Abstract
To demonstrate the mechanisms of the curative effect of Saussurea lappa ethanol extract (SLE) against prostate cancer, we evaluated the effect of SLE on the induction of apoptosis and autophagy and investigated whether SLE-induced autophagy exerts a pro-survival or pro-apoptotic effect in lymph node carcinoma of the prostate (LNCaP) prostate cancer cells. SLE was prepared using 100% ethanol and added to LNCaP cells for 24 hours. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and cell apoptosis was evaluated by Tali assay. The expression of apoptosis-related mRNA and proteins was analyzed by quantitative real-time RT-PCR and western blotting. SLE treatment decreased the viability of LNCaP cells and increased Bax expression while suppressing the expression of pro-caspases-8/9/3, PARP, Bid, and Bcl-2, thereby inducing apoptosis in LNCaP cells. Cell proliferation related proteins, including p-Akt, androgen receptor, and prostate-specific antigen, were suppressed by SLE treatment. SLE also induced autophagy in LNCaP cells, and inhibition of autophagy enhanced the apoptosis induced by SLE treatment. These results suggest that SLE exerts anticancer effects through the induction of both cellular apoptosis and autophagy, and apoptotic cell death can be facilitated by blocking autophagy in SLE-treated LNCaP cells. Therefore, SLE might be a potential anticancer agent for the treatment of prostate cancer.