply demarcated membrane staining, found in the adjacent normal epithelium and well differentiated areas of the tumors, and a cytoplasmic reaction observed mainly in undifferentiated cells. Most of the lesions (97.06%) that showed a high expression of FAS were also positive for ErbB2 at the cell membrane (p=0.001) and both had correlated with the proliferation marker Ki-67. The immunolabeling for ErbB2 at the cell membrane was also stronger in histologically well differentiated lesions while cytoplasmic positivity was found in undifferentiated tumors. FAS and ErbB2 positivity were associated with microscopic characteristics as thickness and lymphatic embolization of the lesion. Our study also showed a strong positive correlation between ErbB2, FAS and USP2a mRNA expression in the SCC samples compared with normal morphologically tissue of the same source. Taken together, the results presented here show that FAS and ErbB2 are co-expressed in oral SCC and suggest that ErbB2 is able to regulate FAS production in these tumors. Moreover, our data point out that these proteins are significantly associated with a poor prognosis / Doutorado / Patologia / Doutor em Estomatopatologia

Uncertainties still exist about the safety of cell phone use and the level of cell phone-driven radiation. The purpose of the current inquiry was to determine the long-term health impacts of cell phone-driven radiation via the use of cell phones. In this cross-sectional study, which was based on socio-ecological theory, secondary data from the 2012 National Health Interview Survey were analyzed to assess the difference in the prevalence of thyroid cancer, mouth/tongue/lip cancer, and heart disease between exposed and non-exposed/less exposed cell phone-driven radiation groups in the United States. Logistic regression was used to address three research questions. Findings initially showed that cell phone use was associated with cancer outcome. However, there was no statistically significant relationship between individuals who were heavy users or sometimes users of cell phones and thyroid or mouth/tongue/lip cancer when compared to individuals who rarely or do not use cell phones. There was a relationship between heavy/sometimes users and heart disease when compared to individuals who rarely/do not use cell phones. Yet, when all the confounders/covariates were included in the model, there was no statistically significant difference between the groups compared. For assessment of thyroid cancer cases among individuals who received 'all/almost all calls' via the cell phones and those who received calls 'sometimes' on cell phones, age and sex were added in the model. Based on the study findings, policy-makers could further explore the implementation of comprehensive regulatory measures to address cell phone safety.