Inhibitory effect of an isopropanolic extract of black cohosh on the invasiveness of MDA-mB 231 human breast cancer cells.

BACKGROUND: The isopropanolic extract of black cohosh (iCR)b has recently been reported to exert antiproliferative and apoptosis-inducing effects on estrogen receptor-positive MCF-7, as well as estrogen receptor-negative MDA-MB 231 human breast cancer cells. To broaden observations, the anti-invasive effects of iCR and its two major fractions triterpene glycosides (TTG) and cinnamic acid esters (CAE) were tested in highly invasive MDA-MB 231 cells. MATERIALS AND METHODS: The effect of drugs upon the invasive potential of MDA-MB231 cells was studied in BD Biocoat Matrigel invasion chambers over a period of 24 h. RESULTS: The suppression of invasion reached 51.8% at 77.4 microg/ml of iCR, an extract concentration where 89% of MDA-MB231 cells were viable. TTG and CAE reduced cell invasion by 34% and 25.5%, respectively, at a dose of 5 microg/ml. The motility of cells was only moderately reduced. CONCLUSION: In this study iCR was found to suppress tumor cell invasion without affecting cell viability. This result together with the antiproliferative and apoptosis-inducing effect of iCR suggest its use as a secure agent in postmenopausal hormone replacement therapy with additional chemopreventive activity.

Apoptosis of human prostate androgen-dependent and -independent carcinoma cells induced by an isopropanolic extract of black cohosh involves degradation of cytokeratin (CK) 18.

BACKGROUND: The inhibitory effects of black cohosh extracts (Cimicifuga syn. Actaea racemosa L.) on the proliferation of human breast cancer cells were reported recently. In this study, we turned examined another hormone-dependent, epidemiologically important tumor disease, prostate cancer. The cell growth inhibitory effect of an isopropanolic extract of black cohosh (iCR) on androgen-sensitive LNCaP and androgen-insensitive PC-3 and DU 145 prostate cancer cells was investigated. MATERIALS AND METHODS: The cytotoxic effect of the extract was determined by WST-1 assay. Apoptosis was determined by the appearance of apoptotic morphology, annexin V-FITC adherence and caspase activation. Cytokeratin (CK) 18 degradation was identified with M30 monoclonal antibody. RESULTS: Regardless of their hormone sensitivity, the growth of prostate cancer cells was significantly and dose-dependently down-regulated by iCR. The drug concentration producing 50% cell growth inhibition in all cell lines after 72h lay between 37.1 and 62.7 microg/ml. Increases in the level of M30 antigen of approximately 1.8-, 5.9- and 5.3-fold over untreated controls were observed in black cohosh-treated PC-3, DU 145 and LNCaP cells, respectively, with the induction of apoptosis being dose- and time-dependent. CONCLUSION: Black cohosh extract kills human hormone-responsive or-unresponsive prostate cancer cells by induction of apoptosis and activation of caspases. This finding suggests that the cell's hormone responsive status is not an important determinant of the response to the extract and that iCR extract may represent a novel therapeutic approach for the treatment of prostate cancer.

Evaluation of cell death caused by triterpene glycosides and phenolic substances from Cimicifuga racemosa extract in human MCF-7 breast cancer cells.

We previously reported that the antiproliferative effect of an isopropanolic-aqueous extract of black cohosh (iCR) on MCF-7 estrogen-responsive breast cancer cell line was due to the induction of apoptosis. Here we address the question to what extent apoptosis induction can be ascribed to one of the two major fractions of iCR, the triterpene glycosides (TTG) or the cinnamic acid esters (CAE). Furthermore, as black cohosh is routinely administered orally, we studied whether its pharmacological effects would withstand simulated liver metabolism. The antiproliferative activity of TTG and CAE as well as of rat liver microsomal S9 fraction-pretreated iCR on MCF-7 cells were investigated by WST-1 assay. The features of cell death induced were tested for apoptosis by flow cytometry (light scatter characteristics, Annexin V binding). Irrespective of S9-pretreatment, 72 h iCR treatment induced a dose-dependent down regulation of cell proliferation with the same IC50 of 55.3 microg/ml dry residue which corresponds to 19.3 microg/ml TTG and 2.7 microg/ml CAE. The degree of apoptotic MCF-7 cells was also comparable. Both, isolated TTG and CAE fractions inhibited cell growth, the IC50 being 59.3 microg/ml and 26.1 microg/ml, respectively. Interestingly, whereas IC50 and apoptosis induction correspond well for the whole extract, TTG and CAE fractions induced apoptosis at concentrations (25 and 5 microg/ml) well below those required for significant growth inhibition. Observation of this study firstly showed that the cell death induced by iCR withstood a metabolic activation system. In addition, TTG and CAE compounds significantly contributed to its apoptotic effect, CAE being the more potent inhibitor of proliferation and apoptosis inducer.

Hyperforin a constituent of St John's wort (Hypericum perforatum L.) extract induces apoptosis by triggering activation of caspases and with hypericin synergistically exerts cytotoxicity towards human malignant cell lines.

Hyperforin (HP) is an abundant component of St John's wort with antibiotic and antidepressive activity. We report here the ability of HP and that of polyphenolic procyanidin B2 (PB-2) to inhibit the growth of leukemia K562 and U937 cells, brain glioblastoma cells LN229 and normal human astrocytes. HP inhibited the growth of cells in vitro with GI(50) values between 14.9 and 19.9 microM. The growth inhibitory effect of PB-2 was more pronounced in leukemia cell lines K562 and U937, the GI(50) concentrations being about 12.5 microM established after 48 h incubation differed significantly (P<0.05) from those of LN229 and normal human astrocytes (103.1 and 96.7 microM), respectively. Further, HP and hypericin (HY) (a naphthodianthrone from St John's wort) acted synergistically in their inhibitory effect on leukemic (K562, U937) cell growth. Cell death occurred after 24 h treatment with HP and PB-2 by apoptosis. A dose-dependent loss of membrane phospholipid asymmetry associated with apoptosis was induced in all cell lines as evidenced by the externalization of phosphatidylserine (PS) and morphological changes in cell size and granulosity by scatter characteristics. In leukemia U937 cells, HP increased the activity of caspase-9 and caspase-3 and in K562 cells caspase-8 and caspase-3. In addition, the broad spectrum caspase inhibitor z-VAD-fmk inhibited both the appearance of PS exposure and the activation of caspases, illustrating the functional relevance of caspase activation during HP-induced apoptosis. Cytocidal effects of HP and its cooperation with HY on tumor growth inhibition in a synergistic manner make the St John's wort an interesting option in cancer warranting further in vitro and in vivo investigation.