Borek C, Ong A, Mason H, Donahue L, Biaglow J E
Proc Natl Acad Sci U S A. 1986 Mar;83(5):1490-4. doi: 10.1073/pnas.83.5.1490.
Results from in vivo and in vitro studies showing that antioxidants may act as anticarcinogens support the role of active oxygen in carcinogenesis and provide impetus for exploring the functions of dietary antioxidants in cancer prevention by using in vitro models. We examined the single and combined effects of selenium, a component of glutathione peroxidase, and vitamin E, a known antioxidant, on cell transformation induced in C3H/10T-1/2 cells by x-rays, benzo[a]pyrene, or tryptophan pyrolysate and on the levels of cellular scavenging systems and peroxide destruction. Incubation of C3H/10T-1/2 cells with 2.5 microM Na2SeO3 (selenium) or with 7 microM alpha-tocopherol succinate (vitamin E) 24 hr prior to exposure to x-rays or the chemical carcinogens resulted in an inhibition of transformation by each of the antioxidants with an additive-inhibitory action when the two nutrients were combined. Cellular pretreatment with selenium resulted in increased levels of cellular glutathione peroxidase, catalase, and nonprotein thiols (glutathione) and in an enhanced destruction of peroxide. Cells pretreated with vitamin E did not show these biochemical effects, and the combined pretreatment with vitamin E and selenium did not augment the effect of selenium on these parameters. The results support our earlier studies showing that free radical-mediated events play a role in radiation and chemically induced transformation. They indicate that selenium and vitamin E act alone and in additive fashion as radioprotecting and chemopreventing agents. The results further suggest that selenium confers protection in part by inducing or activating cellular free-radical scavenging systems and by enhancing peroxide breakdown while vitamin E appears to confer its protection by an alternate complementary mechanism.
体内和体外研究结果表明抗氧化剂可能具有抗癌作用，这支持了活性氧在致癌过程中的作用，并为利用体外模型探索膳食抗氧化剂在癌症预防中的功能提供了动力。我们研究了谷胱甘肽过氧化物酶的一种成分硒和一种已知的抗氧化剂维生素E，对X射线、苯并[a]芘或色氨酸裂解物诱导的C3H/10T-1/2细胞转化的单一和联合作用，以及对细胞清除系统水平和过氧化物破坏的影响。在暴露于X射线或化学致癌物之前24小时，用2.5微摩尔/升亚硒酸钠（硒）或7微摩尔/升α-生育酚琥珀酸酯（维生素E）孵育C3H/10T-1/2细胞，结果显示每种抗氧化剂都能抑制细胞转化，当两种营养素联合使用时具有相加抑制作用。用硒进行细胞预处理导致细胞谷胱甘肽过氧化物酶、过氧化氢酶和非蛋白硫醇（谷胱甘肽）水平升高，并增强了过氧化物的破坏。用维生素E预处理的细胞未显示出这些生化效应，维生素E和硒联合预处理也未增强硒对这些参数的影响。这些结果支持了我们早期的研究，即自由基介导的事件在辐射和化学诱导的转化中起作用。它们表明硒和维生素E单独并以相加方式作为辐射防护剂和化学预防剂起作用。结果进一步表明，硒部分地通过诱导或激活细胞自由基清除系统以及增强过氧化物分解来提供保护，而维生素E似乎通过另一种互补机制提供保护。
