Neuregulin-1 and its potential role in the control of cardiac function.

The rapidly evolving insights into the protective and modulatory function of neuregulin-1 (NRG-1) in the adult heart are discussed in this review. The actions of NRG-1 in the adult heart have begun to be elucidated following the unexpected clinical observation that trastuzumab can cause ventricular dysfunction and increases the risk of cardiomyopathy induced by anthracyclines. Trastuzumab is an inhibitory antibody against the NRG receptor erythroblastic leukemia viral oncogene homolog 2 (ErbB2) and is used in the treatment of breast cancer. In vitro studies have demonstrated that NRG-1 promotes growth and survival of isolated cardiomyocytes. Ventricular dysfunction following anti-ErbB2 treatment was initially explained by a loss of ErbB2-dependent cell survival pathways in the heart. However, in vivo studies in genetically modified mice did not uniformly confirm this finding. More recent studies have revealed that NRG-1 counterbalances the adrenergic inotropic response of the adult myocardium through an obligatory interaction with the muscarinic cholinergic system. In addition, it was demonstrated that cardiac NRG-1 synthesis and release from the cardiac endothelium, the principal source of NRG-1 in the heart, is dynamically controlled by neurohormonal and biomechanical stimuli, allowing adaptive tuning of ErbB signaling during cardiovascular stress. Cardiac NRG-1 is beginning to emerge as a cardioprotective factor implicated in the physiological regulation of myocardial performance and sympathovagal balances. Cardiac NRG-1/ErbB signaling has implications for the treatment of both cancer and heart failure. As novel ErbB inhibitors are currently being tested in broader oncological indications, there is a need to better understand their cardiovascular side effects. It is possible that pharmacological activation of ErbB signaling is an indirect, beneficial effect of the drugs currently used in heart failure, and this could be a promising therapeutic approach for prevention or reversal of myocardial dysfunction. Heart Fail Monit 2008;5(4):119-24.