Effects of co-expression of VP3 and TRAIL in Salmonella typhimurium vector on the growth of gastric cancer cell lines.

Objective:To construct an eukaryotic expression vector carrying chicken anemia virus (VP3) gene and TNF-related apoptosis-inducing ligand (TRAIL) gene,and study its inhibitory effect on gastric cancer cell lines. Methods:VP3 gene was inserted into the expression vector of pBud-TRAIL by molecular coloning technology. The plasmid pBud-TRAIL-VP3 was transformed into attenuated Salmonella typhimurium by electric transformation method and directly transfected into gastric cancer cell lines SGC-7901. The VP3 gene expression was detected by RT-PCR at 48 h after transfection and the expression of green fluorescence protein (GFP) was observed under microscope. The proliferation of gastric cancer cells was assessed by MTT assay. Apoptosis was determined by using AO/EB fluorescence staining. Morphological changes of gastric cancer cells were observed under transmission electron microscope. Results:VP3 gene was correctly inserted into eukaryotic expression vector. We detected the existence of VP3 gene in gastric cancer cells after transfection of the plasmid mediated by attenuated Salmonella typhimurium by RT-PCR. We observed the expression of enhanced green fluorescent protein (EGFP) with fluorescent microscopy after the recombinant plasmid was transfected into gastric cells. The recombinant plasmid significantly inhibited the growth of gastric cancer cells (P0.05). AO/EB fluorescence staining indicated transfection of pBud-TRAIL-VP3 markedly increased the apoptotic rate of gastric cancer cells (P0.05). Transfected cells presented typical morphologic features of apoptosis under transmission electron microscope. Conclusion:VP3 gene and TRAIL gene could be introduced into gastric cancer cells by attenuated Salmonella typhimurium and had stable expressions. They had synergistic effects in inhibiting the proliferation and inducing apoptosis of gastric cancer cells.