THE FIELD BEAN PROTEASE INHIBITOR HAS THE POTENTIAL TO SUPPRESS B16F10 MELANOMA CELL LUNG METASTASIS IN MICE

Metastasis is a characteristic and fatal feature of human malignancies . Its regulation is therefore of the utmost significance to clinicians . The present study was undertaken to determine whether a legume-deriv ed protease inhibitor (PI) of trypsin/ chymotrypsin, the field bean PI (FBPI), also has plasmin inhibitory activity and can inhibit pulmonar y metastasis of B16F10 melanoma cells systemically injected into BDF1 mice. Two approaches to the problem were made. In the first, the melan oma cells were exposed to two different concentrations of the FBPI pri or to their inoculation into animals. In the second, the mice were tre ated intraperitoneally with FBPI at a dose of 100 mg/kg body weight on ce daily for 10 days, the treatment being started soon after the syste mic injection of the tumour cells. The study revealed that both modes of FBPI treatment could effectively block lung cell metastasis by the melanoma cells and that FBPI has plasmin blocking activity. Since urok inase type plasminogen activator and plasmin are known to play signifi cant roles in tumour cell metastasis, the dose-dependent inhibitory ef fect of FBPI with antiplasmin activity on tumour cell metastasis sugge sts that its antimetastatogenic action is probably mediated through it s plasmin inhibitory action. (C) 1998 Published by Elsevier Science Ir eland Ltd. All rights reserved.