Metallothionein in toxicology

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Metallothioneins (MT) are ubiquitous low molecular weight cysteine-rich (30%) proteins with different biological roles in nutrition and toxicology. MT binds with both essential metals (Zn & Cu) and toxic metals (Cd & Hg). MT levels are high in organs of young mammals and proliferating epithelial cells, including certain cancer cells with nuclear localization. It can store Zn & Cu, and protect against toxicity of Cd & Hg. The expression of MT can be induced by certain metals and other factors. The high MT levels in metastatic cancer cells may be linked to the increased demand for metal ions in these cells. In addition, MT in cancer cells can protect against persistent oxidative stress. The high expression of MT has been associated with protection against DNA damage, oxidative stress and apoptosis. In cancer cells, the tumor suppressor gene p53 status influences the intracellular redox conditions and also affect the express of MT. The various protective mechanisms of MT will be discussed. (Rad. Res 148:235-39, 1977. J. Tr. Ele. Med. Biol 35:18-29, 2016).