Doxorubicin 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 15 mg/kg of
doxorubicin once; and 2) in a chronic model, they receive 3 mg/kg weekly for 12 wk. Using echocardiography, we have monitored left ventricular function during treatment in the chronic model and seen the expected development of
dilated cardiomyopathy. Treated mice showed histological abnormalities similar to those seen in patients with
doxorubicin cardiomyopathy. To investigate transcriptional regulation in these models, we used a muscle-specific
cDNA microarray. We have identified genes that respond to
doxorubicin exposure in both models 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. These include STARS, a
hypertrophy-responsive gene;
SNF1-kinase, a potential modulator of
ATP levels; and AXUD1, a downstream target of the proapoptotic regulator AXIN1.