Induction of metallothionein in a human astrocytoma cell line by interleukin‐1 and heavy metals

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Abstract
The effects of cytokines and heavy metals on the expression and localization of metallothioneins (MTs) within U373MG astrocytoma cells were analyzed by using indirect immunofluorescence using a monoclonal anti‐MT antibody (MT45). IL‐1, CdCl2 (50μM) or ZnCI2, (500μM) remarkably augmented intracellular MT levels, whereas IL‐6 or 10 μM of ZnCl2 showed no inducing activity. From 24 to 48 h after the addition of CdCl2 or IL‐1, immunoreactive MTs were found in the cytoplasm and the nucleus. After 72 h, immunoreactive MTs accumulated in a granular form near the cell surfaces in the presence of CdCl2 (50 μM) or IL‐1 plus ZnCI2 (10 μM). However, this accumulation was not observed when only IL‐1 was added. Thus, Zn2+ facilitated the appearance of the granular form of immunoreactive MTs at a concentration where they do not induce MTs by themselves.