cPLA2alpha and COX-2 in Cholangiocarcinoma

描述(申请人提供)：胆管细胞癌是一种高度恶性的胆道肿瘤，其发病率和死亡率正在上升。早期诊断很困难，目前还没有有效的化学预防或治疗方法。我们的长期目标是明确胆管上皮肿瘤发生和发展的细胞机制，并开发治疗胆管细胞癌的新疗法。在之前的资助期间，我们提供了支持胞浆磷脂酶A21(CPLA21)和环氧合酶-2(COX-2)衍生的前列腺素(PG)信号在胆管癌细胞生长中的重要作用的数据。我们已经证明EP1是一个关键的前列腺素受体，通过反式激活表皮生长因子受体(EGFR)在cPLA21/COX-2诱导的胆管癌变中起重要作用。在目前的继续方案中，我们假设EP1反式激活EGFR对2-连环蛋白和诱导型一氧化氮合酶(INOS)的激活至关重要，这些关键分子之间的相互作用持续存在胆管炎症并推动癌变。因此，我们推测，同时抑制EP1和EGFR可能协同干扰胆管癌变的关键步骤，并提供有效的化学预防和治疗。本研究的具体目的是：(1)评估我们的假设，即cPLA21和COX-2蛋白的S亚硝化是诱导型一氧化氮合酶调控胆管癌变的新机制；(2)检测cPLA21/COX-2/PGE2诱导的人胆管癌细胞中2-连环蛋白的激活及其机制；(3)检测EP1介导的EGFR反式激活在iNOS表达中的作用，并评价同时抑制EP1和EGFR对胆管癌细胞生长的影响。将采用培养胆管癌细胞和动物模型的互补方法。这项拟议的研究具有重要意义，因为它将研究胆管癌变过程中的重要信号通路，并评估用于化学预防和治疗的新的靶向治疗方法。胆管细胞癌是一种发生在胆道内的高度恶性的上皮性肿瘤，其发病率和死亡率正在上升。我们实验室最近的研究表明，胞浆磷脂酶A21(CPLA21)和环氧合酶-2(COX-2)衍生的前列腺素(PG)信号在胆管癌细胞生长中起着重要作用。我们已经证明，抑制COX-2可以阻止胆管癌细胞在培养和SCID小鼠体内的生长。然而，鉴于某些COX-2抑制剂增加了心血管副作用，迫切需要开发替代的化学预防策略，同时针对PG和其他与胆管癌变相关的关键信号通路，有望在副作用较小的情况下提供协同的抗肿瘤作用。我们正在进行的研究将阐明cPLA21和COX-2衍生的PG信号与其他生长调节通路如EGFR、iNOS和2-catenin之间的相互作用。对这些方面的进一步了解将有助于制定更有效的治疗策略。此外，将通过培养的肿瘤细胞和实验动物模型来检测同时抑制EP1和EGFR对胆管癌细胞生长的影响。这项拟议的研究将确定胆管癌发生和发展的分子机制，并为这种毁灭性恶性肿瘤的化学预防和治疗提供重要的治疗意义。

DESCRIPTION (provided by applicant): Cholangiocarcinoma is a highly malignant neoplasm of the biliary tract and its incidence and mortality is rising. Early diagnosis is difficult and currently there is no effective chemoprevention or treatment. Our long-term goal is to define the cellular mechanisms responsible for tumor development and progression in biliary epithelia and to develop new therapies for cholangiocarcinoma. During the previous grant period, we have provided data supporting the important role of cytosolic phospholipase A21 (cPLA21) and cyclooxygenase-2 (COX-2)-derived prostaglandin (PG) signaling in cholangiocarcinoma growth. We have shown that EP1 is a key prostaglandin receptor that importantly contributes to cPLA21/COX-2-induced cholangiocarcinogenesis through transactivation of epidermal growth factor receptor (EGFR). In the current continuation proposal, we hypothesize that transactivation of EGFR by EP1 is crucial for activation of 2-catenin and inducible nitric oxide synthase (iNOS) and that the interactions of these key molecules perpetuate bile duct inflammation and drive carcinogenesis. Consequently, we postulate that simultaneous inhibition of EP1 and EGFR may synergistically disrupt the key steps in cholangiocarcinogenesis and provide effective chemoprevention and treatment. The specific aims of this ongoing investigation are: (1) To evaluate our hypothesis that S-nitrosylation of cPLA21 and COX-2 protein is a novel mechanism by which iNOS regulates cholangiocarcinogenesis; (2) To examine the effect and mechanism for cPLA21/COX-2/PGE2-induced 2-catenin activation in human cholangiocarcinoma cells; and (3) To examine the role of EP1-mediated EGFR transactivation in iNOS expression and to evaluate the effect of concomitantly inhibiting EP1 and EGFR on cholangiocarcinoma growth. Complementary approaches of cultured cholangiocarcinoma cells and animal models will be employed. The proposed research is highly significant since it will investigate important signaling pathways during cholangiocarcinogenesis and evaluate novel targeted therapy for chemoprevention and treatment. PUBLIC HEALTH RELEVANCE Cholangiocarcinoma is a highly malignant epithelial neoplasm arising within the biliary tract and its incidence and mortality is rising. Recent studies in our lab demonstrate an important role of cytosolic phospholipase A21 (cPLA21) and cyclooxygenase-2 (COX-2)-derived prostaglandin (PG) signaling in cholangiocarcinoma growth. We have shown that inhibiting COX-2 prevents the growth of cholangiocarcinoma cells in culture and in SCID mice. However, in light of the increased cardiovascular side effect associated with some COX-2 inhibitors, it is imperative to develop alternative chemopreventive strategy that simultaneously targets PG and other related key signaling pathways in cholangiocarcinogenesis, which is expected to provide synergistic anti-tumor effect with lesser side effect. Our ongoing investigation will elucidate the interplays between the cPLA21 and COX-2-derived PG signaling and other growth-regulatory pathways such as EGFR, iNOS and 2-catenin. Further knowledge on these aspects will help develop more effective therapeutic strategy. Moreover, the effect of simultaneous inhibition of EP1 and EGFR on cholangiocarcinoma growth will be examined by using cultured tumor cells and experimental animal models. The proposed research will define the molecular mechanisms responsible for cholangiocarcinoma development and progression and provide important therapeutic implications for the chemoprevention and treatment of this devastating malignancy.