A Methylene Chloride Fraction of Saururus Chinensis Induces Apoptosis Through the Activation of Caspase-3 in Prostate and Breast Cancer Cells

The aerial parts of Saururus chinensis (SC) have been used for the treatment of edema, fever, jaundice, and inflammatory diseases in Korean folk medicine for centuries. However, the mechanism by which SC exerts these anti-tumorigenic activities in human prostate and breast cancer cells has not yet been fully understood. In this study, we report on the methylene chloride fraction from SC exerting cytotoxicity against prostate and breast cancer cells in a dose-dependent manner. Specifically, SC exerted the most potent cytotoxicity in LNCaP and MCF-7 cells. SC was shown to down-regulate various angiogenetic (VEGF), proliferative (Cyclin D₁, anti-apoptotic (Bcl-2) gene products in these cells. SC also increased the number of annexin V-positive apoptotic bodies and the sub-G1 DNA contents of the cell cycle undergoing apoptosis through caspase-3 activation in both LNCaP and MCF-7 cells. We further confirmed that caspase-3 plays an important role in SC-induced apoptosis in LNCaP and MCF-7 cells through the use of the caspase-3 inhibitor. Moreover, we observed that SC potentiated paclitaxel-induced apoptosis in MCF-7 cells and sauchinone is a major active constituent of SC, which could induce apoptosis in the cells. Taken together, our data provide the evidence that SC induces apoptosis depending on caspase-3 activation and overcomes the natural biological resistance to chemotherapy found in human prostate and breast cancer cells.