Psychosocial stress exacerbates doxorubicin-induced cardiotoxicity in adult C57BL/6N mice

Psychosocial stress is an established cardiovascular risk factor, and is a huge burden challenging cancer patients undergoing chemotherapy treatment. Doxorubicin (DOX), a widely used chemotherapeutic agent, is known to induce cardiotoxicity. However, the impact of concurrent psychosocial stress on DOX-induced cardiotoxicity remains unclear. This study aimed to leverage a clinically relevant ‘two-hit’ tumor-free and tumor-bearing mouse models to determine the independent and combined effect of DOX in the presence/absence of exposure to mouse model of chronic stress, namely the chronic subordination stress (CSS) on cardiac functions and identify the underlying molecular mechanisms. Twelve-week-old tumor-free male C57BL/6 N mice were administered 3 doses of DOX (8 mg/kg/week) or vehicle in the presence/absence of CSS for 26 days. Cardiac function was evaluated using echocardiography. Bulk RNA sequencing was conducted to identify differentially expressed genes (DEGs), with key genes validated by real-time PCR. Cardiomyocyte size, myocardial inflammation, and fibrosis were assessed histologically. A clinically relevant tumor-bearing mouse model was also established by subcutaneous inoculation of EL4 lymphoma cells followed by concurrent DOX treatment in the presence or absence of CSS. Neither CSS nor DOX alone induced significant cardiac dysfunction. However, the combination of CSS and DOX led to both systolic and diastolic dysfunction and increased mortality. Expression of Nppa Nppb, and Myh7 markers of cardiotoxicity were significantly elevated by DOX, with CSS further amplifying Nppa expression. RNA sequencing revealed upregulation of cardiac remodeling-associated genes (Lgals3, Sprr1a, Angptl2, Ltbp2, and Cilp) under combined CSS and DOX exposure. Gene set enrichment analysis further demonstrated enrichment of inflammatory, extracellular matrix remodeling, and fibrotic signaling pathways, along with dysregulation of metabolic and cell cycle-associated processes. Histopathological analysis confirmed aggravation of myocardial inflammation and fibrosis in the combined CSS and DOX group. In the tumor-bearing model, CSS increased the expression of cardiotoxicity-associated genes (Nppa, Nppb, and Myh7) in DOX-treated mice without significantly affecting tumor growth. Psychosocial stress worsens DOX-induced cardiotoxicity, as evidenced by increased mortality, exacerbated cardiac dysfunction, and activated inflammatory and pro-fibrotic pathways. This study highlights psychosocial stress as a risk factor for adverse cardiovascular outcomes in cancer patients receiving potentially cardiotoxic chemotherapy.