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

描述（申请人提供）：原发性肝癌是人类常见的恶性肿瘤，死亡率高，其发病率在世界范围内呈上升趋势，尤其是在美国。它主要发生在先前存在的慢性炎症性肝脏疾病，包括慢性肝炎和肝硬化。我们实验室最近的研究表明，前列腺素（PG）代谢在肝脏炎症和癌变中起重要作用。在这项研究中，我们假设前列腺素信号传导的水平和激活状态是决定细胞对转化生长因子-？(TGF - ?)。具体来说，我们假设增强的胞质磷脂酶A2？（cPLA2?）和环氧化酶-2 （COX-2）控制的PG信号破坏TGF-？-介导的有丝分裂抑制，该机制通过TGF-?的选择和扩增，在肝癌发生中起关键作用。抵抗性发育不良和肿瘤上皮细胞更迅速地向恶性转化和肿瘤发展。因此，阻断PG信号可能恢复TGF-??的生长抑制作用。预防肝癌的发生。本应用程序提出了一系列实验来评估上述假设。cPLA2表达改变的人肝癌细胞？和COX-2测定其对TGF-?的响应。Smad2/3的siRNA将被引入人肝癌细胞，稳定表达反义cPLA2？或COX-2，这些细胞将在体外和SCID小鼠体内进行增殖和凋亡分析。靶向表达cPLA2？和COX- 2在肝脏中的作用将被开发并用于检测TGF-？-调节Smad激活、有丝分裂抑制、细胞凋亡和肝癌发生。cPLA2吗?COX-2转基因和敲除小鼠将与TGF-？受体II型敲除小鼠以确定肝脏再生和den诱导的肝癌发生。最后，利用培养的肝星状细胞和实验动物模型来验证我们的假设：TGF-？纤维化肝星状细胞中的PG信号在肝纤维化和癌变的发病过程中起关键作用。这些研究结果有望为人类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肿瘤，目前尚无有效的化学预防或系统治疗方法。我们提出这个应用是为了检验我们的假设，即前列腺素信号的水平和激活状态是决定细胞对TGF-？阻断前列腺素信号通路可能恢复TGF-？预防肝癌的发生。将进行一系列实验来评估这一中心假设。我们提出的实验结果有望揭示TGF-？前列腺素信号通路在肝癌发生和治疗中的重要意义。

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.