Fig. 6.

RGE and RGS enhance the cytotoxic effect of doxorubicin in hepatocellular carcinoma cells. (A) Western blots of cell lysates from HepG2 cells pretreated with RGE for 30 min, then treated with doxorubicin (2.5μM) for an additional 12 h. (B) HepG2 cells were treated with 2.5μM doxorubicin, RGE, or RGE in combination with doxorubicin, for 7 h. Fluorescence was then observed with a confocal microscope. SK-Hep1 (C) and HepG2 (D) cells were pretreated with RGE for 30 min before addition of doxorubicin for another 24 h and cell number was examined by MTT. Error bars are mean ± SEM. ***p < 0.005, ****p < 0.001. (E) SK-Hep1 and HepG2 cells were pretreated with 2 mg/ml RGE or 0.2 mg/mL RGS for 1 h and then 2.5μM doxorubicin was treated for an additional 24 h. The cell viability was analyzed by MTT assay and lactate dehydrogenase release assay. Data represent the mean ± SEM. **p < 0.01 and ****p < 0.001. CQ, chloroquine; DOXO, doxorubicin; LDH, lactate dehydrogenase; MTT, tetrazolium colorimetric test; RGE, red ginseng extract; RGS, red ginseng saponin fraction; SEM = standard error of the mean.