Induction of apoptosis in human breast adenocarcinoma MCF-7 cells by prodelphinidin B-2 3,3′-di-O-gallate from Myrica rubra via Fas-mediated pathway

Myrica rubra Sieb et Zucc. (Myricaceae) is well known as a rich source of tannins. Prodelphinidin B-2 3,3′-di-O-gallate (PB233′OG) is a proanthocyanidin gallate that has been reported to exhibit antioxidant and antiviral activity. In this study, we evaluated the anti-proliferative activity of PB233′OG isolated from the bark of M. rubra in human breast adenocarcinoma MCF-7 cells. To identity the anti-cancer mechanism of PB233′OG, we assayed its effect on apoptosis, cell cycle distribution, and levels of p53, p21/WAF1, Fas/APO-1 receptor and Fas ligand. The results showed that PB233′OG induced apoptosis of MCF-7 cells without mediation of p53 and p21/WAF1. We suggest that Fas/Fas ligand apoptotic system is the main pathway of PB233′OG-mediated apoptosis of MCF-7 cells. Our study reports here for the first time that the activity of the Fas/Fas ligand apoptotic system may participate in the anti-proliferative activity of PB233′OG in MCF-7 cells.