MT3 (metallothionein 3) is a cysteine-rich metal-binding protein encoded on chromosome 16 that plays critical roles in metal homeostasis, oxidative stress protection, and neurological function. MT3 binds heavy metals including zinc and copper with high affinity 1, and functions as a radical scavenger to protect against oxidative injuries 2. In the central nervous system, MT3 specifically controls metal ion loading in peptides associated with neurodegenerative disease, including amyloid-β, α-synuclein, and prion proteins implicated in Alzheimer's, Parkinson's, and spongiform encephalopathies 3. MT3 expression is particularly high in astrocytes, where it is necessary for cellular homeostasis maintenance and appears to provide neuroprotection during aging 4. Emerging evidence indicates MT3 participates in cancer biology, with differential MT3 expression identified in ferroptosis-related prognostic models for breast cancer where it may influence tumor development and therapeutic response 5. Additionally, MT3 has been implicated in tumor formation, progression, and drug resistance mechanisms across various malignancies 1. These findings position MT3 as a multifunctional protein with potential therapeutic relevance in neurodegenerative and malignant diseases.