Diwadkar-Navsariwala Veda, Diamond Alan M
Department of Human Nutrition, University of Illinois at Chicago, Chicago, IL 60612, USA.
J Nutr. 2004 Nov;134(11):2899-902. doi: 10.1093/jn/134.11.2899.
Selenium is effective in reducing cancer incidence in animal models, and epidemiologic data, as well as supplementation trials, have indicated that selenium is likely to be effective in humans. The mechanism by which selenium prevents cancer remains unknown. The mammalian genome encodes 25 selenoprotein genes, each containing one or more molecules of selenium in the form of the amino acid selenocysteine, translationally inserted into the growing peptide in response to the UGA codon. There is evidence that several of these proteins may be involved with the mechanism by which selenium provides its anticancer effects. Data are reviewed indicating that genetic variants of the cytosolic glutathione peroxidase are associated with increased cancer risk, and that loss of one of the copies of this same gene may be involved with malignant progression. Similarly, allelic differences in the gene for a second selenoprotein, Sep15, may be relevant to the protection provided by selenium, and allelic loss at this locus have been reported as well. These data, along with the differential expression patterns reported for other selenoproteins in tumor vs. normal tissues, support the role of selenoproteins in the chemoprotection by selenium.
硒在动物模型中可有效降低癌症发病率，流行病学数据以及补充试验表明，硒可能对人类也有效。硒预防癌症的机制尚不清楚。哺乳动物基因组编码25个硒蛋白基因，每个基因都含有一个或多个以硒代半胱氨酸形式存在的硒分子，这些硒分子会响应UGA密码子而翻译插入到正在生长的肽中。有证据表明，其中几种蛋白质可能与硒发挥抗癌作用的机制有关。本文综述了相关数据，这些数据表明胞质谷胱甘肽过氧化物酶的基因变异与癌症风险增加有关，并且该基因的一个拷贝缺失可能与恶性进展有关。同样，另一种硒蛋白Sep15基因的等位基因差异可能与硒提供的保护作用有关，并且也有关于该位点等位基因缺失的报道。这些数据，连同肿瘤组织与正常组织中其他硒蛋白的差异表达模式，都支持了硒蛋白在硒的化学保护作用中的作用。
