Specific killing effects of double suicide gene system on pancreatic cancer Capan-2 cells / 肿瘤

ABSTRACT

Objective: To evaluate the specific killing effect of adenovirus (Ad)-mediated double suicide gene system (CD/TK fusion genes) driven by VEGF promoter on pancreatic cancer Capan-2 cells. Methods: VEGF-positive Capan-2 cells were transfected with Ad-VEGFP-CDTK. Ad-free vector acted as negative control. The transfection efficiency was observed and the transcription of CDTK gene was detected by RT-PCR. The Capan-2 cells were treated with 5-fluorocytosine (5-FC) and ganciclovir (GCV) at different concentrations. The effects of the double suicide gene system on cell proliferation and the bystander effects were assessed by MTT assay. Then morphological changes were observed by electronic microscopy and distribution of cell cycle was determined by flow cytometry. Human pancreatic cancer Capan-2 cells were subcutaneously implanted into nude mice. The tumor inhibition rate was calculated. Results: The infection rates of the two resultant recombinant Ads in Capan-2 cells were not significantly different, and they were gradually elevated with the increase in multiple of infection (MOI) of Ads. MTT assay showed that pre-drug dose-dependently inhibited the growth of Capan-2 cells. Apparent bystander effects were also observed. Electronic microscopy demonstrated apoptotic changes of Capan-2 cells. Typical apoptotic peak was detected in double suicide gene system-treated group by flow cytometry. Cell cycle distribution analysis showed that the proportion of G0/G1 increased and the number of cells in G2/M and S phase decreased after treatment. The implanted tumor model was successfully established in nude mice. The tumor size was decreased significantly after treatment with double suicide gene system. Conclusion: The promoter of VEGF regulated double suicide gene system can specifically kill pancreatic cancer Capan-2 cells and induce apoptosis in vitro. And it significantly inhibites the growth of implanted pancreatic tumor in nude mice.