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: 6512182
• 负责人: Alice P Pentland
• 金额: $ 30.94万
• 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/6512182
• 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.

众所周知，紫外线照射是一种完全的致癌物，可以诱发和促进皮肤的基底细胞和鳞状细胞癌。最近的研究表明，环氧合酶产物前列腺素B2(PGE2)对鳞状细胞癌的启动和促进做出了重要贡献。在本实验室最近的研究中，通过选择性环氧合酶-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，调节细胞功能。随着最近四种不同的PGE2受体的克隆，现在有可能剖析前列腺素受体信号转导促进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同时表达前列腺素E2(PGE2)的生长预约型(EP2)和生长抑制型(EP3)受体。我们的数据表明，高浓度的PGE2通过激活低亲和力的EP2受体与cAMP的产生相结合来刺激细胞增殖，而抑制增殖的作用是通过高亲和力的EP3受体介导的，而高亲和力的EP3受体在PGE2浓度低10倍时起作用。与该受体相关的信号通路并不明确，产生大量PGE2的条件也是如此，而PGE2正是驱动其激活的因素。我们的初步数据表明，将EP3受体导入HaCaT细胞会导致细胞增殖减少。相反，EP2正义基因转染的HaCaT细胞增殖率增加。将EP2反义基因导入HaCats细胞后，情况发生了逆转。我们假设在基础条件下，PGE2信号主要通过与COX-1活性相关的高亲和力EP3受体发生，而炎症通过与COX-2相关的低亲和力EP2受体诱导信号。我们还假设紫外线诱导COX-2上调组织PGE2水平，推动EP2介导的辐射细胞增殖。选择性地抑制COX-2，导致通过COX-L产生的低NM浓度的前列腺素E_2，允许选择性地刺激高亲和力的EP3受体，介导促进分化。这项工作将更好地定义紫外线诱导的PGE2的形成、环氧合酶活性和EP受体信号之间的关系，通过广泛的表征基础和紫外线对EP受体信号的影响。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。