title: Enhanced EJ Cell Killing of (125)I Radiation by Combining with Cytosine Deaminase Gene Therapy Regulated by Synthetic Radio-Responsive Promoter.
abstract: OBJECTIVE
  To investigate the enhancing effect of radionuclide therapy by the therapeutic gene placed under the control of radio-responsive promoter.
  
  
  METHODS
  The recombinant lentivirus E8-codA-GFP, including a synthetic radiation-sensitive promoter E8, cytosine deaminase (CD) gene, and green fluorescent protein gene, was constructed. The gene expression activated by (125)I radiation was assessed by observation of green fluorescence. The ability of converting 5-fluorocytosine (5-FC) to 5-fluorourial (5-FU) by CD enzyme was assessed by high-performance liquid chromatography. The viability of the infected cells exposed to (125)I in the presence of 5-FC was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the infected cells exposed to (125)I alone served as negative control and 5-FU as positive control.
  
  
  RESULTS
  The recombinant lentiviral vector was constructed successfully. On exposure of infected cells to (125)I, green fluorescence can be observed and 5-FU can be detected. MTT assay showed that the survival rate for infected cells treated with (125)I was lower compared with the (125)I control group, but higher than the positive control group.
  
  
  CONCLUSIONS
  The synthetic promoter E8 can induce the expression of downstream CD gene under (125)I radiation, and the tumor killing effect of (125)I can be enhanced by combining CD gene therapy with radiosensitive promoter.
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .|2 Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi, China .
authors.forename: Chun-li
authors.initials: CL
authors.lastname: Zhang
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .
authors.forename: Lei
authors.initials: L
authors.lastname: Kang
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .
authors.forename: Rong-Fu
authors.initials: RF
authors.lastname: Wang
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .
authors.forename: Ping
authors.initials: P
authors.lastname: Yan
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .
authors.forename: Lei
authors.initials: L
authors.lastname: Yin
authors.affiliation: 1 Department of Nuclear Medicine, Peking University First Hospital , Beijing, China .
authors.forename: Feng-qin
authors.initials: FQ
authors.lastname: Guo
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000378:metabolism; D002295:Carcinoma, Transitional Cell / Q000473:pathology*; D045744:Cell Line, Tumor; D002470:Cell Survival; D043525:Cytosine Deaminase / Q000235:genetics / Q000378:metabolism*; D051766:Early Growth Response Protein 1 / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005437:Flucytosine / Q000378:metabolism; D005472:Fluorouracil / Q000378:metabolism; D005813:Genes, Synthetic; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D007457:Iodine Radioisotopes / Q000494:pharmacology*; D016086:Lentivirus / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000528:radiation effects*; D011836:Radiation Tolerance; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020080:Tandem Repeat Sequences / Q000235:genetics; D014161:Transduction, Genetic; D001749:Urinary Bladder Neoplasms / Q000473:pathology*
chemical_list: D000964:Antimetabolites, Antineoplastic; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D029968:Escherichia coli Proteins; D007457:Iodine Radioisotopes; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D005437:Flucytosine; D043525:Cytosine Deaminase; C468827:codA protein, E coli; D005472:Fluorouracil
keywords: 125I; 5-fluorocytosine; cytosine deaminase; radiation-sensitive promoter; recombinant lentivirus