Evelyn Iturralde

Background: Doxorubicin is an anthracycline chemotherapeutic drug used for chemotherapy, specifically in breast cancer, lymphomas, leukemias and sarcomas.^1,5 However, cumulative doses of doxorubicin over 450 mg/m² pose a risk of cardiotoxicity. “Doxorubicin-induced cardiotoxicity is characterized by a reduced left ventricular ejection fraction similar to dilated cardiomyopathy.³ Current studies assert that doxorubicin generates free radicals that cause oxidative stress on mitochondria.¹ Cardiomyocytes are the first site of attack and exhibit impaired autophagy and ferroptosis.^1,2,4 New studies utilize cardiac organoids to study these mechanisms. A cardiac organoid is developed by inducing human pluripotent stem cells to undergo differentiation into cardiomyocytes in vitro .² Understanding these mechanisms on a three-dimensional scale may provide opportunities for cardioprotective therapies while maintaining doxorubicin’s efficacy in chemotherapy.

Objective: This narrative review explored the mechanisms by which mitochondrial reactive oxygen species (ROS) accumulation promotes ferroptosis and apoptosis in doxorubicin-induced cardiotoxicity. Additionally, the potential protective pathways that may reduce cardiac injury were examined.

Search Methods: An online search of the PubMed database was conducted from 2020-2025 using the following keywords: “doxorubicin-induced cardiomyopathy”, “ferroptosis”, “mitochondria” and “autophagy”.

Results: Studies demonstrated an increased accumulation of ROS disrupting the mitochondrial electrochemical gradient. There is a decrease in ATP production because ATP synthase can no longer use the gradient to its advantage when phosphorylating ADP to ATP.¹ The respiratory chain of the mitochondrial membrane releases cytochrome c into the cytosol as a response, activating the apoptosis caspase cascade.¹ Reduced ATP levels inhibit AMPK signaling while activating mTOR, resulting in suppression of autophagy.¹ Autophagosomes are formed at MERCs (mitochondria-endoplasmic reticulum contacts) through the formation of the Atg5-Atg12/Atg16L1 complex. Doxorubicin disrupts MERCs by downregulating FUNDC1, an outer membrane protein of the mitochondria. By disrupting MERCs, autophagosome formation is impaired.⁴  Additional studies investigating ferroptosis as a dominant mechanism of cardiomyocyte impairment. Doxorubicin was found to chelate ferric iron, get reduced, and in the process, produce hydroxyl radicals that form lipid peroxides.³ The production of lipid peroxides interferes with the membrane itself, making it more permeable. The result is an impaired mitochondrial membrane potential.³  Downregulation of glutathione peroxidase 4 (GPX4), a protective antioxidant enzyme, further enhances ferroptosis.³ Ferroptosis inhibition with ferrostatin-1 (Fer-1) demonstrated greater cardioprotective effects than apoptosis inhibition with Z-VAD-FMK, suggesting ferroptosis plays a primary role upstream of apoptosis.⁵

Conclusions: Current evidence suggests mitochondrial ROS accumulation and ferroptosis are central contributors to doxorubicin-induced cardiotoxicity. Impaired autophagy and disruption of MERCs amplify cardiomyocyte injury. The cardiac organoids reproduced a dose-dependent decrease in heart rate and increase in arrhythmias; and indicated the evidence of oxidative stress, apoptosis and fibrosis of cardiomyocytes. Cardiac organoids may be useful in evaluating therapeutic interventions such as ferroptosis inhibitors, AMPK activators, and mTOR inhibitors. Further analysis will need to focus on the role of ROS, mitochondrial permeability, and ferroptosis pathways to test cardioprotective strategies.² By identifying protective mechanisms for cardiotoxicity, the dosages of doxorubicin may be increased to more therapeutic levels and target more aggressive stages of cancer.⁵

Works Cited

1. Zhang S, Wei X, Zhang H, et al. Doxorubicin downregulates autophagy to promote apoptosis-induced dilated cardiomyopathy via regulating the AMPK/mTOR pathway. Biomed Pharmacother. 2023;162:114691.
2. Wu X, Williams S, Robidoux J, Sriramula S, Abdel-Rahman A. Advanced cardiac organoid model for studying doxorubicin-induced cardiotoxicity. Toxicol Sci. 2025;208(1):95-103.
3. Tadokoro T, Ikeda M, Ide T, et al. Mitochondria-dependent ferroptosis plays a pivotal role in doxorubicin cardiotoxicity. JCI Insight. 2020;5(9):e132747. Published 2020 May 7.
4. He W, Sun Z, Tong G, et al. FUNDC1 alleviates doxorubicin-induced cardiotoxicity by restoring mitochondrial-endoplasmic reticulum contacts and blocked autophagic flux. Theranostics. 2024;14(9):3719-3738. Published 2024 Jun 17.
5. Liu D, Cheng X, Wu H, et al. CREG1 attenuates doxorubicin-induced cardiotoxicity by inhibiting the ferroptosis of cardiomyocytes. Redox Biol. 2024;75:103293.