Comparison of some antineoplastic drugs on inhibiting thrombin catalizing fibrinogen clotting in vitro

Objective To classify the effect of thrombin, the key enzyme which enables fibrinogen to form fibrin (fibrinogen clotting) on the formation of metasta sis by comparing the inhibition of some antineoplastic drugs on fibrinogen clotting in vitro. Methods Time intervals of different drugs to reach a maximum OD (340 nm) da ta in fibrinogen solution added with thrombin were used in this work. Results It was found that L-4-oxalysine (8-40 mu g/ml) and arabinosyl cytos ine (10-50 mu g/ml) could inhibit the effect of thrombin by extending the f ibrinogen clotting time to 100% - 150% (P< 0.001) and 61% -100% (P < 0.001) while the other antimetastatic drugs razoxane, probimane, adriamycin, harr ingtonine homoharringtonine and alpha-anordrin at the treatment concentrati ons showed no such activity. The positive rate of drugs to thrombin activit y was approximately 25%. Conclusion It suggests that L-4-oxalysine and arabinosyl cytosine may even exhibit antimetastatic effect through thrombin-fibrinogen pathway, and thro mbin might operate in tumor metastasis for only limited step but crutial to fibrin formation in tumor nodules.