Chemoprevention of N‐Nitroso‐N‐methylurea‐induced Rat Mammary Carcinogenesis by Soy Foods or Biochanin A

Abstract

We examined the effects of soybeans, a soy product (miso) and biochanin A, an isoflavone derivative, on N-nitroso-N-methylurea (MNU)-induced rat mammary carcinogenesis. Seven-week-old female CD/Crj rats received a single i.v. dose (40 mg/kg body weight) of MNU. After administration of MNU, rats were fed diet containing 0% (control), 2% or 10% soybeans, or 10% miso as a soy-supplemented diet, or 10 or 50 mg/kg biochanin A. All rats were observed for 18 weeks after MNU administration. At 18 weeks, the multiplicity (mean tumors/rat) of palpable mammary tumors was significantly decreased in the 10% soybean (1.1) and 10% miso (1.2) diet groups compared to the control (2.2) (P<0.05, respectively). In the biochanin A-supplemented diet groups, the incidence (percentage of rats with tumors) was significantly decreased in the 50 mg/kg (32%) diet group compared to the control (80%) (P<0.01), and the multiplicity was significantly decreased in both the 10 mg/kg (0.7) and 50 mg/kg (0.5) diet groups compared to the control (2.2) (P<0.01 and P<0.001, respectively). The proliferative cell nuclear antigen labeling index of mammary tumors was significantly decreased in both biochanin A-supplemented diet groups compared to the control. The present results indicate that soybeans, miso, and biochanin A are useful for the prevention of mammary cancer.

Neuroprotective Effects of Biochanin A against β-Amyloid-Induced Neurotoxicity in PC12 Cells via a Mitochondrial-Dependent Apoptosis Pathway

“…They have also been suggested as novel candidate drugs for AD [29]. As one of the phytoestrogen compounds, biochanin A, has been shown to have an important effect in cancer protection [21,22]. However, there is still much to learn about this phytoestrogen and its beneficial effects on human health.…”

“…Its chemical structure resembles that of endogenous estrogen, which is able to displays agonistic and antagonistic interactions with the estrogen receptor. Over the past few years, biochanin A has been applied in research on cancer prophylaxis and neuroprotection studies [20][21][22][23]. Despite the many considerable efforts to study the beneficial effects of biochanin A, there remains a significant lack of understanding of the effects of this compound on the central nervous system.…”

The role of early life genistein exposures in modifying breast cancer risk

“…The study of Constantinou et al (2001) found that an exposure to SPI that was depleted of IFs had the most significant effect on tumour latency and multiplicity. Also, an exposure to 10% miso Early life genistein exposures in modifying breast cancer risk A Warri et al was reported to reduce mammary tumorigenesis in rats (Gotoh et al, 1998). To summarise, genistein/SPI exposure limited to the prepubertal period appears to reduce later mammary cancer risk in rats, but the effect is mostly lost if the exposure remains high throughout adult life.…”

Effects of phyto-oestrogens on tissues

“…Each of the four studies that used non-fermented, whole soyabean products reported protective effects (Troll et al 1980;Gridley et al 1983;Barnes et al 1990;Gotoh et al 1998b). In the study by Troll et al (1980), however, raw soyabeans were used and the body weight of soyabean-fed rats was 10 % lower than that of control animals.…”