Antitumor effect of cytosine deaminase/5-fluorocytosine suicide gene therapy system mediated by Bifidobacterium infantis on melanoma

Aim:To construct a Bifidobacterium infantis/CD targeting gene therapy systemand observe the antitumor effect of cytosine deaminase/5-fluorocytosine(CD/5-FC)suicide gene therapy system mediated by Bifidobacterium infantis on mela-noma in vitro and in vivo.Methods:A recombinant CD/pGEX-1LamdaT plasmidwas transfected into Bifidobacterium infantis by electroporation.Bifidobac-terium infantis transfected by recombinant CD/pGEX-1LamdaT plasmid was in-cubated with 5-FC anaerobically.Then the supernatant fluid was collected andadded to melanoma B 16-F10 cells to observe the killing effect for B 16-F10 cells.Mice were inoculated with melanoma B 16-F10 cells to establish animal models.The mice were then injected with 5-FC and Bifidobacterium infantis transfectedby recombinant CD/pGEX-1LamdaT plasmid.Results:Two segments of approxi-mate 4.9 kb and 1.3 kb were extracted from the 6.2 kb recombinant plasmid,whichwere equal to the size of the pGEX-1LamdaT plasmid and CD gene,respectively.Sequencing results showed that the full length and sequence of nucleotide acid ofthe inserted gene in extracted recombinant plasmid was completely identical to theCD gene.In vitro,B16-F10 cells treated by supernatant fluid were remarkablydamaged morphologically,and the cell growth was significantly inhibited.Experi-ments on the mice melanoma model showed that after treatment with a combina-tion of transfected Bifidobacterium infantis and 5-FC,the tumor volume wassignificantly inhibited compared with controls.Conclusion:The foreign gene,CD gene,was correctly inserted into pGEX-1LambdaT plasmid and transferredinto Bifidobacterium infantis.CD/5-FC suicide gene therapy system mediated byBifidobacterium infantis demonstrated a good antitumor effect on melanoma invitro and in vivo.