METALLOTHIONEIN INDUCTION BY CADMIUM, CYTOKINES, THROMBIN AND ENDOTHELIN-1 IN CULTURED VASCULAR ENDOTHELIAL-CELLS

Metallothionein induction was investigated using vascular endothelial cells derived from bovine aorta in a culture system. The induction occurred by cadmium (2 and 5 muM) but not by zinc (10 and 300 muM) after a 24-h incubation of the confluent cultures. It was revealed that cytokines including interleukin-1beta, interleukin-6, tumor necrosis factor alpha and transforming growth factor beta (1 ng/ml each) have a capacity of metallothionein induction. In these inducers, only cadmium and tumor necrosis factor alpha exhibited significant cytotoxicity, suggesting that metallothionein is not induced simply in response to cytotoxicity. It was found that either thrombin or endothelin-1 which are coagulation factor or anti-fibrinolytic factor, respectively, also induced metallothionein synthesis. lt was therefore suggested that metallothionein in endothelial cells may be involved in the regulation of the functions of these cells as well as the protection against cytotoxic agents.