Modulation of stress proteins by Cd2+ in a human T cell line☆

Abstract We previously showed in a human T cell line (CEM-C12 cells) that Cd 2+ induced gene expression of stress proteins, metallothionein-II A and heat shock protein 70 in a time- and dose-dependent manner. In the present study, CEM-C12 cells were pretreated for 24 h with 1 μM Cd 2+ and then challenged with toxic concentrations of this metal. We found that maximal expression of the metallothionein-II A and heat shock protein 70 genes was increased and this maximal level occured at higher Cd 2+ toxic concentrations. Actinomycin D chase experiments indicated that Cd 2+ pretreatment did not modify metallothionein-II A mRNA stability. The modulatory effect of Cd 2+ pretreatment was dose-dependent from 100 pM to 1 μM. Such pretreatment also enhanced resistance to Cd 2+ toxicity. Finally, verapamil, a calcium / potassium channel blocker displaced the dose-response curve for Cd 2+ toxicity as well as metallothionein-II A and heat shock protein 70 gene expression to higher Cd 2+ concentrations.