Bastlová T, Podlutsky A
Environmental Medicine Unit, Karolinska Institute, CNT/Novum, Huddinge, Sweden.
Mutagenesis. 1996 Nov;11(6):581-91. doi: 10.1093/mutage/11.6.581.
Styrene-7,8-oxide (SO), the mutagenic in vivo metabolite of the widely used chemical monomer styrene, has been classified as a probable human carcinogen (IARC, 1994). We examined mutations in the hypoxanthine-guanine phosphoribosyl transferase (hprt) gene of primary human T-lymphocytes exposed to 0.2 mM SO for 6 days in vitro. PCR amplification and direct DNA sequencing were used to identify 55 SO-induced mutations from two experiments in which the mutation frequencies increased 3.6 and 4.8 times respectively, and 44 control mutations from untreated T-cell cultures. Base substitutions were the dominating type of mutation in both groups, with 35 and 23 independent changes, of which nine and six respectively, have not previously been described in human T-cells. Frameshift mutations (+/-1 bp) and small deletions (2-200 bp) were less frequent and splicing mutations more frequent among the SO-induced than among the control mutations. In SO-treated mutants, base substitutions in the coding region occurred at 15 sites, nine of which were AT bp, and in the splice donor and acceptor regions six of 10 mutated sites were AT bp. Altogether six independent mutations were found at site 539 in cells from the two SO experiments (four GC > AT and two GC > TA). In the control cultures, base substitutions in the coding and splicing regions were identified at 20 sites, eight of which were AT bp. In published data on hprt mutation in untreated T-cells in vivo and in vitro, 31 of 88 base substitutions have been reported to occur at AT bp. These results indicate that SO-induced mutations at the hprt locus in human T-lymphocytes are predominantly base substitutions, and suggest that in addition to DNA adducts at guanine bases, adducts at A and/or T bases also deserve attention with regard to the mutagenesis of SO.
苯乙烯 -7,8 - 氧化物（SO）是广泛使用的化学单体苯乙烯的体内诱变代谢产物，已被国际癌症研究机构（IARC，1994年）列为可能的人类致癌物。我们检测了体外暴露于0.2 mM SO 6天的原代人T淋巴细胞次黄嘌呤 - 鸟嘌呤磷酸核糖转移酶（hprt）基因中的突变。采用聚合酶链反应（PCR）扩增和直接DNA测序，从两个实验中鉴定出55个SO诱导的突变，其中突变频率分别增加了3.6倍和4.8倍，同时从未经处理的T细胞培养物中鉴定出44个对照突变。两组中碱基替换都是主要的突变类型，分别有35个和23个独立变化，其中分别有9个和6个此前未在人T细胞中描述过。移码突变（±1 bp）和小缺失（2-200 bp）在SO诱导突变中比对照突变中更少见，而剪接突变在SO诱导突变中更常见。在经SO处理的突变体中，编码区的碱基替换发生在15个位点，其中9个是AT碱基对，在剪接供体和受体区域，突变位点中的10个有6个是AT碱基对。在来自两个SO实验的细胞中，总共在539位点发现了6个独立突变（4个GC>AT和2个GC>TA）。在对照培养物中，编码区和剪接区的碱基替换在20个位点被鉴定出来，其中8个是AT碱基对。在已发表的关于体内和体外未经处理的T细胞中hprt突变的数据中，88个碱基替换中有31个据报道发生在AT碱基对。这些结果表明，SO诱导的人T淋巴细胞hprt基因座突变主要是碱基替换，并表明除了鸟嘌呤碱基处的DNA加合物外，A和/或T碱基处的加合物在SO诱变方面也值得关注。
