Pyrrolidine dithiocarbamate inhibits TNF-α-dependent activation of NF-κB by increasing intracellular copper level in human aortic smooth muscle cells

Pyrrolidine dithiocarbamate (PDTC) is a metal-chelating compound that acts as antioxidant or prooxidant and is widely used to study redox regulation of cell function. In the present study, we investigated effects of PDTC and another antioxidant, N-acetyl-L-cysteine (NAC), on TNF-alpha-dependent activation of NF-kappa B in human aortic smooth muscle cells (HASMC), Treatment of the cells with TNF-alpha induced the activation of p65/p50 heterodimer NF-kappa B and increased the mRNA levels of monocyte chemoattractant protein (MCP)-1. Pretreatment with PDTC markedly suppressed the NF-kappa B activation and expression of MCP-1 by inhibiting I kappa B-alpha degradation. In contrast, NAC had no effect. PDTC concomitantly increased the intracellular levels of copper, and bathocuproinedisulfonic acid, a non-cell-permeable chelator of Cu1+, inhibited the PDTC-induced increase in intracellular copper level and reversed the PDTC effects on I kappa B-alpha, NF-kappa B, and MCP-1. These results indicate that TNF-alpha-dependent expression of MCP-1 in HASMC is tightly regulated by NF-kappa B and that intracellular copper level is crucial for the TNF-alpha-dependent activation of NF-kappa B in HASMC. (C) 2000 Academic Press.