Aryl hydrocarbon receptor regulation of the cell cycle by chromatin modification

描述(由申请人提供) 不受控制的细胞增殖是癌症的标志。暴露在环境中的某些化学物质会扰乱细胞增殖的调节，最终导致癌症发生。芳香烃受体(AhR)与许多合成的和天然的化合物结合，包括环境致癌物，如一些多卤代芳烃(如二恶英、多氯联苯)和多环芳烃(如二甲基苯并菲)。AhR信号通路参与了细胞周期的调控和失调，但其调控机制尚不清楚。前面描述的大多数相互作用都是在异步化生长的细胞培养中建立的。这项研究的总体假设是，AhR是一种细胞周期调节因子，它所起的作用，无论是作为细胞周期进程的促进剂还是细胞周期停滞的诱导剂，取决于它与由细胞周期调节剂和染色质修饰物组成的多蛋白复合体的差异结合能力。这项研究建议在哺乳动物细胞培养模型中通过激活芳烃受体信号通路来研究化学诱导致癌的分子机制，方法是1)在细胞周期的特定阶段确定蛋白质-蛋白质与染色质修饰物(组蛋白脱乙酰酶和DNA甲基转移酶)和细胞周期调节因子(E2F转录因子，视网膜母细胞瘤[RB]肿瘤抑制因子)的相互作用，2)通过染色质免疫沉淀(ChIP)实验和基因组学方法(包括ChlP-on-ChIP和ChlP-克隆)评估含AhR的转录复合体对细胞周期基因启动子的靶向，以及3)确定AhR的调节作用如何被致癌的AhR配体破坏。这项研究的结果将提供更好的了解化学诱导的致癌作用，并深入了解暴露于环境毒物后细胞周期中观察到的不同反应的分子机制。此外，这些结果将为开发化学诱导肿瘤的治疗干预措施提供基础研究，并可能预测易患癌症的细胞周期阶段。

DESCRIPTION (provided by applicant) Uncontrolled cell proliferation is the hallmark of cancer. Exposure to certain chemicals in the environment disrupts the regulation of cell proliferation, ultimately leading to carcinogenesis. The aryl hydrocarbon receptor (AhR) binds to numerous synthetic and natural compounds including environmental carcinogens such as some polyhalogenated aromatic hydrocarbons (e.g., dioxins, polychlorinated biphenyls) and polycyclic aromatic hydrocarbons (e.g., dimethylbenzanthracene). The AhR signaling pathway has been implicated in regulation and dysregulation of the cell cycle; however the molecular mechanisms of this regulatory role are unclear. Most of the previously described interactions have been established in asynchronously growing cell cultures. The overall hypothesis of the proposed research is that AhR is a cell cycle regulator and the role it plays, either as a promoter of cell cycle progression or an inducer of cell cycle arrest, depends on its ability to differentially associate with multi-protein complexes comprised of cell cycle regulators and chromatin modifiers. This research proposes to investigate the molecular mechanisms of chemically-induced carcinogenesis initiated through activation of the aryl hydrocarbon receptor signaling pathway in mammalian cell culture models amenable to synchronization by 1) determining protein-protein interactions with chromatin modifiers (histone deacetylases and DNA methyltransferases) and cell cycle regulators (E2F transcription factors, retinoblastoma [RB] tumor suppressors) at specific stages of the cell cycle, 2) assessing the targeting of cell cycle gene promoters by AhR-containing transcriptional complexes by chromatin immunoprecipitation (ChIP) experiments and genomic approaches including ChlP-on-chip and ChlP-cloning, and 3) determining how the regulatory role of AhR is disrupted by carcinogenic AhR ligands. The results from this research will provide a better understanding of chemically-induced carcinogenesis and gain insight into the molecular mechanisms for the varied responses in the cell cycle observed following exposure to environmental toxicants. Furthermore, the results will provide the basic research for developing therapeutic interventions to chemical-induced tumors and may predict cell cycle stages susceptible to cancer.