Enhanced EJ Cell Killing of ¹²⁵I Radiation by Combining with Cytosine Deaminase Gene Therapy Regulated by Synthetic Radio-Responsive Promoter

Abstract

Aim: 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 125I 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 125I 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 125I 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 125I, green fluorescence can be observed and 5-FU can be detected. MTT assay showed that the survival rate for infected cells treated with 125I was lower compared with the 125I control group, but higher than the positive control group.Conclusion: The synthetic promoter E8 can induce the expression of downstream CD gene under 125I radiation, and the tumor killing effect of 125I can be enhanced by combining CD gene therapy with radiosensitive promoter.

Enhanced tumor inhibiting effect of 131I-BDI-1-based radioimmunotherapy and cytosine deaminase gene therapy modulated by a radio-sensitive promoter in nude mice bearing bladder cancer

“…In our previous study, we constructed a recombinant lentivirus E8-codA-GFP, which included a synthetic RSP E8, with eight CArG elements (CC(A/T)6GG sequence), CD suicide gene and GFP gene reporter. Upon infection of EJ BC cells with the recombinant lentivirus, the cells were irradiated with 37, 74 and 148 kBq of Na 125 I aq., in presence of 5-FC [ 8 ]. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay, we demonstrated remarkable killing ability of this novel anti-tumor therapy.…”

“…Our previous experiment found [ 8 ] upon pE8-CD plasmid transfection into EJ cells, the highest transfection efficiency appeared at 48 hours. Therefore, we chose 48 hours after transfection to begin our experiments.…”

Analysis of iodinated quorum sensing peptides by LC–UV/ESI ion trap mass spectrometry

“…Radio-iodination (i.e. incorporation of radioactive iodine such as 123 I, 125 I or 131 I) is a technique commonly used for radioligand investigations, medical imaging and therapy [9] , [10] . Several direct and indirect iodination methods for peptides currently exist.…”