Epigenetic toxicity of polycyclicaromatic hydrocarbons

多环芳烃(PAHs)是香烟烟雾中常见的致癌化合物，对其进行了大量的毒理学研究，重点放在它们的遗传毒性属性上。然而，癌症不仅仅是不可逆转的诱变事件的后果，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。缝隙连接细胞间通讯(GJIC)主要调节表观遗传学改变基因表达的信号转导通路。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。丝裂原活化蛋白激酶(MAPKs)也在 在细胞信号传递中起核心作用。我们将使用一系列与烟草烟雾相关的多环芳烃，并在多能哺乳动物上皮细胞系中确定结构活性与细胞内和细胞内信号机制的关系。我们将通过使用特定的磷脂酶抑制剂和使用小干扰RNA沉默基因的新兴而强大的技术，专门测试假设SA#1，即磷脂酶是GJIC和MAPK响应多环芳烃的上游调节因子。我们将使用层析和最新的蛋白质组学技术来验证假设SA#2，即脂类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 PAHs对GJIC的抑制和MAPK的激活可诱导细胞有丝分裂，阻断细胞的凋亡和分化。我们想指出的是，对于所有的目的，使用生物活性和非活性多环芳烃异构体使我们能够系统地识别调控GJIC和MAPK的特异性分子事件，并减去非特异性事件。总体而言，确定与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表观遗传毒性的宝贵机械信息，从而有助于制定癌症预防和治疗策略。

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 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 vs 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 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.