ROLE OF IRON IN ABESTOS-INDUCED DNA DAMAGE

这项研究的长期目标是调查 石棉致癌中的铁。石棉引起的机理 癌症是未知的。然而，石棉催化了许多同样的事情。 铁和最致癌的石棉形式可能发生的反应 铁含量高达37%。这一建议是基于这样的假设 这种铁对石棉的一些生物效应负有责任。 铁在石棉纤维中或其上可能是活性的，但 铁可能会增加其与02的反应性，从而导致更大的 毒性和致癌性。具体目标是：1)确定 石棉催化的02和02的消耗是否需要铁 自由基的产生和铁动员对这些细胞的影响 两个活动；2)确定02和铁是否负责 石棉在体外对DNA的损伤及是否动员 石棉中的铁会增加石棉引起的DNA损伤；3)确定 石棉诱导的DNA是否需要石棉中的铁或石棉上的铁 叙利亚仓鼠胚胎的损伤、细胞毒性和转化 培养中的细胞；以及4)确定是否可以从 在SHE细胞中吞噬石棉以及这种动员是否会导致 DNA损伤、细胞毒性和转化的数量增加。 去铁胺B与铁形成氧化还原不活跃的螯合物，将 用于确定石棉催化是否需要铁 体外反应和体内生物反应。使用条件 为从石棉中动员铁而设立的-效果 铁与02的反应活性的动员将由 通过使用ESR测量O2消耗和-OH的形成 带有自旋陷阱。以确定是否需要02 石棉引起的DNA损伤(单链断裂和8-OHdG)，石棉 而DNA将在没有02的情况下孵化。02自由基的作用 在启动DNA损伤方面将通过使用特定的 抑制剂(甘露醇、乙醇)或保护酶(超氧化物 歧化酶、过氧化氢酶)。为了确定细胞内的影响 铁在青石棉上的活化引起DNA损伤、细胞毒性和 SHE细胞的转化，细胞将用石棉或 石棉之后是NTA，一种可以穿透细胞的铁络合剂 膜和促进02自由基的形成。

The long term objective of this research is to investigate the role of iron in asbestos-induced cancer. The mechanism by which asbestos causes cancer is unknown. However, asbestos catalyzes many of the same reactions that iron does and the most carcinogenic forms of asbestos can contain as much as 37% iron. This proposal is based upon the hypothesis that iron is responsible for some of the biological effects of asbestos. The iron may be active in or on the asbestos fiber, but mobilization of the iron may increase its reactivity with 02 resulting in greater toxicity and carcinogenicity. The specific aims are: 1) to determine whether iron is required for asbestos-catalyzed 02 consumption and 02 radical generation and determine the effect of iron mobilization on these two activities; 2) To determine whether 02 and iron are responsible for the DNA damage induced by asbestos in vitro and whether mobilization of iron from asbestos increases asbestos-induced DNA damage; 3) to determine whether iron in or on asbestos is required for asbestos-induced DNA damage, cytotoxicity, and transformation in Syrian hamster embryo (SHE) cells in culture; and 4) to determine whether iron can be mobilized from phagocytized asbestos in SHE cells and whether this mobilization results in increased amounts of DNA damage, cytotoxicity, and transformation. Desferrioxamine B, which forms a redox-inactive chelate with iron, will be used to determine whether iron is required for asbestos-catalyzed reactions in vitro and biological responses in vivo. Using conditions established for mobilization of iron from asbestos, the -effect of mobilization on the reactivity of iron with 02 will be determined by measuring 02 consumption and by measuring the formation of -OH using ESR with spin trapping. To determine whether 02 is required for asbestos-induced DNA damage (single strand breaks and 8-OHdG) , asbestos and DNA will be incubated in the absence of 02. The role of 02 radicals in initiating DNA damage will be investigated by using specific inhibitors ( mannitol, ethanol) or protective enzymes (superoxide dismutase, catalase). To determine the effect of intracellular mobilization of iron on crocidolite induced DNA damage, cytotoxicity and transformation of SHE cells, cells will be treated with asbestos or asbestos followed by NTA, an iron chelator that can penetrate cell membranes and promote 02 radical formation.