ABSTRACT
<p><b>OBJECTIVE</b>To investigate the inhibitory effect of the Hedgehog signal pathway blocker (cyclopamine) on DU145 cells.</p><p><b>METHODS</b>We interfered DU145 cells with cyclopamine at the concentrations of 1, 10, 50 and 100 micromol/L and detected its inhibitory effect on the cells by MTT colorimetry assay at 24, 48 and 72 hours, as well as its effect on the cell cycle by flow cytometry. We also determined the difference in the mRNA expression of cyclin E between the experimental and control groups by RT-PCR at 48 hours after 50 +/- micromol/L cyclopamine intervention.</p><p><b>RESULTS</b>Cyclopamine inhibited the DU145 cells in a time- and dose-dependent manner, with inhibition rates of 7.42, 12.70 and 59.15% in the 10, 50 and 100 micromol/L groups respectively at 24 hours, significantly different from that of the blank control group (P < 0.05). It markedly suppressed the proliferation of the DU145 cells at >10 micromol/L at 24 hours. Flow cytometry showed an obviously increased proportion of stage G1 cells at the concentration of >10 micromol/L after 48-hour intervention, with statistically significant differences from the G1 cell proportions in the control, 10 micromol/L and 50 micromol/ L groups, which were (52.17 +/- 2.21)%, (60.13 +/- 2.75)% and (74.30 +/- 3.52)% respectively (P < 0.01). The apoptotic peak was elevated with the increased concentration of cyclopamine. The cyclin E mRNA expression of the DU145 cells was decreased by 61.90% at 48 hours after 50 micromol/L cyclopamine intervention as compared with the blank control group (P < 0.01).</p><p><b>CONCLUSION</b>Cyclopamine can inhibit the proliferation of DU145 cells, and the mechanism may be related with its effect of down-regulating the cyclin E mRNA expression of DU145 cells and blocking them in stage G1. Cyclopamine can also induce the apoptosis of DU145 cells.</p>