Using Adductomics to Characterize Exposures to Carcinogens

 描述(申请人提供)：虽然流行病学证据表明，大多数人类癌症是由未知的致癌物暴露引起的，但流行病学家仍然依赖自我报告的信息来确定暴露的特征，就像他们一个世纪前所做的那样。为了提供来自不同外源性和内源性来源的致癌物暴露的高质量数据，癌症病因学研究应该使用血液中化学物质的非靶向性组学。不幸的是，许多致癌物无法在血液中检测到，因为它们是活体内寿命短的反应性亲电物质。一种评估这些有意义的暴露的方法集中在反应性亲电体和血液蛋白质之间的反应的加合物上。人血清白蛋白(HSA)中的加合物特别吸引人，因为HSA是血清中含量最丰富的蛋白质，而Cys34是血清中反应性亲电物质的主要清除剂。HSA的其他亲核热点包括Lys199和His146。尽管一些HSA加合物的水平与暴露于目标化学物质有关，但过多的未确定的加合物代表着未知的暴露，这无疑会导致癌症的发生。因此，代表所有这些加合物的‘HSA加合物组’对癌症流行病学具有重要的潜在意义。由于所有活性亲电体都是可能的致癌物，可以说，与蛋白质组或代谢组相比，HSA加合物组的测量与人类癌症启动者的发现更相关，这两种组都被用于研究癌症的病因。在NIH之前的资助下，我们使用三重四极杆质谱仪(MS)对人体血清样本进行了Cys34加合物的非靶向分析。尽管该项目提供了概念验证，但覆盖范围仅限于Cys34修饰，三重四极杆MS没有为注释提供准确的质量。我们最近发现，高效液相色谱-高分辨质谱仪更适合于加合物的研究，并开发了一种强大的加合物流水线，用于表征Cys34加合物。拟议项目的目标是通过同时测量Cys34、Lys199和His146的加合物来扩大HSA加合物的覆盖范围。改进技术后，我们将用健康成年人的血浆样本验证方法，并将使用EPIC-意大利前瞻性队列研究的非霍奇金淋巴瘤(NHL)病例和匹配对照的存档血清对癌症流行病学技术进行试点测试。这项技术的成功创新可以改变发现人类癌症起源的方法。

 DESCRIPTION (provided by applicant): Although epidemiologic evidence indicates that most human cancers are caused by unknown exposures to carcinogens, epidemiologists still rely on self-reported information to characterize exposures, much as they did a century ago. To provide high-quality data regarding carcinogen exposures from diverse exogenous and endogenous sources, studies of cancer etiology should use untargeted omics of chemicals in blood. Unfortunately, many carcinogens cannot be measured in blood because they are reactive electrophiles with short life spans in vivo. An avenue for assessing these meaningful exposures focuses on adducts from reactions between reactive electrophiles and blood proteins. Adducts in human serum albumin (HSA) are particularly appealing because HSA is the most abundant protein in serum and Cys34 is the dominant scavenger of reactive electrophiles in serum. Other nucleophilic hotspots of HSA include Lys199 and His146. Although levels of some HSA adducts have been correlated with exposures to targeted chemicals, a plethora of uncharacterized adducts represent unknown exposures that undoubtedly contribute to cancer incidence. Thus the `HSA adductome', representing the totality of such adducts, is of great potential importance to cancer epidemiology. Since all reactive electrophiles are possible carcinogens, measurement of the HSA adductome is arguably more relevant to the discovery of initiators of human cancers than the proteome or the metabolome, both of which are being applied to investigate cancer causation. With previous NIH funding, we used triple-quadrupole mass spectrometry (MS) to perform untargeted analyses of Cys34 adducts with samples of human serum. Although that project provided proof-of-concept, coverage was limited to Cys34 modifications and triple-quadrupole MS did not provide accurate masses for annotation. We recently showed that liquid chromatography-high resolution mass spectrometry was more appropriate for adductomics and developed a robust `adductomics pipeline' for characterizing Cys34 adducts. The goals of the proposed project are to expand coverage of HSA adductomics by simultaneously measuring adducts of Cys34, Lys199 and His146. After improving the technology, we will validate methods with specimens of plasma from healthy adults and will pilot-test the technology for cancer epidemiology with archived serum from incident cases of non-Hodgkin's lymphoma (NHL) and matched controls from the EPIC- Italy prospective cohort study. Successful innovations of this technology can transform approaches to discover the origins of human cancers.