Expression of sense and cis-natural antisense transcripts in the human B lymphoblastic cell line IM-9 after X-ray irradiation

Ionizing radiation (IR) causes DNA injury and induces multiple signal mechanisms, including the regulation of DNA repair, the cell cycle and gene expression through the activation of p53-related pathways. Cis-natural antisense transcripts (cis-NATs), which are transcribed from the DNA strand opposite to that for mRNA of the gene, are recognized as important regulators of gene expression in eukaryotic cells, but the effects on cis-NAT expression by IR are unknown to date. Therefore, we investigated the effects of X-ray irradiation on sense and cis-NAT expression together with mRNA expression using a human B lymphoblast cell line (IM-9) and a custom-microarray. In the present study, the cis-NATs, up- and down-regulated by X-ray irradiation (0 Gy, 1 Gy, 2 Gy and 4 Gy), were investigated using IM-9 cells having a high sensitivity to ionizing radiation and using a custom-microarray containing human sense/antisense probes for approximately 21,000 genes.