Pachymic Acid Induces Apoptosis of EJ Bladder Cancer Cells by DR5 Up-Regulation, ROS Generation, Modulation of Bcl-2 and IAP Family Members

Pachymic acid (PA) is a lanostane-type triterpenoid derived from Poria cocos mushroom that possess various biological effects such as anti-cancer, antiinflammatory and anti-metastasis effects. In this study, we investigated the anti-cancer effects of PA in EJ bladder cancer cells. The results showed that PA significantly inhibited proliferation of EJ cells in a dose-dependent manner. PA induced accumulation of sub-G1 DNA content (apoptotic cell population), apoptotic bodies and chromatin condensation and DNA fragmentation in EJ cells in a dose-dependent manner. PA also induces activation of caspase-3, -8 and -9, and subsequent cleavage of poly (ADP-ribose) polymerase, and significantly suppressed the inhibitor of apoptosis protein family proteins in a dose-dependent manner. Furthermore, PA activates Bid and induced the loss of mitochondrial membrane potential (ΔΨm ) with up-regulated pro-apoptotic proteins (Bax and Bad), down-regulated anti-apoptotic proteins (Bcl-2 and Bcl-xL) and cytochrome c release. In turn, PA increased the generation of reactive oxygen species (ROS); also, the ROS production was blocked by N-acetyl-L-cysteine. The expressions of TNF-related apoptosis inducing ligand and death receptor 5 were up-regulated by PA in a dose-dependent manner, suggesting extrinsic pathway also involved in PA-induced apoptosis. This study provides evidence that PA might be useful in the treatment of human bladder cancer.