Evaluation of fecal microRNA stability in healthy cats

BACKGROUND: Gastrointestinal (GI) cancer accounts for 14% of feline malignancies. There is a great need for reliable noninvasive diagnostic biomarkers to reach a timely diagnosis and initiate treatment. Fecal microRNAs (miRNAs) could be such a biomarker and have shown great potential in colorectal screening in people but have yet to be investigated in cats. OBJECTIVES: We aimed to evaluate the presence and stability of feline fecal miRNA under different storage conditions (room temperature [RT], 4, and −20°C) and to evaluate the expression levels of specific fecal miRNAs collected on three separate days (days 1, 4, and 7) in healthy cats. METHODS: Healthy cats were prospectively recruited. Fecal samples were collected, aliquoted, and stored for 24 hours at RT and then transferred to −20°C, stored for 24 hours at 4°C and then transferred to −20°C, or were immediately placed at −20°C on day 1 or at −20°C on days 4 and 7 postcollection. Expression of 22 miRNAs was investigated using quantitative real‐time PCR. RESULTS: Ten miRNA assays worked well, and one, let‐7b, was used for normalization. No differences in miRNA expression were seen between the three storage temperatures for the nine miRNAs investigated. Only miR‐26a showed a significant increase in expression between samples of days 1 and 7. The rest of the miRNAs levels were stable over time. CONCLUSIONS: Fecal miRNA can be isolated from healthy cats. The expression was stable at different temperatures and for most of the miRNAs over time. Prospective studies evaluating fecal miRNA as biomarkers in cats with GI neoplasia are warranted.