Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase, inhibits the early step in homologous recombination
Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase, inhibits the early step in homologous recombination
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DOI：
10.1111/j.1349-7006.2011.02004.x
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发表时间：
2011-09-01
期刊：
影响因子：
5.7
通讯作者：
Fukushima, Masakazu
中科院分区：
文献类型：
--
作者：
Sakata, Koh-Ichi;Someya, Masanori;Fukushima, Masakazu
Gimeracil（5-氯- 2,4 -二羟基吡啶）是一种二氢嘧啶脱氢酶（DPYD）抑制剂，可降解血液中的嘧啶，包括5-氟尿嘧啶。Gimeracil最初被添加到口服氟嘧啶衍生物S-1中，以延长血清和肿瘤组织中5-氟尿嘧啶的浓度。我们已经报道了gimeracil通过部分抑制DNA双链断裂修复中的同源重组（HR）而具有放射增敏作用。我们研究了gimeracil放射致敏的机制。进行了彗星实验和辐射诱导的各种HR相关蛋白的焦点形成。将DPYD的siRNA转染到HeLa细胞中，研究gimeracil放射致敏的靶蛋白。采用SCneo实验检测siRNA缺失DPYD是否抑制DNA双链断裂的HR修复。中性彗星试验中尾矩增加。Gimeracil抑制了Rad51和复制蛋白A （RPA）的病灶形成，而增加了Nbs1、Mre11、Rad50和FancD2的病灶数量。在辐照前转染DPYD siRNA后，HeLa细胞的放射敏感性增强。转染DPYD siRNA后的放射线致敏程度与gimeracil相似。Gimeracil对dpyd耗竭细胞没有致敏作用。在SCneo实验中，siRNA耗尽DPYD显著降低了新阳性克隆的频率。吉美拉西部分抑制HR的早期阶段。我们发现DPYD是甘美拉西放射致敏的靶蛋白。DPYD抑制剂，如gimeracil，可以通过部分抑制hr介导的DNA修复来增强放疗的疗效。（癌症科学2011；02:1712-1716）
Gimeracil (5-chloro-2, 4-dihydroxypyridine) is an inhibitor of dihydropyrimidine dehydrogenase (DPYD), which degrades pyrimidine including 5-fluorouracil in the blood. Gimeracil was originally added to an oral fluoropyrimidine derivative S-1 to yield prolonged 5-fluorouracil concentrations in serum and tumor tissues. We have already reported that gimeracil had radiosensitizing effects by partially inhibiting homologous recombination (HR) in the repair of DNA double strand breaks. We investigated the mechanisms of gimeracil radiosensitization. Comet assay and radiation-induced focus formation of various kinds of proteins involved in HR was carried out. siRNA for DPYD were transfected to HeLa cells to investigate the target protein for radiosensitization with gimeracil. SCneo assay was carried out to examine whether DPYD depletion by siRNA inhibited HR repair of DNA double strand breaks. Tail moments in neutral comet assay increased in gimeracil-treated cells. Gimeracil restrained the formation of foci of Rad51 and replication protein A (RPA), whereas it increased the number of foci of Nbs1, Mre11, Rad50, and FancD2. When HeLa cells were transfected with the DPYD siRNA before irradiation, the cells became more radiosensitive. The degree of radiosensitization by transfection of DPYD siRNA was similar to that of gimeracil. Gimeracil did not sensitize DPYD-depleted cells. Depletion of DPYD by siRNA significantly reduced the frequency of neopositive clones in SCneo assay. Gimeracil partially inhibits the early step in HR. It was found that DPYD is the target protein for radiosensitization by gimeracil. The inhibitors of DPYD, such as gimeracil, could enhance the efficacy of radiotherapy through partial suppression of HR-mediated DNA repair. (Cancer Sci 2011; 102: 1712-1716)