[ ABSTRACT] AIM:To investigate the effect of DEK downregulation on the apoptosis of gastric carcinoma SGC-7901 cells, and to explore its associations with NF-κB signaling pathway and apoptosis related proteins.METHODS:SGC-7901 cells with different treatments were divided into 3 groups including untreated group, control siRNA group and DEK siRNA group.The expression of DEK at mRNA and protein levels in the SGC-7901 cells was detected by real-time PCR and Western blot.The cell apoptosis was examined by flow cytometry.Furthermore, the activities of caspase-3 and caspase-9 in the SGC-7901 cells were investigated by Caspase-Glo?-3/9 kit.Finally, the expression of key regulatory pro-tein p65 of NF-κB signaling pathway and apoptosis-related proteins Bcl-2 and Bax in the SGC-7901 cells was investigated by Western blot.RESULTS:Compared with untreated group and control siRNA group, the expression of DEK at mRNA and protein levels was significantly downregulated in DEK siRNA group (P<0.05).In addition, the ratios of early phase apoptosis and total apoptosis in DEK siRNA group were markedly higher than those in untreated group and control siRNA group (P<0.05).Most notably, the decrease in p65 and Bcl-2 proteins, increase in Bax protein and the increases of caspase-3 and caspase-9 activities were observed in DEK siRNA group.CONCLUSION:Downregulation of DEK mediates cell apoptosis of gastric carcinoma may be tightly associated with NF-κB signaling pathway.