Progesterone increases epirubicin's apoptotic effects in HepG2 cells by S phase cell cycle arrest.

BACKGROUND/AIMS: The use of chemotherapy in hepatocellular carcinoma is still controversial. The aim of this study was to investigate whether the combined use of epirubicin and progesterone has a synergistic effect on cell proliferation and apoptosis in HepG2 cells. METHODOLOGY: Different concentrations of epirubicin (0.1 microg/ml, 0.25 microg/ml and 0.5microg/ml) or progesterone (12.5 microM, 25 microM and 50 microM) were added to HepG2 cells either alone or in combinations consisting of different concentrations of the two. Their effects on HepG2 cells were studied by (1) XTT assay for analysis of cell proliferation, (2) 3H-Thymidine incorporation for DNA synthesis, (3) annexin V-FITC/ propidium iodide (PI) flowcytometery for cell apoptosis, (4) flowcytometry for cell cycle distributions, and (5) reverse transcription-polymerase chain reaction for expression of cell cycle modulator, cyclin D1. RESULTS: 50 microM progesterone increased both the cytotoxic and apoptotic effects of 0.1 microg/ml epirubicin on HepG2 cells at 48 hr culture due to 50 microM progesterone accumulated cells in S phase of the cell cycle and subsequently reduced cyclin D1 expression. These effects on HepG2 cells induced by this combination were comparable to those induced by 0.5 microg/ml epirubicin alone. CONCLUSIONS: In vitro, progesterone can increase the cytotoxicity and apoptosis induced by epirubicin on HepG2 cells.