Circulating microRNA as biomarkers of canine mammary carcinoma in dogs

Abstract

Background: Differentiating benign from canine malignant mammary tumors requires invasive surgical biopsy. Circulating microRNAs (miRNA) may represent promising minimally invasive cancer biomarkers in people and animals. Objectives: To evaluate the serum mRNA profile between dogs with and without mammary carcinoma, and to determine if any of these markers have prognostic significance. Animals: Ten healthy client-owned female dogs (5 intact, 5 spayed) and 10 dogs with histologically confirmed mammary carcinoma were included; 9 were client-owned, whereas 1 was a research colony dog. Methods: Retrospective study. Serum miRNA was evaluated by RNA deep-sequencing (RNAseq) and digital droplet PCR (dPCR).Expression of candidate biomarkers miR-18a, miR-19b, miR-29b, miR-34c, miR-122, miR-125a, and miR-181a was compared with clinical characteristics, including grade, metastasis, and survival. Results: 452 unique serum miRNAs were detected by RNAseq. Sixty-five individual miRNAs were differentially expressed (>±1.5-fold) and statistically significant between groups. Serum miR-19b (P =.003) and miR-125a (P