Targeted cytoplasmic irradiation with alpha particles induces mutations in mammalian cells
Targeted cytoplasmic irradiation with alpha particles induces mutations in mammalian cells
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DOI：
10.1073/pnas.96.9.4959
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发表时间：
1999-04-27
影响因子：
11.1
通讯作者：
Hei, TK
中科院分区：
文献类型：
--
作者：
Wu, LJ;Randers-Pehrson, G;Hei, TK
自从70多年前X射线被证明可以诱导果蝇突变以来，流行的教条认为电离辐射的遗传毒性效应，如突变和致癌，主要是由于对细胞核的直接损伤。虽然有迹象表明，阿尔法粒子穿过细胞质是无害的，但全部影响仍不清楚，哥伦比亚大学放射研究加速器设施的微束的可用性使其能够在高度局部化的空间区域中靶向和照射单个细胞的细胞质。通过使用双重荧光染料(Hoechst和尼罗红)分别定位细胞核和细胞质，从而避免无意中穿越细胞核，我们在这里展示了细胞质照射在人-金黄地鼠杂交(AL)细胞的CD59(S1)位点上是诱变的，同时造成的细胞毒性最小。诱发的主要突变类型类似于自发起源的突变，与核辐射的突变完全不同。此外，用自由基清除剂和细胞内谷胱甘肽抑制剂进行的实验表明，细胞质辐射的致突变性依赖于活性氧的产生。这些发现表明，细胞质是电离辐射，特别是氡的遗传毒性效应的重要目标，氡是美国肺癌的第二大原因。此外，阿尔法粒子的细胞质穿透可能比核穿透更危险，因为致突变性是通过很少或根本不杀死靶细胞来完成的。
Ever since x-rays were Shown to induce mutation in Drosophila more than 70 years ago, prevailing dogma considered the genotoxic effects of ionizing radiation, such as mutations and carcinogenesis, as being due mostly to direct damage to the nucleus. Although there was indication that alpha particle traversal through cellular cytoplasm was innocuous, the full impact remained unknown, The availability of the microbeam at the Radiological Research Accelerator Facility of Columbia University made it possible to target and irradiate the cytoplasm of individual cells in a highly localized spatial region. By using dual fluorochrome dyes (Hoechst and Nile Red) to locate nucleus and cellular cytoplasm, respectively, thereby avoiding inadvertent traversal of nuclei, we show here that cytoplasmic irradiation is mutagenic at the CD59 (S1) locus of human-hamster hybrid (AL) cells, while inflicting minimal cytotoxicity. The principal class of mutations induced are similar to those of spontaneous origin and are entirely different from those of nuclear irradiation. Furthermore, experiments with radical scavenger and inhibitor of intracellular glutathione indicated that the mutagenicity of cytoplasmic irradiation depends on generation of reactive oxygen species. These findings suggest that cytoplasm is an important target for genotoxic effects of ionizing radiation, particularly radon, the second leading cause of lung cancer in the United States. In addition, cytoplasmic traversal by alpha particles may be more dangerous than nuclear traversal, because the mutagenicity is accomplished by little or no killing of the target cells.