Effect Of Bifidobacterium Infantis-mediated HSV-tk/GCV Suicide Gene Therapy System In Renal Carcinoma Cells Transplanted Nude Mice

Objective:To evaluate the curative effect of bifidobacterium infants(BI)-mediate-d herpes simplex virus thymidine kinase(HSV-TK)/ganciclovir(GCV)suicide gene therapy system on renal carcinoma in nude mice and investigatethe effects of HSV-TK/GCV on renal carcinoma cells apoptosis and p-Stat3,Bcl-xL and Bax expression.Methods:1. The renal carcinoma model was established by subcutaneousinjection of human renal carcinoma cell line786-O into nude mice. Themodel nude mice were randomly divided into4groups, which were treatedby intraperitoneal injection of GCV in combination with tail vein injection ofnormal saline(normal saline group), BI(BI group), BI carrying emptyplasmid pGEX-5X-1(empty plasmid group) and BI carrying recombinantplasmid pGEX-TK(recombinant plasmid group).2. After4weeks treatment, the nude mice weights and the tumorweights were recorded. 3. The apoptosis of renal carcinoma tissue cells was determined byTUNEL assay.4. The expression of p-Stat3, Bcl-xL and Bax protein was determinedby immunohistochemical staining.5. The expression levels of Stat3, Bcl-xL and Bax mRNA weredetected by real-time fluorescent quantitative PCR(Real-time PCR).6. The expression levels of p-Stat3, Bcl-xL and Bax protein weredetected by protein imprinting method(Western Blot).Results:1. After treatment, comparing with the empty plasmid group, thebifidobacterium infants group and the normal saline group, the nude miceweights of recombinant plasmid group increased(P<0.05), the tumor weightsdecreased(P<0.05).2. TUNEL assay showed the apoptosis index of recombinant plasmidgroup was obviously higher than that of the empty plasmid group, thebifidobacterium infants group and the normal saline group(P<0.01).3. Immunohistochemical staining showed the expression of p-Stat3,Bcl-xL protein of recombinant plasmid group was significantly lower thanthat of the empty plasmid group, the bifidobacterium infants group and thenormal saline group(p<0.01). The expression of Bax protein of recombinantplasmid group was significantly higher than that of the empty plasmid group,the bifidobacterium infants group and the normal saline group(p<0.01). 4. The expression levels of Stat3, Bcl-xL mRNA and p-Stat3, Bcl-xLprotein of recombinant plasmid group were significantly lower than that ofthe empty plasmid group, the bifidobacterium group and the normal salinegroup(P<0.01). The expression levels of Bax mRNA and protein ofrecombinant plasmid group were significantly higher than that of the emptyplasmid group, the bifidobacterium infants group and the normal salinegroup(p<0.01).Conclusion:The bifidobacterium infants-mediated HSV-TK/GCV suicide genetherapy system effectively inhibits nude mice renal carcinoma tumor growth,probably through inhibiting Stat3activation and thereby blocking Stat3signaling pathway, decreases the expression of its downstream antiapoptoticprotein Bcl-xL and raises the expression of pro-apoptotic protein Baxinduces to nude mice renal carcinoma cells apoptosis, and thus plays a roleof tumor suppression.