Azathioprine-Induced Carcinogenesis in Mice According to Msh2 Genotype
Azathioprine-Induced Carcinogenesis in Mice According to Msh2 Genotype
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DOI：
10.1093/jnci/djq389
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发表时间：
2010-11-01
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影响因子：
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通讯作者：
Muleris, Martine
中科院分区：
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作者：
Chalastanis, Alexandra;Penard-Lacronique, Virginie;Muleris, Martine
背景硫嘌呤前体药物硫唑嘌呤广泛用于癌症治疗。暴露于该药物导致在体外选择DNA错配修复缺陷细胞克隆。也有人认为，硫嘌呤类药物可能构成了一个危险因素，为人类肿瘤的出现显示微卫星不稳定性（MSI），因为缺乏DNA错配修复。（6-20 mg/kg体重/天）对DNA错配修复基因Msh 2无效（Msh 2（-/-）; n = 27）、杂合（Msh 2（+/-）; n = 22）或野生型（Msh 2（WT）; n = 18）的小鼠进行。对照小鼠（45 Msh 2（-/-）、38 Msh 2（+/-）和12 Msh 2（WT））接受不含硫唑嘌呤的饮用水。使用对数秩和Gehan-Breslow-Wilcoxon检验通过Kaplan-Meier曲线评价硫唑嘌呤对小鼠肿瘤发生和存活的影响。小鼠肿瘤样本的特点是组织学和免疫表型，其MSI状态通过聚合酶链反应分析的三个非编码微卫星标记和免疫组化。通过杂合性丢失分析和整个Msh 2编码序列的逆转录-聚合酶链反应后测序来评估肿瘤样本的Msh 2状态。结果大多数未治疗的Msh 2（WT）和Msh 2（+/-）小鼠在250日龄时保持无症状和存活，而硫唑嘌呤治疗的Msh 2（WT）和Msh 2（+/-）小鼠发展成淋巴瘤并过早死亡（中位存活年龄分别为71和165日龄）。硫唑嘌呤处理的Msh 2（+/-）小鼠出现弥漫性淋巴瘤，缺乏Msh 2表达，并显示MSI，这是由于杂合性丢失或突变导致功能性Msh 2等位基因的体细胞失活。相比之下，硫唑嘌呤治疗的Msh 2（WT）小鼠显示没有明显的肿瘤表型，但组织学检查显示保留Msh 2表达的肿瘤淋巴细胞的显微镜脾病灶，不显示MSI。未处理和硫唑嘌呤处理的Msh 2（-/-）小鼠的寿命较未处理的Msh 2（WT）小鼠（中位生存期为127和107天的年龄，分别）和开发淋巴瘤与MSI.Conclusion硫唑嘌呤诱导的小鼠致癌作用依赖于Msh 2基因的功能拷贝数。
Background The thiopurine prodrug azathioprine is used extensively in cancer therapy. Exposure to this drug results in the selection of DNA mismatch repair-deficient cell clones in vitro. It has also been suggested that thiopurine drugs might constitute a risk factor for the emergence of human neoplasms displaying microsatellite instability (MSI) because of deficient DNA mismatch repair.Methods Azathioprine was administered via drinking water (6-20 mg/kg body weight per day) to mice that were null (Msh2(-/-); n = 27), heterozygous (Msh2(+/-); n = 22), or wild type (Msh2(WT); n = 18) for the DNA mismatch repair gene Msh2. Control mice (45 Msh2(-/-), 38 Msh2(+/-), and 12 Msh2(WT)) received drinking water lacking azathioprine. The effect of azathioprine on tumorigenesis and survival of the mice was evaluated by Kaplan-Meier curves using log-rank and Gehan-Breslow-Wilcoxon tests. Mouse tumor samples were characterized by histology and immunophenotyping, and their MSI status was determined by polymerase chain reaction analysis of three non-coding microsatellite markers and by immunohistochemistry. Msh2 status of tumor samples was assessed by loss of heterozygosity analyses and sequencing after reverse transcription-polymerase chain reaction of the entire Msh2 coding sequence. All statistical tests were two-sided.Results Most untreated Msh2(WT) and Msh2(+/-) mice remained asymptomatic and alive at 250 days of age, whereas azathioprine- treated Msh2(WT) and Msh2(+/-) mice developed lymphomas and died prematurely (median survival of 71 and 165 days of age, respectively). Azathioprine-treated Msh2(+/-) mice developed diffuse lymphomas lacking Msh2 expression and displaying MSI due to somatic inactivation of the functional Msh2 allele by loss of heterozygosity or mutation. By contrast, azathioprine-treated Msh2(WT) mice displayed no obvious tumor phenotype, but histological examination showed microscopic splenic foci of neoplastic lymphoid cells that retained Msh2 expression and did not display MSI. Both untreated and azathioprine-treated Msh2(-/-) mice had a reduced lifespan compared with untreated Msh2(WT) mice (median survival of 127 and 107 days of age, respectively) and developed lymphomas with MSI.Conclusion Azathioprine-induced carcinogenesis in mice depends on the number of functional copies of the Msh2 gene.