在肺癌細胞中p53對修補游離輻射造成的DNA雙股斷裂之影響

• Main Authors: Tsai-hua chen, 陳彩華
• Other Authors: I-Tsuen Chen
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/13975767198183798433

碩士 === 國立陽明大學 === 醫學生物技術研究所 === 88 === Abstract Ionizing radiation（IR）can cause DNA double-strand breaks（DSBs）which trigger apoptosis, cell-cycle arrest, and DNA-repair in mammalian cells. Several genes are induced or activated by IR, including p53. To examine the role of p53 in DSBs repair following irradiation, we performed experiments using isogenic H1299 lung cancer cell lines differing by null or wild-type p53 status. Single-cell gel electrophoresis（or comet assay）was employed in detecting amounts of DNA DSBs generated in individual lung cancer cell after various doses of IR. The extent of comet formation as evidenced by increased tail length was observed in both cell lines. However, the residual DNA DSBs remaining after 2h of incubation were significantly decreased in H1299/p53, suggesting that p53 May participate in the pathway leading to DSBs repair. We also compared the rejoining ability of DSBs in both unirradiated and irradiated H1299 cells by using a DSB rejoining assay. Our results showed that the presence of wild-type p53 enhanced rejoining of a linearized-luciferase-reporter in normal or IR treated H1299/p53 cells. We then asked whether protein phosphorylation contributes to the regulation of IR-mediated p53 activation and affects subsequently DSBs repair. We found that p53 activation was abrogated in the presence of wortmannin, a PI 3-kinase inhibitor. This p53 inactivation correlated with decreased DSB repair in H1299/p53 cells in both comet and DSB rejoining assays. These findings show that IR increases DSB-rejoining activity in mammalian cells with functional p53, suggesting that p53 participates in activating DSB-rejoining following IR. In addition, it suggests PI 3-kinase may regulate p53 in activating DSB-rejoining.