Transcriptional analysis of doxorubicin-induced cardiotoxicity . Mus musculus

Doxorubicin (Dox) is an effective chemotherapeutic agent against a broad range of tumors. However, a threshold dose of doxorubicin causes an unacceptably high incidence of heart failure and limits its clinical utility. We have established two models of doxorubicin cardiotoxicity in mice: 1) in an acute model, mice are treated with 15mg/kg of doxorubicin once; 2) in a chronic model, they receive 3mg/kg weekly for the first 12 of a total of 18 weeks. Using echocardiography, we have monitored left ventricular function of the mouse hearts during treatment in chronic model and seen the expected development of dilated cardiomyopathy (DCM). Treated mice showed histological abnormalities similar to those seen in patients with doxorubicin cardiomyopathy. To investigate transcriptional regulation in these models, we used a microarray we generated with over 5000 independent cDNA clones from murine heart and skeletal muscle. We have identified genes that respond to doxorubicin exposure in both model systems, and confirmed these results using real-time PCR. In the acute model, a set of genes is regulated early and rapidly returns to baseline levels, consistent with the half-life of doxorubicin. In the chronic model, which mimics the clinical situation much more closely, we identified dysregulated genes that implicate specific mechanisms of cardiac toxicity and may serve as biomarkers of doxorubicin induced dilated cardiomyopathy. Keywords: time course Overall design: In the chronic model of doxorubicin-induced cardiotoxicity, mice are injected with 3 mg/kg body weight of doxorubicin weekly for 12 weeks. Treated and control mice were sacrificed and hearts harvested 1 day, 1, 3, 6, 12 and 18 weeks after the first injection.