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. Aim 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. Conclusion Survivin is a selective potent radiation inducible promoter for glioblastoma viral gene therapy and this response to radiation could be independent of CArG motifs.

The Role of the Transcription Factor EGR1 in Cancer

“…The promoter of EGR1 contains the characteristic CArG box sequence for SRF binding, which is activated by radiation ( 76 , 77 ). EGR1 is reported to regulate target genes—after ionizing radiation induces it—e.g., TNF-α , TP53 , RB , and BAX , and to cause tumor cell growth arrest or cell death ( 52 , 78 ).…”

Survivin Promoter-Driven DFF40 Gene Expression Sensitizes Melanoma Cancer Cells to Chemotherapy

“…Previous studies proposed that some stresses like hypoxia and radiation can increase activity of survivin promoters. 21,30 Naoum et al 30 and Yang et al 21 proposed that some regulatory elements responsive to radiation and hypoxia might exist in the sequence of survivin promoter. However, according to the best of our knowledge this is the first report on synergistic effect of survivin-driven gene therapy and chemotherapy.…”

Synthetic and systems biology principles in the design of programmable oncolytic virus immunotherapies for glioblastoma

“…64,65 Radiosensitive promoters such as the survivin promoter, which have increased expression in cells that are exposed to radiation, can be used to selectively express the genetic circuit in irradiated GBMs. 66…”