Abstract # 1118 A Genomic Screening Based Strategy for the Creation of Radiation Inducible Gene Therapy Vectors

Presenter: Advani, Sunil

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Microarray analysis was performed in duplicate for control U-87 cells and the 3 experimental groups using samples harvested 3 hrs post IR. A cutoff of 2 fold induction was used to identify candidate transcripts in the experimental groups. Using stringent criteria, 21 unique transcripts were identified as being upregulated > 2 fold in cell exposed to Ad and IR compared to control U-87 cells. Gene products with the highest level of induction in the combined treatment were growth differentiation factor 15 (GDF15) and B1 for mucin (HAB1). None of the 21 gene products whose transcription was enhanced by the combination of Ad and IR were induced in the presence of Ad alone. 4 of the 21 gene transcripts induced by the combination of Ad and IR were also induced by IR alone. These genes were p21, GADD45a, sestrin1, and GDF15. We have further studied the transcription of p21 and GDF15 using quantitative RT-PCR. For the quantitative RT-PCR studies, samples from 1.5, 3 and 9 hrs post IR were used. The p21 gene product was induced 2 fold at 1.5 hrs, 4 fold at 3 hrs and 1.5 fold at 9 hrs post IR + Ad. There was no quantitative difference in the level of p21 transcription between IR alone or IR + Ad. In contrast the level of GDF15 transcription showed an interaction between IR and Ad. At 3 hrs post IR, GDF15 was elevated 2 fold by IR alone and elevated 4 fold by IR + Ad. Interestingly GDF15 transcription was not enhanced by Ad alone.