GPX3 (glutathione peroxidase 3) is a selenium-containing enzyme that catalyzes the reduction of hydrogen peroxide, lipid peroxides, and organic hydroperoxides using glutathione, thereby protecting cells from oxidative damage 1. As a membrane-associated protein, GPX3 maintains peroxidatic function despite low plasma glutathione concentrations 1. Beyond antioxidant defense, GPX3 exhibits diverse physiological roles: it induces mitochondria-dependent apoptosis and G0/G1 phase arrest through AMPK/ERK1/2 signaling while antagonizing autophagy-related ferroptosis via AMPK/mTOR pathways in benign prostatic hyperplasia 2. GPX3 suppression increases reactive oxygen species levels, triggering apoptosis and autophagy in cardiomyocytes 3. Clinically, selenium supplementation elevates GPX3 levels, reducing thyroid autoimmune responses and improving regulatory T cell function in Hashimoto's thyroiditis 4. In lung metastasis, tumor-polarized GPX3+ alveolar epithelial cells promote immunosuppression by stabilizing HIF-1α and producing interleukin-10, facilitating metastatic niche formation 5. GPX3 expression in extracellular vesicles associates with poor prognosis in acute myeloid leukemia through enhanced mitochondrial function 6. Genetic studies identify GPX3 as a druggable target for amyotrophic lateral sclerosis treatment 7.