HORMONAL MODIFICATIONS OF RADIATION INDUCED MUTAGENESIS

描述（申请人的描述）诱变是一种前体， 癌 穿梭载体系统已经成功地证明， 紫外线辐射（即阳光）导致的特定DNA损伤 可以产生对皮肤细胞中的癌症诱导很重要的突变。 电离辐射暴露是乳腺癌的一个众所周知的原因，然而， 用电离辐射和乳腺细胞进行的类似穿梭载体研究 还没有完成。此外，DNA损伤的致突变潜力 已知细胞中的蛋白质水平受环境因素的调节， 生理压力和药物。然而，激素的潜力（ 乳腺细胞代谢的主要调节剂）来修饰突变 乳腺细胞未知。动物研究表明，激素可以 由于照射时间的影响， 在发情周期或怀孕期间， 大鼠辐射诱发乳腺癌发病率的决定因素。 这是一个应用程序，以评估激素对 电离辐射诱发的乳腺细胞突变。我们的方法 将是测量经处理和/或辐射的诱变- 处理的乳腺细胞在体外，使用穿梭载体。穿梭载体 系统是通用的，因为它们可以用于测量 不同类型细胞中DNA损伤的致突变潜力，或 同一细胞在不同环境条件下的突变 （例如：激素或辐射处理）。DNA在体外会被破坏 用辐射或拟辐射药物，然后转染到 乳腺细胞宿主，在那里受损的DNA将 由细胞DNA修复酶代谢处理。DNA将 然后回收并检测突变。 由于DNA 已知合成、修复和调节酶会受到影响 根据生理状态，我们的假设是激素治疗将 改变辐射产生的突变的数量和类型。 这些信息可能提示DNA修复机制或转导 这些通路是神经反应性的，并可能提示 抑制或预防辐射诱发的乳腺癌。最近 我们实验室的结果表明，辐射诱变可能 通过哺乳动物细胞的两个主要的“易错”DNA修复途径发生 可以用穿梭载体质粒DNA 单链或双链断裂。 我们将使用这样的质粒 为了确定这些通路在乳腺细胞中的潜在作用， 诱变 拟议的研究是一项探索性试验 这个项目有望在未来发展成为一个更全面， 乳腺癌研究项目。 它直接解决了以下问题： 乳腺癌病因学，这是RFA的优先领域。下 这一领域，它还包括三个研究课题， 表达了对RFA的兴趣：辐射、激素和 基因与环境的相互作用此外，根据《公约》的目标， RFA，首席研究员，虽然已经建立， 乳腺癌研究领域的新发现

DESCRIPTION (Applicant's Description) Mutagenesis is a precursor to cancer. Shuttle vector systems have successfully demonstrated that specific DNA lesions resulting from ultraviolet radiation (i.e. sunlight) can produce mutations important to cancer induction in skin cells. Ionizing radiation exposure is a well known cause of breast cancer, yet similar shuttle vector studies with ionizing radiation and mammary cells have not been done. Additionally, the mutagenic potential of DNA damage in cells is known to be modulated by environment factors, such physiological stress and drugs. Yet, the potential of hormones (the major modulators of mammary cell metabolism) to modify mutagenesis in mammary cells is not known. Animal studies suggest that hormones can influence radiation mutagenesis, since the timing of irradiation during the estrous cycle or during pregnancy is a significant determinant of incidence of radiation-induced breast cancer in rats. This is a application to assess the influence of hormones on ionizing-radiation-induced mutagenesis in mammary cells. Our approach will be to measure mutagenesis in hormonally-treated and/or radiation- treated mammary cells in vitro, using shuttle vectors. Shuttle vector systems are versatile in that they can be used to measure either the mutagenic potential of DNA lesions in different types of cells, or mutations in the same cells under different environmental conditions (eg. hormone- or radiation-treated). DNA will be damaged in vitro with radiation or radiomimetic drugs and then transfected into mammary cell hosts, where the damaged DNA will be metabolically processed by cellular DNA repair enzymes. The DNA will then be recovered and assayed for mutations. Since DNA synthesis, repair, and regulatory enzymes are known to be affected by physiological states, our hypothesis is that hormonal treatment will alter both the quantity and type of mutations produced by radiation. This information may suggest DNA repair mechanisms or transduction pathways that are hormonally responsive and may suggest ways of inhibiting or preventing radiation-induced breast cancer. Recent results, from our laboratory, suggest that radiation mutagenesis may occur via two major "error-prone" DNA repair pathways of mammalian cells that can be independently probed using shuttle vector plasmid DNA with either single- or double-strand breaks. We will use such plasmids to determine the potential roles of these pathways in mammary cell mutagenesis. The proposed study represents an exploratory pilot project that will hopefully develop into a future, more comprehensive, breast cancer research project. It directly addresses problems of breast cancer etiology, which is a priority area of the RFA. Under this area, it also incorporates three research topics that are of expressed interest to the RFA: effects of radiation, hormones, and gene- environment interactions. Also, in accordance with the goals of the RFA, the Principal Investigator, although well established, is new to the field of breast cancer research.