COX-2 Mediated Vascular Toxicity of Methylenedianiline

描述（摘自研究者摘要） 血管中膜增生是许多肿瘤病因学中的重要事件， 心血管疾病（CVD），包括高血压、动脉粥样硬化和 再狭窄 CVD继续每年杀死更多的美国人比任何其他 自1984年以来，死于心血管疾病的妇女多于男子（美国心脏协会，2000年）。 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 大鼠间歇性、低剂量接触后， 女性多于男性。 DAPM是一种用于生产 聚氨酯，这是制成多种产品，从地板 覆盖到透析管和乳房植入体。 这一新发现 其他芳族胺，普遍存在的化合物， 各种来源，包括香烟烟雾，染料，腌肉，烤 食物，也可能在CVD的发病中起作用。 在候选人的初步研究中，她已经表明， 用DAPM培养的血管平滑肌细胞（VSMC）导致VSMC 增殖 关于这种新发现的毒性，最近的一份报告 这表明，超过50%的DAPM代谢物与蛋白质结合， 血液可能通过肝外过氧化物酶的代谢形成。 过氧化物酶将芳香胺如DAPM代谢成它们相应的 亚胺，其是能够共价结合的高活性中间体 DNA和蛋白质。 候选人已经表明，VSMC表达过氧化物酶 酶环氧合酶-2（考克斯-2）和用DAPM治疗VSMC结果 暴露后12小时检测到过氧化物酶活性增加。 DAPM或其 因此，代谢物似乎上调了考克斯-2的表达。 最后，VSMC 当细胞同时用N- 乙酰半胱氨酸，一种能够与亲电物质反应的非蛋白质硫醇， 中间体，从而防止这些中间体与 内源性分子和可能防止细胞损伤。 这些结果 表明VSMC能够代谢或生物活化DAPM以产生毒性 中间体的 因此，候选人将测试以下假设：1） DAPM通过VSMC环氧合酶代谢为活性中间体; 2） 由考克斯产生的DAPM的反应性代谢物进一步上调表达 考克斯-2的表达增加;和3）考克斯-2和/或磷脂酶A2 （PLA 2），有助于VSMC增殖率的增加， 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.