Antiestrogenic Activity of Triptolide in Human Breast Cancer Cells MCF‐7 and Immature Female Mouse

ABSTRACT Preclinical Research To investigate the antiestrogenic activity of triptolide in human breast cancer cell line MCF‐7 and immature female C57BL/6 mouse. The effects of triptolide on cell proliferation, cell cycle, and the expression of estrogen receptor alpha (ERα) and progesterone receptor (PR) were examined in MCF‐7 cells. In vivo antiestrogenic effects of triptolide were observed after cotreatment of mice with E2 and triptolide for 4 days. Triptolide dose‐ and time‐dependently inhibited cell growth in untreated or E2‐treated MCF‐7 cells, which was associated with increased S phase arrest. Furthermore, triptolide down regulated the expression of ERα and PR in cells. The expression of ERα and PR in combined group of triptolide with E2 was much higher than that of triptolide alone. Triptolide decreased the E2‐induced uterine weight in mice, while triptolide alone had no effect. Triptolide treatment (90 μg/kg) resulted in extensive degeneration and necrosis of uterine epithelial cells, whereas the same concentration of triptolide in combination with E2 caused morphologic changes in epithelial cells from simple columnar to ellipse, without destruction. Triptolide showed antiestrogenic activity in vitro and in vivo, and the down regulation of ERα and PR expression may be its underlying mechanisms. Drug Dev Res 78 : 164‐169, 2017. © 2017 Wiley Periodicals, Inc.