OBJECTIVETo evaluate the selectively killing effects of combination of adenovirus mediated double suicide gene driven by kinase-domain insert containing receptor (KDR) promoter and survivin antisense oligonucleotide on breast tumor cells and vein endothelial cells.

METHODSHuman embryonal kidney cells 293 were transfected with the plasmids of pAdEasy-KDR-CDglyTK and the adenovirus was generated. The KDR expressive cells of MCF-7, ECV304 were infected by adenovirus and survivin ASODN was transferred into the same cells meanwhile. The infection rates of adenovirus and transfection efficiency of survivin ASODN were observed and the expression of CDglyTK was detected by RT-PCR. The expression of survivin was measured by Western blot. The killing effects and bystander effects on cells were assessed by MTT assay.

RESULTSThe cells infected by the adenovirus mediated double suicide gene could be transfected with the survivin ASODN and the infection rate was not affected as well as the transfection rate. The high expression of CDglyTK gene was found in the two kinds of cells and survivin ASODN decreased the survivin protein level. When survivin ASODN was transferred into MCF-7, ECV304 cells, the survival rates were 56.4% +/- 3.8% and 55.9% +/- 3.6% respectively. The combination of survivin ASODN and AdKDR-CDglyTK gene therapy showed significantly lower survival rate comparing with using each treatment alone (P < 0.05) and the survival rate decreased gradually with the increasing of the concentration of GCV and 5-FC. But the survival rate for combined gene therapy group was slightly lower in GCV 100 microg/ml, 5-FC 2000 microg/ml than that of AdKDR-CDglyTK group (P > 0.05). The combination of survivin ASODN and AdKDR-CDglyTK therapy showed synergistic killing efficacy and more significant bystander effects.

CONCLUSIONThe combined therapy with AdKDR-CDglyTK system and survivin ASODN shows obvious killing effects on breast tumor cells and vein endothelial cells.