Methanol extract of Sanguisorba officinalis L. with cytotoxic activity against PC3 human prostate cancer cells

Sanguisorba officinalis is a natural plant that has been traditionally used for the treatment of inflammatory and metabolic diseases. Several studies have reported that its extracts exhibit anticancer, antioxidative and anti-lipid peroxidation activities. However, the effects of this plant on human prostate cancer cells have not yet been investigated. In the present study, we investigated the inhibitory effects and underlying mechanisms of a methanol extract of Sanguisorba officinalis (MESO) in PC3 human prostate cancer cells. MESO significantly decreased cell growth and induced apoptosis through the intrinsic apoptosis pathway. MESO decreased the expression levels of myeloid cell leukemia-1 (Mcl-1), a Bcl-2-like anti-apoptotic protein that is highly expressed in various cancer cell lines. Expression levels of the pro-apoptotic protein Bax were increased by MESO whereas those of Bak and Bcl-xL were unchanged. In addition, MESO induced the oligomerization of Bax in the mitochondrial outer membrane. These results suggest that MESO inhibits the growth of prostate cancer cells and induces apoptotic cell death by the downregulation of Mcl-1 protein expression and the oligomerization of Bax. Therefore, MESO has potential as a drug candidate for the treatment of prostate cancer.