Epigenetic toxicity of polycyclic aromatic hydrocarbons

描述（由申请人提供）：多环芳烃（PAH）是香烟烟雾中常见的致癌化合物，大量的毒理学研究集中在其遗传毒性属性上。然而，癌症不仅仅是不可逆的诱变事件的结果，还包括可逆的表观遗传事件。因此，有必要在表观遗传水平上重新评估多环芳烃的毒性。间隙连接细胞间通讯（GJIC）集中调节信号转导途径，表观遗传学改变基因表达。有相当多的证据表明GJIC的异常调节与肿瘤促进的非遗传毒性步骤有关。有丝分裂原活化蛋白激酶（MAPK）也在细胞信号传导中发挥核心作用。我们将使用一系列的环境和烟草烟雾相关的多环芳烃和多能哺乳动物上皮细胞系中确定的结构-活性关系与间和细胞内的信号传导机制。我们将通过使用特定的磷脂酶抑制剂和使用小干扰RNA沉默基因的新兴和强大的技术来具体测试假设SA#1，即磷脂酶是响应于多环芳烃的GJIC和MAPK的上游调节剂。我们将使用色谱法和最先进的蛋白质组学技术来测试假设SA#2，即脂质衍生的第二信使从质膜释放，并激活细胞信号蛋白。我们还将测试假设SA#3，即通过多环芳烃抑制GJIC和激活MAPK将诱导有丝分裂，并阻断凋亡和分化。我们想指出的是，使用生物活性与非活性PAH异构体的所有目标，使我们能够系统地确定特定的GJIC和MAPK的调节分子事件，并减去非特异性事件。总的来说，确定环境和烟草相关的多环芳烃对关键信号事件的影响将提供关于这些化合物的表观遗传毒性的宝贵的基于机制的信息，从而有助于开发癌症的预防和治疗策略。

DESCRIPTION (provided by applicant): Considerable toxicological research on polycyclic aromatic hydrocarbons (PAHs), which are prevalent compounds in cigarette smoke that contribute to cancer, has focused on their genotoxic attributes. However, cancer is not solely the consequence of non-reversible mutagenic events but also include reversible, epigenetic events. Thus, there is a need to reassess the toxicity of PAHs at the epigenetic level. Gap junctional intercellular communication (GJIC) centrally modulates signal transduction pathways that epigenetically alters gene expression. There is considerable evidence linking abnormal regulation of GJIC with the nongenotoxic steps of tumor promotion. Mitogen activated protein kinases (MAPKs) also play a central role in cell signaling. We will use a series of environmental and tobacco smoke-relevant PAHs and determine structure-activity relationships with inter-and intracellular signaling mechanisms in pluripotent mammalian epithelial cell lines. We will specifically test the hypothesis SA#1 that phospholipases are the upstream regulators of GJIC and MAPK in response to PAHs by using specific phospholipase inhibitors and the emerging and powerful technique of silencing genes using small interfering RNA. We will use chromatography and state of the art proteomic techniques to test the hypothesis SA#2 that lipid-derived second messengers are released from the plasma membrane, and activate cell signal proteins. We will also test the hypothesis SA#3 that inhibition of GJIC and activation of MAPK by PAHs will induce mitogenesis, and block apoptosis and differentiation. We would like to note that the use of biologically active versus inactive PAH isomers for all of the aims allows us to systematically identify molecular events that are specific to the regulation of GJIC and MAPK and subtract out non-specific events. Overall, determining the effect of environmental and tobacco-relevant PAHs on key signaling events would provide invaluable mechanistically based information on the epigenetic toxicity of these compounds, thereby aiding in the development of preventative and therapeutic strategies for cancer.