Immunohistochemical localization of metallothionein in human thyroid tumors

High levels of metallothionein (MT) are present in the developing mammalian liver; however, a remarkable decrease is observed during postnatal life after weaning. This developmental profile is similar to that of certain oncofetal gene products such as alpha-fetoprotein, which is used as a tumor marker. This study deals with the reexpression of MT genes in thyroid tumors. With an immunohistochemical method, the presence of MT was investigated in tissue sections of normal and neoplastic human thyroid glands. Tissue sections of 34 thyroid tumors and 10 normal human thyroid glands were studied by means of the peroxidase-antiperoxidase method. MT was localized in 31 of the thyroid gland tumors. MT was also present in two of the normal thyroid glands. These findings indicate that although high levels of MT are mainly found in the fetal liver, it may also be expressed actively in certain human thyroid neoplastic tissues, and occasionally in normal thyroid tissue.