Bear Bile Powder （熊胆粉）Induces Apoptosis of Human Hepatocellular Carcinoma Cells via Mitochondrion-Dependent Pathway

Objective： To evaluate the effect of Bear Bile Powder （熊胆粉, BBP） on the growth and apoptosis of HepG2 human hepatocellular carcinoma cells, and investigate the possible molecular mechanisms mediating its anti-cancer activity. Methods： HepG2 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. Results： The 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）. Conclusions： BBP 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.