Reactive oxygen species generated by PAH o-quinones cause change-in-function mutations in p53.
Reactive oxygen species generated by PAH o-quinones cause change-in-function mutations in p53.
复制标题
DOI：
10.1021/tx010177m
复制
发表时间：
2002-05
影响因子：
4.1
通讯作者：
Deshan Yu;J. Berlin;T. Penning;J. Field
中科院分区：
文献类型：
--
作者：
Deshan Yu;J. Berlin;T. Penning;J. Field
烟草烟雾中的多环芳烃（PAHs）可能通过代谢活化成为最终致癌物而导致人类肺癌。p53是该疾病中最常见的突变肿瘤抑制基因之一。对p53突变数据库的分析表明，G至T颠换是肺癌的标志性突变。醛酮还原酶（AKR）活化PAH反式二氢二醇接近致癌物以产生其相应的反应性和氧化还原活性的邻醌，例如，苯并[a]芘-7，8-二酮（BP-7，8-dione）。我们采用酵母报告系统，以确定是否PAH邻醌或ROS，他们产生的原因在p53的功能突变的变化。N-甲基-N-亚硝基-N '-硝基胍（一种标准烷基化诱变剂）用作阳性对照。MNNG引起突变酵母菌落的剂量依赖性增加，在最高浓度下，8-14%的酵母菌落发生突变，其特征在于p53 DNA结合结构域中的G：C至A：T转变。在氧化还原循环条件（NADPH和CuCl（2））下，用微摩尔浓度的（+/-）-抗-7，8-二羟基-9 α，10 α-环氧-7，8，9，10-四氢-苯并[a]芘（抗BPDE，一种终极致癌物）或亚微摩尔浓度的BP-7，8-二酮处理p53 cDNA也以剂量依赖性方式引起p53突变。我们发现，没有观察到突变体与PAH邻醌或NADPH单独。由BP-7，8-二酮引起的p53突变被ROS清除剂减弱，并被超氧化物歧化酶和过氧化氢酶的组合完全消除，表明超氧阴离子和羟基自由基都是负责的突变剂。检测到的大部分突变是单点突变，并且不是随机发生的。超过46%的BP-7，8-二酮诱导的突变是G：C到T：A颠换，与8-氧代-dGuo或其次级氧化产物的形成一致。此外，这些突变中有25%位于p53中的热点，这是已知的肺癌突变。总之，这些数据表明，PAH邻醌产生内源性诱变剂（ROS），导致p53失活。这些观察结果提供了一种替代途径G到T颠换，占主导地位的p53在肺癌。
Polycyclic aromatic hydrocarbons (PAHs) in tobacco smoke may cause human lung cancer via metabolic activation to ultimate carcinogens. p53 is one of the most commonly mutated tumor suppressor genes in this disease. An analysis of the p53 mutational database shows that G to T transversions are a signature mutation of lung cancer. Aldo-keto reductases (AKRs) activate PAH trans-dihydrodiol proximate carcinogens to yield their corresponding reactive and redox-active o-quinones, e.g., benzo[a]pyrene-7,8-dione (BP-7,8-dione). We employed a yeast reporter system to determine whether PAH o-quinones or the ROS they generate cause change-in-function mutations in p53. N-Methyl-N-nitroso-N'-nitro-guanidine, a standard alkylating mutagen was used as a positive control. MNNG caused a dose-dependent increase in mutant yeast colonies and at the highest concentrations 8-14% of the yeast colonies were mutated and were characterized by G:C to A:T transitions in the p53 DNA binding domain. Treatment of p53 cDNA with micromolar concentrations of (+/-)-anti-7,8-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene, (anti-BPDE, an ultimate carcinogen) or sub-micromolar concentrations of BP-7,8-dione in the presence of redox-cycling conditions (NADPH and CuCl(2)) also caused p53 mutations in a dose-dependent manner. We found that no mutants were observed with PAH o-quinones or NADPH alone. p53 mutagenesis by BP-7,8-dione was attenuated by ROS scavengers and completely abrogated by a combination of superoxide dismutase and catalase, indicating that both superoxide anion and hydroxyl radicals were the responsible mutagens. The bulk of the mutations detected were single-point mutations and were not random in occurrence. Over 46% of BP-7,8-dione-induced mutations were G:C to T:A transversions, consistent with the formation of 8-oxo-dGuo or its secondary oxidation products. In addition, 25% of these mutations were at hotspots in p53 which are known to be mutated in lung cancer. Together these data suggest that PAH o-quinones generate an endogenous mutagen (ROS) which leads to p53 inactivation. These observations provide an alternative route to G to T transversions that dominate in p53 in lung cancer.