<i>LINE-1</i> Methylation Status in Canine Splenic Hemangiosarcoma Tissue and Cell-Free DNA

Abstract

Splenic hemangiosarcoma is one of the most common malignant tumors in dogs, and early diagnosis is of great importance for achieving a good prognosis. DNA methylation plays an important role in cancer development. Long interspersed nuclear element 1 (<i>LINE-1</i>) is the most abundant repetitive element in the genome. <i>LINE-1</i> hypomethylation has been shown to be related to carcinogenesis in humans, and it has been used as a novel cancer biomarker. This study aimed to evaluate the methylation status of <i>LINE-1</i> in tumor tissue and circulating cell-free DNA and assess its clinical significance in canine splenic hemangiosarcoma. Genomic DNA was isolated from splenic masses of 13 dogs with hemangiosarcoma, 11 with other malignant tumors, and 15 with benign lesions. <i>LINE-1</i> methylation was quantified using methylation-sensitive and -insensitive restriction enzyme digestion followed by real-time polymerase chain reaction. Additionally, blood samples were collected from eight patients to isolate cell-free DNA to determine <i>LINE-1</i> methylation status changes during the treatment course. <i>LINE-1</i> methylation in tumor samples was significantly lower in patients with hemangiosarcoma than in those with other malignant tumors and benign lesions. Non-significant but similar results were observed for the cell-free DNA samples. Our results demonstrate that <i>LINE-1</i> methylation status is a potential biomarker for splenic hemangiosarcoma.