Soluble epoxide hydrolase as a novel target of colitis-induced carcinogenesis

描述（由申请人提供）：该项目的总体目标是提供一种有效的预防结肠炎引起的癌症的药物。慢性结肠炎是结肠癌的一个公认的危险因素；结肠炎诱导的异常花生四烯酸（AA）代谢物的增加是导致癌症发展的关键事件。环氧二碳三烯酸（EETs）是AA代谢产物，具有抗炎活性；在生理条件下，eet通过酶溶环氧化物水解酶（sEH）转化为相应的二羟基二碳三烯酸（DHETs）而迅速失活（1,2）。sEH的抑制阻止了环氧化物的完全水解，减少了eet向DHETs的转化。我们的初步研究表明，1)sEH抑制剂AUDA- nBE和t-AUCB通过抑制巨噬细胞/中性粒细胞活性、降低iNOS表达及其介导的硝基酪氨酸形成，显著抑制结肠炎和溃疡的形成。2) AUDA-nBE诱导PPAR- γ活性，抑制NF-kB信号传导。iNOS、COX2、5-LOX、硝基氧化应激和VCAM-1也被体外细胞系抑制（15）。3)长期给药t-AUCB可抑制小鼠结肠炎诱导的发育不良和癌的发生。我们的假设是将sEH作为预防结肠炎诱导癌变的新方法，即通过抑制sEH显著减少eet向其相应的DHETs的转化。提出的抑制炎症的机制是通过抑制炎症细胞募集，调节花生四烯酸代谢物谱，进一步靶向ppar - γ和NF-kB途径，导致cox - 2,5 - lox， iNOS和VCAM-1的抑制。具体目的如下：1)在我们的新型dss诱导的癌变模型中，利用sEH敲除小鼠确定sEH在结肠炎诱导癌变中的作用，并在双敲除（sEH和IL-10）小鼠中建立自发性结肠炎-癌变模型。2)在DSS诱导和自发性结肠炎小鼠模型中，确定高效选择性sEH抑制剂作为化学预防剂对结肠炎诱导癌变的有效性。3)确定sEH抑制剂在上述两个特定目的动物标本、体外细胞系和条件ppar - γ敲除小鼠标本中抑制结肠炎诱导癌变的机制。公共卫生相关性：慢性炎症是导致人类癌症的最重要因素之一。慢性结肠炎是结肠癌的一个公认的危险因素。该项目的目标是提供一种有效的化合物来预防结肠炎引起的结肠癌。环氧二碳三烯酸（EETs）是AA代谢产物，具有抗炎活性。sEH的抑制阻止了环氧化物的完全水解，减少了eet向DHETs的转化。因此，抑制EET-sEH可能是抗结肠炎致癌性的有效途径。在本项目中，我们以独特的小鼠模型，结合分子病理学和药理学方法，利用强效和选择性的sEH抑制剂和sEH基因敲除小鼠，研究基于预防结肠炎驱动癌变的机制。

DESCRIPTION (provided by applicant): The overarching goal for this project is to provide an efficient agent for the prevention of colitis-induced cancer. Chronic colitis is a well-recognized risk factor of colon cancer; an increase in colitis-induced aberrant arachidonic acid (AA) metabolites is a key event leading to cancer development. Epoxyeicosatrienoic acids (EETs) are AA metabolites with anti-inflammatory activity; under physiological conditions, EETs are quickly inactivated as they are converted to their corresponding dihydroxyeicosatrienoic acids (DHETs) by the enzyme soluble epoxide hydrolase (sEH) (1, 2). The inhibition of sEH prevents the complete hydrolysis of the epoxide, reducing the conversion of EETs to DHETs. Our preliminary studies have shown that 1) sEH inhibitors AUDA- nBE and t-AUCB significantly inhibit colitis and ulcer formation by suppressed macrophage/neutrophile activity as well as decreased iNOS expression and its mediated nitrotyrosine formation. 2) AUDA-nBE induced PPAR- gamma activity and inhibited NF-kB signaling. iNOS, COX2, 5-LOX, nitro-oxidative stress and VCAM-1 was also inhibited in vitro cell lines (15). 3) Long-term administration of t-AUCB inhibited development of colitis- induced dysplasia and carcinoma in rodent models. Our hypothesis is targeting sEH as a novel approach for the prevention of colitis-induced carcinogenesis is through inhibiting sEH significantly to reduce the conversion of EETs to their corresponding DHETs. The proposed mechanism for the inhibition of inflammation is by suppressing inflammatory cell recruitment, modulating the arachidonic acid metabolite profile and further targeting the PPAR-gamma and NF-kB pathways to lead to an inhibition of COX-2, 5-LOX, iNOS, as well as VCAM-1. The following specific aims are performed: 1) Determine the role of sEH in colitis-induced carcinogenesis using sEH knockout mice in our novel DSS-induced carcinogenesis model, and a spontaneous colitis-carcinogenesis model in double-knockout (sEH and IL-10) mice. 2) Determine the effectiveness of the highly potent and selective sEH inhibitor as a chemopreventive agent against colitis-induced carcinogenesis in both DSS- induced and spontaneous colitis-carcinogenesis mouse models. 3) Determine the mechanism for the inhibition of colitis-induced carcinogenesis by sEH inhibitors in specimens from animals used in the aforementioned two specific aims as well as from in vitro cell lines and conditional PPAR-gamma knockout mice. PUBLIC HEALTH RELEVANCE: Chronic inflammation is one of the most important factors contributing to human cancer. Chronic colitis is a well-recognized risk factor of colon cancer. The goal for this project is to provide an efficient compound for prevention of colitis-induced colon cancer. Epoxyeicosatrienoic acids (EETs) are AA metabolites with anti- inflammatory activity. The inhibition of sEH prevents the complete hydrolysis of the epoxide, reducing the conversion of EETs to DHETs. Thus, EET-sEH inhibition would be efficient pathway for anti-colitis induced carcinogensis. In this project, we are in unique position to investigate the mechanism based prevention of colitis-driven carcinogenesis using potent and selective sEH inhibitor and sEH gene knockout mice combined with unique mouse models molecular pathology and pharmacology approaches.