GENISTEIN REDUCES TUMOR-NECROSIS-FACTOR ALPHA-INDUCED PLASMINOGEN-ACTIVATOR INHIBITOR-1 TRANSCRIPTION BUT NOT UROKINASE EXPRESSION IN HUMANENDOTHELIAL-CELLS

The plasminogen activator inhibitor PAI-1 is markedly elevated in vivo and in vitro upon exposure to the inflammatory mediators tumor necros is factor alpha (TNF alpha), interleukin-1 (IL-1), and bacterial lipop olysaccharide. Here we report that the isoflavone compound genistein p revents the increase in synthesis of PAI-1 induced by these inflammato ry mediators in human endothelial cells in vitro, and partially reduce s the basal PAI-1 production by these cells. These effects of genistei n were accompanied by a decrease in PAI-1 mRNA and in a suppression of the PAI-1 transcription rate as shown by run-on assay. A specific act ion of genistein, probably by inhibiting a tyrosine protein kinase, is likely, because the structural genistein analogue daidzein, which has a low tyrosine protein kinase inhibitor activity, did not inhibit PAI -1 synthesis. Vanadate, a tyrosine protein phosphatase inhibitor, incr eased PAI-1 production. The effect of genistein on PAI-1 synthesis was rather selective. Herbimycin A also reduced PAI-1 synthesis, but seve ral other tyrosine protein kinase inhibitors, namely tyrphostin A47, m ethyl-2,5-dihydroxy-cinnamate, and compound 5, were unable to do so. A ll these tyrosine protein kinase inhibitors reduced basic fibroblast g rowth factor (b-FGF)-induced [H-3]thymidine incorporation in endotheli al cells. This indicates that the effeet of genistein on PAI-1 transcr iption proceeds independently of its effect on mitogenesis. In contras t to TNF alpha-induced PAI-1 production, the transcription and synthes is of urokinase-type plasminogen activator (u-PA) was not inhibited by genistein. A TNF alpha-mutant (Trp(32)Thr(86)TNF alpha) that specific ally recognizes the 55-kD TNF-receptor, mimicked the effects of TNF al pha on both PAI-1 and u-PA. Because genistein affected PAI-1,but not u -PA induced by this mutant, involvement of different TNF-receptors can not underlie the difference in the effects of genistein on PAI-1 and u -PA synthesis. Because genistein also inhibited PAI-1 induction by thr ombin and IL-4, it is likely that genistein does not act on a TNF alph a-receptor-coupled protein kinase but on the signal transduction pathw ay enhancing PAI-1 transcription. Our results suggest that the TNF alp ha-induced signal transduction pathway of PAI-1 transcription involves a genistein-sensitive step that is not involved in the induction of u -PA by TNF alpha. Given the limited sensitivity to several other tyros ine protein kinase inhibitors, this genistein-sensitive step may be a potential target for pharmacologic intervention to reduce elevated pla sma PAI-1 levels. (C) 1994 by The American Society of Hematology.