Growth inhibition and cytotoxicity induced by Bowman‐Birk inhibitor concentrate in cisplatin‐resistant human ovarian cancer cells

Abstract

Bowman‐Birk inhibitor (BBI) is a soybean‐derived anticarcinogenic protease inhibitor that was shown to potentiate the cytotoxicity of cisplatin in our previous studies. To assess the potential of BBI as a sensitizing agent for the chemotherapy of cisplatin‐resistant cancers, we evaluated the effects of a soybean concentrate enriched in BBI (known as BBI concentrate or BBIC) on cell growth and clonogenic survival of a human ovarian cancer cell line, A2780, and its cisplatin‐resistant sublines, C30 and C200. The presence of BBI and BBIC in the cell culture medium reduced the clonogenic survival of the A2780, C30, and C200 cells in a dose‐dependent manner and enhanced cisplatin‐induced growth inhibition and/or cytotoxicity. BBIC alone showed greater inhibitory effects on growth in the cisplatin‐resistant cell lines. These results suggest that BBI and BBIC could be useful agents for the treatment of cancers, especially with cisplatin, in tumors resistant to this important anticancer agent.