Résumé
Objective To evaluate the selectively killing effect of adenovirus(Ad)mediated double suicide gene driven by VEGF promoter on pancreatic cancer cell SW1990. Methods VEGFexpressing SW1990 were infected by Ad-VEGFP-CDTK and Ad-null.respectively.The infection rate was observed and the expression of CDTK was detected by RT-PCR and Western blotting.Followed by treatment with 5-FC and GCV killing effects were evaluated and bystander effects were analyzed by MTF.Pathological character of cells was observed by electron microscopy and distribution of cell cycle was detected by flow cytometry.The caspase-3 activity was detected by absorption spectrometry. Results The infection rate of the resultant recombinant Ad to SW1990 cells was not apparently different.RT-PCR and Western blotting demonstrated product of CDTK gene in SW1990 cell infected by Ad-VEGFP-CDTK.Prodrug could inhibit proliferation of SW1990 and the effect was dose-dependent.There was considerable bystander effect as observed by MTF.Apoptotic peak was also shown by flow cytometry.Morphologic features of apoptosis in SW1990 cells were displayed via electron microscopy.Cells at the G0-G1 phase was increasing and the rate at the G2-M and S phase was decreased by prodrug.The caspase-3 activity gradually rised with the increasing concentration of the prodrug. Conclusions The CDTK fusion gene system controlled by VEGF promoter has killing effect on the VEGF-expressing SW1990 cells and inducing the cell apoptosis.
Résumé
Objective To study the effects of suicide gene system mediated by adenovirus containing the CD-TK fusion gene controlled by human vascular endothelial growth factor(VEGF)promoter on apoptosis of human hepatocellular carcinoma cells HepG2 in vitro.Methods The VEGF-expressing HepG2 cells were infected by adenovirus vector containing CD-TK fusion gene controlled by the VEGF promoter(Ad-VEGFP-CDglyTK).The infection efficiencies in HepG2 cells were observed under a fluorescence microscope.The toxic effect of 5-fluorocytosine(5-FC)and ganciclovic(GCV)on infected cells was determined by light microscopy,electron-microscopy and flow cytometry(FCM).Results The transfection efficiency in HepG2 cells increased with the increasing adenoviral titer.The pro-drug(5-FC and GCV)could induce apoptosis of HepG2 cells in certain range of dosage(the doses of GCV+5-FC:1mg/L + 20mg/L,10mg/L + 40mg/L,100mg/L + 60mg/L)at the multiplicity of infection(MOI)of 100.The effect showed a time-dependent manner.HepG2 cells showed typical morphologic changes of apoptosis after administration of the pro-drug(GCV:10mg/L,5-FC:40mg/L)for 72 hours:chromatin condensation and disposition along nuclear membrane.Karyopyknosis and karyoklasis were seen under electron microscopy(?10 000).Apoptotic peak was also shown in HepG2 cells treated with the pro-drug(5-FC and GCV)by flow cytometry.The cell apoptosis rate was increased accordingly as the concentration of pro-drug(5-FC and GCV)increased.The apoptosis was increased obviously in comparison with the negative control group(P