Suppression of Carcinogenesis in the Intestines of Mm Mice by the Soybean-derived Bowman-Birk Inhibitor1

We haveperformedexperimentsto determinewhetherthe soybean derivedproteaseinhibitor,Bowman-Birkinhibitor(BBI), hasthe ability to affect intestinalcarcinogenesisn Mm mice.Mm micehavean auto somally dominantly inherited predisposition to multiple intestinal neo plasmsand are knownto havea very high spontaneous rate of tumor development in boththesmallintestineandcolon.BBI wasadministered in the diet asBBI Concentrate(BBIC), the form of BBI which is currently being evaluated in human trials as a cancerchemopreventiveagent.We observed that 0.5% dietary BBIC led to a 42—50%reduction In the numberof tumors/mousein the small intestineand colonand a 41% reduction of tumorigenesisin the colon when the data are analyzed in tenns of the fraction of micebearing tumors. Thus, tumor developmentin both the small intestine and colon of Mm mice can be significantly suppressedby BBIC, despitethe fact that theanimalscarry a predisposing mutation that leads to a markedly increasedintestinal tumor incidence and mortalityrate.