Background
Radiotherapy (RT) is a cornerstone treatment for thoracic malignancies; however, unintentional cardiac irradiation may lead to radiation-induced heart disease (RIHD), a major late complication associated with fibrosis, vascular dysfunction, arrhythmias, and heart failure. Oxidative stress, mitochondrial dysfunction, inflammation, and cell death are key mechanisms underlying RIHD development. BCL2 Interacting Protein 3 (BNIP3) is a stress-responsive regulator of autophagy and apoptosis that is activated under hypoxic and oxidative conditions. Although BNIP3 has been implicated in several cardiovascular pathologies, its contribution to radiation-induced cardiac injury remains incompletely understood. This study aimed to investigate whether modulation of the BNIP3 pathway could attenuate radiation-induced endothelial and cardiac damage.
Methods and Results
Human coronary artery endothelial cells (HCAECs) were exposed to ionizing radiation (8Gy) and treated with a BNIP3-targeted peptide antagonist. Radiation-induced oxidative stress, apoptosis, autophagy, inflammation, and DNA damage were assessed using cellular, molecular, and immunohistochemical approaches. BNIP3 pathway modulation significantly reduced intracellular and cytoplasmic reactive oxygen species (ROS) accumulation following irradiation. In addition, radiation-induced apoptotic and autophagic responses were markedly attenuated at both cellular and protein levels. Preliminary analyses further demonstrated reduced inflammatory signaling in peptide-treated cells compared with irradiated controls. Immunohistochemical evaluation revealed a significant decrease in radiation-induced DNA double-strand breaks, supporting the protective effect of BNIP3 pathway modulation against genotoxic stress.
To validate these findings in vivo, studies were initiated using a C57BL/6 mouse model of cardiac irradiation. Early echocardiographic assessments performed at day 1 and weeks 1, 2, and 4 post irradiation demonstrated evidence of acute cardiac injury at day 1, while peptide-treated animals exhibited altered responses compared with irradiated controls. Limited functional changes observed at later time points suggest the presence of early compensatory mechanisms. In addition, serum-based biomarker analyses showed trends consistent with the echocardiographic findings, further supporting the observed cardiac responses following irradiation and BNIP3 pathway modulation. Long-term analyses are currently ongoing.
Conclusion
Our findings identify BNIP3 as a potential mediator of radiation-induced cardiovascular injury.
Modulation of the BNIP3 pathway reduced oxidative stress, apoptosis, autophagy, inflammatory responses, and DNA damage following irradiation. These results support further investigation of BNIP3-targeted approaches as a promising strategy to mitigate RT-associated cardiotoxicity.
