Nishioka Takeshi, Miyai Yusuke, Haga Hisashi, Kawabata Kazushige, Shirato Hiroki, Homma Akihiro, Shibata Kenichiro, Yasuda Motoaki
Department of Biomedical Sciences and Engineering, Faculty of Health Sciences, Graduate School of Health Sciences, Hokkaido University, Sapporo, Japan.
Cell Struct Funct. 2009;34(1):17-22. doi: 10.1247/csf.08041. Epub 2009 Mar 17.
To find a new molecule that affects p53-dependent radiosensitivity.
A mouse sarcoma cell line, QRsP(p53+/+), was used. From this cell line, we established a radiosensitive clone and a radioresistant one. Colony assay, p53 gene transfer, a luciferase assay for p53 and p21, animal transplantation experiment, and DNA array analyses were performed.
Microarray showed marked reduction of a transcription factor, ATF5, both in vitro and in vivo for the radiosensitive clone. Interestingly, flow cytometric analysis demonstrated marked apoptosis for the radiosensitive clone by p53 cloned adenovirus infection. Luciferase reporter assay revealed that ATF5 suppressed the transactivational activity of p53 and p63. By ATF5 gene transfer, the radiosensitive clone regained resistance to both ionizing-radiation and Ad-p53 infection-induced cell death. Surprisingly, time-lapse cell migration observation revealed greater cell motility for ATF5-transfected radiosensitive clone.
It seems likely that ATF5 is a potent repressor of p53 and elevated expression of ATF5 in a tumor may relate to enhanced malignant phenotypes, such as radioresistance or greater cell motility.
寻找一种影响p53依赖性放射敏感性的新分子。
使用小鼠肉瘤细胞系QRsP(p53+/+)。从该细胞系中，我们建立了一个放射敏感克隆和一个放射抗性克隆。进行了集落测定、p53基因转移、p53和p21的荧光素酶测定、动物移植实验以及DNA阵列分析。
微阵列显示，放射敏感克隆在体外和体内的一种转录因子ATF5均显著减少。有趣的是，流式细胞术分析表明，通过p53克隆腺病毒感染，放射敏感克隆出现明显凋亡。荧光素酶报告基因测定显示，ATF5抑制p53和p63的反式激活活性。通过ATF5基因转移，放射敏感克隆对电离辐射和Ad-p53感染诱导的细胞死亡重新获得抗性。令人惊讶的是，延时细胞迁移观察显示，ATF5转染的放射敏感克隆具有更大的细胞运动性。
ATF5似乎是p53的有效抑制剂，肿瘤中ATF5表达升高可能与增强的恶性表型有关，如放射抗性或更大的细胞运动性。
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