TISSUE FACTOR-DEPENDENT VASCULAR ENDOTHELIAL GROWTH-FACTOR PRODUCTIONBY HUMAN FIBROBLASTS IN RESPONSE TO ACTIVATED FACTOR-VII

The transmembrane protein tissue factor (TF) is the cell surface recep tor for coagulation factor VII (FVII) and activated factor VII (FVIIa) . Recently, TF has been identified as a regulator of angiogenesis, tum or growth, and metastasis. This study was designed to link the binding of FVII(a) to its receptor, TF, with the subsequent triggering of ang iogenesis through vascular endothelial growth factor (VEGF) production by human lung fibroblasts. We report that incubation of fibroblasts, which express constitutive surface TF, with FVII(a) induces VEGF synth esis. FVII(a)-induced VEGF secretion, assessed by a specific enzyme-li nked immunosorbent assay, was time-and concentration-dependent. VEGF s ecretion was maximal after 24 hours of incubation of the cells with 10 0 nmol/L FVII(a) and represented a threefold induction of the basal VE GF level. Reverse transcriptase-polymerase chain reaction analysis of VEGF detected three mRNA species of 180, 312, and 384 bp corresponding , respectively, to VEGF(121), VEGF(165), and VEGF(189). A 2.5- to 3.5- fold increase was observed for the 180- and 312-bp transcripts at 12 a nd 24 hours, respectively. FVII(a)-dependent VEGF production was inhib ited by a pool of antibodies against TF, pointing to the involvement o f this receptor. On specific active-site inhibition with dansyl-glutam yl-glycinyl-arginyl chloromethyl ketone, FVIIa lost 70% of its capacit y to elicit VEGF production. Consistent with this, the native form (zy mogen) of FVII only had a 1.8-fold stimulating effect. Protein tyrosin e kinase and protein kinase C are involved in signal transduction lead ing to VEGF production, as shown by the inhibitory effects of genistei n and GF 109203X. The results of this study indicate that TF is essent ial for VIIa-induced VEGF production by human fibroblasts and that its role is mainly linked to the proteolytic activity of the TF-VIIa comp lex, (C) 1998 by The American Society of Hematology.