OXIDATIVE MECHANISMS IN CHROMIUM CARCINOGENESIS

铬致癌的氧化机制

• 批准号: 6619590
• 负责人: KENT D SUGDEN
• 金额: $ 19万
• 依托单位: UNIVERSITY OF MONTANA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6619590
• 关键词: DNA damage; DNA repair; Escherichia coli; ascorbate; chemical carcinogenesis; chromium; cysteine; cytosine; deoxyribose; electron spin resonance spectroscopy; gas chromatography mass spectrometry; gel electrophoresis; gene mutation; genetic strain; glutathione; guanine; high performance liquid chromatography; molecular oncology; nucleic acid structure; oligonucleotides; oxidation; plasmids

Chromium(VI) compounds pose a serious health risk to occupationally and environmentally exposed human populations. Exposure to Cr(VI) produces lung carcinomas in humans and laboratory animals. The overall objective of this research project is to elucidate the mechanism by which chromium(VI) compounds act as carcinogens. The hypotheses to be tested in this research project are: (1) that high valent +5 and +4 oxidation states of chromium are the primary intermediates that lead to oxidative DNA damage via direct DNA-metal interactions; (2) that reduction of Cr(VI) by intracellularly important reductants such as glutathione, ascorbate and cysteine form ligand-based radicals leading to oxidative DNA lesions but are of a lesser significance than oxidation by high valent chromium; (3) that these oxidative lesions are manifested in repair-deficient prokaryotic cell systems which are selectively sensitive to the DNA lesions detected in the in vitro studies. The specific aims of the proposed research are: (1) The mechanism of direct- or metal-centered oxidation of DNA by high valent chromium will be measured using model high valent Cr(V) compounds. Oxidation products arising from H-atom abstraction at the C1', C3', C4' and C5' of deoxyribose will be determined by HPLC and GC/MS using the model dinucleotide sugar oxidation substrate, 5',3'-di-O-Acetyl- d(TpT). Formation of guanine and cytosine base oxidation products will be determined using model dinucleotide substrates of d(GpG) and d(CpC). Base- and sequence-specificity of reactions with oligonucleotides will be determined by gel electrophoresis for formation of frank strand breaks and alkali-labile sites. The effect of aerobic vs anaerobic atmospheres will be determined on the above reactions. (2) The role of ligand-based radicals of glutathione, ascorbate and cysteine in the formation of DNA oxidation products will be probed by the specific (non-chromium) generation of these radical species and through their in situ formation by reduction with Cr(VI). The formation and fate of the radicals will be monitored by EPR. Measurement of sugar and base oxidation products as well as the formation of frank strand breaks and alkali-labile sites will be carried out as described in specific aim 1. (3) Selective lethality of Cr(VI) in DNA repair-deficient strains of E. coli will be determined. The synergistic effects of added ascorbate or modulation of intracellular glutathione levels will be determined. Transformation of a plasmid into the sensitive E. coli strains will be carried out for later extraction and measurement of base and sugar oxidation products and mutations. The proposed studies should give insight into the mechanisms of chromium(Vl)-induced DNA damage critical to the formation of cancer. Understanding these mechanisms may allow reduction of risk to exposed human populations.

铬（VI）化合物对职业和环境接触人群构成严重的健康风险。暴露于Cr（VI）会导致人类和实验室动物患肺癌。 本研究项目的总体目标是阐明铬（VI）化合物作为致癌物的机制。 本研究项目中待检验的假设是：（1）高价+5和+4氧化态铬是通过直接DNA-金属相互作用导致DNA氧化损伤的主要中间体;（2）细胞内重要还原剂如谷胱甘肽还原Cr（VI），抗坏血酸盐和半胱氨酸形成基于配体的自由基，导致氧化性DNA损伤，但比高价铬氧化的重要性小;（3）这些氧化损伤表现在修复缺陷的原核细胞系统中，其对体外研究中检测到的DNA损伤选择性敏感。 本研究的具体目标是：（1）以高价铬（V）化合物为模型，研究了高价铬直接或金属中心氧化DNA的机理。 使用模型二核苷酸糖氧化底物5 '，3'-二-O-乙酰基- d（TpT），通过HPLC和GC/MS测定脱氧核糖C1 '、C3'、C4'和C5'处H原子提取产生的氧化产物。 鸟嘌呤和胞嘧啶碱基氧化产物的形成将使用d（GpG）和d（CpC）的模型二核苷酸底物进行测定。 将通过凝胶电泳确定与寡核苷酸反应的碱基和序列特异性，以形成明显的链断裂和碱不稳定位点。 需氧与厌氧气氛的影响将根据上述反应确定。(2)谷胱甘肽，抗坏血酸和半胱氨酸在DNA氧化产物的形成中的配体为基础的自由基的作用将探测这些自由基物种的特定（非铬）代，并通过其原位形成与Cr（VI）还原。 自由基的形成和命运将由EPR监测。 如具体目标1所述，对糖和碱氧化产物以及明显链断裂和碱不稳定位点的形成进行测量。(3)Cr（VI）对大肠杆菌DNA修复缺陷株的选择性致死作用大肠杆菌进行测定。 将确定添加抗坏血酸盐或调节细胞内谷胱甘肽水平的协同效应。 将质粒转化敏感的E.大肠杆菌菌株将进行后期提取和测量的基础和糖的氧化产物和突变。拟议的研究应该深入了解铬（VI）诱导的DNA损伤对癌症形成至关重要的机制。 了解这些机制可能有助于降低暴露人群的风险。

项目成果

Guanine and 7,8-dihydro-8-oxo-guanine-specific oxidation in DNA by chromium(V).

DNA 中鸟嘌呤和 7,8-二氢-8-氧代-鸟嘌呤被铬 (V) 特异性氧化。

• DOI: 10.1289/ehp.02110s5725
• 发表时间: 2002
• 期刊: Environmental health perspectives
• 影响因子: 10.4
• 作者: Sugden,KentD;Martin,BrookeD
• 通讯作者: Martin,BrookeD

Formation of modified cleavage termini from the reaction of chromium(V) with DNA.

铬 (V) 与 DNA 反应形成修饰的切割末端。

• DOI: 10.1016/s0162-0134(99)00189-0
• 发表时间: 1999
• 期刊: Journal of inorganic biochemistry
• 影响因子: 3.9
• 作者: Sugden,KD

Oxidative activation of the human carcinogen chromate by arsenite: a model for synergistic metal activation leading to oxidative DNA damage.

亚砷酸盐氧化激活人类致癌物铬酸盐：导致氧化性 DNA 损伤的协同金属激活模型。

• DOI: 10.1016/j.tiv.2004.03.001
• 发表时间: 2004
• 期刊: Toxicology in vitro : an international journal published in association with BIBRA
• 作者: Sugden,KentD;Rigby,KevinM;Martin,BrookeD
• 通讯作者: Martin,BrookeD

Inhibition by methylated organo-arsenicals of the respiratory 2-oxo-acid dehydrogenases.

• DOI: 10.1016/j.jorganchem.2008.12.028
• 发表时间: 2009-03-15
• 期刊: Journal of organometallic chemistry
• 影响因子: 2.3
• 作者: Bergquist ER;Fischer RJ;Sugden KD;Martin BD
• 通讯作者: Martin BD