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Vascular endothelial growth factors (VEGF) play important roles in angiogenesis, vasculogenesis and endothelial cell growth. In endothelial cancers, secreted VEGF proteins induce endothelial cell proliferation, promote cell migration, inhibit apoptosis and induce blood vessel permeabilization. VEGFA is frequently overexpressed in human colorectal cancers (CRC) and its expression correlates with tumor progression and invasiveness. In this study we examine the effect of knocking down VEGFA expression by infecting RKO colorectal cancer cells with lentiviral particles containing VEGFA-targeting RNAi constructs. We found that suppressing VEGFA dramatically decreased RKO cell proliferation, colony formation, invasion, migration and tumor growth. Furthermore, VEGFA knock-down reduced MAPK pathway signaling and Smac/DIABLO expression. These results suggest that lentivirus-mediated RNAi knock-down of VEGFA could be an effective therapy for the treatment of CRC.

The immunogenicity of adenovirus that causes the clearance by the host, is the major barrier to successful gene transfer. Some special cells such as cornea-epithelial cells and testicular Sertoli cells can induce apoptosis in immune cells with Fas molecule through expression and secretion of Fas ligand (FasL). Aims: To construct FasL and inducible nitric-oxide synthase (iNOS) co-expressed PCA_(13) plasmid used for packing of adenovirus, so as to observe the immunoprotective effect of FasL on adenovirus vector. Methods: By way of internal ribosome entry site (IRES), genetic engineering techniques as preparation and transformation of competent cells, plasmid extraction, agarose gel electrophoresis, restriction enzymolysis were used for the construction of polycistron adenoviral expression vector PCA_(13)/FasL-IRES-iNOS, which could co-express with FasL and iNOS gene after multi-subcloning steps. Results: FasL and iNOS gene connected with IRES were successfully cloned to PCA_(13) plasmid and verified by enzymolysis (600 bp FasL, 1000 bp IRES and 4000 bp iNOS), and the gene sequence was concordant with the Genebank. Conclusions: It is one of the crucial steps to construct successfully the polycistron adenoviral expression vector PCA_(13)/FasL-IRES-iNOS for the gene therapy of portal hypertension.