Team:Nanjing China Bio/Safety2

To confirm the distribution of VNP20009 in mouse tissues and to verify the tumor-specific gene induction, we detected GFP expression in tumor, liver, and spleen by fluorescence microscopy. We found the VNPpLacZ-GFP (with constitutive promoter) could induce expression not only in necrotic tumor but also in spleen and liver tissue. However, VNPpNirBeGFP (with tumor specific promoter) could only be induced in hypoxic and necrotic tumor tissue.


Fluorescence microscopy shows the preferential accumulation of VNP20009 pNirBeGFP in necrotic and hypoxic areas inB16F10 tumors. The nirB promoter could be induced specifically in this area but not in liver or spleen. N, necrotic tumor area; V, vital tumorcells. This experiment was carried out in triplicate.
Expression of TRAIL in S. typhimurium effectively driven bynirB promoter.
We designed plasmid constructs expressinggenes of interest for Salmonella- mediated tumor-targeted therapy using the nirB promoter. Our fluorescence microscopy revealed that the nirB promoter could effectively drive theexpression of GFP in S. typhimuriumstrain VNP20009 carryingthe plasmid construct pNirBeGFP under hypoxia,suggesting that the nirB promoter was a potent promoter.


S. typhimurium strain VNP20009 carryingpNirBeGFP or peGFP was grown for 24 h under anaerobic or aerobic conditions. Expression of GFP was examined by fluorescence microscope