Abstract
A derivative of murine immortal NIH/PG13Luc cells stably transfected with p53-dependent luciferase reporter plasmid was used for detection of transcriptional activity of p53 in response to radiations. This cell line was sensitive enough to detect p53 response to low dose rate γ-ray irradiation (ranging from 0.1-5 cGy/h for 60Co γ-rays) as well as to acute X-ray. The cells irradiated by low dose rate γ-ray (1 cGy/h at 72 h, and 5 cGy/h at 72 h) undergo growth arrest that was correlated with p53-mediated CDKN1A/p21 up-regulation. Microarray analysis showed up-regulation of seven p53-mediated genes, CDKN1A/p21, MDM2, SIP27, CCNG1/cyclin G1, EI24/PIG8, POLK, and BAX, at 1 to 10 cGy/h exposure: CDKN1A/p21 and CCNG1/cyclin G1, were significantly increased at more than 1 cGy/h, whereas MDM2 and BAX showed increase at more than 10 cGy/h exposure. Taken together, the data suggested that cells show differential response to the different doses of radiation and involve more than one pathway. (This work was supported by Aomori Prefecture, Japan.) [J Radiat Res 44:388-389 (2003)]
