American ginseng and breast cancer therapeutic agents synergistically inhibit MCF-7 breast cancer cell growth

BACKGROUND AND OBJECTIVES: American ginseng (Panax quinquefolius L.) purportedly alleviates menopause symptoms because of putative estrogenicity. METHODS: Using a standardized American ginseng (AG) extract in MCF-7 breast cancer cells, the objectives were to evaluate the ability of AG to induce the estrogen- regulated gene pS2 by Northern blot analysis, determine the effect on cell growth using the MTT assay, and evaluate the cell cycle effects by flow cytometry. RESULTS: AG and estradiol equivalently induced RNA expression of pS2. AG, in contrast to estradiol, caused a dose-dependent decrease in cell proliferation (P < 0.005). AG had no adverse effect on the cell cycle while estradiol significantly increased the proliferative phase (percent S-phase) and decreased the resting phase (G(0)-G(1) phase) (P < 0.005). Concurrent use of AG and breast cancer therapeutic agents resulted in a significant (P < 0.005) suppression of cell growth for most drugs evaluated. CONCLUSIONS: In vitro use of AG and breast cancer therapeutics synergistically inhibited cancer cell growth.