OBJECTIVE To investigate whether nimesulide can suppress tumor growth and induce apoptosis in SGC-7901 gastric cancer cells and to explore the molecular mechanism involved.METHODS SGC-7901 cells were cultured in RPMI 1640 medium containing different concentrations of nimesulide (0,12.5, 50, 100, 200, 400 μmol/L). The MTT assay, morphological observation, electron microscopy (EM), immunohistochemical analysis and West blot analysis were employed to investigate the effects of nimesulide on the SGC-7901 cells and to explore possible related molecular mechanisms.RESULTS Nimesulide inhibited the growth of SGC-7901 cells and elicited typical apoptotic morphologic changes. Nimesulide also decreased NF-κB and Bcl-2 expression, but increased the level of the Bax protein.The positive rate of Bcl-2 protein expression at 0, 50, 100 and 200 μmol/L of nimesulide was 58.3±14.0%, 50.2±9.9%, 32.8±5.0% and 22.7± 5.5% respectively based on immunohistochemical staining. The positive rate of Bax protein expression was 22.0±5.7%, 29.2±6.5%, 42.7±5.9% and 74.5±9.1% and the NF-κB expression was 74.2±10.9%, 61.8±7.6%,36.7±10.9% and 17.5±12.3%, Significant differences were found between 0 μmol/L and 100 μmol/L and 200 μmol/L. West blot analysis also showed that the expression of NF-κB was decreased.CONCLUSION Nimesulide suppresses tumor growth and induces apoptosis by inhibiting NF-κB expression, which may be related to the overexpression of Bax relative to Bcl-2 expression.