OBJECTIVETo study the inhibitory effect of adenovirus-mediated fusion gene system driven by KDR promoter on the proliferation of human gastric adneocarcinoma SCG7901 cells and observe the bystander effect in vitro.

METHODSSCG7901, ECV304 and HepG2 cells were infected with Ad-KDR-CDglyTK and Ad-CMV-CDglyTK at a multiplicity of infection (MOI) of 100, and the infection efficiency and the mRNA expressions of the transferred fusion gene were investigated. GCV and/or 5-FC at different concentrations were added into the culture medium of the infected cells to observe the targeted antitumor effect and bystander effect of CDglyTK suicide gene driven by KDR promoter.

RESULTSWith the MOI of the adenovirus of 100, the fluorescence emitted by green fluorescent protein (GFP) was observed in 95% of the infected SCG7901, ECV304 and HepG2 cells. All the cells infected by Ad-CMV-CDglyTK and SCG7901 and ECV304 cells infected by Ad-KDR-CDglyTK were highly sensitive to the prodrugs. In comparison, HepG2 cells infected with Ad-KDR-CDglyTK did not show much sensitivity to the two prodrugs. Following treatment with the prodrugs at the same concentration, the infected SCG7901 and ECV304 cells exhibited gradually lowered survival rates as the culture time was prolonged, whereas the transgenic HepG2 cells showed no such time-dependent changes. When the non-infected cells were cocultured with the transgenic cells, the bystander effect of CDglyTK gene was observed, which increased with the ratio of the transgenic cells. In these mixed cell culture systems, GCV and 5-FC showed obvious synergetic effect in suppressing the cell survival.

CONCLUSIONThe CDglyTK fusion gene system driven by KDR promoter can inhibit the proliferation of SCG7901 and ECV304 cells with obvious bystander effect in vitro. The combination of the prodrugs produces obvious synergetic effect against the cell survival.