Partitioned Extracts ofBauhinia championiiInduce G0/G1Phase Arrest and Apoptosis in Human Colon Cancer Cells

Abstract

Bauhinia championii (Benth.) is one of the commonly used herbs in Taiwan. The stem of this plant has been used to treat epigastria pain and rheumatoid arthritis. However, the antitumor activities of this herb have never been reported. This study aims to investigate the mechanism of anticancer activity of the extracts from B. championii (BC). BC was fractionated with a series of organic solvents, including n-hexane (H), ethyl acetate (EA), 1-butanol (B), and water (W). We first investigated the effects of BC-H, BC-EA, BC-B and BC-W partitioned fraction on cell viability. In HCT 116 colon cancer cell lines, BC-EA showed the highest inhibition of cell viability and changed the morphology of cells. With dose- and time-dependent manners, BC-EA inhibited the proliferation of HCT 116 cells by inducing apoptosis and G0/G1 phase arrest of cell cycle. To determine the underlying mechanisms, down-regulated CDK2, Cyclin D, and Cyclin E and up-regulated p16, p21, and p53 may account for the cell cycle arrest, while the apoptotic effect of BC-EA may attribute to increased intracellular Ca, loss of mitochondria membrane potential (), increase of Bax, Bak, puma, and AIF, and decrease of Bcl-2. Furthermore, the inactivation of Ras signaling pathway by BC-EA also contributed to its apoptotic effect on HCT 116. Our study demonstrates that BC-EA not only inhibits cell growth but also induces apoptosis through inhibiting Ras signal pathway and increasing p53 expression levels. We suggest that BC-EA may be a new dietary supplement and a useful tool to search for therapeutic candidates against colon cancer.