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Master's Dissertation
DOI
10.11606/D.23.2006.tde-22052006-114723
Document
Author
Full name
Michelly Marin Peruzetto
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2006
Supervisor
Committee
Martins, Marília Trierveiler (President)
Neves, Adriana da Costa
Sousa, Suzana Cantanhede Orsini Machado de
Title in Portuguese
"A presença das proteínas hMLH1 e hMSH6 do sistema de reparo do mau pareamento do DNA em queilites actínicas e carcinomas epidermóides de lábio"
Keywords in Portuguese
Imunoistoquímica
Carcinoma epidermóide de lábio
Fotocarcinogênese
hMLH1
hMSH6
Queilite actínica
Sistema de reparo de mau pareamento do DNA
Abstract in Portuguese
A queilite actínica (QA) é o resultado da exposição crônica dos lábios à radiação ultravioleta do sol. É considerada uma lesão cancerizável e calcula -se que cerca de 10% a 20% evoluirão para carcinoma epidermóide. Já foi sugerido que virtualmente todos os carcinomas epidermóides de lábio (CEL) iniciem como QA. Sabe-se que as radiações solares têm a capacidade de alterar o DNA e que, nesse contexto, os genes de reparo de DNA têm papel fundamental em reparar essas alterações e limitar os danos causados. Porém, estes genes também podem ser vítimas das radiações ultravioletas do sol. O objetivo deste trabalho foi estudar a participação dos genes de reparo de mau pareamento (RMP) do DNA em QA de diferentes graus de atipia e comparar os achados ao carcinoma de lábio relacionado à QA. Para tanto, foram analisadas nestas lesões a expressão e distribuição das proteínas codificadas por dois destes genes, hMLH1 e hMSH6, através da imunoistoquímica. Foi observado que a expressão das duas proteínas diminuía de acordo com o agravamento da indiferenciação celular das lesões. A partir disto, pode-se concluir que a diminuição na expressão de hMLH1 e hMSH6 parece estar relacionada com a progressão do grau de atipia nas QA, e, conseqüentemente, com a tumorigênese do CEL. Além disso, a proteína hMSH6 não pareceu ter um papel importante no reparo do DNA do epitélio labial normal.
Title in English
The presence of proteins hMLH1 and hMSH6 of DNA mismatch repair system in actinic cheilitis and squamous cell carcinoma of the lip
Keywords in English
Photocarcinogenesis
Actinic cheilitis
DNA mismatch repair system
hMLH1
hMSH6
Immunohistochemistry
Lip squamous cell carcinoma
Abstract in English
Actinic cheilitis (AC) results from chronic and excessive exposure of the lips to the ultraviolet radiation in sunlight. AC is recognized as a potentially malignant condition and it is estimated that 10% to 20% will become lip squamous cell carcinoma (LSCC). It has been suggested that virtually every LSCC was initially AC. It is well known that solar radiation causes DNA damage and, in this context, the DNA repair systems play an extremely important role in restoring the injuries. The purpose of this study was to evaluate the participation of the mismatch repair (MMR) system in AC with all grades of dysplasia, as well as, LSCC related to AC. The protein expression and distribution of two of these genes, hMLH1 and hMSH6 were analyzed by means of immunohistochemistry. The results have shown an association between decreased expression of hMLH1 and hMSH6 proteins and the progression of the dysplasia in AC and, therefore, LSCC carcinogenesis. In addition, the hMSH6 protein does not seem to have a primary role in DNA repair of the normal lip epithelium.
 
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MichellyMPeruzetto.pdf (838.71 Kbytes)
Publishing Date
2006-06-20
 
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