Abstract: Abstract Objective:To investigate the effect of inhibition and its mechanism about the selective COX-2 inhibitor celecoxib， and NF-kB inhibitor pyrrolidine dithiocarbamate (PDTC) on human gastric cancer cell line SGC-7901.Methods:SGC-7901 cells were respectively treated in vitro with celecoxib (50、100 μmol/L)and PDTC(50、100 μmol/L) or combination（25/25、50/50 μmol/L）. The methyl thiazolyl tetrazolium (MTT) assays were used to measure the growth inhibition rate of cells. TUNEL assays were used to measure the in situ apoptosis of gastric cancer cells .RT-PCR assays the expression levels of COX-2、NF-kB、caspase-3. Results:The growth of gastric cancer cells were inhibited after treated 72 hours with celecoxib， PDTC or the combination group (P<0.05)，but the combination groups(25/25 μmol/L)didn't do more than the celecoxib (50 μmol/L)groups. The combination groups(50/50 μmol/L) are more effective than single drugs with 100μmol/L(P <0.05). After treated 24 hours by the groups of celecoxib（100μmol/L） ，PDTC （100 μmol/L）or combination groups（50/50 μmol/L），the apoptosis index was significantly different compared with negative control，and the combination groups had higher effect (P <0.05).the expression of COX-2、NF-kB were decreased (P <0.05)and caspase-3 was increased (P <0.05) when the cells had been exposed to celecoxib （100 μmol/L）or PDTC （100μmol/L）by 12 hours，and compared with them，the combination groups (50/50 μmol/L) had obvious changes(P <0.05).Conclusion:Both the celecoxib and PDTC can inhibite the proliferation and promote the apoptosis of gastric cancer cells.the mechanism may associated with inhibiting the expression of NF-kB、COX-2，then promote the expression of caspase-3.

Key words: stomach neoplasms, nf-kappa b, apoptosis, cyclooxygenase 2, Celecoxib, PDTC, gastric cancer cellsSGC-7901