title: Survivin a radiogenetic promoter for glioblastoma viral gene therapy independently from CArG motifs.
abstract: BACKGROUND
  Radiogenetic therapy is a novel approach in the treatment of cancer, which employs genetic modification to alter the sensitivity of tumor cells to the effect of applied radiation.
  
  
  OBJECTIVE
  To select a potent radiation inducible promoter in the context of brain tumors and to investigate if CArG radio responsive motifs or other elements in the promoter nucleotide sequences can correlate to its response to radiation.
  
  
  METHODS
  To select initial candidates for promoter inducible elements, the levels of mRNA expression of six different promoters were assessed using Quantitative RTPCR in D54 MG cells before and after radiation exposure. Recombinant Ad/reporter genes driven by five different promoters; CMV, VEGF, FLT-1, DR5 and survivin were constructed. Glioma cell lines were infected with different multiplicity of infection of the (promoter) Ad or CMV Ad. Cells were then exposed to a range of radiation (0-12 Gy) at single fraction. Fluorescent microscopy, Luc assay and X-gal staining was used to detect the level of expression of related genes. Different glioma cell lines and normal astrocytes were infected with Ad survivin and exposed to radiation. The promoters were analyzed for presence of CArG radio-responsive motifs and CCAAT box consensus using NCBI blast bioinformatics software.
  
  
  RESULTS
  Radiotherapy increases the expression of gene expression by 1.25-2.5 fold in different promoters other than survivin after 2 h of radiation. RNA analysis was done and has shown an increase in copy number of tenfold for survivin. Most importantly cells treated with RT and Ad Luc driven by survivin promoter showed a fivefold increase in expression after 2 Gy of radiation in comparison to non-irradiated cells. Presence or absence of CArG motifs did not correlate with promoter response to radiation. Survivin with the best response to radiation had the lowest number of CCAAT box.
  
  
  CONCLUSIONS
  Survivin is a selective potent radiation inducible promoter for glioblastoma viral gene therapy and this response to radiation could be independent of CArG motifs.
authors.affiliation: Alexandria Comprehensive Cancer Center, Alexandria, Egypt.
authors.forename: George E
authors.initials: GE
authors.lastname: Naoum
authors.affiliation: Division of Human Gene Therapy, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Zeng B
authors.initials: ZB
authors.lastname: Zhu
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Buchsbaum
authors.affiliation: Cancer Biology Division, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Curiel
authors.affiliation: Alexandria Comprehensive Cancer Center, Alexandria, Egypt. W.o.arafaat@gmail.com.|Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA. W.o.arafaat@gmail.com.|Clinical Oncology Department, Alexandria University, 3 Azarita Street, Alexandria, 21131, Egypt. W.o.arafaat@gmail.com.
authors.forename: Waleed O
authors.identifier: http://orcid.org/0000-0002-6617-5992
authors.initials: WO
authors.lastname: Arafat
keywords: CArG motifs; Gene therapy; Glioblastoma multiforme; Promoter; Survivin; Transcription regulation