BASIC MECHANISM OF ESTROGEN-INDUCED CANCER

激素与美国三分之一的癌症有关。 雌激素尤其与乳腺癌有关， 女性生殖道 己烯雌酚（DES），一种合成 雌激素与人类癌症密切相关，可诱发100%的癌症。 六个月内的仓鼠 有证据表明雌激素 具有肿瘤促进活性。此外，雌激素也可能 参与肿瘤的发生。 在此，建议发起一项 对雌激素代谢物可能 通过一种或多种途径提高背景诱变。 以下 关于雌激素致突变潜力的具体问题，使用 DES的活性代谢物作为模型，将在本 项目(1)己烯雌酚-4 '，4”-醌（DES Q）是否致突变 通过与DNA的直接共价或非共价相互作用？(2)如果 是致突变的，（a）哪种DNA碱基是最常见的突变靶点？ (b)突变的特异性是什么？ 调制器的诱变影响诱变DES Q？(c)是否 诱变活性与核苷酸水平的DNA损伤有关 序列？(3)如果它不是诱变性的，DNA损伤是否会发生， 导致显著的诱变增强？实验策略 用于检测诱变的方法包括体外加合模型DNA 基因组，它们在大肠杆菌或培养的人类宿主中的复制 细胞，鉴定和序列水平表征任何 标记基因突变。 DES 0的DNA损伤将通过以下方法进行评估： 通过后标记，放射性雌激素与DNA的共价结合 方法，通过旨在检测隐蔽损害的方法，以及通过 目前用于在序列水平上定位损伤位点的分子方法。 DES Q与DNA的非共价相互作用的致突变潜力将 在一个实验系统中进行评估，在该系统中，DNA将在 在DES Q的存在下体外转染，然后转染 复制DNA以评估致突变后果。

Hormones are involved in a third of all cancers in the United States. Estrogens in particular have been implicated in cancers of the breast and of the female genital tract. Diethylstilbestrol (DES), a synthetic estrogen strongly linked to human cancer, can induce cancer in 100% of hamsters within six months. There is evidence to suggest that estrogens have a tumor promoting activity. In addition, estrogens may also participate in tumor initiation. Here, it is proposed to initiate a rigorous examination of the possibility that metabolites of estrogens can elevate background mutagenesis by one or more pathways. The following specific questions concerning the mutagenic potential of estrogens, using a reactive metabolite of DES as the model, will be addressed in this project. (1) Is diethylstilbestrol-4',4"-quinone (DES Q) mutagenic through a direct covalent or non-covalent interaction with DNA? (2) If it is mutagenic, (a) which DNA base is the most frequent mutational target? (b) what is the mutational specificity and which of the known genetic modulators of mutagenesis affect mutagenesis by DES Q? (c) does the mutagenic activity correlate with DNA damage at the level of nucleotide sequence? (3) If it is not mutagenic, does DNA damage occur without leading to significant mutagenic enhancement? The experimental strategy for detecting mutagenesis consists of in vitro adduction of model DNA genomes, their replication in Escherichia coli or in cultured human host cells, identification and sequence-level characterization of any mutations in marker genes. DNA damage by DES 0 will be assessed by covalent binding of radioactive estrogen to DNA, by the post-labeling method, by methods aimed at detecting cryptic damage, as well as by current molecular methods for mapping damage sites at the sequence level. Mutagenic potential of the non-covalent interactions DES Q with DNA will be assessed in an experimental system in which DNA will be replicated in vitro in the presence of DES Q, followed by transfection of the replicated DNA to evaluate mutagenic consequences.