Comparative pharmacologic effects on tissue factor activity in normal cells and an established cell line

The tissue factor (thromboplastin) activity of cells grown in vitro is modulated by exogenous drugs. The activity of human foreskin fibroblasts and umbilical vein smooth muscle cells is enhanced by 10(-6) M hydrocortisone or 1 mM butyrate. Activity is suppressed in these cells by 10(-6) M colchicine whereas 10(-4) M chloroquine has little or no effect. Two established cell lines, WISH or HeLa cells, have elevated tissue factor activity in the presence of colchicine or chloroquine and suppressed activity with exogenous hydrocortisone. Their activity is also decreased by 10 mM butyrate whereas 1 mM butyrate does not alter activity. Colchicine and butyrate apparently act via a mechanism unrelated to their effect on microtubules since it is possible to dissociate activity changes from morphologic changes. Umbilical vein endothelial cell tissue factor activity responds uniquely to exogenous drugs. Hydrocortisone or 10(-5) M vinblastine (or colchicine) only minimally alters activity. Endothelial cells are not simply refractory toward all drugs, however, since chloroquine dramatically enhances activity whereas 1 mM butyrate suppresses it. The low specific activity of endothelial cells and their apparently unique drug response may be another measure of their function as an in vivo hemostatic barrier.