Cardiotoxicity is one of the major safety concerns in drug development. Therefore, detecting and monitoring cardiotoxicity throughout preclinical and clinical studies is important for pharmaceutical companies. The present study was conducted in order to explore a plasma miRNA biomarker for cardiotoxicity in rats. As organ specificity is an important factor for a biomarker, we analyzed the miRNA microarray dataset in 55 organs/tissues in normal male rats. Based on this analysis, 5 miRNAs consisting of miR-208 (heart-specific), miR-1, miR-133a, miR-133b (heart and skeletal muscle-specific) and miR-206 (skeletal muscle-specific) were selected. Next, we evaluated the usefulness of those 5 miRNAs as circulating biomarkers in rats administered with single-dose isoproterenol or doxorubicin. Plasma miR-208 was consistently increased through 24 h after dosing in rats administered with isoproterenol, whereas plasma concentrations of cardiac troponin (cTn) showed transient elevation. In contrast, the plasma levels of miR-1, miR-133a, miR-133a and miR-206 were elevated after treatment with doxorubicin, probably as a result of skeletal muscle toxicity. Additionally, the plasma miR-208 level was elevated even after repeat-dose administration (once daily for 7 days) of isoproterenol under which the pathological condition proceeded to the sub-chronic phase such as fibrosis. Thus, our data suggest that miR-208 is a promising plasma biomarker for cardiotoxicity in rats. Monitoring of plasma miR-208 levels in rats may lead to more accurate evaluation of cardiotoxicity in preclinical studies.
MicroRNAs (miRNAs) are small (~22 nucleotide) noncoding RNAs that play pivotal roles in regulation of gene expression. The value of miRNAs as circulating biomarkers is now broadly recognized; such tissue-specific biomarkers can be used to monitor tissue injury and several pathophysiological conditions in organs. In addition, miRNA profiles of normal organs and tissues are important for obtaining a better understanding of the source of modulated miRNAs in blood and how those modulations reflect various physiological and toxicological conditions. This work was aimed at creating an miRNA atlas in rats, as part of a collaborative effort with the Toxicogenomics Informatics Project in Japan (TGP2). We analyzed genome-wide miRNA profiles of 55 different organs and tissues obtained from normal male rats using miRNA arrays. The work presented herein represents a comprehensive dataset derived from normal samples profiled in a single study. Here we present the whole dataset with miRNA profiles of multiple organs, as well as precise information on experimental procedures and organ-specific miRNAs identified in this dataset.
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