cPLA2alpha, COX-2 and TGF-beta in Liver Cancer

cPLA2α、COX-2 和 TGF-β 在肝癌中的作用

• 批准号: 8133553
• 负责人: Tong Wu
• 金额: $ 21.29万
• 依托单位: TULANE UNIVERSITY OF LOUISIANA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-15 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8133553
• 关键词: cPLA2alpha; COX; TGF; beta; Liver

DESCRIPTION (provided by applicant): Primary liver cancer is the common malignant neoplasm in human with high mortality and its incidence is rising worldwide, especially in the United States. It occurs largely in the preexisting chronic inflammatory liver disorders, including chronic hepatitis and cirrhosis. Recent studies from our lab show that prostaglandin (PG) metabolism plays an important role in liver inflammation and carcinogenesis. In this grant we hypothesize that the level and activation status of prostaglandin signaling represents a key factor that determines the cellular response to transforming growth factor-? (TGF-?). Specifically, we postulate that enhanced cytosolic phospholipase A2? (cPLA2?) and cyclooxygenase-2 (COX-2) controlled PG signaling subverts TGF-?-mediated mitoinhibition and this mechanism is critically involved in liver carcinogenesis through selection and expansion of TGF-? resistant dysplastic and neoplastic epithelial cells that progress more rapidly toward malignant transformation and tumor development. Therefore, blocking PG signaling may restore the growth- inhibitory action of TGF-??and prevent hepatocarcinogenesis. This application proposes a series of experiments to evaluate the above hypotheses. Human liver cancer cells with altered expression of cPLA2? and COX-2 will be utilized to determine their response to TGF-?. siRNA for Smad2/3 will be introduced into human liver cancer cells stably expressing antisense cPLA2? or COX-2 and these cells will be analyzed for proliferation and apoptosis, in vitro and in SCID mice. Transgenic mice with targeted expression of cPLA2? and COX- 2 in the liver will be developed and utilized to determine TGF-?-regulated Smad activation, mitoinhibition, apoptosis, and hepatocarcinogenesis. The cPLA2? and COX-2 transgenic and knockout mice will be crossed with the TGF-?receptor type II knockout mice to determine liver regeneration and DEN-induced hepatocarcinogenesis. Finally, cultured hepatic stellate cells and experimental animal models will be utilized to evaluate our hypothesis that TGF-? and PG signaling in the fibrogenic hepatic stellate cells is critically involved in the pathogenesis of liver fibrosis and carcinogenesis. Results from the proposed studies are expected to provide important therapeutic implications for the chemoprevention and treatment of human liver cancer. PUBLIC HEALTH RELEVANCE: Primary liver cancer is a highly malignant neoplasm in human and currently there is no effective chemoprevention or systematic therapy. This application is proposed to examine our hypothesis that the level and activation status of prostaglandin signaling represents a key factor that determines the cellular response to TGF-? and that blocking prostaglandin signaling may restore the growth-inhibitory action of TGF-? and prevent hepatocarcinogenesis. A series of experiments will be performed to evaluate this central hypothesis. Results of the proposed experiments are expected to reveal an important link between TGF-? and prostaglandin signaling pathways in liver carcinogenesis and provide important therapeutic implications.

描述（由申请人提供）：原发性肝癌是死亡率高的人类中常见的恶性肿瘤，其发病率在全球范围内上升，尤其是在美国。它主要发生在早期存在的慢性炎性肝疾病中，包括慢性肝炎和肝硬化。我们实验室的最新研究表明，前列腺素（PG）代谢在肝脏炎症和致癌作用中起着重要作用。在这笔赠款中，我们假设前列腺素信号的水平和激活状态代表了决定细胞对转化生长因子的反应的关键因素。 （TGF-？）。具体而言，我们假设增强了胞质磷脂酶A2？ （CPLA2？）和环氧合酶-2（COX-2）受控的PG信号传导颠覆TGF - ？？ - 通过选择和扩展TGF-的介导的有丝氨酸抑制作用，这种机制与肝癌发生了严重涉及？耐药性发育不良和肿瘤上皮细胞更快地朝着恶性转化和肿瘤发育发展。因此，阻断PG信号传导可能会恢复TGF的生长抑制作用，并防止肝癌发生。该应用程序提出了一系列评估上述假设的实验。人肝癌细胞的CPLA2表达改变了？将使用COX-2来确定它们对TGF-？的响应。 SMAD2/3的siRNA将被引入稳定表达反义CPLA2的人肝癌细胞中？或COX-2和这些细胞将在体外和SCID小鼠中分析增殖和凋亡。转基因小鼠具有CPLA2的靶向表达？将开发并利用肝脏中的Cox-2来确定TGF - ？ - 调节的Smad激活，线抑制，凋亡和肝癌发生。 CPLA2？ COX-2转基因和基因敲除小鼠将与TGF-？受体II型敲除小鼠交叉，以确定肝脏再生和DEN诱导的肝癌发生。最后，将利用培养的肝星状细胞和实验动物模型来评估我们的TGF-的假设？纤维化肝星状细胞中的PG信号传导与肝纤维化和癌变的发病机理至关重要。拟议研究的结果预计将为人肝癌的化学预防和治疗提供重要的治疗意义。公共卫生相关性：原发性肝癌是人类高度恶性的肿瘤，目前尚无有效的化学预防或系统治疗。提出了该应用程序来检验我们的假设，即前列腺素信号的水平和激活状态代表了决定细胞对TGF-的反应的关键因素？阻止前列腺素信号传导可能会恢复TGF-的抑制作用作用？并防止肝癌发生。将进行一系列实验以评估这一中心假设。提出的实验的结果有望揭示TGF-之间的重要联系？肝癌发生中的前列腺素信号通路，并提供重要的治疗意义。