cPLA2alpha and COX-2 in Cholangiocarcinoma

描述（申请人提供）：胆管癌是一种胆道高度恶性肿瘤，发病率和死亡率呈上升趋势。早期诊断是困难的，目前没有有效的化学预防或治疗。我们的长期目标是明确负责胆管上皮肿瘤发生和进展的细胞机制，并开发新的胆管癌治疗方法。在之前的资助期间，我们已经提供了支持胞质磷脂酶A21 （cPLA21）和环氧化酶-2 （COX-2）衍生的前列腺素（PG）信号传导在胆管癌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，通过表皮生长因子受体（EGFR）的反激活，在cPLA21/ cox -2诱导的胆管癌发生中起重要作用。在目前的继续提案中，我们假设EP1对EGFR的反激活对于2-连环蛋白和诱导型一氧化氮合酶（iNOS）的激活至关重要，并且这些关键分子的相互作用使胆管炎症持续存在并驱动癌变。因此，我们假设同时抑制EP1和EGFR可能协同破坏胆管癌发生的关键步骤，并提供有效的化学预防和治疗。本研究的具体目的是：(1)验证我们的假设，即cPLA21和COX-2蛋白的s -亚硝基化是iNOS调控胆管癌发生的新机制；(2)探讨cPLA21/COX-2/ pge2诱导的2-catenin在人胆管癌细胞中的活化作用及机制；(3)研究EP1介导的EGFR反激活在iNOS表达中的作用，评价同时抑制EP1和EGFR对胆管癌生长的影响。将采用培养胆管癌细胞和动物模型相结合的方法。该研究将探索胆管癌发生过程中的重要信号通路，并评估新的靶向化疗预防和治疗方法，具有重要意义。胆管癌是一种发生在胆道内的高度恶性上皮肿瘤，其发病率和死亡率正在上升。我们实验室最近的研究证实了胞质磷脂酶A21 （cPLA21）和环氧化酶-2 （COX-2）衍生的前列腺素（PG）信号在胆管癌生长中的重要作用。我们已经证明，在培养和SCID小鼠中，抑制COX-2可以阻止胆管癌细胞的生长。然而，鉴于一些COX-2抑制剂对心血管的副作用增加，开发同时针对PG和其他相关关键信号通路的替代化学预防策略势在必行，以期在副作用较小的情况下提供协同抗肿瘤效果。我们正在进行的研究将阐明cPLA21和cox -2衍生的PG信号和其他生长调节途径（如EGFR、iNOS和2-catenin）之间的相互作用。进一步了解这些方面将有助于制定更有效的治疗策略。此外，EP1和EGFR同时抑制对胆管癌生长的影响将通过培养肿瘤细胞和实验动物模型进行研究。该研究将明确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.