Novel Role of Ref-1 in Pancreatic Cancer Etiology and Progression

描述（由申请人提供）：绝大多数被诊断患有胰腺癌的人将接受最终失败或最多只能延长他们的寿命约6 - 10周的治疗。目前的标准治疗包括吉西他滨和厄洛替尼，或手术和放疗。胰腺肿瘤对治疗特别耐受，这至少部分是由于其缺氧性质和纤维化表型。已经鉴定了几种分子靶点，然而，缺乏对胰腺肿瘤进展及其对传统疗法的抗性的主要贡献者的信号传导途径和分子机制的研究。因此，迫切需要鉴定胰腺癌中的新靶点，其提供针对这种可怕疾病的最有希望的临床效用。这项工作的长期目标是了解胰腺导管腺癌（PDAC）生存和转移的关键途径，并开发一种通过治疗性调节这些关键途径来改善患者预后的疗法。氧化还原因子-1（Ref-1）是一种参与基因表达转录调控的还原-氧化（redox）因子。转录因子、HIF-1、NF？B和AP-1受Ref-1调节，并参与胰腺肿瘤生长和对缺氧的反应。这项工作的目的是确定在PDAC以及肿瘤微环境中抑制Ref-1功能的结果。我们的数据表明，在原位模型中抑制Ref-1可减少转移性病变的数量和患者来源的异位异种移植物的生长。此外，使用选择性抑制剂或氧化还原死亡的Ref-1突变体阻断Ref-1的氧化还原活性，抑制PDAC细胞系的增殖、迁移和粘附，降低转录水平。 HIF-1、NF？B和AP-1，并干扰基质诱导的肿瘤增殖。基于这些结果，中心假设是Ref-1的氧化还原功能是胰腺肿瘤生长和转移的关键调节剂;因此，抑制其功能将干扰缺氧信号传导途径并显著阻断胰腺癌进展。为了解决这一假设，提出了三个目标。目的1：确定调节肿瘤细胞和基质成纤维细胞中Ref-1的氧化还原活性的生物学效应;目的2和3：利用一种新的方法， 在胰腺癌的原位小鼠模型（Aim 2）和胰腺癌的遗传小鼠模型（Aim 3）中测定Ref-1单独和与吉西他滨组合阻断氧化还原功能的功效。成功完成该项目后，我们将确定Ref-1抑制对胰腺肿瘤生长和转移的影响，以及Ref-1调节如何影响缺氧信号通路和胰腺癌进展。这些新知识预计将产生一种新的策略来消除胰腺肿瘤异质环境中的多种生存机制。此外，评价Ref-1抑制对肿瘤生长和增殖、细胞凋亡、转移和对缺氧的反应的影响将包括对Ref-1抑制产生治疗PDAC的新方法的潜力的彻底评估。

DESCRIPTION (provided by applicant): The vast majority of people diagnosed with pancreatic cancer will undergo treatment that will ultimately fail or at best only extend their livs by ~6 - 10 weeks. Current standard-of-care consists of Gemcitabine with erlotinib, or surgery and radiation. Pancreatic tumors are especially resistant to therapy which is due at least in part to their hypoxic nature and fibrotic phenotype. Several molecular targets have been identified, however, investigation of the signaling pathways and molecular mechanisms that are major contributors to pancreatic tumor progression and its resistance to traditional therapies is lacking Thus, there is a critical need to identify novel targets in pancreatic cancer that offer the most promise for clinical utility against this dreaded disease. The long-term goal of this work is to understand the critical pathways for survival and metastasis of pancreatic ductal adenocarcinoma (PDAC) and develop a therapy that improves patient outcome by therapeutically modulating these critical pathways. The novel target, redox factor-1 (Ref-1), is a reduction-oxidation (redox) factor involved in the transcriptional regulation of gene expression. Transcriptional factors, HIF-1¿, NF?B, and AP-1 are regulated by Ref-1 and are implicated in pancreatic tumor growth and the response to hypoxia. The objective of this work is to determine the outcome of inhibiting the function of Ref-1 in PDAC as well as in the tumor microenvironment. Our data indicates that inhibition of Ref-1 in an orthotopic model reduces the number of metastatic lesions and growth of patient-derived ectopic xenografts. Furthermore, blocking the redox activity of Ref-1, using a selective inhibitor or a redox-dead Ref-1 mutant, inhibits the proliferation, migration, & adhesion of PDAC cell lines, decreases the transcriptional activation of HIF-1, NF?B, and AP-1, and interferes with stromal-induced tumor proliferation. Based on these results, the central hypothesis is that the redox function of Ref-1 is a critical regulator of pancreatic tumor growth and metastasis; therefore, inhibiting its function will interfere with hypoxia signaling pathways and markedly block pancreatic cancer progression. To address this hypothesis, three aims are proposed. Aim 1:determine the biological effects of modulating Ref-1's redox activity in tumor cells and in stromal fibroblasts; Aims 2 & 3: utilize an orthotopic mouse model of pancreatic cancer (Aim 2) and a genetic mouse model of pancreatic cancer (Aim 3) to determine the efficacy of blocking the redox function of Ref-1 alone and in combination with Gemcitabine. Upon successful completion of this project, we will establish the effects of Ref-1 inhibition on the pancreatic tumor growth and metastasis as well as how Ref-1 modulation affects hypoxia signaling pathways and pancreatic cancer progression. This new knowledge is expected to result in a fresh strategy to knock out multiple survival mechanisms within the heterogeneous milieu of pancreatic tumors. Moreover, evaluation of the effects of Ref-1 inhibition on tumor growth and proliferation, apoptosis, metastasis, and response to hypoxia will comprise a thorough assessment of the potential for Ref-1 inhibition to yield new approaches to treat PDAC.