title: Isoflavone intake inhibits the development of 7,12-dimethylbenz(a)anthracene(DMBA)-induced mammary tumors in normal and ovariectomized rats.
abstract: To determine the associations between isoflavone (49.72% genistin, 5.32% daidzin, 34.54% glycitin) and breast cancer risk, 150 rats were given 5 mg 7,12-dimethylbenz(a)anthracene and half of them were ovariectomized. Then normal rats and ovariectomized rats were divided into 5 groups: control group, isoflavone high (HI), middle (MI), or low (LI) dose group consuming 100, 500, or 1000 mg isoflavones/kg diet, estrogen group (2.5 mg stilboestrol/kg diet). After 24 weeks, tumor incidences were 73% in control group, 7% in HI, 7% in MI, 27% in LI, and 80% in estrogen group for normal rats; 60% in control group, 13% in HI, 7% in MI, 13% in LI, and 73% in estrogen group for ovariectomized rats. Isoflavone treatment decreased tumor incidence and mean tumor number per rat and increased mean latent period compared with those in control group and estrogen group group significantly (p<0.05). The mRNA and protein expression of estrogen receptor β were significantly higher in isoflavone treatment groups than those in control group group. Moreover, isoflavone treatment significantly decreased 8-hydroxydeoxyguanosine content and increased superoxide dismutase level in normal rats and decreased malondialdehyde concentrations in ovariectomized rats compared with control group. In conclusions, isoflavone intake significantly inhibited the development of premenopausal and postmenopausal mammary tumors.
authors.affiliation: Department of Social Medicine and Health Education, School of Public Health, Peking University Health Science Center, 38 Xueyuan Road, Haidian District, Beijing 100191, China.
authors.forename: Defu
authors.initials: D
authors.lastname: Ma
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Peking University Health Science Center, 38 Xueyuan Road, Haidian District, Beijing 100191, China.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Social Medicine and Health Education, School of Public Health, Peking University Health Science Center, 38 Xueyuan Road, Haidian District, Beijing 100191, China.
authors.forename: Titi
authors.initials: T
authors.lastname: Yang
authors.affiliation: Department of Social Medicine and Health Education, School of Public Health, Peking University Health Science Center, 38 Xueyuan Road, Haidian District, Beijing 100191, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xue
authors.affiliation: Department of Social Medicine and Health Education, School of Public Health, Peking University Health Science Center, 38 Xueyuan Road, Haidian District, Beijing 100191, China.
authors.forename: Peiyu
authors.initials: P
authors.lastname: Wang
keywords: estrogen receptor; isoflavones; mammary tumors; ovariectomized rats