Enhancement of pancreatic carcinogenesis by raw soy protein isolate: quantitative rat model and nutritional...

Foods containing soybean products have been shown to modify the biochemical and physiological status of the pancreas of several species of experimental animals. Recently, these products have been implicated as a factor in the causation of pancreatic neoplasms. Extensive experimental studies into the possible mechanisms need to be undertaken. Experimental details of a rat/azaserine model for the study of pancreatic carcinogenesis are reviewed. Emphasis is given to the quantitative components of this model and the adaptation of this model to the two-stage (initiation-promotion) concept of carcinogenesis. Particular attention is devoted to considerations of the experimental diets. Application of these concepts to the study of the postinitiational effects of raw and heated soybean protein isolate with and without the addition of high levels of unsaturated fat were undertaken. The results indicate that raw soybean isolate enhanced the growth of azaserine-induced pancreatic foci; whereas, a high level of unsaturated fat had a minimal effect. The effects of the soybean isolate were abolished by heat treatments, but the effects of the unsaturated fat would not be expected to be abolished by similar treatment with heat.