ASSOCIATION BETWEEN LINE-1 HYPOMETHYLATION IN CANINE MAMMARY TUMOR TISSUES: IMPLICATIONS FOR DIAGNOSIS AND RESEARCH

With the increase in dog life expectancy, canine mammary cancer has become the most critical and frequent neoplasm in dogs. As in humans, this type of cancer has spontaneous development and is influenced by several risk factors, such as age and hormonal exposure in addition to genetic and epigenetic factors. Thus, knowing that epigenetic patterns influence a variety of biological mechanisms, such development cancer, this study aimed to correlate the methylation pattern of LINE-1 elements in healthy and neoplastic canine mammary tissue, as well as in isolated cell lines of carcinoma canine with tumoral aggressiveness degree. To this end, a retrospective study was conducted in which genomic DNA was extracted from histological sections of biopsies and cell lines using the phenol/chloroform method. To determine the percentages, the genomic DNA was pretreated with methylation-sensitive endonucleases and then amplified by qPCR with primers specific for the L1td1 gene. The results revealed that both the tumor cell lines and the canine adenoma and inflammatory carcinoma samples are hypomethylated relative to normal tissue. However, it was not possible to confirm the relationship between the percentage of LINE-1 hypomethylation and tumor aggressiveness in canine breast cancer. Therefore, the combined analysis of our results allows us to conclude that the methylation pattern of LINE-1 elements can be used as a molecular biomarker to differentiate normal canine mammary tissue from neoplastic canine mammary tissue. However, to confirm whether there is a relationship between the degree of methylation of LINE-1 elements and tumor staging, further studies with canine samples are needed.