The interaction of tomato powder and soy germ on prostate carcinogenesis in the TRAMP model

Abstract

Epidemiological and laboratory studies support the hypotheses that diets rich in soy or tomato products may reduce the risk of prostate cancer (PCa). The objective of this study was to examine the efficacy of dietary tomato and soy germ, alone and in combination, for prevention of PCa in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Four week old, male C57BL/6 × FVB TRAMP mice (n=119) were randomized to consume: AIN‐93G control, 10% tomato powder (TP), 2% soy germ (SG) or 10% tomato powder with 2% soy germ (TP+SG) for 14 weeks. Tomato lycopene and soy germ isoflavones were bioavailable and accumulated in the serum and prostate. 100% of mice fed the control diet had PCa, while incidence was significantly lower in mice consuming TP (61%, p<0.001), SG (66%, p<0.001) and TP+SG (45%, p<0.001). The protection offered by TP+SG was not synergistic, but it was quantitatively the most effective intervention. The ratio of proliferative index to apoptotic index in the prostate was over two times higher in the controls (161 ± 19) than mice consuming TP (75 ± 20, p=0.009), SG (62 ± 19, p=0.001) and TP+SG (70 ± 19, p =0.002), suggesting a greater stimulus for malignant progression in the control group. Maximally effective strategies for PCa prevention may result from optimizing combinations of nutrients and bioactives provided in scientifically designed novel food products targeting high risk populations.Grant Funding Source: NIH (1 F31 CA153804‐01A1 and PHS‐1‐R01 CA125384)