Immunostaing of p53 associated with absence of mutations in TP53 gene in dogs with lymphoma/Imunorreatividade da p53 associada a ausencia de mutacoes no gene TP53 em linfomas caninos

TP53 mutations are usually involved in cancer, but sequencing and immunohistochemistry results are often controversial. Thus, the aim of this study was to associate TP53 sequence with p53 immunostaining in dogs with lymphoma. Tumor samples were collected from 12 dogs with lymphoma and were included in this study. Histopathological diagnosis was performed according to Kiel classification. Immunohistochemistry was performed to identify immunophenotype as well as p53 expression. Polyclonal antibody anti-p53 (CM1) was used at a 1:500 dilution. The region that encompasses exons 4-9 was amplified by f PCR reactions and sequencing was then performed. Nevertheless, gene mutations were not observed in any sequence. In conclusion, immunoreactivity of p53 by means of immunohistochemistry should not be indicator of presence of mutations in the core domain of TP53 gene. Key words: dog, imunohistochemistry, lymphosarcoma, p53, sequencing. Sabendo-se da influencia das mutacoes no gene TP53 no desenvolvimento das neoplasias e da discrepancia entre os resultados obtidos pelas tecnicas de sequenciamento e imunoistoquimica, esta pesquisa teve como objetivo relacionar a sequencia do TP53 com a imunorreatividade da p53. Foram obtidas amostras de linfoma de 12 caes. O diagnostico histopatologico foi determinado pela classificacao de Kiel. O imunofenotipo e a imunomarcacao da p53 foram determinados por imunoistoquimica. Para reacao com a p53, utilizou-se anticorpo policlonal anti-p53 (CM1) na diluicao de 1:500. A regiao do gene TP53 compreendida entre os exons quatro e nove foi amplificada por PCR e submetida ao sequenciamento. Apesar dos resultados obtidos pela imunoistoquimica, nenhuma mutacao foi encontrada nas sequencias analisadas. Concluise que a imunorreatividade da p53 pela imunoistoquimica nao pode ser atribuida a presenca de mutacoes no dominio central do gene TP53. Palavras-chave: cao, imunoistoquimica, linfossarcoma, p53, sequenciamento.