The role of epidermal, fibroblast and endothelial cell COX-2 in skin cancer

描述（由申请人提供）：临床证据、流行病学结果和实验动物研究压倒性地表明，考克斯-2过表达在许多上皮癌的发展中起调节作用，甚至是因果作用。 最近的研究表明，间质成纤维细胞和血管内皮细胞调节上皮肿瘤的形成。 还存在大量相关数据表明，基质成纤维细胞和血管内皮细胞中的考克斯-2表达-而不是在起始的上皮肿瘤前体细胞中-可能介导上皮癌的肿瘤前出现和随后的进展。 然而，现有的考克斯-2药理学实验和整体Cox 2敲除小鼠不允许生理学或遗传学分析来确定特定的细胞群-成纤维细胞、上皮细胞或血管内皮细胞-其中考克斯-2过表达在肿瘤发展中起关键作用。 我们已经开发了（i）Cox 2 COE转基因小鼠，其中我们可以在靶细胞和组织中有条件地过表达考克斯-2，以及（ii）Cox 2 flox小鼠，其中我们可以有条件地删除靶细胞和组织中的Cox 2基因。 通过将COX 2 COE小鼠和Cox 2flox小鼠与其中他莫昔芬调节的CreERT重组酶在上皮细胞、基质成纤维细胞或血管内皮细胞中表达的转基因小鼠杂交，我们将能够确定（1）上皮细胞中是否过量产生考克斯-2，成纤维细胞和/或血管内皮细胞调节癌症发展和（2）上皮细胞中是否需要考克斯-2表达，成纤维细胞或血管内皮细胞用于癌症发展。 皮肤癌是研究得最好的上皮肿瘤诱导模型之一。 我们选择皮肤癌来研究考克斯-2在上皮癌发展过程中在上皮细胞、间质成纤维细胞和血管内皮细胞中的作用，因为关于该模型的大量文献，可以容易地非侵入性地监测肿瘤，并且可以容易地局部激活CreERT。 “宽，本申请的“长期目标和具体目标”是确定（1）考克斯-2是否在上皮癌的发展中发挥调节和/或所需的作用，以及（2）其中细胞启动的上皮肿瘤前体细胞和/或基质成纤维细胞和/或血管内皮细胞-考克斯-2调节预-恶性上皮肿瘤发展或良性肿瘤进展为癌。 这项研究与公共卫生的相关性。 考克斯-2抑制剂仍被研究作为上皮癌的治疗和预防剂，尽管有心血管副作用。“下游”考克斯-2通路效应物（前列腺素类脱氢酶和受体）已成为类似研究的目标。 如果我们能够精确定位考克斯-2表达和前列腺素类效应物调节癌症发展的细胞类型，我们可能能够以较低浓度和较短时间应用药理学试剂来靶向这些步骤。 我们预计我们将能够确定考克斯-2癌症增强的关键细胞和时间。

DESCRIPTION (provided by applicant): Clinical evidence, epidemiological results and experimental animal studies overwhelmingly suggest that COX-2 over-expression plays a modulatory and even causal role in development of many epithelial cancers. Recent studies demonstrate that stromal fibroblasts and blood vessel endothelial cells modulate epithelial tumor formation. There also exist substantial correlative data suggesting that COX-2 expression in stromal fibroblasts and blood vessel endothelial cells - and not in the initiated epithelial tumor precursor cells - may mediate pre-neoplastic emergence and subsequent progression of epithelial cancers. However, existing COX-2 pharmacologic experiments and global Cox2 knockout mice do not permit either physiological or genetic analyses to determine the specific cell populations - fibroblasts, epithelial or blood vessel endothelial cells - in which COX-2 over expression plays a critical role(s) in tumor development. We have developed (i) COX2 COE transgenic mice, in which we can conditionally over-express COX-2 in targeted cells and tissues and (ii) Cox2flox mice, in which we can conditionally delete the Cox2 gene in targeted cells and tissues. By crossing COX2 COE mice and Cox2flox mice to transgenic mice in which a tamoxifen-regulated CreERT recombinase is expressed in either epithelial cells, stromal fibroblasts or blood vessel endothelial cells, we will be able to determine (1) whether COX-2 over production in epithelial cells, fibroblasts and/or blood vessel endothelial cells modulates cancer development and (2) whether COX-2 expression is required in epithelial cells, fibroblasts or blood vessel endothelial cells for cancer development. Skin cancer is among the best-studied epithelial tumor induction models. We chose skin cancer to study the role(s) of COX-2 in epithelial cells, stromal fibroblasts and blood vessel endothelial cells during development of epithelial cancer because of the extensive literature on this model, the ease with which tumors can be monitored non-invasively, and the ease with which CreERT can be activated locally. The "broad, long-term objectives and specific aims" of this application are to determine (1) whether COX-2 plays a modulatory and/or a required role(s) in development of epithelial cancer and (2) in which cell(s) - initiated epithelial tumor precursor cell and/or stromal fibroblast and/or blood vessel endothelial cell - COX-2 modulates either pre-malignant epithelial tumor development or progression of benign tumors to carcinomas. The relevance of this research to public health. COX-2 inhibitors are still investigated as therapeutic and preventive agents for epithelial cancers, despite cardiovascular side effects. "Down-stream" COX-2 pathway effectors (prostanoid synthases and receptors) have become targets for similar research. If we can pinpoint the cell type(s) in which COX-2 expression and the prostanoid effectors regulate cancer development, we may be able to target those steps with lower concentrations and less prolonged application of pharmacologic agents. We anticipate we will be able to define the critical cells and times for COX-2 cancer enhancement.