Abstract: The aim was to present our attempts on investigating the pro-apoptosis and growth suppression effects of antiprogestin mifepristone on androgen-independent prostate cancer cell lines LNCaPC_4-2, PC3 in vitro. Using SRB method, the inhibition rates of different concentrations of mifepristone on the two cell lines were studied after drug 3 d, 5 d and 7 d after administration. The study also assessed the apoptosis rates induced by 15 μmol/L mifepristone on LNCaPC_4-2, PC3 cell lines after 24 h, 48 h treatment. When the LNCaPC_4-2 cell line and the PC3 cell line were treated with 20 μmol/L mifepristone, the corresponding rates were 55.79%, 66.37%, 71.54% and 87.42%, 98.15 %, 100% on the 3 rd day, 5 th day and 7 th day. When the two cell lines were dealt with different concentrations of mifepristone 2.5 μmol/L, 5 μmol/L, 10 μmol/L, 15 μmol/L, 20 μmol/L, the corresponding suppression rates on the 7 th day were: 17.07%, 35.77%, 53.66%, 63.41%, 71.54 % and 48.25%, 63.42%, 82.37%, 95.31 %, 100% respectively. Using flow cytometry method, the apoptosis rates of 15 μmol/L mifepristone for LNCaPC_4-2 cell line were: 19.30% at 24 h and 30.04 % at 48 h, for PC3 cell line was 44.52% at 24 h. Antiprogestin mifepristone can induce apoptosis of androgen-independent prostate cancer cell lines LNCaPC_4-2, PC3 in vitro. This pro-apoptosis effect is time-and-dose dependent.

Key words: mifepristone, androgen-independent, prostate cancer, cell line, apoptosis