miRNA sequencing of rat hearts treated chronically with rofecoxib or its vehicle

We reported previously that chronic treatment with the Cyclooxygenase-2 inhibitor, rofecoxib, increased acute mortality in rats exposed to ischemia/reperfusion injury (I/R). This manifestation of hidden cardiotoxicity was attributed to the proarrhythmic effect of the drug on the ischemic heart. However, rofecoxib also had beneficial effects on ischemic injury, manifesting as decreased infarct size. In the present study, we aimed to identify molecular changes caused by chronic rofecoxib treatment in the heart. Rats were treated with 5.12 mg/kg rofecoxib or its vehicle for four weeks. Messenger RNA (mRNA), microRNA (miRNA) deep sequencing data, and proteomic datasets of left ventricular tissue samples were used for an unbiased differential expression analysis followed by in silico molecular network analysis and experimental target validation. Using mass spectrometry and filtering criteria, 26 proteins were identified that exhibited pronounced changes in protein expression or phosphorylation due to chronic rofecoxib treatment. The transcriptomic analysis showed mild alterations in the heart´s mRNA- and miRNA expression. The posttranscriptional regulation of mRNAs by miRNAs did not result in differential protein expression. This is the first demonstration that chronic rofecoxib treatment affects posttranslational modification and expression of several proteins in the heart. These are potential off-target effects that could account for the hidden cardiotoxic and/or cardioprotective effects of rofecoxib.