Inhibition of Transformation of Mammary Preneoplastic Nodules to Tumor in C3H Mice Fed a Phenylalanine-Deficient Diet

Summary

The effect of diets deficient in phenylalanine(P) on the transformation from hyperplastic alveolar nodules (HAN) to tumors in the mammary glands of C3H/Crgl mice is reported. Five groups of C3H/Crgl virgin female mice, 5 weeks old, each with 2 isologous HAN transplanted into the inguinal, gland-free mammary fat pads, were fed semipurified diets with 5 P levels ranging from 0.090–0.300% for 40 weeks. The relationship of the percent of P in the diet to the percent of the nodule outgrowths containing tumors to the time (days) when 50% of the outgrowths contained tumors was as follows: 0.300%:90%:112 days; 0.150%:71 %:160 days; 0.135%:62%:264 days; 0.120%:51 %:280 days; and 0.090%:42%:> 300 days. The mice fed 0.090 and 0.120% P diets had poorly developed mammary glands and atrophic ovaries with almost no corpora lutea. The non-tumor-bearing inguinal fat pads were filled approximately 40% with nodule outgrowth compared to more than 80% for all other groups. Thus the abnormal ovaries, the poor gland development, the arrested growth of nodule cell populations, and the dependency of tumor formation on correct hormonal combinations indicate that the reduction of tumor formation from 90–42% by a P-deficient diet (with part of the inhibition accounted for by depression of food intake) may be due to a disturbed hormonal milieu.