Ursodeoxycholic acid induces apoptosis of hepatocellular carcinoma cells in vitro

Ursodeoxycholic acid (UDCA) is widely used to treat chronic liver diseases, and its cytoprotective effect on normal hepatocytes has been shown. This study aimed to investigate the apoptotic effects of UDCA on hepatocellular carcinoma (HCC) cells and the underlying molecular events in vitro.HCC cells were treated by UDCA at different doses and periods of time to assess cell morphology, viability, apoptosis and gene expression using methyl thiazolyl tetrazolium (MTT), Annexin V/propidium iodide (PI) stain, transferase dUTP nick end labeling (TUNEL), enzyme-linked immunosorbent assay (ELISA), immunocytochemistry and quantitative reverse transcription polymerase chain reaction, respectively.UDCA treatment reduced cell viability but induced HCC cell apoptosis in dose-dependent and time-dependent manners. UDCA arrested HepG2 cells at phase S of the cell cycle. At the gene levels, UDCA downregulated Bcl-2 and second mitochondria-derived activator of caspase (Smac) protein expressions, but upregulated Bax and Livin proteins in HCC cells. At the highest concentration, UDCA inhibited Livin mRNA expression but increased Smac and caspase-3 mRNA expressions as well as the activity of caspase-3 in HCC cells.The induction of HCC cell apoptosis by UDCA was dose-dependent and time-dependent and was mediated by the regulation of Bax to Bcl-2 ratio, the expressions of Smac and Livin, and caspase-3 expression and activity.