Exploiting Caveolae-Dependent Albumin Endocytosis to Optimize Therapy in Pancreatic Cancer

 描述(申请人提供)：胰腺癌(PC)是一种典型的疾病，以抵抗治疗和不良结局为特征。迫切需要发现新的治疗方法，并确定现有的治疗方法是否对某些患者无效。最近，在吉西他滨中加入NaB-紫杉醇(Abraxane(R))可以提高缓解率和PC的存活率，但增加了毒性。NAB-紫杉醇是一种白蛋白结合的化疗药物，被认为是通过小窝/gp60介导的白蛋白内吞进入细胞。小窝是50-100 nm的膜内陷，负责内吞作用、胆固醇稳态和信号转导。小窝蛋白-1(Cav-1)是小窝的主要结构成分，其基因敲除可导致小窝消失。我们的初步数据表明，Cav-1在PC中过度表达，与预后不良有关，并具有包括迁移、侵袭和耐药在内的致癌特性。我们的数据还表明，Cav-1的表达对于白蛋白和NaB-紫杉醇进入PC细胞的细胞内转运是重要的。因此，我们假设Cav-1水平调节进入，并可以预测对NaB-紫杉醇的反应。此外，我们寻求通过确定其他提高NaB-紫杉醇疗效的策略和测试新的白蛋白偶联化疗药物来改进NaB-紫杉醇。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对NaB-紫杉醇的反应；(2)确定Cav-1表达是否介导对新型白蛋白偶联化疗药物的反应；以及(3)测试改善对NaB-紫杉醇反应的策略。我们将通过白蛋白和NaB-紫杉醇摄取的分析、细胞毒性分析和凋亡通路的激活来测试Cav-1水平是否影响一组PC细胞对NaB-紫杉醇的反应。我们将在体内扩展这些研究，以评估Cav-1的缺失是否会改变患者来源的异种移植和原生PC小鼠模型对NaB-紫杉醇的反应。此外，我们将确定肿瘤、间质和血液中的Cav-1水平是否可以预测接受NAB-紫杉醇治疗的PC患者的样本对NAB-紫杉醇的反应。此外，我们将测试似乎优于NaB-紫杉醇的新型白蛋白-化疗结合物，并确定Cav-1水平是否也调节它们的反应。最后，我们将测试其他增加Cav-1表达的策略，以进一步增强细胞对NaB-紫杉醇的敏感性。如果成功，这些研究将确定Cav-1对白蛋白进入PC肿瘤细胞非常重要，并决定白蛋白结合化疗的反应。此外，这些研究可以通过预测哪些肿瘤可能受益于NaB-紫杉醇，通过基于Cav-1表达的分层治疗来实现个性化治疗。最后，这些研究被设计为首次通过靶向Cav-1/小窝依赖的白蛋白内吞途径来完善PC的现有治疗方法。

 DESCRIPTION (provided by applicant): 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(r)) 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.