Growth Inhibitory Activity of Extracts and Purified Components of Black Cohosh on Human Breast Cancer Cells

Abstract

The purpose of this study was to determine whether black cohosh contains constituents that inhibit the growth of human breast cancer cells, and therefore might eventually be useful in the prevention or treatment of breast cancer. Black cohosh rhizomes were extracted with methanol/water and fractionated by solvent-solvent partitioning to yield three fractions: hexane, ethyl acetate and water. The ethyl acetate fraction displayed the highest potency in two cell-based assays, growth inhibition and cell cycle analysis. This fraction inhibited growth of both the ER+ MCF7 and ER-MDA-MB-453 human breast cancer cell lines with IC50 values of about 20 and 10 micro g/ml, respectively. It also induced cell cycle arrest at G1 when tested at 30 micro g/ml and at G2/M at 60 micro g/ml in MCF7 cells. This suggests that the extract contains a mixture of components with the more active (or more abundant) causing G1 arrest and the less active causing G2/M arrest. We then examined specific components in this extract. The triterpene glycoside fraction obtained by polyamide column chromatography, and the specific triterpene glycosides actein, 23-epi-26-deoxyactein and cimiracemoside A, inhibited growth of the MCF7 human breast cancer cells and induced cell cycle arrest at G1. The most potent compound, actein, decreased the level of cyclin D1, cdk4 and the hyperphosphorylated form of the pRb protein and increased the level of p21cip1 in MCF7 cells, changes that may contribute to the arrest in G1. Further studies are in progress to identify the mechanisms by which actein and related compounds present in black cohosh inhibit growth of human breast cancer cells.

Growth inhibitory activity of extracts and compounds from Cimicifuga species on human breast cancer cells

“…Our previous experiments (Einbond et al, 2004) indicated that of the black cohosh triterpene glycosides tested, actein was the most potent. To further characterize the nature of the active components, we tested the effects of a series of triterpene glycosides from related Cimicifuga species on cell proliferation ( Table 2).…”

“…The number of attached viable cells was counted 96 hours later using a model Z F Coulter Counter (Coulter Electronics Inc., Hialeah, FL) and IC 50 values were calculated, as previously described (Einbond et al, 2004). Cell viability was calculated by comparing cell counts in treated samples relative to cell counts in the DMSO or DMSO/ethanol control and converted to percentage.…”

“…We and others had shown that extracts enriched in triterpene glycosides and specific triterpene glycosides isolated from black cohosh possess anticancer activity (Nesselhut et al, 1993;Dixon-Shanies and Shaikh, 1999;Watanabe et al, 2002;Bodinet and Freudenstein, 2004;Einbond et al, 2004;Hostanska et al, 2004a,b), but the precise mechanism and nature of the active components are not yet known. The purpose of this study is to determine: (1) the nature of the active anticancer components in black cohosh and related Cimicifuga species, and (2) the effect of the triterpene glycoside actein (Fig.…”

The growth inhibitory effect of actein on human breast cancer cells is associated with activation of stress response pathways

“…12 Antibody to ATF3 was obtained from Santa Cruz Biotechnology (Santa Cruz, CA). Realtime quantitative RT-PCR was performed on 2 technical replicates of at least 2 biological sample replicates (For MCF7: 2 technical replicates).…”

“…12 Therefore, in the present study we focused on the former cell line. We first determined effects on the growth of MDA-MB-453 cells after treating the cells with increasing concentrations of actein for 96 hr.…”