title: Antitumor effects of a dual-specific lentiviral vector carrying the Escherichia coli purine nucleoside phosphorylase gene.
abstract: The Escherichia coli purine nucleoside phosphorylase/Fludarabine phosphate (ePNP/Fludara) suicide system has several drawbacks, such as side-effects and the low efficiency of ePNP expression. In this study, we evaluated the antitumor effects of the dual-specific 8HSEs-hTERTp-ePNP/Fludara suicide system under hyperthermia in vitro and in vivo. Luciferase activities from the 8HSEs‑hTERT and CMV promoters were compared using the dual luciferase assay in SW480 (high hTERT expression) and MKN74 cells (hTERT-negative) in the presence and absence of hyperthermia. Then, we investigated the effects of overexpressing the suicide gene ePNP using 8HSEs‑hTERT-driven lentiviral vectors with Fludara on in vitro cell viability, side-effects, apoptosis, cycle distribution, colony formation and in vivo xenograft tumor growth. At 43˚C, luciferase activity from the 8HSEs‑hTERT promoter was significantly increased in SW480 cells, but not in MKN74 cells. Importantly, luciferase activities from the 8HSEs‑hTERT promoter were much higher than from the CMV promoter in hTERT-expressing SW480 cells under heated conditions. The in vitro quantitative analysis showed a 4-fold higher ePNP protein expression from the 8HSEs‑hTERT promoter at 43˚C than at 37˚C in SW480 cells and the ePNP mRNA expression in SW480 cells at 43˚C was also higher than at 37˚C. Conversely, ePNP mRNA and protein expression were low, almost absent, in hTERT-negative MKN74 cells with or without hyperthermia. After Fludara addition, cell cytotoxicity assays showed that the significant inhibitory effect of the 8HSEs‑hTERTp-ePNP on SW480 cells was dose- and time-dependent with hyperthermia. The 8HSEs‑hTERTp-ePNP/Fludara suicide system significantly inhibited SW480 cell viability, colony formation, cell cycle progression and induced apoptosis in vitro, but also induced significant bystander effects, especially under the heated conditions. At the protein level, the suicide system significantly promoted Bax, caspase-3 and p53 expression and suppressed Bcl-2 expression. In sections from mouse xenografts, TUNEL assays showed that the suicide system reduced xenograft growth and induced SW480 apoptosis. These results indicated that the combinatorial cancer- and heat-specific promoter system has great potential for improving the efficacy of cancer treatment with hyperthermia. The 8HSEs‑hTERTp-ePNP/Fludara system may serve as a powerful strategy for cancer gene therapy combined with hyperthermia.
authors.affiliation: Department of Oncology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of General Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Sun
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Junhui
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Gao
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Jianbao
authors.initials: J
authors.lastname: Zheng
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D045744:Cell Line, Tumor; D004926:Escherichia coli / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D041722:Genes, Transgenic, Suicide / Q000235:genetics; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics / Q000627:therapeutic use*; D049452:Green Fluorescent Proteins; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D009369:Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D011683:Purine-Nucleoside Phosphorylase / Q000096:biosynthesis / Q000235:genetics* / Q000627:therapeutic use; D019098:Telomerase / Q000235:genetics / Q000627:therapeutic use; D023041:Xenograft Model Antitumor Assays
chemical_list: D049452:Green Fluorescent Proteins; D011683:Purine-Nucleoside Phosphorylase; C509186:TERT protein, human; D019098:Telomerase