Treatment with soybean-derived Bowman Birk inhibitor increases serum prostate-specific antigen concentration while suppressing growth of human prostate cancer xenografts in nude mice

BACKGROUND. Bowman Birk inhibitor (BBI) is an anticarcinogenic serine prote ase inhibitor that may inhibit the protease activity of prostate-specific a ntigen (PSA) and the growth of human prostate cancer xenografts in nude mic e. METHODS. Human prostate cancer xenografts were established by implanting LN CaP cells into the prostate glands of NCRNU-M athymic nude mice. The animal s with established tumors were maintained on a control diet or diets supple mented with 1% BBI or 1%, 2%, or 3% BBI concentrate (BBIC) for 6 weeks. The serum PSA concentrations were determined before and after the BBI or BBIC treatment period. The final tumor loads were determined at autopsy. RESULTS. Treatment with BBI or BBIC decreased the final tumor load and incr eased the tumor doubling time and PSA density in the nude mice bearing huma n prostate cancer xenografts. CONCLUSIONS. BBI and/or BBIC could be useful for prostate cancer treatment. (C) 1999 Wiley-Liss.