Extracts of the plant Eurycoma longifolia have been shown to possess cytotoxic, antimalarial, anti-ulcer, antipyretic and plant growth inhibition activities. The present study investigated the effects of extracts and their chromatographic fractions from the root of E. longifolia on the growth of a human breast cancer cell line, MCF-7. Our data indicated that E. longifolia extracts and fractions exert a direct antiproliferative activity on MCF-7. The bioassay-guided root fractionation resulted in the isolation of three active fractions, F5, F6 and F7, which displayed IC50 values of (6.17+/-0.38) microg/ml, (4.40+/-0.42) microg/ml and (20.00+/-0.08) microg/ml, respectively. The resultant from F7 purification, F16, exhibited a higher cytotoxic activity towards MCF-7, (IC50=15.23+/-0.66 microg/ml) and a certain degree of selectivity against a normal breast cell line, MCF-10A (IC50=66.31-0.47 microg/ml). F16 significantly increased apoptosis in MCF-7 cells, as evaluated by the Tdt-mediated dUTP nick end labelling assay and nuclear morphology. Western blotting revealed down-regulation of the anti-apoptotic Bcl-2 protein expression. F16, however, did not affect the expression of the pro-apoptotic protein, Bax. These results, therefore, suggest that F16 has antiproliferative effects on MCF-7 cells by inducing apoptosis through the modulation of Bcl-2 protein levels.
Xanthorrhizol is a natural sesquiterpenoid compound isolated from the rhizome of Curcuma xanthorrhiza Roxb (Zingiberaceae). Xanthorrhizol was tested for a variety of important pharmacological activities including antioxidant and anti-inflammatory activities. An antiproliferation assay using the MTT method indicated that xanthorrhizol inhibited the proliferation of the human breast cancer cell line, MCF-7, with an EC50 value of 1.71 microg/ml. Three parameters including annexin-V binding assay, Hoechst 33258 staining and accumulation of sub-G1 population in DNA histogram confirmed the apoptosis induction in response to xanthorrhizol treatment. Western-blotting revealed down-regulation of the anti-apoptotic bcl-2 protein expression. However, xanthorrhizol did not affect the expression of the pro-apoptotic protein, bax, at a concentration of 1 microg/ml, 2.5 microg/ml and 5 microg/ml. The level of p53 was greatly increased, whilst PARP-1 was cleaved to 85 kDa subunits, following the treatment with xanthorrhizol at a dose-dependent manner. These results, thereby, suggest that xanthorrhizol has antiproliferative effects on MCF-7 cells by inducing apoptosis through the modulation of bcl-2, p53 and PARP-1 protein levels.
BACKGROUND: Styrylpyrone derivative (SPD) is a plant-derived pharmacologically active compound extracted from Goniothalamus sp. Previously, we have reported that SPD inhibited the proliferation of MCF-7 human breast cancer cells by inducing apoptotic cell death, while having minimal effects on non-malignant cells. Here, we attempt to further elucidate the mode of action of SPD. RESULTS: We found that the intrinsic apoptotic pathway was invoked, with the accumulation of cytosolic cytochrome c and processing of the initiator caspase-9. Cleaved products of procaspase-8 were not detected. Next, the executioner caspase-7 was cleaved and activated in response to SPD treatment. To confirm that apoptosis was induced following caspase-7 activation, the caspase inhibitor Ac-DEVD-CHO was used. Pre-incubation of cells with this inhibitor reversed apoptosis levels and caspase-7 activity in SPD-treated cells to untreated levels. CONCLUSIONS: Taken together, these results suggest SPD as a potent antiproliferative agent on MCF-7 cells by inducing apoptosis in a caspase-7-dependent manner.
Xanthorrhizol is a natural sesquiterpenoid compound isolated from the rhizome of Curcuma xanthorrhizza Roxb (Zingerberaceae). Recent studies of xanthorrhizol in cell cultures strongly support the role of xanthorrhizol as an antiproliferative agent. In our study, we tested the antiproliferative effect of xanthorrhizol using different breast cancer cell lines. The invasive breast cancer cell line, MDA-MB-231, was then selected for further investigations. Treatment with xanthorrhizol caused 50% growth inhibition on MDA-MB-231 cells at 8.67 +/- 0.79 microg/ml as determined by sulforhodamine B (SRB) assay. Hoechst 33258 nuclear staining assay showed the rate of apoptosis of MDA-MB-231 cells to increase in response to xanthorrhizol treatment. Immunofluorescence staining using antibody MitoCapture and fluorescein isothiocyanate (FITC)-labeled cytochrome c revealed the possibility of altered mitochondrial transmembrane potential and the release of cytochrome c respectively. This was further confirmed by Western-blotting, where cytochrome c was showed to migrate from mitochondrial fraction to the cytosol fraction of treated MDA-MB-231 cells. Caspase activity assay showed the involvement of caspase-3 and caspase-9, but not caspase-6 or caspase-8 in MDA-MB-231 apoptotic cell death. Subsequently, cleavage of PARP-1 protein is suggested. These data suggest treatment with xanthorrhizol modulates MDA-MB-231 cell apoptosis through the mitochondria-mediated pathway subsequent to the disruption of mitochondrial transmembrane potential, release of cytochrome c, activation of caspase-3 and caspase-9, and the modulation of PARP-1 protein.
The cytotoxicity of goniothalamin was found to be strong towards both cancerous (HGC-27, MCF-7, PANC-1, HeLa), and non-cancerous (3T3) cell lines, especially in cases of dividing cells. Drug exposure studies indicated that the cytotoxic action of goniothalamin was time- and dose-dependent. At the ultrastructural level, goniothalamin-induced cytotoxicity revealed a necrotic mode of cell death towards MCF-7 cells.
It has been suggested that combined effect of natural products may improve the treatment effectiveness in combating proliferation of cancer cells. The present study was undertaken to evaluate the possibility that the combination of xanthorrhizol and curcumin might show synergistic growth inhibitory effect towards MDA-MB-231 human breast cancer cells via apoptosis induction. The effective dose that produced 50% growth inhibition (GI50) was calculated from the log dose-response curve of fixed-combinations of xanthorrhizol and curcumin generated from the sulforhodamine B (SRB) assay. The experimental GI50 value was used to determine the synergistic activity of the combination treatment by isobolographic analysis and combination-index method. Further investigation of mode of cell death induced by the combination treatment was conducted in the present study.