ERBB3 Influences the Ferroptosis Pathway Via Modulation of Lipid Peroxidation and GSH Synthesis in Gastric Cancer

Gastric cancer remains one of the most lethal malignancies worldwide, with high relapse rates and limited survival for patients with advanced disease. Despite advances in targeted therapies and immune checkpoint inhibition, intrinsic tumor heterogeneity poses challenges for effective treatment. The HER3 receptor (ERBB3) has emerged as an important player in cancer progression, contributing to aggressive tumor behavior and poor prognosis. Recent evidence indicates that activating ferroptosis—an iron-dependent, non-apoptotic form of cell death—offers a promising strategy to inhibit cancer growth. In gastric cancer, ferroptosis plays a crucial role, and promoting this process may open new avenues for therapeutic intervention. Ferroptosis is characterized by iron-mediated lipid peroxidation of cell membranes and is critically regulated by the cystine/glutamate antiporter system (SLC7A11) and glutathione peroxidase 4 (GPX4). Our study aimed to investigate the relationship between ERBB3 and ferroptosis in gastric cancer. We found that high ERBB3 expression correlated with resistance to ferroptosis-inducing agents, including GPX4 and SLC7A11 inhibitors, across multiple cell lines. Vice versa, ERBB3 inhibition with TX1-85-1 induced lipid peroxidation in gastric cancer cells, with effects most pronounced in cell lines expressing higher SLC7A11 levels. Knockdown of ERBB3 reproduced these effects, suggesting SLC7A11 as a predictive marker. Importantly, combined inhibition of ERBB3 and GPX4 significantly enhanced lipid peroxidation and cytotoxicity, while ERBB3 activation by co-treatment with the ERBB3 ligand heregulin reduced lipid peroxidation in cells with lower baseline SLC7A11 expression. Analysis of glutathione levels and SLC7A11 expression further supported the role of ERBB3 in modulating ferroptosis sensitivity. These findings identify ERBB3 as a critical regulator of ferroptosis and a promising target for enhancing ferroptosis-mediated cell death. Its inhibition in combination with ferroptosis inducers may thus represent a particularly promising and efficacious therapeutic strategy in gastric cancer.