Early Cardiac Proteomic Profiling in a Long-Latency Doxorubicin Cardiomyopathy Model Exhibits Sexual Dimorphism for Cardioprotection

Anthracycline-induced cardiotoxicity remains a major limitation in cancer therapy, with substantial inter-individual variability in susceptibility, including documented sex differences. However, the molecular basis underlying these disparities remains incompletely understood. In this study, we employed large-scale data-independent acquisition proteomics in a long-latency rat model of doxorubicin-induced cardiomyopathy to characterize early cardiac proteomic remodeling. Longitudinal echocardiography demonstrated a significantly greater decline in fractional shortening in males compared to females. Early proteomic profiling identified 5184 proteins and revealed widespread remodeling across metabolic, mitochondrial, cytoskeletal, and stress-response pathways. While doxorubicin induced broad proteomic changes in both sexes, two-way limma-based sex-stratified analyses identified 430 proteins exhibiting significant sex-by-treatment interactions. Our results suggested that doxorubicin was associated with alterations in oxidative phosphorylation, fatty acid metabolism, and calcium handling pathways. A female-specific upregulation of mitochondrial proteins, including Sco1, Cox17, and Atp2a2, which may be associated with preserved energetics and Ca2+ handling, was detected. In contrast, male hearts demonstrated reduced Micu1 and RyR2 together with increased levels of Ppp1ca, findings that may indicate alterations in mitochondrial function and, excitation-contraction coupling. We also observed lower levels of calcineurin (Ppp3cb) in females. Baseline proteomic differences between sexes further implied distinct regulatory states that may shape the cardiac response to doxorubicin.Together, these findings suggest early proteomic remodeling upon doxorubicin treatment and represent candidate molecular targets that warrant functional validation in future studies. This work offers hypothesis-generating mechanistic insights into sex-specific responses to anthracycline-induced cardiomyopathy and underscores the importance of incorporating sex as a biological variable in cardio-oncology research.