Abstract B42: Estrogenic activities of Chinese medicinal formula Si-Wu-Tang on breast cancer cells

Chinese medicinal herbs provide a promising source to develop alternative and complementary medicine for cancer prevention. Si-Wu-Tang (SWT, or Si-Wu decoction) comprises the combination of four herbs, Paeoniae, Angelicae, Chuanxiong and Rehmanniae. It is one of the most popular traditional medicines for women's health although the mechanism of the pharmacological action has not been clarified. The microarray gene expression profiles of SWT on human breast cancer cell line MCF-7 showed high similarity to that of β-estradiol (E2)-treated MCF-7 cells in the “Connectivity Map” (cMAP) database in our previous study (Wen et al, PLoS ONE, 2011), indicating novel estrogen-like activity. The objective of this study is to investigate the effects of SWT and its individual herbal components on the estrogen response pathways. The Sulforhodamine B (SRB) cell proliferation assay and luciferase estrogen-responsive element (ERE) reporter assay on MCF-7 (ER-positive) and MDA-MB-231 (ER-negative) cells were used to examine such estrogenic effect. The cells in 96-well plates were treated with SWT or its components for 48 hours before staining with SRB solution. SWT stimulated cell growth in the MCF-7 cell line at low concentrations (1.5 and 3.0 mg/ml), while at high concentrations (> 6.0 mg/ml) SWT inhibited the growth of both cell lines. This growth inhibitory effect of SWT was significantly higher in MDA-MB-231 cells than in MCF-7 cells. The combination of SWT with tamoxifen showed enhanced growth inhibitory effects on MCF-7 cells but did not show the same effects in MDA-MB-231 cells. All herbal components of SWT except for Paeoniae similarly induced growth of MCF-7 cells at low concentrations (1.5 and 3.0 mg/ml). At higher concentrations, all of the components showed cytotoxicity. In MCF-7 cells, the cytotoxicity is in the order of Paeoniae (IC₅₀ = 2.6 + 0.16) >Angelicae (IC₅₀ = 3.1 + 0.073) >Chuanxiong (IC₅₀ = 5.7 + 0.57) >Rehmanniae (IC₅₀>12 mg/ml). In MDA-MB-231 cells, the cytotoxicity is in the same order of Paeoniae (IC₅₀ = 1.1 + 0.21) >Angelicae (IC₅₀ = 2.8 + 0.20) >Chuanxiong (IC₅₀ = 5.9 + 0.47) >Rehmanniae (IC₅₀>12 mg/ml). To quantify the effect on ERE when exposed to SWT and components, MCF-7 cells were plated in 96-well plates and co-transfected with plasmids containing ERE and renilla luciferases. Then the cells were treated with various concentrations of SWT (0.256 - 5.12 mg/ml). The results of the dual luciferase assays revealed that SWT induced a dose dependent increase in the activation of ERE in MCF-7 cells. Except for Paeoniae, all of the herbal components of SWT also induced a significant increase in the ERE activity. In conclusion, the data obtained in this study indicate that SWT possesses estrogenic activity. Our results support the clinical use of SWT for estrogen related diseases and suggest a potential new application for chemoprevention of estrogen-dependent or –independent types of breast cancer.

Citation Format: Jeffery Fan, Mandy Liu, Zhijun Wang, Zhong Zuo, Moses Chow, Ying Huang. Estrogenic activities of Chinese medicinal formula Si-Wu-Tang on breast cancer cells. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B42.