Screening of differential expressive genes in murine cells following radon exposure

This study was designed to construct and identify the subtracted cDNA library in peripheral blood cells of BALB/c mice and tracheal-bronchial epithelial cells of Wistar rats following exposure to radon inhalation. Two groups of the animals were exposed in a radon chamber at an accumulative dose of 100 WLM, while control animals were housed in a room at a background dose of 1 WLM. To construct a subtracted cDNA library enriched with differentially expressed genes, the SMART technique and suppression subtractive hybridization (SSH) assay were performed. The obtained forward and reverse cDNA fragments were directly inserted into a pMD-18 vector and transformed into Escherichia coli JM109. In total, 593 white bacterial clones were selected from both forward- and reverse-subtracted libraries. Among them, 81 clones were chosen for their differential expressions based on reverse Northern blot. Portions of these cDNA clones were also verified by a quantitative real-time polymerase chain reaction (PCR). The screening resulted in 14 upregulative and 8 downregulative known function/annotation genes, which were revealed to be functionally related to cell proliferation, cell oxidative and DNA damage, apoptosis, and tumor promotion. Access numbers were obtained from the GenBank for 11 unknown expressed sequence tags (EST). Analysis of biological roles of these cDNA fragments may provide further insight into mechanisms underlying adverse molecular events induced by high-dose radon exposure.