Growth responsiveness of murine DMBA-induced salivary tumors to a soy protein-based diet rich in isoflavones

ACTIS AB; CREMONEZZI DC; JOEKES S; LAMPE J; VALENTICH MA

NUTRITION RESEARCH

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2006 vol. 26 p. 271 - 276

0271-5317

Salivary glands are sex hormone?dependent organs, with structure, function and tumor behavior regulated in part by steroid hormones. Soy protein contains isoflavones that have weak estrogenic activity. These compounds are hypothesized to play a role in cancer protection, specially in breast and prostate. The objective of this study was to determine the responsiveness of murine salivary tumors to a soy protein?based diet rich in isoflavones. Fifty 10-week-old BALB/c mice of both sexes were used. Fifteen males were assigned to casein treatment (C, control), and 16 males and 19 females to soy protein (SP, 2.28 mg isoflavones as aglycone units per gram protein). In experiment 1 (EXP 1), we tested the effect of the diet in males, and in experiment 2 (EXP 2), we examined the effect of sex on response to SP. After 2 weeks, tumors were induced by 9,10dimethyl-1,2-benzanthracene. The animals were killed 13 weeks later, and body weight, in vivo tumor diameter (weeks 1, 6, and 11 of evolution), gland and tumor volumes, and tumor remission were evaluated. In EXP 1, males on SP had higher tumor volumes compared with those on C; however, this difference was not statistically significant. Tumor remission did not differ by treatment. In EXP 2, tumors were different in male and female mice fed the SP diet. Males developed bigger tumors than females. No sex differences were found in tumor remission. This study demonstrated a differential response to an SP-based diet rich in isoflavones, in female mice as compared with males.