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Previous issue date: 2006-02-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Squamous cell carcinoma is the most common malignant neoplasm in the oral cavity, accounting for more than 90% of all malignancies in this location. Cyclooxygenases (COX s) are key enzymes on arachidonic acid metabolism and prostaglandin synthesis, being expressed basically in two forms: the constitutive (COX-1) and the inducible (COX-2). Increased levels on the expression of COX-2 have been implicated in the pathogenesis tumor progression of various forms of human cancer, including oral squamous cell carcinoma, some of what suggesting a possible interaction between COX-2 and the protein expressed by the tumor suppressor gene p53, mutated in more than 50% of all human cancers. The mean of the present research consisted in analyze the correlation between the expression of COX-2 and p53, at the protein level, as well as evaluate the difference on the expression of these two proteins with the histological grading of malignancy. 34 cases of oral squamous cell carcinoma were selected and graded according to the histological grading system proposed by Bryne (1998) and the labeling indexes (LI s) for COX-2 and p53 evaluated using immunohistochemistry method. The results revealed that COX-2 was expressed in increased levels in most of the specimens, although there was no statistic significant correlation between LI s from COX-2 and p53 (p>0.05), and there were no statistical differences on the expression of these proteins between tumors of high and low grade of malignancy (p>0.05). Interestingly, the expression of COX-2 and p53 was detected in fragments of dysplastic oral epithelium adjacent to tumor areas, on basal and suprabasal layers. The absence of statistical correlation between the expression of COX-2 and p53 proteins do not rule ot the existence of a relation between them, were it may reflect the diversity of regulatory pathways between both, different direct and indirect inhibitory effects of COX-2 over p53, as well as the wide range of activation macheenisms for COX-2 and mutational status of the p53 gene Another conclusion point that the increased expression of COX-2 observed in oral squamous cell carcinomas suggest a role for this protein in the processes of pathogenesis and tumoral evolution of this malignant neoplasm / O carcinoma epiderm?ide ? a neoplasia maligna mais comum na cavidade oral, representando mais de 90% das malignidades nesta localiza??o. As cicloxigenases (COX s) s?o enzimas chave no metabolismo do ?cido aracd?nico e s?ntese de prostaglandinas, sendo expressas basicamente sob duas formas: uma constitutiva (COX-1) e uma induzida (COX-2). N?veis elevados na express?o da COX-2 t?m sido implicados na patog?nese e progress?o tumoral em diversos tipos de c?ncer em humanos, incluindo o carcinoma epiderm?ide oral, alguns dos quais sugerindo uma poss?vel intera??o entre a COX-2 e a prote?na expressa pelo gene supressor tumoral p53, mutado em mais de 50% de todos c?nceres humanos. O prop?sito da presente pesquisa consistiu em analisar a correla??o entre a express?o de COX-2 e p53, em n?vel de prote?na, bem como avaliar a diferen?a na express?o destas duas prote?nas em rela??o ao grau histol?gico de malignidade. Para tal, foram selecionados 34 casos de carcinoma epiderm?ide oral, os quais foram classificados de acordo com o sistema de grada??o histol?gica de malignidade proposto por Bryne (1998) e cujos ?ndices de positividade para COX-2 e p53 foram avaliados atrav?s da t?cnica imuno-histoqu?mica. O resultados revelaram que a COX-2 esteve expressa em n?veis elevados na maior parte dos esp?cimes analisados, embora n?o se tenha verificado correla??o estatisticamente significativa entre os IP s da COX-2 e da p53 (p>0,05), tampouco diferen?a estatisticamente significativa entre a express?o destas prote?nas entre tumores de alto e baixo grau de malignidade (p>0,05). Interessantemente, foi detectada a express?o da COX-2 e da p53 em fragmentos de epit?lio oral displ?sico, nas camadas basal e parabasal, adjacentes ao tumor. A aus?ncia de correla??o estat?stica entre a express?o das prote?nas COX-2 e p53 n?o descarta a exist?ncia de uma rela??o entre as mesmas, podendo refletir a diversidade de vias regulat?rias entre ambas, os diferentes efeitos inibit?rios diretos e indiretos da COX-2 sobre a p53, bem como os in?meros mecanismos de ativa??o da COX-2 e o estado mutacional do gene p53. Conclui-se ainda que a elevada express?o da COX-2 observada em carcinomas epiderm?ides orais sugere um papel desta prote?na dentro dos processos de patog?nese e evolu??o tumoral desta neoplasia maligna
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17137 |
| Date | 17 February 2006 |
| Creators | Goulart Filho, Jo?o Augusto Vianna |
| Contributors | CPF:41291824472, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4794937Z9, Bento, Patr?cia Meira, CPF:48698024491, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4776885U7&dataRevisao=null, Freitas, Roseana de Almeida, CPF:28444361453, http://lattes.cnpq.br/9512014003639405, Galv?o, H?bel Cavalcanti |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Patologia Oral, UFRN, BR, Odontologia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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