Dail Mary B, Shack L Allen, Chambers Janice E, Burgess Shane C
Center for Environmental Health Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi 39762, USA.
Toxicol Sci. 2008 Dec;106(2):556-69. doi: 10.1093/toxsci/kfn198. Epub 2008 Sep 16.
A global proteomics approach was applied to model the hepatic response elicited by the toxicologically well-characterized xenobiotic phenobarbital (PB), a prototypical inducer of hepatic xenobiotic metabolizing enzymes and a well-known nongenotoxic liver carcinogen in rats. Differential detergent fractionation two-dimensional liquid chromatography electrospray ionization tandem mass spectrometry and systems biology modeling were used to identify alterations in toxicologically relevant hepatic molecular functions and biological processes in the livers of rats following a 5-day exposure to PB at 80 mg/kg/day or a vehicle control. Of the 3342 proteins identified, expression of 121 (3.6% of the total proteins) was significantly increased and 127 (3.8%) significantly decreased in the PB group compared to controls. The greatest increase was seen for cytochrome P450 (CYP) 2B2 (167-fold). All proteins with statistically significant differences from control were then analyzed using both Gene Ontology (GO) and Ingenuity Pathways Analysis (IPA, 5.0 IPA-Tox) for cellular location, function, network connectivity, and possible disease processes, especially as they relate to CYP-mediated metabolism and nongenotoxic carcinogenesis mechanisms. The GO results suggested that PB's mechanism of nongenotoxic carcinogenesis involves both increased xenobiotic metabolism, especially induction of the 2B subfamily of CYP enzymes, and increased cell cycle activity. Apoptosis, however, also increased, perhaps, as an attempt to counter the rising cancer threat. Of the IPA-mapped proteins, 41 have functions which are procarcinogenic and 14 anticarcinogenic according to the hypothesized nongenotoxic mechanism of imbalance between apoptosis and cellular proliferation. Twenty-two additional IPA nodes can be classified as procarcinogenic by the competing theory of increased metabolism resulting in the formation of reactive oxygen species. Since the systems biology modeling corresponded well to PB effects previously elucidated via more traditional methods, the global proteomic approach is proposed as a new screening methodology that can be incorporated into future toxicological studies.
采用全球蛋白质组学方法，对毒理学特征明确的外源性物质苯巴比妥（PB）引发的肝脏反应进行建模。PB是肝脏外源性物质代谢酶的典型诱导剂，也是大鼠中一种著名的非遗传毒性肝致癌物。运用差异去污剂分级分离二维液相色谱电喷雾电离串联质谱法和系统生物学建模，来识别大鼠肝脏在以80mg/kg/天的剂量暴露于PB 5天或接受溶剂对照后，毒理学相关肝脏分子功能和生物学过程的改变。在鉴定出的3342种蛋白质中，与对照组相比，PB组中有121种蛋白质（占总蛋白质的3.6%）表达显著增加，127种蛋白质（占3.8%）表达显著降低。细胞色素P450（CYP）2B2的增加最为显著（167倍）。然后，使用基因本体论（GO）和 Ingenuity 通路分析（IPA，5.0 IPA-Tox）对所有与对照组有统计学显著差异的蛋白质进行细胞定位、功能、网络连通性和可能的疾病过程分析，特别是与CYP介导的代谢和非遗传毒性致癌机制相关的过程。GO结果表明，PB的非遗传毒性致癌机制既涉及外源性物质代谢增加，尤其是CYP酶2B亚家族的诱导，也涉及细胞周期活性增加。然而，细胞凋亡也增加了，这可能是为了应对不断上升的癌症威胁。根据假设的细胞凋亡与细胞增殖失衡的非遗传毒性机制，在IPA映射的蛋白质中，有41种具有促癌功能，14种具有抗癌功能。根据代谢增加导致活性氧形成的竞争理论，另外22个IPA节点可归类为促癌。由于系统生物学建模与先前通过更传统方法阐明的PB效应非常吻合，因此提出全球蛋白质组学方法作为一种新的筛选方法，可纳入未来的毒理学研究。
