Identification of gamma-radiation induced early response genes by subtractive hybridization Method: Sangwoo Bae, Korea Cancer Center Hospital, Korea

Full text: In order to determine early response genes that are induced by gamma-radiation, we screened messenger RNA from human lung cancer cell line, NCI-H460, for differentially expressed-genes after 2 hours of gamma irradiation. Dose-dependent gene expression profile was established by screening mRNA samples prepared from 1cGy, 1Gy or 10Gy irradiated NCI-H460 cells. Each dose of gamma irradiation produced distinctive set of early induced-genes. 1cGy of gamma irradiation induced expression of genes that are involved in various cellular metabolism such as glycolysis (phosphoglycerate mutase 1, 2-phosphopyruvate-hydratase-alpha-enolase), nucleotide metabolism (hypothetical protein FLJ12484, inosine monophosphate dehydrogenase 2, SnRNP core protein SmD2), translation (ribosomal phosphoprotein P0), and iron metabolism (ferritin L-chain). 1Gy of gamma irradiation induced genes involved in cell cycle (CDC2L1, centrin and galectin 3), cellular calcium regulation (copine1 and calcyclin), and p53 transactivation (p53R2). 10Gy gamma-irradiation induced apoptosis-related genes including BAD, BID, BAK, AIF, BAX, and DR5. Of particular note are genes that are regulated by p53, which is one of the major regulators of radiation response. P53 target genes (PGAM1, p53R2, BID, BAX, and DR5) were induced within two hours of gamma irradiation with doses ranging from 1cGy to 10Gy. This observation suggests that p53 transactivates early radiation response genes in broad range of dose and the resulting induced genes may mediate later radiation response. We find it very useful to use those identified genes as markers for dose-specific gamma-radiation and to study effect of various treatments on radiation response by following those gene expressions