Effects of chemopreventive agents on DNA damage response

描述（由申请人提供）： 苯并[a]芘（B[a]P）是一种典型的多环芳烃，由不完全燃烧产生，是香烟烟雾和烧焦食品中的主要致癌物。多环芳烃（如B[a]P）是主要的环境污染物，暴露范围很广。高活性和致突变性的B[a]P代谢物（+）-7R，8 S-二羟基-9S，10 R-环氧-7，8，9，10-四氢苯并[a]芘（BPDE）被认为在人类肺癌发生中起重要作用。化学预防是一种相对较新且有前途的预防癌症的策略。染料木黄酮、姜黄素和白藜芦醇等化学预防剂具有许多分子靶点，影响几种信号传导途径，并对肺癌、乳腺癌、前列腺癌和结肠癌具有强烈的抗增殖作用。这三种成分作为癌症化学保护剂最近受到了极大的关注。很少有人研究染料木黄酮、白藜芦醇和姜黄素对PAH诱导的DNA损伤和修复反应的化学预防作用。核苷酸切除修复的全局基因组修复组分由响应于DNA损伤的p53诱导调节。DNA损伤后，P53以剂量和时间依赖性方式被诱导。已知具有致突变性的低剂量BPDE不能诱导p53介导的对DNA损伤的反应。我们的初步结果表明，预处理与白藜芦醇和姜黄素的组合，使p53诱导低剂量BPDE曝光。我们推测，化学预防剂可以“敏化”细胞，以响应低剂量的遗传毒物诱导的DNA损伤，通过诱导p53，激活全球基因组DNA修复过程，允许更有效的DNA修复。本研究旨在探讨化学预防剂对BPDE诱导的人肺细胞DNA损伤的细胞反应的影响。我们的目的是确定化学预防剂（单独和组合）对p53介导的（1）细胞周期进程和（2）DNA修复诱导的调节的机制和作用。实验方法将包括蛋白质印迹法来测量人肺细胞中的p53和调节信号蛋白，并通过32 P-后标记分析来测量BPDE诱导的DNA加合物形成和修复率。这些结果将可能阐明化学预防机制，并提供更深入的了解在更生理相关的环境暴露剂量下DNA损伤和修复的机制。

DESCRIPTION (provided by applicant): Benzo[a]pyrene (B[a]P) is a prototypical polycyclic aromatic hydrocarbon produced by incomplete combustion and is a major carcinogen present in cigarette smoke and charred foods. PAH such as B[a]P are major environmental pollutants and exposure is widespread. The highly reactive and mutagenic B[a]P metabolite (+)-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) is believed to play a significant role in human lung carcinogenesis. Chemoprevention is a relatively new and promising strategy to prevent cancer. Chemopreventive agents such as genistein, curcumin and resveratrol have a number of molecular targets, impact several signalling pathways and have strong antiproliferation effects on lung, breast, prostate and colon cancers. These three constituents have received a great deal of attention recently as cancer chemoprotective agents. Little work has been done to investigate the chemoprevention effects of genistein, resveratrol and curcumin with respect to PAH-induced DNA damage and repair responses. The global genomic repair component of nucleotide excision repair is regulated by p53 induction in response to DNA damage. P53 is induced in a dose and time-dependent manner after DNA damage. Low dose BPDE which is known to be mutagenic fails to induce the p53 mediated response to DNA damage. Our preliminary results suggest that pretreatment with a combination of resveratrol and curcumin enables p53 induction by low dose BPDE exposure. We hypothesize that chemopreventive agents may "sensitize" the cell to respond to low dose genotoxicant induced DNA damage through induction of p53 which activates global genomic DNA repair process allowing more efficient DNA repair. This study aims to investigate the effects of chemoprevention agents on cellular responses to BPDE-induced DNA damage in human lung cells. We aim to determine mechanism and effects of chemopreventive agents (singly and in combination) on p53 mediated regulation of (1) cell cycle progression and (2) DNA repair induction. Experimental approaches will include western blot to measure p53 and regulated signaling proteins in human lung cells and measure BPDE-induced DNA adduct formation and repair rate by 32P-post-labeling analyses. The results will likely illuminate a chemoprevention mechanism and also provide a deeper understanding of the mechanism of DNA damage and repair under a more physiologically relevant environmental exposure dose.