20(S)-Protopanaxadiol (
PPD), a
ginsenoside isolated from Pananx quinquefolium L., has been shown to inhibit growth and proliferation in several
cancer cell lines. The aim of this study was to evaluate its anticancer activity in human
breast cancer cells. MCF-7 cells were incubated with different concentrations of 20(S)-PPD and cytotoxicity was evaluated by MTT assay. Occurrence of apoptosis was detected by
DAPI and
Annexin V-FITC/PI double staining. Mitochondrial membrane potential was measured with
Rhodamine 123. The Bcl-2 and Bax expression were determined by Western blot analysis.
Caspase activity was measured by colorimetric assay. 20(S)-PPD dose-dependently inhibited cell proliferation in MCF-7 cells, with an IC50 value of 33.3 μM at 24h. MCF-7 cells treated with 20(S)-PPD presented typical apoptosis, as observed by morphological analysis in cell stained with
DAPI. The percentages of
annexin V-FITC positive cells were 8.92%, 17.8%, 24.5% and 30.5% in MCF-7 cells treated with 0, 15, 30 and 60μM of 20(S)-PPD, respectively. Moreover, 20(S)-PPD could induce mitochondrial membrane potential loss, up-regulate Bax expression and down-regulate Bcl-2 expression. These events paralleled activation of
caspase-9, -3 and PARP cleavage. Apoptosis induced by 20(S)-PPD was blocked by
z-VAD-fmk, a pan-
caspase inhibitor, suggesting induction of
caspase-mediated apoptotic cell death. In conclusion, the 20(S)-PPD investigated is able to inhibit cell proliferation and to induce
cancer cell death by a
caspase-mediated apoptosis pathway.