MicroRNAs as biomarkers for liver injury: Current knowledge, challenges and future prospects

MicroRNAs (miRNAs) are short regulatory RNAs that are involved in various biological processes that regulate gene expression posttranscriptionally. Changes in miRNA expression can be detected in many physiological and pathological events, such as liver injury. Drug induced liver injury is a life threatening condition that frequently requires organ transplantation. Hepatotoxicity is also one of the major causes of drug failure in clinical trials and of drug withdrawal from the market. The profiling of miRNA expression shows great promise in monitoring liver injury, in the prediction of outcome in patients, and in the identification of liver-reactive compounds in toxicological assessment. Recent studies have demonstrated organ-specificity of some miRNAs (i.e., miR-122), which are released into biological fluids as a result of hepatocyte damage. This attests to the potential of miRNAs as noninvasive biomarkers to detect liver toxicity. This review presents information on miRNA signatures of hepatotoxicity and on the application of promising miRNA biomarkers in preclinical safety assessment. We further discuss the technical challenges associated with these emerging biomarkers for early diagnosis and detection of hepatotoxicity.