Neuregulin-1β Mitigates Doxorubicin-Induced Cardiotoxicity via in Cardiac Fibroblasts

Anthracyclines such as doxorubicin (DOX) are widely used in cancer treatment, but their benefits are offset by dose-related cardiotoxicity. Neuregulin-1β (NRG1) has been studied as a cardioprotective factor, yet its mechanisms during DOX treatment, particularly in the presence of cancer, are not well understood. This study evaluated daily recombinant NRG1 co-administered with DOX in 4T1-tumor-bearing female BALB/c mice. The mice were randomized to saline, DOX (3 mg/kg i.p. on days 0, 3, 6, 9; cumulatively 12 mg/kg) or DOX + NRG1 (20 µg/kg i.p. daily, starting one day before DOX). Body weight and tumor growth were monitored throughout treatment. Cardiac structure and function were assessed by transthoracic echocardiography at baseline and before sacrifice. Mechanistic studies included left ventricular proteomics and single-cell RNA-seq. We also used human 3D cardiac microtissues and 2D primary cardiac fibroblast-enriched cultures under defined experimental conditions, with targeted fibroblast gene perturbations. We found that early DOX exposure induced systolic dysfunction and pathological remodeling, while daily NRG1 preserved the ejection fraction and attenuated structural changes without impairing anti-tumor efficacy. Proteomic analysis identified as one of the most strongly upregulated proteins soon after DOX exposure, an effect that was reversed by NRG1. Notably, has not previously been implicated in anthracycline cardiotoxicity or NRG1-mediated protection. Single-cell RNA sequencing localized expression to cardiac fibroblasts. Mechanistically, we found that modulation was associated with altered processing and fibroblast survival under DOX-induced stress; its suppression by NRG1 was linked to reduced fibroblast apoptosis and a shift toward a pro-survival-associated state. In human cardiac microtissues, NRG1 treatment or fibroblast-specific knockdown accelerated cardiomyocyte contraction dynamics. These changes occurred without an increase in apoptosis and point to a paracrine effect of fibroblasts on cardiomyocyte function. Additionally, scRNA-seq revealed an fibroblast subpopulation associated with early pro-fibrotic activation that expanded after DOX but was reduced by NRG1. Taken together, NRG1 preserved cardiac function during anthracycline treatment while maintaining anti-tumor efficacy. Our data identify fibroblast-associated signaling, particularly through , as a potential contributor to the early protective effects of NRG1. These findings add a new dimension to the understanding of NRG1 cardioprotection and suggest that fibroblast-myocyte interactions may contribute to the early cardiac response to DOX.