CYCLOOXYGENASE AND PGE2 RECEPTOR FUNCTION IN SKIN CANCER

皮肤癌中环加氧酶和 PGE2 受体的功能

• 批准号: 6606294
• 负责人: Alice P Pentland
• 金额: $ 0.56万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-05 至 2005-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6606294
• 关键词: cell growth regulation; cell proliferation; enzyme mechanism; genetically modified animals; hairless mouse; human tissue; isozymes; keratinocyte; laboratory mouse; light adverse effect; prostaglandin endoperoxide synthase; prostaglandin receptor; protein protein interaction; radiation carcinogenesis; receptor expression; skin neoplasms; tissue /cell culture; transfection; ultraviolet radiation

Ultraviolet light exposure is known to be a complete carcinogen inducing & promoting basal cell and squamous cell carcinoma of the skin. Recent work has shown that significant contributions to squamous cell carcinoma initiation and promotion are made by the cyclooxygenase product prostaglandin B2(PGE2). In recent studies from this lab, UV-induced tumor formation was decreased nearly 60% by treatment of SKH hairless mice with the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib. This protection may also occur in humans. P6~ interacts with specific cellular receptors to regulate cell function. With the recent cloning of four different PGE2 receptors, it is now possible to dissect some of the mechanisms by which prostaglandin receptor signaling may act to enhance UV tumorigenesis. Our preliminary work demonstrates that primary human keratinocytes express both growth-stipulatory (EP2) and growth- inhibitory (EP3) receptors for prostaglandin E2 (PGE2) in significant amounts. Our data shows that high concentrations of PGE2 stimulate proliferation by activating low-affinity EP2 receptors coupled to production of cAMP, while inhibition of proliferation is mediated by high- affinity EP3 receptors which are active at 10-fold lower concentrations of PGE2. The signaling pathways linked to this receptor are poorly defined, as are the conditions for generating quantities of PGE2 which drive its activation. Our preliminary data have shown that transfection of the EP3 receptor into HaCaT cells results in decreased proliferation. In contrast, EP2 sense transfected HaCaTs have increased proliferative rates. EP2 antisense transfection into HaCats reverses this picture. We hypothesize that under basal conditions, PGE2 signaling occurs primarily through the high affinity EP3 receptor linked to COX-1 activity, while inflammation induces signaling via the low affinity EP2 receptor linked to COX-2.We also hypothesize that UV-induced upregulation of COX-2 increases tissue PGE2 levels, driving EP2-mediated proliferation in irradiated cells. Selective COX-2 inhibition, resulting in low nM concentrations of PGE2 produced via COX-l, permits selective stimulation of high affinity EP3 receptors mediating enhanced differentiation. The work proposed will better define the relationship between UV-induced PGE2 formation, cyclooxygenase activity, and EP receptor signaling through extensive characterization of basal and UV effects on EP receptor signaling. EP receptor effects on keratinocyte proliferation, apoptosis and differentiation will be studied as markers of cutaneous neoplasia.

已知紫外线照射是一种完全致癌物质，可诱导和促进皮肤基底细胞癌和鳞状细胞癌。最近的研究表明，环加氧酶产物前列腺素 B2 (PGE2) 对鳞状细胞癌的发生和促进做出了重大贡献。在该实验室最近的研究中，用选择性环氧合酶 2 (COX-2) 抑制剂塞来昔布治疗 SKH 无毛小鼠，紫外线诱导的肿瘤形成减少了近 60%。这种保护也可能发生在人类身上。 P6~与特定的细胞受体相互作用来调节细胞功能。随着最近克隆了四种不同的 PGE2 受体，现在可以剖析前列腺素受体信号传导增强紫外线肿瘤发生的一些机制。我们的初步工作表明，原代人角质形成细胞大量表达前列腺素 E2 (PGE2) 的生长规定 (EP2) 和生长抑制 (EP3) 受体。我们的数据表明，高浓度的 PGE2 通过激活与 cAMP 产生偶联的低亲和力 EP2 受体来刺激增殖，而增殖的抑制是由高亲和力 EP3 受体介导的，该受体在 PGE2 浓度低 10 倍时才具有活性。与该受体相关的信号传导途径尚不明确，产生大量 PGE2 驱动其激活的条件也是如此。我们的初步数据表明，将 EP3 受体转染到 HaCaT 细胞中会导致增殖减少。相比之下，EP2 有义转染的 HaCaT 增殖率增加。 HaCats 中的 EP2 反义转染扭转了这一局面。我们假设在基础条件下，PGE2 信号传导主要通过与 COX-1 活性相关的高亲和力 EP3 受体发生，而炎症则通过与 COX-2 活性相关的低亲和力 EP2 受体诱导信号传导。我们还假设紫外线诱导的 COX-2 上调会增加组织 PGE2 水平，从而驱动受辐射细胞中 EP2 介导的增殖。选择性COX-2抑制导致通过COX-1产生低nM浓度的PGE 2 ，允许选择性刺激介导增强分化的高亲和力EP3受体。拟议的工作将通过广泛表征基础和紫外线对 EP 受体信号传导的影响，更好地定义紫外线诱导的 PGE2 形成、环氧合酶活性和 EP 受体信号传导之间的关系。 EP 受体对角质形成细胞增殖、凋亡和分化的影响将作为皮肤肿瘤的标志物进行研究。