COX-2 Mediated Vascular Toxicity of Methylenedianiline

描述(摘自调查人员摘要) 血管中层增生在许多疾病的病因中是一个重要事件。 心血管疾病(CVD)，包括高血压、动脉粥样硬化和 血管再狭窄。每年死于心血管疾病的美国人比以往任何一年都要多。 自1984年以来，死于心血管疾病的女性多于男性(AHA，2000)。 这位候选人的实验室最近发现了一种以前未知的效应 暴露于芳香胺4，4‘-二氨基二苯基甲烷(DAPM， 4，4‘-亚甲基二苯胺)：肝脏和肝脏的血管中层增生 小剂量间歇性暴露对大鼠肺组织的影响 女性多于男性。DAPM是一种用于生产 聚氨基甲酸酯，可制成从地板到地板的大量产品 透析管和乳房植入物的覆盖物。这一新发现提出了 其他芳香胺，普遍存在于 各种来源，包括香烟烟雾、染料、腌肉和烤肉 食物，也可能在心血管疾病的发病中起作用。 在候选人的初步研究中，她已经证明了治疗 血管平滑肌细胞(VSMC)与DAPM共培养可诱导VSMC 扩散。与这种新发现的毒性有关，最近的一份报告 提示超过50%的DAPM代谢物与蛋白质结合在 血液很可能是通过肝外过氧化物酶的代谢形成的。 过氧化物酶将DAPM等芳香胺代谢成相应的 亚胺，它们是能够共价结合的高活性中间体 到DNA和蛋白质。候选人已经证明VSMC表达过氧化物酶 环氧合酶-2(COX-2)和DAPM结果治疗VSMC 在暴露后12h检测到过氧化物酶活性升高。DAPM或ITS 因此，代谢物似乎上调了COX-2的表达。最后，VSMC 当细胞同时用N-氨基丁酸处理时，细胞的增殖受到抑制 乙酰半胱氨酸，一种能够与亲电分子反应的非蛋白硫醇 中间体，从而防止这些中间体与 内源性分子，并可能防止细胞损伤。这些结果 提示VSMC具有代谢或生物激活DAPM的能力 中间体。因此，候选人将检验以下假设：1) VSMC环氧合酶将DAPM代谢成活性中间体；2) COX产生的DAPM活性代谢物进一步上调其表达 3)COX-2和/或磷脂酶A2表达的增加 (PLA2)，有助于提高VSMC的增殖率 DAPM。

DESCRIPTION (Taken from the Investigator's Abstract) Vascular medial hyperplasia is an important event in the etiologies of many cardiovascular diseases (CVD), including hypertension, atherosclerosis, and restenosis. CVD continues to kill more Americans each year than any other disease, and since 1984, more women are dying from CVD than men (AHA, 2000). The candidate's laboratory has recently discovered a previously unknown effect of exposure to the aromatic amine 4,4'-diaminodiphenylmethane (DAPM, 4,4'methylenedianiline): vascular medial hyperplasia in both the liver and lung following intermittent, low-dose exposure of rats, with greater effects in females than males. DAPM is a compound used in the production of polyurethanes, which are made into a plethora of products ranging from floor coverings to dialysis tubing and breast implants. This new discovery raises the possibility that other aromatic amines, ubiquitous compounds found in a variety of sources, including cigarette smoke, dyes, cured meats, and grilled food, may also have roles in the onset of CVD. In the candidate's preliminary studies, she has shown that treatment of vascular smooth muscle cells (VSMC) in culture with DAPM leads to VSMC proliferation. Relevant to this newly revealed toxicity, a recent report suggested that greater than 50% of DAPM metabolite bound to protein in the blood is likely formed through metabolism by extrahepatic peroxidase enzymes. Peroxidase enzymes metabolize aromatic amines like DAPM to their corresponding imines, which are highly reactive intermediates capable of binding covalently to DNA and protein. The candidate has shown that VSMC express the peroxidase enzyme cyclooxygenase-2 (COX-2), and that treatment of VSMC with DAPM results in increased peroxidase activity detected 12h after exposure. DAPM or its metabolites thus appear to upregulate the expression of COX-2. Finally, VSMC proliferation is attenuated when cells are simultaneously treated with N- acetylcysteine, a nonprotein thiol capable of reacting with electrophilic intermediates, thus preventing reactions of these intermediates with endogenous molecules and possibly preventing cell damage. These results suggest that VSMC are capable of metabolizing or bioactivating DAPM to toxic intermediates. Thus, the candidate will test the following hypotheses: 1) DAPM is metabolized to reactive intermediates by VSMC cyclooxygenase; 2) reactive metabolites of DAPM produced by COX further upregulate the expression of COX-2; and 3) this increase in expression of COX-2, and/or phospholipase A2 (PLA2), contributes to increases in rates of VSMC proliferation in response to DAPM.