Exploiting caveolae-dependent albumin endocytosis to optimize therapy in pancreatic cancer

项目摘要： 胰腺癌（PC）是一种以治疗耐药和预后差为特征的疾病。有一个 迫切需要发现新的治疗方法，并确定现有的治疗方法是否在某些情况下无效。 患者最近，已显示向吉西他滨中添加白蛋白结合型紫杉醇（Abraxane®）改善了对肿瘤的治疗效果。 PC的缓解率和生存率，以增加毒性为代价。白蛋白结合型紫杉醇是一种白蛋白结合型紫杉醇， 假设化疗剂通过小窝/gp 60介导的白蛋白进入细胞 内吞作用小窝是50-100 nM的膜内陷，负责内吞、胆固醇 稳态和信号转导。小窝蛋白-1（Caveolin-1，Cav-1）是小窝的主要结构成分， 基因敲除Cav-1消除了小窝。我们的初步数据表明，Cav-1是过度表达， 并与PC的预后不良相关，并赋予致癌特性，包括迁移，侵袭， 对治疗的抵抗我们的数据还表明，Cav-1表达对于细胞内转运是重要的。 白蛋白和白蛋白结合型紫杉醇进入PC细胞。因此，我们假设Cav-1水平调节进入， 预测对白蛋白结合型紫杉醇的反应。此外，我们寻求通过鉴定其他的抗白蛋白结合型紫杉醇的药物来改善白蛋白结合型紫杉醇。 增加白蛋白结合型紫杉醇功效的策略和通过测试新的白蛋白结合的化学治疗剂。 我们的具体目标包括：（1）确定Cav-1表达是否介导白蛋白摄取和应答 （2）为了确定Cav-1表达是否介导对新的白蛋白缀合的紫杉醇的应答， 化学治疗剂;和（3）测试改善对白蛋白结合型紫杉醇的反应的策略。我们将测试卡- 1水平影响PC细胞系中白蛋白和白蛋白结合型紫杉醇的反应， 紫杉醇摄取、细胞毒性测定和凋亡途径的激活。我们将在2010年扩展这些研究。 使用患者来源的异种移植物评估Cav-1的缺失是否改变对nab-紫杉醇的应答， PC的本地小鼠模型。此外，我们将确定肿瘤、间质、 和血液预测从接受nab-紫杉醇治疗的PC患者获得的样本中对nab-紫杉醇的反应。 紫杉醇。此外，我们将测试新的白蛋白-化疗结合物，其表现出上级于nab- 紫杉醇，并确定Cav-1水平是否也调节其反应。最后，我们将测试其他策略 以增加Cav-1表达，从而进一步使细胞对nab-紫杉醇敏感。如果成功，这些研究 将确定Cav-1对于PC肿瘤细胞中白蛋白的进入是重要的，并决定对白蛋白的反应- 化学疗法。此外，这些研究可以通过预测哪些治疗可以实现个性化治疗。 通过基于Cav-1表达的分层治疗，肿瘤可能受益于nab-紫杉醇。最后这些 研究旨在通过靶向Cav-1/caveolae， 依赖白蛋白内吞途径。

PROJECT ABSTRACT: Pancreatic adenocarcinoma (PC) is a disease typified by resistance to therapy and poor outcomes. There is a pressing need to discover new therapies and determine whether existing therapies will be ineffective in certain patients. Recently, the addition of nab-paclitaxel (Abraxane®) to gemcitabine has been shown to improve response rates and survival in PC, at the expense of added toxicity. Nab-paclitaxel is an albumin-bound chemotherapeutic which has been hypothesized to enter the cell through caveolae/gp60-mediated albumin endocytosis. Caveolae are 50-100 nM membrane invaginations responsible for endocytosis, cholesterol homeostasis, and signal transduction. Caveolin-1 (Cav-1) is the principal structural component of caveolae, and genetic knockdown of Cav-1 ablates caveolae. Our preliminary data indicate that Cav-1 is over-expressed and associated with poor prognosis in PC, and confers oncogenic properties including migration, invasion, and resistance to therapy. Our data also suggest that Cav-1 expression is important for intracellular transport of albumin and nab-paclitaxel into PC cells. Thus, we hypothesize that Cav-1 levels regulate entry and can predict response to nab-paclitaxel. In addition, we seek to improve upon nab-paclitaxel by identifying other strategies which increase nab-paclitaxel efficacy and by testing novel albumin-conjugated chemotherapeutics. Our specific aims include: (1) To determine whether Cav-1 expression mediates albumin uptake and response to nab-paclitaxel; (2) To determine whether Cav-1 expression mediates response to novel albumin-conjugated chemotherapeutics; and (3) To test strategies to improve response to nab-paclitaxel. We will test whether Cav- 1 levels affect response to nab-paclitaxel in a panel of PC cell lines through analysis of albumin and nab- paclitaxel uptake, cytotoxicity assays, and activation of apoptotic pathways. We will extend these studies in vivo to assess whether loss of Cav-1 alters response to nab-paclitaxel using patient-derived xenograft and autochthonous mouse models of PC. In addition, we will determine whether Cav-1 levels in tumor, stroma, and blood predict response to nab-paclitaxel in samples obtained from patients with PC receiving nab- paclitaxel. Furthermore, we will test novel albumin-chemotherapy conjugates that appear superior to nab- paclitaxel and determine whether Cav-1 levels also regulate their response. Lastly, we will test other strategies to increase Cav-1 expression in order to further sensitize cells to nab-paclitaxel. If successful, these studies will establish that Cav-1 is important for albumin entry in PC tumor cells and dictates response to albumin- bound chemotherapies. Furthermore, these studies could allow personalization of therapy by predicting which tumors are likely to benefit from nab-paclitaxel, by stratifying therapy based on Cav-1 expression. Finally, these studies are designed to be the first to refine an existing therapy in PC through targeting of the Cav-1/caveolae- dependent albumin endocytic pathway.