Role of COX-2 in UVB-induced beta-catenin signaling in keratinocytes

COX-2 在 UVB 诱导的角质形成细胞 β-连环蛋白信号传导中的作用

• 批准号: 8046689
• 负责人: JILL C. PELLING
• 金额: $ 25.31万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-27 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8046689
• 关键词: Role; COX; UVB; induced; beta

DESCRIPTION (provided by applicant): Over one million new cases of UVB-induced non-melanoma skin cancer are diagnosed yearly in the US. Cellular response to UVB results in induction of cyclooxygenase-2 (COX-2), a key enzyme in the conversion of arachidonic acid to prostaglandins, and overexpression of COX-2 is implicated in many forms of cancer, including skin cancer. Our laboratory and others have reported that COX-2 expression is induced in keratinocytes and skin following UVB exposure. COX-2 and prostaglandin production have been shown by our Co-investigator Susan Fischer to be critical for murine skin carcinogenesis. The ¿-catenin signaling cascade is another important signaling pathway involved in tumorigenesis in a variety of tissues. Recently, Castellone et al. reported that COX-2 and its metabolite PGE2 promoted the growth of colon cancer cells by signaling through ¿-catenin. To the best of our knowledge, this link between COX-2 and ¿-catenin signaling, where COX-2 is induced by UVB exposure, has yet to be identified in normal epidermis. Our laboratory has obtained preliminary evidence that treatment of normal human epidermal keratinocytes (NHEKs) with UVB radiation resulted in increased levels of the signaling form of ¿-catenin (active ¿-catenin), concurrent with elevated COX- 2 expression. Given that UVB radiation induces COX-2 expression and PGE2 production, and our preliminary evidence that PGE2 treatment of NHEKs results in increased expression of active ¿-catenin, we propose to test the novel hypothesis that exposure to UVB radiation results in increased ¿-catenin signaling in the skin, which is dependent on COX-2 expression, and contributes to inappropriate proliferation of keratinocytes, leading to skin carcinogenesis. We propose to test this hypothesis in cell-based studies using primary mouse and human keratinocytes, as well as in mouse epidermis in vivo using COX-2+/- heterozygote mice and EP2-/- knockout mice and in human skin tumor samples. Furthermore, we will employ a novel strategy for transdermal delivery of the ¿-catenin inhibitor, ICAT, to test whether inhibition of ¿-catenin signaling attenuates UVB-induced hyperplasia. Aim #1 will investigate the effect of UVB on ¿-catenin signaling in cultured mouse and human keratinocytes to determine if UVB-induction of active ¿-catenin is transcriptionally functional, is dependent on COX-2 expression, and is part of a positive feedback loop. Aim #2 will investigate the effect of UVB radiation on ¿-catenin signaling and subsequent effects on epidermal proliferation in vivo. This Aim will also establish whether UVB-induced ¿-catenin signaling in mouse skin is dependent on COX-2 expression in vivo and whether a positive feedback loop between ¿-catenin and COX-2 exists in vivo. Aim #3 will investigate the involvement of ¿-catenin signaling in UVB-induced skin cancer and determine if inhibition of ¿-catenin signaling can prevent UVB-induced tumors. Demonstrating the existence of a "UVB/COX-2/¿-catenin axis" in epidermis and identifying its contribution to skin carcinogenesis would have significant impact in the fields of normal skin biology and skin cancer.

描述（由申请人提供）：在美国，每年诊断出超过100万例UVB诱导的非黑色素瘤皮肤癌新病例。细胞对UVB的反应导致环氧合酶-2（考克斯-2）的诱导，环氧合酶-2是花生四烯酸转化为胡萝卜素的关键酶，并且考克斯-2的过表达涉及许多形式的癌症，包括皮肤癌。我们的实验室和其他实验室已经报道了在UVB暴露后角质形成细胞和皮肤中诱导考克斯-2表达。考克斯-2和前列腺素的产生已经被我们的合作研究者Susan Fischer证明是小鼠皮肤癌发生的关键。连环蛋白信号级联是另一个重要的信号通路，参与多种组织中的肿瘤发生。最近，Castellone等报道考克斯-2及其代谢产物PGE 2通过<$-catenin信号传导促进结肠癌细胞的生长。据我们所知，考克斯-2和连环蛋白信号之间的这种联系， 考克斯-2是由UVB照射诱导的，在正常表皮中尚未被鉴定。我们的实验室已经获得了初步证据，即用UVB辐射处理正常人表皮角质形成细胞（NHEK）导致<$-连环蛋白（活性<$-连环蛋白）的信号形式水平增加，同时考克斯- 2表达升高。考虑到UVB辐射诱导考克斯-2表达和PGE 2产生，以及我们的初步证据表明PGE 2治疗NHEKs导致活性<$-连环蛋白表达增加，我们建议测试新的假设，即暴露于UVB辐射导致皮肤中<$-连环蛋白信号传导增加，这依赖于考克斯-2表达，并有助于角质形成细胞的不适当增殖，导致皮肤癌变。我们建议在使用原代小鼠和人角质形成细胞的基于细胞的研究中，以及在使用考克斯-2+/-杂合子小鼠和EP 2-/-敲除小鼠的小鼠表皮中以及在人皮肤肿瘤样品中，检验这一假设。此外，我们将采用一种新的策略，透皮递送的<$-连环蛋白抑制剂，ICAT，以测试是否抑制<$-连环蛋白信号减弱UVB诱导的增生。目的#1将研究UVB对培养的小鼠和人角质形成细胞中<$-连环蛋白信号传导的影响，以确定UVB诱导活性<$-连环蛋白是否具有转录功能，是否依赖于考克斯-2表达，是否是正反馈环的一部分。目的#2将研究UVB辐射对<$-catenin信号传导的影响以及随后对体内表皮增殖的影响。该目的还将确定UVB诱导的小鼠皮肤中的<$-catenin信号传导是否依赖于体内考克斯-2的表达，以及<$-catenin和考克斯-2之间是否存在体内正反馈回路。目的#3将研究<$-连环蛋白信号传导在UVB诱导的皮肤癌中的参与，并确定<$-连环蛋白信号传导的抑制是否可以预防UVB诱导的肿瘤。证明表皮中存在“UVB/考克斯-2/-连环蛋白轴”并鉴定其对皮肤癌发生的贡献将在正常皮肤生物学和皮肤癌领域中具有显著影响。