0bjective:To study the proliferative and apoptotic effects of NS398

a selective COX-2 inhibitor

on renal carcinoma cell line 786-O in vitro. Methods:786-O cells were treated with different concentrations of NS398 for24

48

72 and 96 h.The proliferation of 786-O cells was studied by MTT assay.Immuno cytochemistry was used to detect the expressions of COX-2 . The expression of COX-2 mRNA was analyzed by reverse transcription-polymerase chain raction(RT-PCR).Flow cytometric analysis was used to detect the apoptosis status of 786-O cells. Results:NS398 resulted in significant antiproliferative effects on 786-O cells in dose and time dependent manner. Immunocytochemistry showed the expressions of COX-2 were significantly inhibited by NS398. RT-PCR showed the expressions of COX-2 were significantly inhibited by NS398. Apoptosis rate were 31.5%±2.1% and 14.3%±1.4%

respectively in the 786-O cells treated with NS398 in different concentrations of 180 μumol/L and 30 μmol/L

which was significantly higher than in the control group 2.1%±0.4%. Conclusion:NS398 could effectively suppress the growth of 786-O cells and induce apoptosis

the mechanism of which probably relates to its inhabited expression of COX-2.