Chromium (VI) induces both bulky DNA adducts and oxidative DNA damage at adenines and guanines in the p53 gene of human lung cells
Chromium (VI) induces both bulky DNA adducts and oxidative DNA damage at adenines and guanines in the p53 gene of human lung cells
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DOI：
10.1093/carcin/bgs237
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发表时间：
2012-10-01
期刊：
影响因子：
4.7
通讯作者：
Tang, Moon-shong
中科院分区：
文献类型：
--
作者：
Arakawa, Hirohumi;Weng, Mao-wen;Tang, Moon-shong
铬(VI)[Cr(VI)]是一种普遍存在的环境致癌物质，通常认为在人体细胞中主要诱发二元和三元脱氧鸟苷(DG)-DNA加合物。然而，在铬暴露相关的肺癌中发现了p53基因的腺嘌呤(A)和鸟嘌呤(G)突变。应用UvrABC核酸酶和甲酰胺基嘧啶糖基酶(FPG)，以及连接介导的聚合酶链式反应(PCR)方法，对铬(VI)处理的人肺细胞p53基因中块状DNA加合物(BDA)和氧化DNA损伤(ODD)的分布进行了定位。我们发现BDA和ODD都形成于2‘-脱氧腺苷(DA)和DG碱基上。为了了解铬诱导DNA损伤的原因，我们绘制了细胞中三种主要铬形式铬(III)、铬(VI)和铬(V)诱导的p53基因DNA片段中BDA加合物和ODD的分布。我们发现：(1)CA-处的da是主要的铬(VI)结合部位，其次是-GG-和G-。铬(VI)不与GGG-结合，(2)铬(VI)DNA结合的特异性与以GGG-和GG-为主的铬(III)DNA结合有明显不同，(3)铬(V)结合部位包括所有的铬(VI)和铬(III)DNA结合部位，(4)铬(VI)和铬(V)在G-处诱导FPG敏感部位。综上所述，这些结果表明，在dA和dG残基上，铬(VI)对BDA和ODD的诱导是通过铬(V)中间体进行的。我们认为，这些铬(VI)诱导的BDA和ODD有助于p53基因的突变，从而导致肺癌的发生。
Chromium (VI) [Cr(VI)], a ubiquitous environmental carcinogen, is generally believed to induce mainly mutagenic binary and ternary Cr(III)deoxyguanosine (dG)-DNA adducts in human cells. However, both adenine (A) and guanine (G) mutations are found in the p53 gene in Cr exposure-related lung cancer. Using UvrABC nuclease and formamidopyrimidine glycosylase (Fpg), and ligation-mediated PCR methods, we mapped the distribution of bulky DNA adducts (BDA) and oxidative DNA damage (ODD) in the p53 gene in Cr(VI)-treated human lung cells. We found that both BDA and ODD formed at 2'-deoxyadenosine (dA) and dG bases. To understand the causes for these Cr-induced DNA damages, we mapped the distribution of BDA adducts and ODD in the p53 gene DNA fragments induced by Cr(III), Cr(VI) and Cr(V), the three major cellular Cr forms. We found that (i) dA at CA- is a major Cr(VI) binding site followed by -GG- and G-. Cr(VI) does not bind to GGG-, (ii) Cr(VI)DNA binding specificity is distinctly different from the Cr(III)DNA binding in which GGG- and GG- are preferential sites, (iii) Cr(V) binding sites include all of Cr(VI) and Cr(III)DNA binding sites and (iv) Cr(VI) and Cr(V) induce Fpg-sensitive sites at G-. Together, these results suggest that Cr(VI) induction of BDA and ODD at dA and dG residues is through Cr(V) intermediate. We propose that these Cr(VI)-induced BDA and ODD contribute to mutagenesis of the p53 gene that leads to lung carcinogenesis.