PT  - JOURNAL ARTICLE
AU  - Thae Hyun Kim
AU  - Jae Suk Woo
AU  - Yong Keun Kim
AU  - Ki Hyung Kim
TI  - Silibinin induces cell death through ROS-dependent down-regulation of Notch-1/ERK/Akt signaling in human breast cancer cells
AID  - 10.1124/jpet.113.207563
DP  - 2014 Jan 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - jpet.113.207563
4099  - http://jpet.aspetjournals.org/content/early/2014/01/28/jpet.113.207563.short
4100  - http://jpet.aspetjournals.org/content/early/2014/01/28/jpet.113.207563.full
AB  - The present study was undertaken to determine the underlying mechanism of silibinininduced cell death in human breast cancer cell lines MCF7 and MDA-MB-231. Silibinininduced cell death was attenuated by antioxidants, N-acetylcysteine (NAC) and Trolox, suggesting that the effect of silibinin was dependent on generation of reactive oxygen species (ROS). Western blot analysis showed that silibinin induced down-regulation of ERK and Akt. When cells were transiently transfected with constitutively active MEK (caMEK) and Akt (caAkt), they showed resistance to silibinin-induced cell death. Silibinin decreased the cleavage of Notch-1 mRNA and protein levels. Notch-1-overexpressed cells were resistant to the silibinin-induced cell death. Inhibition of Notch-1 signaling was dependent on ROS generation. Overexpression of Notch-1 prevented silibinin-induced inhibition of ERK and Akt phosphorylation. Silibinin-induced cell death was accompanied by increased cleavage of caspase-3 and was prevented by caspase-3 inhibitor in MDA-MB-231 cells, but not in MCF7 cells. Silibinin induced translocation of apoptosis inducing factor (AIF), which was blocked by NAC, and transfection of caMEK and caAkt. Silibinin-induced cell death was prevented by silencing of AIF expression using small interfering AIF (siAIF) RNA in MCF7 cells, but not in MDA-MB-231 cells. In conclusion, Silibinin induces cell death through an AIFdependent mechanism in MCF7 cells and a caspase-3-dependent mechanism in MDA-MB- 231 cells and ROS generation and Notch-1 signaling act upstream of the ERK and Akt pathway. These data suggest that silibinin may serve as a potential agent for induction of apoptosis in human breast cancer cells.