OBJECTIVETo evaluate the effect of Bear Bile Powder(, BBP) on the growth and apoptosis of HepG2 human hepatocellular carcinoma cells, and investigate the possible molecular mechanisms mediating its anti-cancer activity.

METHODSHepG2 cells were treated with 0.4-1.0 mg/mL of BBP for 24, 48 and 72 h. The viability of HePG2 cells was determined by MTT assay. Cellular morphology was observed via phase-contrast microscopy. Fluorescence-activated cell sorting analysis with Annexin-V/propidium idodide and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzimidazol-carbocyanine iodide (JC-1) staining was performed to determine cell apoptosis and the loss of mitochondrial membrane potential, respectively. Activation of caspase-9 and -3 was evaluated by a colorimetric assay.

RESULTSThe treatment with 0.4-1 mg/mL of BBP for 24, 48, or 72 h respectively reduced cell viability significantly by 7%-60%, 20%-90% or 25%-98%, compared with the untreated control cells (P<0.01). In addition, BBP treatment induced morphological changes in HepG2 cells. Furthermore, after treated with 0, 0.4, 0.6, 0.8 and 1.0 mg/mL of BBP, apoptosis cells (including early and late apoptotic cells) were 18.0%±1.3%, 34.9%±2.2%, 33.9%±2.8%, 37.4%±2.8% and 46.0%±2.5%, respectively (P<0.05); and the percentage of cells with reduced JC-1 red fluorescence were 6.6%±0.8%, 8.5%±0.8%, 13.5%±1.6%, 17.6%±2.3% and 46.7%±3.6%, respectively (P<0.01). Finally, BBP treatment significantly and dose-dependently induced activation of both caspase-9 and caspase-3 in HepG2 cells (P<0.05).

CONCLUSIONSBBP could inhibit the growth of HepG2 hepatocellular cancer cells through mitochondrion-mediated apoptosis, which may, in part, explain its anti-cancer activity. BBP may be a potential novel therapeutic agent for the treatment of hepatocellular carcinoma.