Effect of curcumin on the proliferation and apoptosis of hepatic stellate cells

This study was designed to investigate the effect of curcumin (diferuloylmethane) on the proliferation and apoptosis of hepatic stellate cells (HSC). The cell line HSC-T6 (1.25 x 10(5) cells/mL) was incubated with curcumin and HSC proliferation was detected by a methyl thiazolyl tetrazolium colorimetric assay. HSC apoptosis was detected by flow cytometry, transmission electron microscope and agarose gel electrophoresis. HSC proliferation was significantly inhibited in a concentration-dependent manner (10.6 to 63.5%) after incubation with 20-100 microM curcumin, compared with a control group. At 20, 40, and 60 microM, after 24 h of incubation, curcumin was associated with a significant increase in the number of HSC in the G2/M phase, and a significant decrease in cell numbers in the S phase (P < 0.05). At these concentrations, curcumin was also associated with an increase in the apoptosis index of 15.3 +/- 1.9, 26.7 +/- 2.8, and 37.6 +/- 4.4%, respectively, compared to control (1.9 +/- 0.6%, P < 0.01). At 40 microM, the curcumin-induced apoptosis index at 12, 24, 36, and 48 h of incubation was 12.0 +/- 2.4, 26.7 +/- 3.5, 33.8 +/- 1.8, and 49.3 +/- 1.6%, respectively (P < 0.01). In conclusion, curcumin inhibits the in vitro proliferation of HSCs in the G2/M phase of the cell cycle and also induces apoptosis in a concentration- and time-dependent manner. The in vivo effect of curcumin on HSCs requires further investigation.