Expression profile of circulating serum microRNAs in dogs with lymphoma

- Micro RNAs (miRNAs) are small single strand non-coding RNAs.
- Circulating serum miRNAs have been detected in body fluids.
- Of the 277 miRNA genes, 85 were detected in canine serum.
- MiR-25 was differentially expressed in serum in the lymphoma and control groups.
- Serum miRNAs show promise as non-invasive biomarkers for veterinary diseases.

Serum microRNAs (miRNAs) are mediators of cell-to-cell communication and alter the cellular microenvironment; they are stable for hours under certain conditions in body fluids despite the presence of RNases. Certain miRNAs have been found to be altered in the serum or plasma of humans with various cancers and may represent promising, non-invasive biomarkers for various diseases in humans and animals. The objective of this study was to determine the expression profile of circulating miRNAs in the serum of dogs with lymphoma. Serum samples were obtained from 61 dogs with lymphoma and 40 control dogs, and real-time reverse transcription-polymerase chain reaction was used for miRNA measurement. In order to select candidate genes, a comprehensive expression analysis was undertaken prior to validation of several candidate miRNAs.Of 277 miRNAs, five (let-7b, miR-223, miR-25, miR-92a, and miR-423a) were selected as candidates. The expression levels of four miRNAs (let-7b, miR-223, miR-25, miR-92a) were significantly reduced in the lymphoma group, whereas miR-423a levels were significantly increased compared to the controls. When the lymphoma cases were categorized into high- or low-grade as well as into their anatomic form, miR-25 levels were lower in the serum samples from the lymphoma group compared to those from the control group. Although the biological function of serum miRNAs still remains unclear, determining their functional roles in serum and tissues will contribute not only to the identification of potential biomarkers but also to the elucidation of the pathogenesis of canine lymphoma.