Calmodulin Regulates Fas-Mediated Apoptosis: A Target for Cancer Therapy

6.项目摘要/摘要。胆管细胞癌是一种高度恶性的肿瘤，起源于 肝内外胆管系统的胆管细胞。我们小组和其他人的研究发现 调控细胞死亡/凋亡通路为胆管癌细胞提供潜在的新途径 心理治疗。胆管癌细胞死亡受体(Fas)表达下调和Fas配体表达上调 保护细胞免于凋亡，促进其在小鼠体内的成瘤。此外，几种抗凋亡剂 Fas信号通路中的介体，包括蛋白激酶B/AKT和Flice样抑制蛋白 (FLIP)在胆管癌细胞中上调，使癌细胞对凋亡具有更强的抵抗力 并将Fas诱导的信号转移到生存和增殖途径。与人胆管细胞癌 我们发现Fas的表达与肿瘤的分化程度有关。我们发现了 钙调素拮抗剂诱导胆管癌细胞凋亡的机制 Fas介导的细胞凋亡途径与抑制小鼠肿瘤发生。机械学研究进一步确定 钙依赖的CaM与Fas的直接结合受Fas激活的调节。此外, CaM被招募到Fas激活的死亡诱导信号复合体(DISC)中。一名Cam拮抗者和一名 钙离子螯合剂抑制CaM在Fas诱导的视盘中的募集，并阻断FADD在视盘中的募集 提示CaM/Fas结合有助于Fas激活的盘的形成。最近，我们发现 CaM与另一种在胆管癌细胞中升高并激活的碟状蛋白FliP结合 Fas激活后的生存信号。因此，我们假设CaM是Fas-1的关键调节因子。 死亡受体信号通路，并代表着一个潜在的治疗靶点 胆管癌。在这项申请中，我们将继续追求我们的长期目标，即了解 Fas死亡受体信号通路在胆管细胞癌发病机制中的作用 钙调素在调节Fas激活盘中的作用及其与Fas、CaM/Flip结合的作用 对胆管癌细胞增殖和凋亡的调控及动物模型的致瘤作用。 具体目的是：1)研究CaM在调节Fas信号通路中的作用 以及2)CaM/Fas/Flip相互作用在调控胆管癌细胞中的作用 小鼠胆管癌变的实验研究。目前的研究将确定基本机制。 CaM通过Fas途径调节信号，从而促进进一步的研究来翻译这些 对病人护理策略和治疗方法的研究结果。考虑到癌症是人类最重要的健康之一 针对退伍军人群体中存在的问题，我们的研究将有助于改善退伍军人的健康状况。

6. Project Summary/Abstract. Cholangiocarcinoma is a highly malignant tumor that arises from cholangiocytes of the intra- and extra-hepatic biliary system. Studies from our group and others have found that modulating cell death/apoptosis pathways provide potential novel avenues for cholangiocarcinoma therapy. Downregulating the death receptor (Fas) and upregulating Fas Ligand in cholangiocarcinoma cells protect cells from apoptosis and enhance their tumorigenesis in mice. Further, several anti-apoptotic mediators in the Fas signaling pathways, including protein kinase B/AKT and FLICE like Inhibitory Protein (FLIP) are upregulated in cholangiocarcinoma cells, which render the cancer cells more resistant to apoptosis and divert Fas-induced signaling to survival and proliferative pathways. With human cholangiocarcinoma samples we demonstrated that the expression of Fas is associated with tumor differentiation. We have found that antagonists of calmodulin (CaM) induce apoptosis of cholangiocarcinoma cells via a mechanism related to the Fas-mediated apoptosis pathways and inhibit tumorigenesis in mice. Mechanistic studies further identified Ca2+-dependent direct binding between CaM and Fas, which is regulated upon Fas-activation. In addition, CaM is recruited into the Fas-activated death inducing signaling complex (DISC). A CaM antagonist and a calcium chelator inhibit recruitment of CaM into the Fas-induced DISC and block the recruitment of FADD into the DISC, suggesting that CaM/Fas binding contributes to Fas-activated DISC formation. Recently, we found that CaM binds to FLIP, another DISC protein that is elevated in cholangiocarcinoma cells and activates survival signals upon Fas activation. Therefore, we hypothesize that CaM is a critical regulator of the Fas- death receptor signaling pathway and represents a potential therapeutic target for cholangiocarcinoma. In this application, we will continue pursuing our long-term goal of understanding the Fas death receptor signaling pathways in the pathogenesis of cholangiocarcinoma by focusing on determining the role of CaM in regulating the Fas-activated DISC and the function of CaM/Fas and CaM/FLIP binding in regulating proliferation and apoptosis of cholangiocarcinoma in culture and tumorigenesis in animal models. The Specific Aims are: 1) characterize the function of CaM in regulating Fas signaling pathways in cholangiocarcinoma cells; and 2) characterize the role of the CaM/Fas/FLIP interaction in regulating cholangiocarcinoma tumorigenesis in mice. The present studies will define the fundamental mechanisms by which CaM regulates signaling through the Fas pathway, thus facilitating further studies to translate these findings into strategies and therapies for patient care. Considering that cancer is one of the important health problems in the Veteran's population, our studies will lead to improvement of the health of veterans.