Ursolic Acid Causes Cell Death in PC-12 Cells by Inducing Apoptosis and Impairing Autophagy.

Ursolic acid (UA) is a natural pentacyclic triterpene that has various biological activities, including anticancer and anti-inflammatory effects. This study investigated the ability of UA to cause cell death in pheochromocytoma (PC-12) cells. UA was cytotoxic to PC-12 cells (half-maximum inhibitory concentration=53.2 μM) and significantly reduced the clonogenic ability of PC-12 cells. It also triggered apoptosis by reducing the level of B-cell lymphoma 2 (BCL2), activating caspase-3, and inducing cleavage of poly (ADP-ribosyl) polymerase. To investigate the effects of UA treatment on the induction and progression of autophagy, the levels of p62 and the conversion of the microtubule-associated protein light chain 3 (LC3)-I to LC3-II, which are important markers of autophagic flux, were monitored. UA treatment induced the accumulation of p62 and increased the LC3-II/LC3-I ratio. These results demonstrate that UA treatment induced autophagy, but the downstream signaling pathway was blocked. In summary, this study shows that UA kills PC-12 cells by inducing apoptosis and impairing autophagy progression.