Combs G F, Gray W P
Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA.
Pharmacol Ther. 1998 Sep;79(3):179-92. doi: 10.1016/s0163-7258(98)00014-x.
The element selenium (Se) was recognized only 40 years ago as being essential in the nutrition of animals and humans. It is recognized as being an essential component of a number of enzymes, in which it is present as the amino acid selenocysteine. Se compounds have also been found to inhibit tumorigenesis in a variety of animal models, and recent studies indicate that supplemental Se in human diets may reduce cancer risk. The antitumorigenic activities have been associated with Se intakes that correct nutritionally deficient status in animals, as well as higher intakes that are substantially greater than those associated with maximal expression of the selenocysteine-containing enzymes. Therefore, it is proposed that while some cancer protection, particularly that involving antioxidant protection, involves selenoenzymes, specific Se metabolites, which are produced in significant amounts at relatively high Se intakes, also discharge antitumorigenic functions. According to this two-stage model of the roles of Se in cancer prevention, individuals with nutritionally adequate Se intakes may benefit from Se supplementation. Evidence for chemoprevention by Se and for the apparent mechanisms underlying these effects is reviewed to the end of facilitating the development of the potential of Se compounds as cancer chemopreventive agents.
元素硒（Se）直到40年前才被认定为动物和人类营养中的必需元素。它被认为是多种酶的重要组成部分，在这些酶中它以氨基酸硒代半胱氨酸的形式存在。人们还发现硒化合物在多种动物模型中可抑制肿瘤发生，并且最近的研究表明，人类饮食中补充硒可能降低患癌风险。抗肿瘤活性与纠正动物营养缺乏状态的硒摄入量有关，也与大大高于含硒代半胱氨酸酶最大表达量的较高摄入量有关。因此，有人提出，虽然一些癌症预防作用，特别是涉及抗氧化保护的作用，与含硒酶有关，但在相对高的硒摄入量下大量产生的特定硒代谢物也具有抗肿瘤功能。根据硒在癌症预防中作用的这一两阶段模型，硒摄入量营养充足的个体可能从补充硒中获益。本文综述了硒化学预防的证据以及这些作用背后明显的机制，以便促进将硒化合物开发为癌症化学预防剂的潜力。
