Modulation of synthesis of specific proteins in endothelial cells by copper, cadmium, and disulfiram: An early response to an angiogenic inducer of cell migration

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Abstract
Copper, cadmium, and disulfiram (an ionophore for copper) modulate the synthesis of several polypeptides in two clonal lines of bovine aortal endothelial cells. After treatment of type 1 endothelial cells with 10−3 M CuSO4 or 10−5 M CdCl2 four cell-associated polypeptides (Mr = 28,000, 32,000, 73,000, and 83,000 daltons) were induced. In contrast, in Type 2 endothelial cells, which have cultural characteristics distinct from Type 1, only one new cell-associated protein (Mr = 32,000 and 40,000 daltons) was induced. Other differences are revealed by analyses of proteins secreted into the growth medium. In particular low levels of only CuSO4 (10−6 M) enhanced the synthesis in Type 2 cells of a protein (Mr = 220,000 daltons) identified as fibronectin. Since only copper ions induced fibronectin, we propose that the mechanism of induction of fibronectin synthesis, in contrast to the induction of cell−associated polypeptides, does not involve a sulphydryl−containing receptor molecule. It is suggested that the specific enhancement of fibronectin synthesis by copper ions may be a controlling event in the stimulation by copper ions of endothelial cell migration and angiogenesis.