Effect Of Bifidobacterium Infantis-mediated TK/GCV Suicide Gene Therapy System In A Rat Model Of Bladder Cancer

Objective: To evaluate the curative effect of Bifidobacteriuminfantis-mediated thymidine kinase (BI-TK) suicide gene therapy system onbladder cancer in a Sprague-Dawley (SD) rat model of bladder tumors andstudy the effect of BI-TK suicide gene therapy system on bladder cancer cellapoptosis and Fas/Fas ligand expression in the rat bladder tumor model.Methods:(1) The recombinant plasmid of expressing TK suicide gene wasconstructed.(2) Bifidobacterium infantis-mediated HSV-TK/GCV suicide genetherapy system was constructed.(3) The rat models of bladder cancer induced by intravesicalN-methyl-N-nitrosourea (MNU) were randomly divided into three groups:normal saline/ganciclovir (GCV) control group (normal saline group),BI-pGEX-5X-1/GCV group (empty plasmid group) and BI-pGEX-TK/GCVtreatment group (recombinant plasmid group). Each group was treated withinjecting into tumor-bearing rats via tail vein, followed by intraperitonealinjection of GCV, a total of4weeks of treatment. (4) The weights of rat bladder tumors of each group were determined4weeks after treatment. Apoptosis of bladder tumor cells in each group weredetermined by TUNEL assay. Fas/FasL expressions were detected by reversetranscription PCR (RT-PCR) and western blotting.Results:(1) The recombinant plasmid of expressing TK suicide gene wasSuccessfully constructed.(2) Bifidobacterium infantis-mediated HSV-TK/GCV suicide genetherapy system was Successfully constructed.(3) Comparing with the normal saline group and empty plasmid group,the weight of bladders in recombinant plasmid group were significantlylower (P<0.05).(4) While various degrees of apoptosis of the tumor cells were detectedin all groups by TUNEL assay, apoptosis was mostly notable in theBI-pGEX-TK/GCV treatment group (P<0.05).(5) RT-PCR and western blotting further demonstrated that theBI-pGEX-TK/GCV treatment group had the highest level of Fas/FasL geneand protein expressions than those of normal saline group and the emptyplasmid group (P<0.05).Conclusion:(1) The BI-pGEX-TK/GCV suicide gene therapy system caneffectively inhibit rat bladder tumor growth. (2) The effect of BI-pGEX-TK/GCV suicide gene therapy systeminhibit rat bladder tumor growth, possibly through activating the Fas/FasLpathway, thus inducing apoptosis of the rat bladder tumor cells.