The method of safety evaluation of chemopreventive agents based on the ability of damaging human genes

基于破坏人体基因能力的化学预防剂安全性评价方法

基本信息

批准号：
10557040
负责人：
KAWANISHI Shosuke
金额：
$ 7.62万
依托单位：
Mie University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

Cancer chemoprevention is very important in preventive medicine. Attempts have been made for cancer chemoprevention using antioxidants, such as vitamins and flavonoids, which have been believed to be promising chemopreventive agents. However, a recent epidemiological study revealed that the administration of β-carotene to male smokers caused an increase in the incidence of lung cancer. In this study, to develop the method for safety evaluation of antioxidants, we examined DNA damage induced by antioxidants using human cultured cells and ^<32>P-labeled DNA fragments obtained from the human c-Ha-ras protooncogene and the p16 and p53 tumor suppressor genes. We found that β-carotene metabolites, retinol and retinal, induced DNA damage by generating reactive oxygen species in the presence of Cu(II). In human cultured cells, these metabolites caused DNA cleavage and a significant increase in the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), an oxidative product of guanine, at low concentrations. Vitamin E (α-tocopherol) and N-acetylcysteine were also capable of causing oxidative DNA damage. Among the flavonoids tested, quercetin caused oxidative DNA damage in cultured cells, whereas luteolin did not. Isothiocyanates also caused oxidative DNA damage through the formation of thiol compounds. Allyl isothiocyanate caused stronger DNA damage than benzyl isothiocyanate and phenethyl isothiocyanate. These finding indicate that antioxidants can serve as proxidants, capable of causing carcinogenesis via oxidative DNA damage. The present study provided insight into the development of a sensitive method to evaluate the safety of chemopreventive agents on the basis of their DNA-damaging ability.

癌症化学预防在预防医学中非常重要。已经尝试使用抗氧化剂（例如维生素和类黄酮）进行癌症化学预防，这些抗氧化剂被认为是有希望的化学预防剂。然而，最近的一项流行病学研究表明，β-胡萝卜素对雄性吸烟者的施用导致肺癌事件的增加。在这项研究中，为了开发对抗氧化剂的安全评估方法，我们检查了使用人培养细胞诱导的抗氧化剂诱导的DNA损伤，以及 ^<32> p标记的DNA片段，从人的C-HA-HA-RAS原蛋白以及P16和P53肿瘤抑制基因中获得的DNA损伤。我们发现β-胡萝卜素代谢物，视黄醇和视网膜，通过在Cu存在下产生活性氧诱导DNA损伤（II）。在人培养的细胞中，这些代谢产物引起DNA清洁，并在低浓度下形成8-氧-7,8-二氢-2'-脱氧鸟苷（8-氧化物），鸟嘌呤的氧化产物。维生素E（α-生育酚）和N-乙酰半胱氨酸也能够引起氧化性DNA损伤。在测试的类黄酮中，槲皮素在培养的细胞中引起氧化性DNA损伤，而叶黄素则没有。异硫氰酸盐还通过硫醇化合物的形成引起氧化性DNA损伤。异硫氰酸烯丙基烯丙基酯与异硫氰酸苯甲酸苯甲酸苯甲酸苯甲酸苯甲酸苯甲酸苯甲酸酯和异硫氰酸苯甲酸苯甲酸苯甲酸酯引起强大的DNA损伤。这些发现表明抗氧化剂可以用作近端，能够通过氧化DNA损伤引起癌变。本研究提供了对一种敏感方法的开发，以根据其DNA损害能力评估化学预防剂的安全性。