ELABELA-32 Alleviates Doxorubicin-Induced Chronic Cardiotoxicity by Inhibiting the TGF-β/Smad Signaling Pathway

Cardiac fibrosis, oxidative stress, and cardiomyocyte Apoptosis are key contributors to the progression of doxorubicin (DOX)-induced cardiotoxicity. ELABELA (ELA) is an early endogenous ligand of apelin receptor (APJ/APLNR), which is a G protein-coupled receptor with seven transmembrane domains. Our present study aimed to investigate the protective role and underlying mechanism of ELA-32 in mitigating oxidative stress and fibrosis associated with DOX-induced cardiotoxicity. Using a mouse model of chronic DOX cardiotoxicity (5 mg/kg, i.p, once a week for four times, the total cumulative dose is 20 mg/kg), it was found that exogenous administration of ELA-32 using a microinjection pump significantly improved cardiac function, reduced oxidative stress, and myocardial fibrosis, and enhanced survival. Furthermore, pretreatment with ELA-32 peptide protected rat cardiomyocytes (H9C2 cells) from DOX-induced cytotoxicity in vitro. However, these cardioprotective effects of ELA-32 were no longer observed after activation of the Smad signaling pathway using TGF-β1. In summary, ELA-32 attenuated DOX-induced cardiac fibrosis through by modulating the TGF-β/Smad signaling pathway, thus highlighting its potential as a therapeutic agent for preventing chronic DOX-related cardiotoxicity.