Tissue factor and cancer procoagulant expressed by glioma cells participate in their thrombin-mediated proliferation

The relationship between coagulation cascade activation and glioma cell pro liferation was examined. The human glioma cell lines T98G, TM-1 and normal human astrocyte cell strain (NHA) were examined. Using anti-tissue factor ( TF) antibody, immunocytochemical detection of TF antigen was obtained in bo th cell lines and cell strain. TF antigen in cell lysates was also measured by enzyme linked immunosorbent assay (ELISA). In a one-stage clotting assa y, T98G, TM-1 and NHA revealed procoagulant activity (PCA) in normal human plasma and factor VII deficient plasma. PCA in normal human plasma was sign ificantly inhibited by both inhibitory anti-TF antibody and cysteine protea se inhibitor HgCl2. This result indicates that T98G, TM-1 and NHA cells exp ress not only TF but also cancer procoagulant (CP) at the same time. In a cell proliferation assay, thrombin induced proliferation in T98G and T M-1 cells in a dose-dependent fashion and in NHA cell in a bell-shaped fash ion. This mitogenic stimulant was inhibited by the specific thrombin inhibi tor hirudin. The combinations of coagulation factors II, V, and X with or w ithout factor VII induced proliferation in T98G, TM-1, and NHA cells. The m aximal mitogenic stimulatory effects were larger in glioma cells than in NH A. These mitogenic stimulatory effects were also inhibited by hirudin. Each coagulation factor on its own or in any other combination of coagulation f actors had no proliferative effect. Thus, these mitogenic stimulatory effec ts were considered to be the effect of thrombin. In conclusion, T98G and TM-1 human glioma cells express two different types of procoagulants TF and CP. In the presence of coagulation factors, these glioma cells can generate thrombin and this thrombin generation is capable of inducing glioma cell proliferation in vitro.