Enhanced expression of cyclooxygenase(COX)-2 in human renal cell carcinoma cells:evidence for anti-proliferation and apoptosis induction through inhibition of COX-2 expression by NS398

Objective To evaluate the effects of NS398,a selective cyclooxygenase-2(COX-2) inhibitor on cellular proliferation and apoptosis in human RCC cell line,and to examine possible mechanisms responsible for the anti-proliferative effects of NS398.Methods Human RCC cell line 786-0 was maintained in culture using standard technique and treated with NS398 at doses of 25,50,100,150 and 200 μM,respectively.Cellular inhibition was measured by MTT at 24 and 48 h.Apoptosis was evaluated by Flow Cytometry.Reverse transcription-polymerase chain reaction(RT-PCR) and Western blotting were used to examine the expression of COX-2 and Bcl-2 at mRNA and protein levels.Results NS398 exhibited significant cell growth inhibition at 24 hr and 48 hr in the 786-0 cells in time and concentration-dependent manner.COX-2 and Bcl-2 were significantly decreased by NS398 both at mRNA and protein levels.NS398 inhibited proliferation of 786-0 cells through G0/G1 phase arrest along with induction of apoptosis in dose-dependent manner.Conclusions Over-expression of COX-2 mRNA and protein exist in human 786-0 RCC cell line and COX-2 may play a crucial role in carcinogenesis of RCC.NS398 can suppress the proliferation of 786-0 RCC cells by induction of apoptosis.The possible mechanism of induction of apoptosis in 786-0 cells is inhibition of COX-2 expression and suppression of Bcl-2 by NS398.The results suggest that COX-2 may become a new target gene for RCC treatment,and NS398 may be a potentially effective agent against human RCC expressing COX-2.