EXPERIMENTAL RADIOTHERAPY, CARCINOGENSIS, AND PROTECTORS

这项调查的最终目标是确定 化学预防策略，以降低遗传毒性损害的风险 癌症治疗期间对正常组织的治疗药物 潜在可治愈的肿瘤性疾病。即将推出的实验模型 使用的包括C3H小鼠系统，在该系统中， 次黄嘌呤-鸟嘌呤磷酸核糖转移酶(HPRT)基因与肿瘤 将调查放射和化疗引起的反应， 以及一些啮齿动物细胞系统中的化学预防 将对选定的辐射防护剂的有效性进行表征和 形成了鲜明对比。机械问题和应用问题都将得到解决。这个 要调查的三个具体目标是：A)发展 维持细胞毒作用的化学预防策略 对荷微小肺癌的小鼠的实验性治疗，同时最小化 对正常细胞的遗传毒性风险；B)表征 自发性转移过程中的化学预防作用 形成；以及C)细胞对电势的反应的特征 选定的啮齿动物细胞系统中的化学预防化合物，以评估 测定细胞内谷胱甘肽的有用性，谷胱甘肽S- 转移酶、硫醇水平、蛋白激酶C活性、DNA大小 损伤和修复，分次剂量存活和修复的变化，以及 HPRT基因座突变的频率可作为 化学预防。具有以下特性的待研究的辐射防护化合物 潜在的化学预防活性包括S-2-(3-氨基丙氨基)乙基 硫代磷酸(WR-2721)，2-(氨丙基)氨基]乙硫醇(WR- 1065)及其二硫化物(WR-33278)、N-乙酰半胱氨酸(NaC)、 前药核糖-半胱氨酸(Rib Cys)和卡托普利。将使用的治疗剂 分别是~(60)Co和X射线、环磷酰胺和顺铂。的模型 肿瘤性疾病是四种小鼠同基因肿瘤，即纤维肉瘤 纤维肉瘤(NFSA)、乳腺癌(MCAK)和淋巴瘤 可以在C3H小鼠的肺部或侧翼生长。应使用的技术 包括高效液相色谱法和单溴双胺荧光标记法检测硫醇和 二硫化物水平，通过测量测定蛋白激酶C的活性 多肽磷酸化水平因其他原因而修正为背景 碱性洗脱测定DNA单链断裂的蛋白激酶 及其相关的修复动力学，以及T-T细胞HPRT突变检测。 小鼠和选定的培养细胞系统中的淋巴细胞。HPRT 突变系统不被认为是癌症发生的预测因子，但 而是被认为是评估基因组的一个很好的标记 损坏。这项提案将调查硫醇化合物的功效，如 用于放射和化疗的化学预防药物。

The ultimate goal of this investigation is the characterization of chemopreventive strategies to reduce the risk of genotoxic damage to normal tissues by cancer therapy agents during the treatment of potentially curable neoplastic disease. The experimental models to be used include a C3H mouse system, in which both mutagenesis at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus and tumor response as a result of radiation and chemotherapy will be investigated, and a number of rodent cell systems in which the chemopreventive effectiveness of selected radioprotector agents will be characterized and contrasted. Both mechanistic and applied issues will be addressed. The three specific aims to be investigated are A) the development of chemoprevention strategies to maintain cytotoxic effectiveness of experimental therapies in mice bearing micro lung tumors, while minimizing the genotoxic risk to normal cells; B) The characterization of chemopreventive effects on the process(es) of spontaneous metastasis formation; and C) the characterization of cellular responses to potential chemopreventive compounds in selected rodent cell systems, to assess the usefulness of measuring intracellular glutathione, glutathione S- transferase, and thiol levels, protein kinase C activity, magnitude of DNA damage and repair, changes in split dose survival and repair, and frequency of mutations at the hprt locus as intermediate biomarkers for chemoprevention. Radioprotector compounds to be studied which possess potential chemopreventive properties include S-2-(3-aminopropylamino)ethyl phosphorothioic acid (WR-2721), 2-((aminopropyl)amino]ethanethiol (WR- 1065) and its disulfide form (WR-33278), N-acetylcysteine (NAC), the prodrug ribose-cysteine (Rib Cys) and captopril. Therapy agents to be used are 60Co and x-ray radiation, cytoxan, and cisplatin. The models for neoplastic disease are four mouse syngeneic tumors, i.e., fibrosarcoma (FSa) fibrosarcoma (NFSA), mammary carcinoma (MCAK), and a lymphoma which can be grown in the lungs or flanks of C3H mice. Techniques to be used include HPLC and monobromobimane fluorescent labeling to assay thiol and disulfide levels, determination of protein kinase C activity by measuring peptide phosphorylation levels corrected for background due to other protein kinases, alkaline elution to measure single-strand breaks in DNA and their associated kinetics of repair, and the hprt mutation assay in T- lymphocytes of mice and in selected cultured cell systems. The hprt mutation system is not proposed to be a predictor of carcinogenesis, but rather is considered to be an excellent marker for assessing genomic damage. This proposal will investigate the efficacy of thiol compounds as chemopreventive agents for use with radiation and chemotherapy.