Sanada Hisakazu, Ohsumi Tomoka, Koyama Naomi, Miyashita Taishi, Hashimoto Kazuto
Pharmacokinetics and Safety Department, Drug Research Center, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646, Japan.
Pharmacokinetics and Safety Department, Drug Research Center, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646, Japan.
Mutat Res Genet Toxicol Environ Mutagen. 2016 Nov 15;811:65-69. doi: 10.1016/j.mrgentox.2016.02.005. Epub 2016 Mar 2.
In vivo phosphatidylinositol glycan, class A (Pig-a) gene mutation assay using peripheral blood is known to be a novel and useful tool to evaluate the mutagenicity of compounds. Recently, the rat PIGRET assay which is an improved method for measuring Pig-a mutant cells in reticulocytes with magnetic enrichment of CD71 positive cells has been developed. Several reports showed that the PIGRET assay could detect the increase of Pig-a mutant frequency earlier than the Pig-a assay in total red blood cells (RBC Pig-a assay). Therefore, as part of a collaborative study by the Mammalian Mutagenicity Study (MMS) Group of the Japanese Environmental Mutagen Society, the usefulness of the PIGRET assay in comparison to the RBC Pig-a assay has been assessed for 24 compounds with various mechanisms of action. In the present study, we performed the PIGRET assay and RBC Pig-a assay with a nucleoside analogue, azidothymidine (AZT), and compared the results in these assays. We administered a single dose of AZT to rats by oral gavage up to 2000mg/kg and examined Pig-a mutant frequencies at days 7, 14 and 28 by PIGRET and RBC Pig-a assays. No significant increases in mutant frequency were observed after administration of AZT in both the RBC Pig-a and PIGRET assays and comparable to the previous results of the International Workshop on Genotoxicity Testing (IWGT) workgroup. AZT has been thought to induce not only DNA chain termination as a pharmacological effect but also a large deletion on the genome DNA. The Pig-a assays may be less sensitive to compounds such as AZT which induce large deletions on the genome DNA.
利用外周血进行体内磷脂酰肌醇聚糖A类（Pig-a）基因突变试验是评估化合物致突变性的一种新颖且有用的工具。最近，已开发出大鼠PIGRET试验，这是一种改进方法，用于通过磁性富集CD71阳性细胞来测量网织红细胞中的Pig-a突变细胞。几份报告表明，PIGRET试验比全红细胞中的Pig-a试验（RBC Pig-a试验）能更早地检测到Pig-a突变频率的增加。因此，作为日本环境诱变剂学会哺乳动物致突变性研究（MMS）小组合作研究的一部分，已对24种具有不同作用机制的化合物评估了PIGRET试验相对于RBC Pig-a试验的有效性。在本研究中，我们用核苷类似物叠氮胸苷（AZT）进行了PIGRET试验和RBC Pig-a试验，并比较了这些试验的结果。我们通过口服灌胃给大鼠单次给予高达2000mg/kg的AZT，并在第7、14和28天通过PIGRET试验和RBC Pig-a试验检测Pig-a突变频率。在RBC Pig-a试验和PIGRET试验中，给予AZT后均未观察到突变频率有显著增加，且与遗传毒性测试国际研讨会（IWGT）工作组的先前结果相当。AZT不仅被认为作为一种药理作用会诱导DNA链终止，还会导致基因组DNA的大片段缺失。Pig-a试验可能对诱导基因组DNA大片段缺失的化合物（如AZT）不太敏感。
