Landi S, Ponzanelli I, Hirvonen A, Norppa H, Barale R
Dpt. of Scienze dell'Ambiente e del Territorio, Pisa University, Italy.
Mutat Res. 1996 Mar 26;351(1):79-85. doi: 10.1016/0027-5107(95)00215-4.
Spontaneous and diepoxybutane (DEB)-induced sister-chromatid exchanges (SCEs) were examined in whole-blood lymphocyte cultures of 3 men and 4 women. A strong increase in mean number of SCEs per cell with increasing DEB concentrations (0, 2, and 4 microM) was observed in cultures of all subjects, but 3 of the donors were clearly more sensitive than the others. The SCE measurements were repeated 2-6 times per donor over a period of 55 months to assess the stability of the individual SCE response. The results showed that SCE induction by DEB was steady in the individuals during the follow-up at each DEB dose, with no significant differences among the repeated experiments. At 4 microM DEB, the DEB-sensitive and -resistant donors could be reliably be differentiated from each other in all trials. As DEB-sensitivity has been suggested to be due to the lack of glutathione S-transferase (GST) T1, the donors were genotyped for the presence of GSTT1 and GSTM1 genes. The 3 individuals found to be DEB-sensitive were all of the GSTT1 null genotype, whereas the 4 DEB-resistant donors were GSTT1 positive, which supported the role of the GSTT1 gene in determining DEB-sensitivity. Three of the DEB-resistant and none of the DEB-sensitive had the GSTM1 null genotype. Thus, the lack of the GSTM1 gene was not associated with the DEB-sensitivity trait. In conclusion, the present findings show that individual SCE responses to treatment of cultured human lymphocytes with DEB can reliably be reproduced in repeated trials. The results confirm that the GSTT1 gene but not the GSTM1 gene is important in determining individual sensitivity to the in vitro genotoxicity of DEB.
在3名男性和4名女性的全血淋巴细胞培养物中检测了自发的以及由1,4 - 丁二醇二缩水甘油醚（DEB）诱导的姐妹染色单体交换（SCEs）。在所有受试者的培养物中，均观察到随着DEB浓度（0、2和4 microM）增加，每个细胞的SCE平均数量显著增加，但有3名供体明显比其他供体更敏感。在55个月的时间里，对每个供体重复进行2 - 6次SCE测量，以评估个体SCE反应的稳定性。结果表明，在随访期间，每个DEB剂量下个体对DEB诱导的SCE反应是稳定的，重复实验之间无显著差异。在4 microM DEB时，在所有试验中均可可靠地区分对DEB敏感和耐药的供体。由于有人提出DEB敏感性是由于缺乏谷胱甘肽S - 转移酶（GST）T1，因此对供体进行了GSTT1和GSTM1基因存在情况的基因分型。发现的3名对DEB敏感的个体均为GSTT1无效基因型，而4名对DEB耐药的供体GSTT1呈阳性，这支持了GSTT1基因在决定DEB敏感性中的作用。4名对DEB耐药的供体中有3名具有GSTM1无效基因型，而对DEB敏感的个体均无此基因型。因此，GSTM1基因的缺失与DEB敏感性特征无关。总之，目前的研究结果表明，在重复试验中可以可靠地重现个体对用DEB处理培养的人淋巴细胞的SCE反应。结果证实，GSTT1基因而非GSTM1基因在决定个体对DEB体外遗传毒性的敏感性方面很重要。
