REGULATION OF PGHS-2 SYNTHESIS--ROLE OF LIPID MEDIATORS

我们的长期目标是确定前列腺素合成的作用 在细胞生长控制方面。最近的几项研究表明， 前列腺素内源性过氧化物合成酶-2(PGHS-2)在脑出血中的作用 细胞动态平衡。PGHS-2基因缺失导致严重的 小鼠肾脏病理。相反，过表达PGHS-2会导致 在抵抗细胞凋亡方面，这可能有助于癌症的发生。 这些观察结果提出了可能的机制来解释 抑制前列腺素合成降低癌症的观察 人类的风险。为了实现这一长期目标，我们将确定 脂类介质在调节前列腺素合成中的作用。 在我们之前的研究中，我们使用了Madin-Darby犬肾细胞 研究前列腺素合成对肿瘤促进剂的反应 12-O-十四酰-佛波醇-13-乙酸酯(TPA)我们发现TPA 通过磷脂酶D(PLD)刺激磷脂酸(PA)的产生。 在TPA刺激的细胞中，PLD产生的PA是细胞膜所必需的 Raf-1与诱导PGHS-2基因表达的相关性。在……里面 相比之下，表皮生长因子对PGHS-2的诱导作用不明显 依赖于PLD或蛋白激酶C(PKC)。这些数据表明， 有不同的途径可以导致PGHS-2的诱导。其中一个 通路显然需要PKC、PLD和Raf-1。另一条道路 既不需要PKC也不需要PLD，但可能需要Raf-1或类似的激酶 活动。为了进一步确定这些控制PGHS-2的途径 综合我们将追求以下具体目标：1)确定 磷脂酶D在蛋白激酶C依赖的信号转导中的作用 2)明确Raf-1在前列腺素调控中的作用 综合。总之，这些研究将使我们更好地了解 前列腺素合成的控制并导致进一步的研究 PGHS-2在生长控制中的作用。此外，新的目标是 治疗干预应该变得显而易见，可以用来 制定更具选择性和更少的治疗策略 比目前可用的不良影响更大。

Our long-term goal is to determine the role of prostaglandin synthesis in cellular growth control. Several recent studies indicate the importance of prostaglandin endoperoxide synthase, type 2 (PGHS-2) in cellular homeostasis. Deletion of the PGHS-2 gene results in severe renal pathology in mice. In contrast, overexpression of PGHS-2 results in resistance to apoptosis which may contribute to carcinogenesis. These observations suggest potential mechanisms to explain the observation that inhibition of prostaglandin synthesis decreases cancer risk in humans. To approach this long-term goal we will determine the role of lipid mediators in the regulation of prostaglandin synthesis. In our previous studies, we have used the Madin-Darby canine kidney cell line to study prostaglandin synthesis in response to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We find that TPA stimulates phosphatidic acid (PA) production by phospholipase D (PLD). In TPA-stimulated cells, the PA produced by PLD is required for membrane association of Raf-1 and for induction of PGHS-2 gene expression. In contrast, induction of PGHS-2 by epidermal growth factor is not dependent on PLD or protein kinase C (PKC). These data indicate that there are distinct pathways that result in PGHS-2 induction. One of the pathways apparently requires PKC, PLD and Raf-1. Another pathway requires neither PKC nor PLD but may require Raf-1 or a similar kinase activity. To further define these pathways for the control of PGHS-2 synthesis we will pursue the following specific aims: 1) to determine the role of phospholipase D in protein kinase C-dependent signalling and 2) to define the role of Raf-1 in the control of prostaglandin synthesis. Together these studies will give us a better understanding of the control of prostaglandin synthesis and lead to further studies of the role of PGHS-2 in growth control. In addition, new targets for therapeutic intervention should become apparent that can be used to develop treatment strategies that are more selective and have less adverse effects than those currently available.