Circulating levels of miR-122 increase post-mortem, particularly following lethal dosing with pentobarbital sodium: implications for pre-clinical liver injury studies

Abstract

microRNA-122 (miR-122) is increasingly being measured in pre-clinical and clinical settings due to greater sensitivity and hepatic specificity compared to the gold standard liver injury biomarker alanine aminotransferase (ALT). In pre-clinical studies, various culling methods can be employed prior to collection of blood samples, including lethal injection with pentobarbital sodium (Pentoject). However, little is known about whether such an approach could alter the circulating levels of miR-122 and compromise the interpretation of data. We therefore exposed C57BL/6J mice to saline or the model hepatotoxin paracetamol and collected blood samples pre-cull ( tail bleed) and post-cull ( cardiac puncture following exposure to a rising concentration of CO or intraperitoneal injection of Pentoject). Compared to pre-cull levels there was a significant increase in serum miR-122 level in mice culled with CO and, to a much greater extent, in mice culled with Pentoject. As a result, whilst the serum level of miR-122 increased in Pentoject-culled animals exposed to paracetamol, the higher level in saline-treated mice rendered this difference statistically non-significant, in contrast to findings in animals culled with CO. ALT levels were unaffected by sacrifice method. Consistent with the findings, exposure of primary mouse hepatocytes to Pentoject provoked a rapid and concentration-dependent release of miR-122 into the culture media. Thus, for optimal design and interpretation of data from pre-clinical liver injury studies in which miR-122 is to be used as a biomarker, we recommend that blood samples are collected pre-cull whenever possible, and that lethal injection with Pentoject is avoided.

Serum miR‑338‑5p has potential for use as a tumor marker for retinoblastoma

“…With the in-depth study of tumors and associated miRNAs, circulating miRNAs have attracted increasing attention. It has been revealed that miRNA expression can be detected in serum, cerebrospinal fluid and a number of other bodily fluids and may derive from the active release of apoptotic, necrotic or live tumor cells, although the precise origin of circulating miRNAs has not yet been universally identified (11–13). The presence of circulating miRNAs within bodily fluids alongside proteins and other particles makes them resistant to degradation via ribonucleases (13).…”