Endocrine Abstracts

Extracts of black cohosh (BCE) are frequently used as an alternative to conventional HRT to treat menopausal symptoms, particularly in Germany and the United States. In fact, BCE is the 14th most popular herbal product in the US and in 2003 sales were at least $15.7 million. Evidence for an increased incidence of breast cancer in long-term users of HRT has reduced its use and may increase the use of alternative treatments. These still require rigorous scientific investigation, not only as to their effectiveness but also their safety. We have investigated the effects of an ethanolic extract of black cohosh (BNO 1055) on the growth of an oestrogen receptor (ER)-positive (MCF-7) and an ER-negative (MDA-MB-231) breast cancer cell line and its effects on enzymes that convert androstenedione (17β-hydroxysteroid dehydrogenase (HSD)/aromatase), oestrone (17β-HSD) and oestrone sulphate (17β-HSD/sulphatase) to oestradiol. Using conventional culture techniques, cell growth was measured over a 4-day period with Almar Blue. BCE inhibited growth but only at the highest concentrations (50 and 100 μg/ml) tested. The activity of the enzymes was measured by culturing cells for 48 h in the presence of BCE and appropriate steroid substrates (10⁻⁷ M). The conversion of substrates to oestradiol was highest for oestrone and lowest for oestrone sulphate. BCE was ineffective in inhibiting the conversion of oestrone or androstenedione to oestradiol but a dose-dependent effect of BCE on the conversion of oestrone sulphate to oestradiol in both cell lines was observed with significant inhibition (P<0.05) occurring at 10 μg/ml. These results will be compared with the effects of genistein, a major constituent of soy, which is also used widely as an alternative therapy to conventional HRT. The results show that BCE has no stimulatory effects on the growth of breast cancer cell lines and may offer some protection against the local production of oestrogens by inhibiting oestrone sulphatase.