Estrogenic activities of 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside and physcion in MCF-7 cells

Polygonum multiflorum (PM) is a perennial herbal medicine that inhibits osteopenia of osteoporosis caused by estrogen deficiency and shows estrogen-like activity. Components such as 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (TSG), physcion, rhein, emodin, and chrysophanol are contained in PM, and TSG and physcion of the stilbene and anthraquinone series are dominant in PM. Among them, TSG and physcion are known to have various biological activities, but the estrogen activity is unknown. In this study, we investigated the estrogenic activities of TSG and physcion in MCF-7 cells (a breast cancer cell line). Cell proliferation and cytotoxicity were measured using BrdU assay and cell counting kit-8. The cell cycle of MCF-7 cells and expression of estrogen receptor alpha (ERα) were analyzed using FACS. Both TSG and physcion dose-dependently stimulated cell proliferation of MCF-7 cells in the concentration range 1 to 100 μM. Furthermore, this proliferation was inhibited by cotreatment with the estrogen receptor antagonist ICI 182,780. Treatment with TSG (10 to 100 μM) or physcion (1 to 100 μM) was found to increase the proportion of cells in the S phase significantly, and this increase was also inhibited by ICI 182,780 cotreatment. In addition, the nuclear expression of ERα in MCF-7 cells was significantly upregulated by TSG (1 to 100 μM) or physcion (10 to 100 μM) but these upregulations were also inhibited by ICI 182,780 cotreatment. These observations indicate both TSG and physcion and induce estrogen-like activity via ERα.