Effects of p53 mutations on cellular sensitivity to ionizing radiation.
Effects of p53 mutations on cellular sensitivity to ionizing radiation.
复制标题
p53 突变对细胞对电离辐射敏感性的影响。
DOI：
10.1097/00000421-200110000-00014
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Keng,PC
中科院分区：
文献类型：
--
作者：
Matsui,Y;Tsuchida,Y;Keng,PC
在超过50%的人类肿瘤中发现了p53肿瘤抑制基因的突变，包括乳腺癌、结肠癌、肺癌和口腔癌。然而，p53突变在放射敏感性中的意义及其潜在机制仍不清楚。在这项研究中，我们测量了p53突变对细胞周期延迟，细胞凋亡和辐射敏感性的影响，使用不同形式的p53突变转染的小鼠细胞。野生型p53和p53-p53小鼠胚胎成纤维细胞分别用作阳性和阴性对照。用0- 9-戈伊γ射线照射指数生长的细胞，然后测定细胞存活、p53表达、细胞周期检查点和凋亡。克隆形成试验测定的细胞存活率表明，p53突变细胞通常比野生型p53细胞对电离辐射更敏感。蛋白质印迹分析表明，暴露于6-戈伊γ射线增加野生型p53细胞中p53表达水平的2 - 3倍。然而，在相同的照射后时期，突变p53的细胞中p53水平保持不变。用6-戈伊γ射线照射在所有细胞系中产生G2/M阻滞，表明p53可能不参与G2/M检查点。然而，所有的突变体细胞未能显示任何显着的G1/S阻滞后照射，这表明G1/S阻滞可能与辐射敏感性。最后，在6-戈伊γ射线照射后，野生型和p53突变细胞系中检测到非常少的细胞凋亡（Tat介导的dUTP缺口末端标记[TUNNEL]和形态学测定< 3%）。我们的研究结果表明，突变形式的p53代表的表型，影响辐射敏感性，是不依赖于凋亡途径。
Mutations in the p53 tumor suppressor gene have been found in more than 50% of human tumors including those in breast, colon, lung, and oral cavity. However, the significance of p53 mutation in radiation sensitivity and its underlying mechanisms still remains unclear. In this study, we have measured the effects of p53 mutation on cell cycle delay, apoptosis, and radiation sensitivity using mouse cells transfected with different forms of p53 mutations. Wild-type p53 and p53-Null mouse embryo fibroblast cells were used as positive and negative controls, respectively. Exponentially growing cells were irradiated with 0-to 9-Gy gamma rays and then assayed for cell survival, p53 expression, cell cycle checkpoint, and apoptosis. Cell survivals determined by clonogenic assay show that p53 mutant cells are generally more sensitive to ionizing radiation than cells with wild-type p53. Western blot analysis indicates that exposure to 6-Gy gamma rays increases the p53 expression levels by two-to threefold in wild-type p53 cells. However, the p53 level remains unchanged in cells with mutant p53 during the same postirradiation period. Irradiation with 6-Gy gamma rays produces G2/M arrest in all cell lines, indicating that p53 is probably not involved in the G2/M checkpoint. However, all mutant cells fail to show any significant G1/S arrest after irradiation, suggesting that G1/S arrest may be implicated in radiation sensitivity. Finally, there is very little apoptosis (< 3% by Tat-mediated dUTP nick-end labeling [TUNNEL] and morphologic assays) detected in wild-type and p53 mutant cell lines after 6-Gy gamma rays. Our results suggest that mutant forms of p53 represent a phenotype that affects the radiation sensitivity and is not dependent on the apoptotic pathway.