Objective: To investigate the effect of 3-bromopyruvate (3-BP) in sensitizing hepatocellular carcinoma cells to cisplatin-induced apoptosis and its possible mechanism.
Methods: The growth inhibition of HepG2 and SMMC7721 cells following exposures to different concentrations of 3-BP and cisplatin was measured by MTT assay. The apoptosis of cells treated with 100 µmol/L 3-BP with or without 8 µmol/L cisplatin was assessed using flow cytometry with PI staining, and the activity of caspase-3 and intracellular ATP level were detected using commercial detection kits; the expression of XIAP and PARP was analyzed using Western blotting.
Results: 3-BP produced obvious inhibitory effects on HepG2 and SMMC7721 cells at the concentrations of 50-400 µmol/L with IC50 values of 238.9∓13.9 µmol/L and 278.7∓11.7 µmol/L for a 48-h treatment, respectively. Cisplatin also inhibited the growth of HepG2 and SMMC7721 cells at the concentrations of 2-32 µmol/L, with IC50 values of 16.4∓0.9 µmol/L and 20.9∓1.8 µmol/L after a 48-h treatment, respectively. Treatment with 100 µmol/L 3-BP combined with 8 µmol/L cisplatin for 48 h resulted in a growth inhibition rate of (60.6∓2.2)% in HepG2 cells and (56.8∓2.3)% in SMMC7721 cells, which were significantly higher than those in cells treated with 3-BP or cisplatin alone. The combined treatment for 48 h induced an apoptotic rate of (51.1∓4.3)% in HepG2 cells and (46.5∓3.9)% in SMMC7721 cells, which were also markedly higher than those in cells with 3-BP or cisplatin treatment alone.
Conclusion: 3-BP can sensitize HepG2 and SMMC7721 cells to cisplatin-induced apoptosis possibly by causing intracellular ATP deficiency, down-regulating XIAP, and increasing caspase-3 activity.