Localization of zinc and metallothionein in the rat bladder epithelium during carcinogenesis induced by N-butyl-N-(4-hydroxybutyl) nitrosamine

This study investigated the presence of zinc and expression of metallothionein (MT) in different pathological changes of the rat bladder induced by administration of N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). Using the Timm staining method, the presence of zinc was observed in normal and benign hyperplastic epithelial cells of the rat bladder, particularly in the malignant bladder tumor, induced by the administration of BBN. Immunohistochemically, MT expression was detected only in noninvasive (30%) and invasive transitional cell carcinoma (80%) of the rat bladder where the tumor cells were rich in zinc. Our data suggest that: (1) growth and development of the rat bladder tumor, especially malignant tumors, may have a high requirement for zinc and (2) MT synthesis may be induced by a high zinc concentration in rat bladder tumor cells.