Molecular Consequences of Genetic Variations in the Glutathione Peroxidase 1 Selenoenzyme
Molecular Consequences of Genetic Variations in the Glutathione Peroxidase 1 Selenoenzyme
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DOI：
10.1158/0008-5472.can-09-1791
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发表时间：
2009-10-15
期刊：
影响因子：
11.2
通讯作者：
Diamond, Alan M.
中科院分区：
文献类型：
--
作者：
Zhuo, Pin;Goldberg, Marci;Diamond, Alan M.
越来越多的数据表明，含硒的细胞溶质谷胱甘肽过氧化物酶（GPx-1）是癌症风险的决定因素，也是硒化学预防特性的介体。GPx-1的遗传变异已被证明与几种类型的恶性肿瘤的癌症风险相关。为了研究GPx-1酶活性和基因型之间的关系，我们测量了人类淋巴细胞中GPx-1酶活性和蛋白质水平，作为存在两种常见变异的函数：密码子198处的亮氨酸/脯氨酸多态性和可变数量的丙氨酸重复密码子。这些细胞系之间GPx活性的差异，以及在低水平补充硒的培养基的反应，表明基因型以外的因素是显着的，在确定活动。为了将研究限制于基因型效应，在转染GPx-1表达构建体后，将人MCF-7细胞工程化以专门表达代表密码子198亮氨酸或脯氨酸与5或7个丙氨酸重复密码子的组合的等位基因变体。选择转染子并分析GPx-1酶活性和蛋白质水平。GPx-1与5丙氨酸和亮氨酸在密码子198显示出显着更高的诱导时，细胞与硒孵育，并显示出不同的热变性模式相比，GPx-1编码的其他检查的等位基因。使用淋巴细胞和MCF-7获得的集体数据表明，内在和外在因素共同作用，最终确定可用于保护细胞免受DNA损伤和诱变的这种酶的水平。[Cancer Res 2009;69（20）：8183-90]
Accumulating data have implicated the selenium-containing cytosolic glutathione peroxidase, GPx-1, as a determinant of cancer risk and a mediator of the chemopreventive properties of selenium. Genetic variants of GPx-1 have been shown to be associated with cancer risk for several types of malignancies. To investigate the relationship between GPx-1 enzyme activity and genotype, we measured GPx-1 enzyme activity and protein levels in human lymphocytes as a function of the presence of two common variations: a leucine/proline polymorphism at codon 198 and a variable number of alanine-repeat codons. Differences in GPx activity among these cell lines, as well as in the response to the low-level supplementation of the media with selenium, indicated that factors other than just genotype are significant in determining activity. To restrict the study to genotypic effects, human MCF-7 cells were engineered to exclusively express allelic variants representing a combination of either a codon 198 leucine or proline and either 5 or 7 alanine-repeat codons following transfection of GPx-1 expression constructs. Transfectants were selected and analyzed for GPx-1 enzyme activity and protein levels. GPx-1 with 5 alanines and a leucine at codon 198 showed a significantly higher induction when cells were incubated with selenium and showed a distinct pattern of thermal denaturation as compared with GPx-1 encoded by the other examined alleles. The collective data obtained using both lymphocytes and MCF-7 indicate that both intrinsic and extrinsic factors cooperate to ultimately determine the levels of this enzyme available to protect cells against DNA damage and mutagenesis. [Cancer Res 2009;69(20):8183-90]