Chemoprevention of N-nitroso-N-methylurea-induced rat mammary carcinogenesis by soy foods or biochanin A.
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.
Gotoh
T
T
Department of Cancer Research, Research Institute for Radiation Biology and Medicine, Hiroshima University.
Yamada
K
K
Yin
H
H
Ito
A
A
Kataoka
T
T
Dohi
K
K
D000818:Animals; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D002273:Carcinogens; D002455:Cell Division / Q000187:drug effects; D004032:Diet; D005260:Female; D019833:Genistein / Q000627:therapeutic use*; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D008770:Methylnitrosourea; D051381:Rats; D017207:Rats, Sprague-Dawley; D013025:Glycine max
D016588:Anticarcinogenic Agents; D002273:Carcinogens; D008770:Methylnitrosourea; D019833:Genistein; C004541:biochanin A