PHYSICAL AND CHEMICAL INTERACTIONS OF BPDE AND DNA

BPDE 和 DNA 的物理和化学相互作用

• 批准号: 2090278
• 负责人: Thomas Meehan
• 金额: $ 14.33万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-07-01 至 1997-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2090278
• 关键词: DNA; X ray crystallography; acidity /alkalinity; adduct; anions; benzopyrenediol epoxide; cations; chemical kinetics; cis trans isomerization; conformation; covalent bond; deoxycytidine; halogens; nuclear magnetic resonance spectroscopy; nucleic acid chemical synthesis; nucleic acid sequence; oligonucleotides; physical chemical interaction; polynucleotides; stereoisomer; synthetic nucleotide

Tumor initiation by chemical carcinogens is thought to result from binding to DNA that leads to activation/deactivation of critical proto- oncogenes and suppressor genes. We have been studying the environmental pro-carcinogen benzo(a)pyrene (BaP), as a model for understanding molecular carcinogenesis. BaP is converted into a potent chemical carcinogen by cellular metabolism and this intermediate is 7R,8S- dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydroBP ((+)-anti-BPDE). A (-)- anti-BPDE enantiomer is also made but this metabolite has 50-fold less biological activity. Both of these stereoisomers bind to DNA to form major and minor adducts and conformational studies have been hampered by the availability of only microgram quantities of heterogeneously modified DNAs for study. Since the biological properties of the carcinogenic and non-carcinogenic stereoisomers may result from differences in conformation, one goal of this research is to synthesize sufficient quantities of both the major and minor BPDE adducts to carry out these studies. Another goal is to characterize important minor adducts, such as those formed by cis opening of the BPDE adducts to carry out these studies. Another goal is to characterize important minor adducts, such as those formed by cis opening of the BPDE epoxide and dCyd alkylation products, since they may be responsible for the mutagenic properties of the carcinogen. Our specific aims are to (i) synthesize BPDE-modified deoxynucleotides and BPDE-modified oligodeoxynucleotides (ODNs), (ii) carry out conformational studies on the modified monomers and oligomers, (iii) study the mechanism of cis adduct formation, and (iv) analyze the structure and characterize the occurrence of dCyd adducts in DNA. The approach will be to synthesize BPDE-deoxynucleosides and incorporate them into site-specific, carcinogen-modified ODNs. The ODNs will be made with BPDE-modified dGuo and dAdo employing cis and trans deoxynucleoside adducts derived from both the (+)- and (-)-anti-stereoisomers. Synthetic methods for making BPDE-dCyd adducts will be developed, and this carcinogen-modified deoxynucleoside will also be used to construct ODNs containing a single, site-specific lesion. Conformations will be evaluated by UV, CD, fluorescence, and NMR spectroscopies and by X-ray crystallography. We will study the mechanism and properties of the halogen-catalyzed formation of cis adducts with DNA. We will also complete the characterization and occurrence of dCyd adducts in DNA, in order to assess their importance to the biological effects of BaP. The long term goal of this work is to determine the relative biological activity of each of the BPDE-DNA adducts that are formed, in order to assess which one(s) may be responsible for the tumor initiating properties of this important and ubiquitous environmental contaminant.

化学致癌物的肿瘤开始被认为是由 与DNA结合，导致关键原始原型的激活/失活 癌基因和抑制基因。 我们一直在研究环境 pro-加霉菌原苯并（A）pyrene（BAP），作为理解的模型 分子癌变。 BAP转化为有效的化学物质 细胞代谢和该中间体的致癌物为7R，8S- Dihydroxy-9s，10R- epoxy-7,8,9,10四氢螺旋体（（（+） - 抗BPDE）。 A（ - ） - 也制作了抗BPDE映体，但该代谢物的较小50倍 生物活性。 这两种立体异构体与DNA结合以形成 主要的和次要的内收和构象研究受到了阻碍 仅可用数量的异质修改的可用性 DNA进行研究。 由于致癌和 非癌症立体异构体可能是由于差异 构象，这项研究的目标是合成足够的 主要和小型BPDE加合物的数量以执行这些 研究。 另一个目标是表征重要的次要加合物，例如 作为由BPDE加合物的顺式开放形成的那些 研究。 另一个目标是表征重要的次要加合物，例如 如由BPDE环氧和DCYD烷基化的CI形成的那些 产品，因为它们可能负责 致癌物。 我们的具体目的是（i）合成BPDE修饰 脱氧核苷酸和BPDE修饰的寡脱氧核苷酸（ODN），（ii） 对修饰的单体和低聚物进行构象研究， （iii）研究CIS加合物形成的机制，（iv）分析 结构并表征DNA中DCYD加合物的发生。 这 方法将是合成BPDE-脱氧核苷并将其合并 进入特定于现场的致癌ODN。 ODN将与 BPDE修饰的DGUO和DADO采用顺式和反式脱氧核苷 源自（+） - 和（ - ） - 抗sTEREOISOMASERS的加合物。 合成的 将开发制作BPDE-DCYD加合物的方法，这 致癌的脱氧核苷也将用于构造ODN 包含一个特定于部位的病变。 构象将是 通过UV，CD，荧光和NMR光谱法以及X射线评估 晶体学。 我们将研究 与DNA的CIS加合物形成卤素催化的形成。 我们也会 完成DNA中DCYD加合物的表征和发生 为了评估其对BAP生物学作用的重要性。 这 这项工作的长期目标是确定相对生物学 为了 评估哪一个可能负责肿瘤的启动 这种重要且无处不在的环境污染物的特性。