Protective Effects of Amino Acids on Plasmid DNA Damage Induced by Therapeutic Carbon Ions
Protective Effects of Amino Acids on Plasmid DNA Damage Induced by Therapeutic Carbon Ions
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DOI：
10.1667/rade-21-00033.1
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发表时间：
2021-08-01
影响因子：
3.4
通讯作者：
Yasuda, Hiroshi
中科院分区：
文献类型：
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作者：
Yogo, Katsunori;Murayama, Chieko;Yasuda, Hiroshi
副作用少的辐射防护剂可用于直接诱导DNA聚集性损伤的碳离子治疗。为了找到最有效的辐射防护剂，我们研究了所选氨基酸的作用，这些氨基酸可能对治疗性碳离子具有化学DNA修复功能。在本研究中，我们使用了五种氨基酸：色氨酸（Trp）、半胱氨酸（Cys）、蛋氨酸（Met）、缬氨酸（瓦尔）和丙氨酸（Ala）。在TE缓冲液（10 mM Tris，1 mM乙二胺四乙酸，pH 7.5）中制备具有17 mM氨基酸的超螺旋pBR 322质粒DNA样品。磷酸盐缓冲盐水（PBS）也用于0.17 mM氨基酸的测定。在日本千叶的国立放射科学和重离子医用加速器研究所，用碳离子束（290 MeV/u）在6 cm展开的布拉格峰上照射样品。DNA断裂作为质粒的变化进行检测，并通过随后在琼脂糖凝胶上电泳进行定量。每种氨基酸的DNA损伤产率和保护因子计算为相对于无试剂对照的比率。Trp和Cys在PBS和TE缓冲液中对碳离子束诱导的质粒DNA损伤具有辐射保护作用，与Met相当。Trp的双链断裂（DSB）产量和保护作用与Cys相当。单链断裂和DSB的产量与本体溶液中羟基自由基的清除能力（清除羟基自由基的速率常数乘以氨基酸浓度）相关。这些数据表明，氨基酸对碳离子诱导的质粒DNA损伤的辐射保护作用可以主要通过清除羟基自由基的能力来解释。这些结果表明，一些氨基酸，如色氨酸，半胱氨酸和蛋氨酸，有很好的潜力，作为辐射保护剂，防止在正常组织中的DNA损伤的碳离子治疗。(C)2021辐射研究学会
Radioprotectors with few , side effects are useful for carbon-ion therapy, which directly induces clustering damage in DNA. With the aim of finding the most effective radioprotector, we investigated the effects of selected amino acids which might have chemical DNA-repair functions against therapeutic carbon ions. In the current study, we employed five amino acids: tryptophan (Trp), cysteine (Cys), methionine (Met), valine (Val) and alanine (Ala). Samples of supercoiled pBR322 plasmid DNA with a 17 mM amino acid were prepared in TE buffer (10 mM Tris, 1 mM ethylenediaminetetraacetic acid, pH 7.5). Phosphate buffered saline (PBS) was also used in assays of the 0.17 mM amino acid. The samples were irradiated with carbon-ion beams (290 MeV/u) on 6 cm spread-out Bragg peak at the National Institute of Radiological Sciences and Heavy Ion Medical Accelerator in Chiba, Japan. Breaks in the DNA were detected as changes in the plasmids and quantified by subsequent electrophoresis on agarose gels. DNA damage yields and protection factors for each amino acid were calculated as ratios relative to reagent-free controls. Trp and Cys showed radioprotective effects against plasmid DNA damage induced by carbonion beam, both in PBS and TE buffer, comparable to those of Met. The double-strand break (DSB) yields and protective effects of Trp were comparable to those of Cys. The yields of both single-strand breaks and DSBs correlated with the scavenging capacity of hydroxyl radicals (rate constant for scavenging hydroxyl radicals multiplied by the amino acid concentration) in bulk solution. These data indicate that the radioprotective effects of amino acids against plasmid DNA damage induced by carbon ions could be explained primarily by the scavenging capacity of hydroxyl radicals. These findings suggest that some amino acids, such as Trp, Cys and Met, have good potential as radioprotectors for preventing DNA damage in normal tissues in carbon-ion therapy. (C) 2021 by Radiation Research Society