Lack of significant effects of genistein on the progression of 7,12-dimethylbenz(a)anthracene-induced mammary tumors in ovariectomized Sprague-Dawley rats.
Genistein is thought to be one of the possible factors for decreasing the incidence of breast cancer in Asian peoples who take soy-rich diets. However, some experimental data suggest that genistein can stimulate breast cancer development via its estrogenic activities. To clarify the influence of genistein on the promotion/progression stage of mammary carcinogenesis, female Sprague-Dawley rats received a single intragastric administration of 7,12-dimethylbenz(a)anthracene (DMBA). When the incidence of palpable mammary tumors reached about 50%, all animals were then subjected to ovariectomy and divided into tumor-bearing [DMBA-tumor (+)] and no-tumor-bearing [DMBA-tumor (-)] groups, with subgroups of each treated with genistein at concentrations of 0, 25, or 250 ppm in soybean-free diet for 36 wk. At terminal sacrifice, the 25-ppm subgroup of DMBA-tumor(+) had a higher tumor incidence and volume, whereas the 250-ppm subgroup showed lower incidence, number, and volume than the 0-ppm subgroup, although differences were not statistically significant. In the DMBA-tumor(-) groups, eventual tumor volumes in the genistein-treated groups were dose dependently smaller than in the 0-ppm subgroup, although again without statistical significance. The present study indicates that genistein does not exert clear inhibitory effects on mammary carcinogenesis in the promotion/progression stage in female rats under ovarian hormone-free conditions.
Ueda
Makoto
M
Division of Pathology, National Institute of Health Sciences, Setagaya-ku, Tokyo 158-8501, Japan.
Niho
Naoko
N
Imai
Toshio
T
Shibutani
Makoto
M
Mitsumori
Kunitoshi
K
Matsui
Takane
T
Hirose
Masao
M
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity; D000818:Animals; D016588:Anticarcinogenic Agents / Q000008:administration & dosage*; D002273:Carcinogens / Q000633:toxicity; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000378:metabolism; D005260:Female; D019833:Genistein / Q000008:administration & dosage*; D015994:Incidence; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D016588:Anticarcinogenic Agents; D002273:Carcinogens; D004967:Estrogens; D015127:9,10-Dimethyl-1,2-benzanthracene; D019833:Genistein