Doxorubicin-induced Cardiotoxicity is Propagated by Paracrine Signaling through Small Extracellular Vesicles

Cardiovascular disease (CVD) is the leading cause of death worldwide. Chemotherapy-induced CVD is increasingly recognized as a contributor to long-term morbidity in cancer survivors. Doxorubicin (DOX) is a widely used chemotherapeutic to treat breast cancer, one of the most common cancers in the United States. However, over 10% of treated women experience acute cardiotoxicity immediately following treatment, and approximately 2% develop severe cardiotoxicity up to 10 years after treatment, yet the mechanisms driving this delayed onset remain unclear. Here, we show that DOX treatment of cardiac cells changes their function and paracrine signaling profile. Subsequent exposure of healthy cells to altered extracellular vesicles (EV) recapitulates the effects of direct DOX exposure in 2D/3D in vitro models, suggesting a mechanism for propagating initial injury. Plasma-EV miRNA profiling of blinded patient samples revealed distinct clustering by DOX-cardiotoxicity risk, with high-risk patients exhibiting miRNA signatures similar to those from DOX-treated models. Pathway analysis of miRNAs linked them to cardiac homeostasis and cardiotoxicity-related mechanisms, supporting the potential of plasma-EV miRNAs as noninvasive biomarkers for early risk stratification and personalized cardioprotective interventions in oncological care, and targeting of key miRNA clusters to enhance understanding of and intervention strategies for preventing the onset of DOX cardiotoxicity. STATEMENT OF SIGNIFICANCE: Doxorubicin is an effective chemotherapy drug, but its use is limited by cardiotoxicity that can appear during treatment or years later. The mechanisms driving this delayed injury remain poorly understood. In this study, we show for the first time that small extracellular vesicles released from doxorubicin-treated cardiac cells can propagate doxorubicin-like dysfunction to healthy cardiac cells even in the absence of the drug itself. We further identify broad miRNA cargo changes in these vesicles and show that related vesicle-associated miRNA shifts are also detectable in patient plasma. These findings provide new mechanistic insight into anthracycline cardiotoxicity and highlight extracellular vesicle-associated miRNAs as promising candidates for minimally invasive diagnosis and future therapeutic intervention.