title: Dual specific antitumor effects of Semliki Forest virus-based DNA vector carrying suicide Escherichia coli purine nucleoside phosphorylase gene via Salmonella.
abstract: The Escherichia coli purine nucleoside phospho-rylase/2-fluoro-2-deoxyadenosine (ePNP/F-dAdo) suicide system has demonstrated a powerful killing and bystander effects on tumor cells. However, several drawbacks to this approach remain to be resolved, such as the side-effects and the low efficiency of ePNP-targeted expression. A human telo-merase reverse transcriptase promoter-driven Semliki Forest virus-based DNA vector (pShT-ePNP) with high expression of the ePNP gene was constructed. Live attenuated Salmonella typhimurium 7207 (SL7207) was used initially as a vehicle to targetly transfer the large alphavirus vector into tumor cells. The in vitro quantitative analysis showed ~2-fold higher green fluorescent protein (GFP) expression for pShT-GFP than for conventional cytomegalovirus (CMV) promoter-mediated eukaryotic expression plasmids such as pIRES-GFP and the targeted expression of the ePNP gene in tumor cells was also detected by RT-PCR. After F-dAdo addition, the enzymatic conversion of F-Ado into 2-fluoroadmine (F-Ade) was tested by HPLC. Cell cytotoxicity assays showed that the significant inhibitory effect of the SL/pShT-ePNP system on tumor cells was dose- and time-dependent. Following oral administration, recombinant bacteria targetly allocated within the solid tumor and the expression of ePNP and GFP genes in vivo were detected by RT-PCR or observed by fluorescence microscopy. SL/pShT-ePNP and F-dAdo were also found to exert powerful therapeutic effects in combination against tumor growth and for prolonging the lifespan of tumor-bearing mice. These findings suggest that the SL/pShT-ePNP system may serve as a powerful strategy for tumor therapy.
authors.affiliation: Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China.
authors.forename: Zhi-Hao
authors.initials: ZH
authors.lastname: Chen
authors.forename: Ge-Ling
authors.initials: GL
authors.lastname: Huang
authors.forename: Ya-Qin
authors.initials: YQ
authors.lastname: Tu
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiang
authors.forename: Wu-Xing
authors.initials: WX
authors.lastname: Dai
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D019496:Cancer Vaccines / Q000235:genetics / Q000494:pharmacology*; D003839:Deoxyadenosines / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D041722:Genes, Transgenic, Suicide; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics / Q000494:pharmacology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic; D011683:Purine-Nucleoside Phosphorylase / Q000235:genetics*; D012486:Salmonella typhimurium / Q000235:genetics; D012672:Semliki forest virus / Q000235:genetics*; D019098:Telomerase / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D019496:Cancer Vaccines; D003839:Deoxyadenosines; D049452:Green Fluorescent Proteins; C030964:2'-fluoro-2'-deoxyadenosine; D011683:Purine-Nucleoside Phosphorylase; C509186:TERT protein, human; D019098:Telomerase