Induction of a bystander mutagenic effect of alpha particles in mammalian cells
Induction of a bystander mutagenic effect of alpha particles in mammalian cells
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DOI：
10.1073/pnas.030420797
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发表时间：
2000-02-29
影响因子：
11.1
通讯作者：
Hei, TK
中科院分区：
文献类型：
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作者：
Zhou, HN;Randers-Pehrson, G;Hei, TK
自从一百多年前伦琴发现x射线以来，人们一直认为电离辐射的有害影响，如突变和致癌，主要是由于对DNA的直接损害。尽管基于微剂量估计支持旁观者效应的证据似乎是一致的，但这种核外/细胞外效应的直接证据有限。使用精密带电粒子微束，我们在这里表明，假设没有旁观者调制效应，随机选择20%的a (L)细胞，每个细胞有20个α粒子照射，导致突变分数比预期高3倍。此外，多重PCR分析表明，诱导的突变体类型与自然起源的突变体类型有显著不同。用自由基清除剂DMSO预处理细胞对致突变发生率无影响。相比之下，用40 μ M剂量的林丹预处理细胞，抑制细胞间通讯，显著降低突变体产量。在这些实验中使用的二甲基二甲苯和林丹的剂量是无毒和非致突变的。当随机选择5-10%的细胞，每个细胞20个α粒子照射时，我们进一步检测了诱变率。结果同样表明，假设没有旁观者效应，突变体产量高于预期。我们的研究提供了明确的证据，表明辐照细胞可以在未被α粒子直接穿过的邻近细胞中诱导旁观者诱变反应，并且细胞间的通信过程在介导旁观者现象中起关键作用。
Ever since the discovery of X-rays was made by Rontgen more than a hundred years ago, it has always been accepted that the deleterious effects of ionizing radiation such as mutation and carcinogenesis are attributable mainly to direct damage to DNA. Although evidence based on microdosimetric estimation in support of a bystander effect appears to be consistent, direct proof of such extranuclear/extracellular effects are limited. Using a precision charged particle microbeam, we show here that irradiation of 20% of randomly selected A(L) cells with 20 alpha particles each results in a mutant fraction that is 3-fold higher than expected, assuming no bystander modulation effect. Furthermore, analysis by multiplex PCR shows that the types of mutants induced are significantly different from those of spontaneous origin. Pretreatment of cells with the radical scavenger DMSO had no effect on the mutagenic incidence. In contrast, cells pretreated with a 40 mu M dose of lindane, which inhibits cell-cell communication, significantly decreased the mutant yield. The doses of DMSO and lindane used in these experiments are nontoxic and nonmutagenic. We further examined the mutagenic yield when 5-10% of randomly selected cells were irradiated with 20 alpha particles each. Results showed, likewise, a higher mutant yield than expected assuming no bystander effects. Our studies provide clear evidence that irradiated cells can induce a bystander mutagenic response in neighboring cells not directly traversed by alpha particles and that cell-cell communication process play a critical role in mediating the bystander phenomenon.