Anti-androgenic action by red clover-derived dietary isoflavones reduces non-malignant prostate enlargement in aromatase knockout (ArKo) mice.

BACKGROUND: Red clover (RC)-derived dietary isoflavones have been implicated as potential preventative agents for the development and prevalence of non-malignant prostate diseases. This study investigated whether dietary isoflavones inhibit prostate growth in vivo in the aromatase knock-out (ArKO) mouse that exhibits lifelong elevation of androgens leading to prostate enlargement. METHODS: Adult (11-week-old) wild-type (WT) and ArKO mice were fed on protein matched isoflavones free (IF) and RC (isoflavone rich) diets for 28 days. Individual prostate lobes and testes were weighed and collected for histological analysis and serum androgens were measured. Responses were compared to castration and estrogen administration to ArKO mice to determine the mechanism of action. RESULTS: ArKO mice fed on IF diet exhibited enlarged prostate lobes and elevated serum androgens compared to WT mice. Following 28 days of RC diet, ArKO VP, AP, and SV weights were reduced to WT weights, although testis and body weights remained unaltered. Stereological analysis of VPs revealed a reduction in all components of the tissue, particularly the lumen. The RC diet reduced ArKO serum testosterone and dihydrotestosterone to WT levels. In comparison to castration and estrogen administration, the dietary isoflavones were shown to be anti-androgenic rather than weakly estrogenic, mimicking responses observed in the castrated ArKO, rather than estrogen treated ArKOs. CONCLUSIONS: This study demonstrates that RC-derived isoflavones have a significant effect on prostatic growth, and are capable of reducing the enlarged non-malignant prostate phenotype of the adult ArKO mouse, by acting as anti-androgenic agents rather than weak estrogenic substances.

Induction of apoptosis in low to moderate-grade human prostate carcinoma by red clover-derived dietary isoflavones.

Epidemiological evidence suggests a geographical basis for the incidence of prostate cancer and dietary factors, including isoflavone consumption, may be linked to this phenomenon. This paper reports a nonrandomized, nonblinded trial with historically matched controls from archival tissue designed to determine the effects of acute exposure to a dietary supplement of isoflavones in men with clinically significant prostate cancer before radical prostatectomy. Thirty-eight patients were recruited to the study upon diagnosis of prostate cancer. Before surgery, 20 men consumed 160 mg/day of red clover-derived dietary isoflavones, containing a mixture of genistein, daidzein, formononetin, and biochanin A. Serum PSA, testosterone, and biochemical factors were measured, and clinical and pathological parameters were recorded. The incidence of apoptosis in prostate tumor cells from radical prostatectomy specimens was compared between 18 treated and 18 untreated control tissues. There were no significant differences between pre- and posttreatment serum PSA, Gleason score, serum testosterone, or biochemical factors in the treated patients (P > 0.05). Apoptosis in radical prostatectomy specimens from treated patients was significantly higher than in control subjects (P = 0.0018), specifically in regions of low to moderate-grade cancer (Gleason grade 1-3). No adverse events related to the treatment were reported. This report suggests that dietary isoflavones may halt the progression of prostate cancer by inducing apoptosis in low to moderate-grade tumors, potentially contributing to the lower incidence of clinically significant disease in Asian men. The assessment of new prostatic therapies aimed at increasing apoptosis should control for intake of dietary isoflavones.

Prostate phenotypes in estrogen-modulated transgenic mice.

Estrogen-modulated transgenic mice, such as estrogen receptor-knockouts (alphaERKO and betaERKO), aromatase-knockout (ArKO) and aromatase-overexpressing (AROM+) mice, have contributed to our understanding of the roles of estrogens in male reproductive biology, including prostate growth and development. Varying pathological changes of the prostate have been described as being the result of aberrant actions of estrogen, both directly through the estrogen receptors or indirectly by altering the endocrine status of these mice. This article identifies the consequences of aberrant estrogen signaling on prostate growth and development. Further characterization and manipulation of these estrogen-modulated transgenic mice will lead to a more complete understanding of the hormonal regulation of the mammalian prostate gland.