An Engineered Bivalent Neuregulin Protects Against Doxorubicin-Induced Cardiotoxicity with Reduced Pro- Neoplastic Potential

Background—Doxorubicin (DOXO) is an effective anthracycline chemotherapeutic, but its use is limited by cumulative dose-dependent cardiotoxicity. Neuregulin-1β (NRG1B) is an ErbB receptor family ligand that is effective against DOXO-induced cardiomyopathy in experimental models but is also pro-neoplastic. We previously showed that an engineered bivalent neuregulin-1β (NN) has reduced pro-neoplastic potential compared to the epidermal growth factor (EGF)-like domain of NRG1B (NRG), an effect mediated by receptor biasing towards ErbB3 homotypic interactions uncommonly formed by native NRG1B. Here, we hypothesized that a newly formulated, covalent NN would be cardioprotective with reduced pro-neoplastic effects compared to NRG. Methods and Results—NN was expressed as a maltose-binding protein fusion in E. coli. As established previously, NN stimulated anti-neoplastic or cytostatic signaling and phenotype in cancer cells, whereas NRG stimulated pro-neoplastic signaling and phenotype. In neonatal rat cardiomyocytes (NRCM), NN and NRG induced similar downstream signaling. NN, like NRG, attenuated the double-stranded DNA breaks associated with DOXO exposure in NRCM an