[Equol and its enantiomers inhibited urethane-induced lung cancer in mice].

OBJECTIVE: To investigate the effects and mechanisms of equol and its enantiomers on urethane-induced lung cancer in mice. METHODS: A total of 120 5-week-old male C57BL/6 mice were randomly divided into 8 groups: lung cancer tumor control group (CG), genistein control group (GCG), low dose racemic equol group (LEG), high dose racemic equol group (HEG), low dose R-equol group (LRE), high dose R-equol group (HRE), low dose S-equol group (LSE) and high dose S-equol group (HSE). Urethane was injected subcutaneously twice a week for 4 weeks to induce lung cancer and then the mice were fed for 4 months. The body weight and food intake of each group were measured and recorded weekly. After the mice were sacrificed, the blood, livers and lungs of the mice were collected. The incidence of lung cancer in each group was recorded. The concentration of serum superoxide dismutase (SOD), malondialdehyde (MDA) and 8-hydroxydeoxygunosine (8-OHdG) were detected by the corresponding kits. Western blotting was used to detect the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in the livers. Between-group differences in body weight and food intake of the mice were compared using repeated measures ANOVA, and ANOVA for the differences between non-repeated measurements, with post hoc analysis using Tukey's method if there were between-group differences. Comparisons of categorical data were performed by chi-square test, and if there were differences between the groups, the Bonferroni method was used for pairwise comparison. RESULTS: A total of 49 in the 120 mice developed lung cancer. The overall incidence of lung cancer was 40.8%. Compared with the control group, the incidence of lung cancers in each experimental group was lower, and the difference was statistically significant. The incidence of lung cancer in the high-dose experimental group was significantly lower than that in the low-dose experimental group. However, the incidence of lung cancer was similar in the three equol groups and the genistein group at the same dose. Compared with the control group, the high-dose experimental group had higher serum SOD concentration, lower MDA and 8-OHdG concentrations, and the differences were statistically significant. Western blotting analysis showed that the expression levels of Nrf2 protein in the experimental groups were higher than those in the control group except the low-dose racemic equol group, and the Nrf2 protein expression level in the high-dose equol groups was higher than that in the low-dose equol groups. CONCLUSION: Racemic equol and its enantiomers mayinhibit lung carcinogenesis through antioxidant effects.

[Effects of equol on colon cancer cell proliferation].

OBJECTIVE: To investigate the effect of equol on the proliferation of colom cancer cells and to explore the mechanisms. METHODS: Colon cancer cells (DLD1,HCT15,COLO205,LOVO,SW480) were incubated, the cell proliferation was identified by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell proliferation assay. Reverse transcription PCR and Western blot were used to measure the mRNA and the protein expression of estrogen receptor and nuclear factor (erythroid-derived 2)-like 2 (Nrf2)in the colon cancer cells, respectively. Moreover, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell proliferation assay was used to investigate the effect of estrogen receptor(ER) inhibitor,ERα agonist, and estrogen receptor ERßagonist on the cell proliferation. RESULTS: ERα was faintly expressed in the DLD-1 and HCT-15 cells. However, ERß expression in DLD1, HCT15, COLO205, LOVO, and SW480 colon cancer cells. Different concentrations of equol (0, 0.5, 1, 5, 10 µmol/L) significantly inhibited the growth of HCT-15 cell with the expression of ERα and ERß.More-over, different concentrations of equol (0, 0.5, 1, 5, 10 µmol/L) significantly inhibited the growth of LOVO, and SW480 cells with the ERß expression in a dose-dependent manner as demonstrated with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell proliferation assay. mRNA expressions of ERα and ERß in HCT-15 were stimulated significantly. Western blotting proved that the protein expressions of ERα and ERß increased with the increasing of equol dose. Moreover we found significant difference of Nrf2 protein expression in HCT-15 cell stimulated by different concentrationss of equol. After the similation of estrogen receptor inhibitor, ERα agonist, or ERß agonist, we found that only dif-ferent concentrations of ERß agonist(0, 1, 10, 100, 1 000, 10 000 nmol/L) significantly inhibited the growth of HCT-15, LOVO, and SW480 in adose-dependent manner. Estrogen receptor inhibitor and ERα agonistdid not present significant effect on the cell proliferation of HCT-15, LOVO, and SW480. CONCLUSION: Equol inhibited the colon cancer cell proliferation by its estrogenic activities and antioxidant activities.