Gene expression in mammalian cells after exposure to 95 MeV/amu argon ions

Abstract

High LET radiations, such as heavy ions or neutrons, have an increased biological effectiveness compared to X-rays for gene mutation, genomic instability and carcinogenesis. Estimating the biological risks from space radiation encountered by cosmonauts will continue to influence long term duration in space, such as the planned mission to Mars. The human radiation responsive genes CDKN1A (p21/WAF), GADD45a (GADD45), GADD45b (MyD118), RRM2b (p53R2) and BRCA2 (FancD1), involved in cell cycle control or damage repair, were screened for gene expression changes in MCF-7 cells by quantitative real-time reverse transcription PCR (qRT-PCR) assay, using cDNA obtained from total RNA isolated at various time points after irradiation with accelerated doses of 36-argon ions and X-rays. Examination of the expression profiles 2 and 12 h after exposure reveals a pattern consistent with a population of cells in the early response to DNA damage and invoking cell stress responses. Interesting new data showing different expression patterns according to the gene and the type of ionizing radiation used could be obtained. Results show, that the signaling and repair activities induced after heavy ion or X-ray exposure are not the same and gene expression patterns may become useful indicators for distinguishing different types of radiation in relation to their biological effects.