Análise da expressão e do padrão de metilação dos genes p15INK4B E p16INK4A e seus reguladores BMI-1, MYC E TBX2 em tumores mamários caninos.

Abstract

Câncer is a complex disease resulting from the accumulation of genetic and epigenetic changes in control and in the activity of several genes, especially those involved in the differentiation and growth processes leading to abnormal cell proliferation. This disease among pets, especially dogs, has been growing over the years. The most common câncer in female dogs is the breast, accounting for 50% of ali cancers that affect these animais. Among the commonly altered genes, are regulators of the cell cycle. Several families of genes undergo change, among them the CKI family, which includes pl5INK4b and pl6INK4a. It is known that the expression of these two genes is negatively regulated by protein products of genes BMI-1, MYC and TXB2, and these changes may lead then to câncer. Thus, the aim of our study was to evaluate the pattern of methylation and expression of above five genes in canine mammary tumors in dogs from the Belém, Pará. Eighty-five samples of tumor tissue and non-neoplastic, from 40 animais were collected at the Veterinary Hospital of the Universidade Federal Rural da Amazônia. For the methylation pattern analysis, after DNA extraction, samples were converted by action of sodium bisulfite and subjected to sequence PCR Bissulfite technique for the detection of methylated possible areas. For the analysis of RNA expression, conversion to cDNA was taken and subsequent quantification of the transcripts using quantitative PCR. The emission of fluorescence was captured with the help of the ABI PRISM 7500 Sequence Detection System. BMI-1, MYC and pl6INK4a showed no change in methylation pattern or the expression. TXB2 showed a slight decrease in expression data, while pl5INK4b showed an increase, however, in both cases, these changes were not statistically significant correlations with clinicopathological data analyzed. Thus, genes MYC, BMI-1 and pl6INK4a do not seem to be essential for triggering breast câncer in canines, suggesting that pl5INK4b and TXB2 may be regulated by other genetic and epigenetic mechanisms, requiring further study for confirmation.