Effects of Smad4 over-expression on proliferation of human gastric cancer cells and activation of NF-κB pathway

Objective:To construct pEGFP-C1-Smad4 expression vector and to observe the influence of Smad4 over-expression on the proliferation of human gastric cancer SGC7901 cells and its relationship with nuclear factor kappa B (NF-κB). Methods:Recombinant expression vector pEGFP-C1-Smad4 was constructed and was used to transfect human gastric cancer SGC7901 cells. EGFP expression in transfected cells was detected by fluoroscopy. Smad4 and NF-κB expression in transfectant was examined by Western blotting. Effect of Smad4 over-expression on activation of NF-κB and proliferation of transfected SGC7901 cells were examined by electrophoretic mobility shift assay (EMSA) and MTT assay,respectively. Results:Expression of EGFP in transfected SGC7901 cells was observed under fluorescence microscope. Smad4 was over-expressed in transfected SGC7901 cells,accompanied by down-regulation of NF-κB p65 expression in the tranfectants. EMSA and MTT demonstrated that Smad4 over-expression significantly inhibited the activation of NF-κB and the proliferation of SGC7901 cells (P0.05,P0.01). Conclusion:Smad4 over-expression can greatly inhibit the proliferation of human gastric cancer cells,probably through down-regulation of NF-κB pathway.