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

描述(申请人提供)：绝大多数被诊断为胰腺癌的人将接受最终失败的治疗，或者最多只能延长他们的肝脏6-10周。目前的标准护理包括吉西他滨和厄洛替尼，或手术和放射治疗。胰腺肿瘤对治疗的抵抗力尤其强，这至少部分是由于其缺氧性和纤维化表型。一些分子靶点已经被确定，然而，对胰腺肿瘤进展的主要因素和对传统治疗耐药的信号通路和分子机制的研究还很缺乏，因此，迫切需要在胰腺癌中识别新的靶点，为临床治疗这种可怕的疾病提供最大的希望。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调节这些关键途径来改善患者预后的治疗方法。新靶点氧化还原因子-1(Ref-1)是一种参与基因表达转录调控的氧化还原(Redox)因子。转录因子HIF-1、NF-B和AP-1受Ref-1调控，参与胰腺肿瘤的生长和对低氧的反应。这项工作的目的是确定在PDAC和肿瘤微环境中抑制Ref-1功能的结果。我们的数据表明，在原位模型中抑制Ref-1可以减少转移灶的数量和患者来源的异位移植物的生长。此外，使用选择性抑制剂或氧化还原死亡的Ref-1突变体来阻断Ref-1的氧化还原活性，可以抑制PDAC细胞系的增殖、迁移和黏附，减少转录 HIF-1、NF-B和AP-1的激活，并干扰间质诱导的肿瘤增殖。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因子；因此，抑制其功能将干扰缺氧信号通路，显著阻止胰腺癌的进展。为了解决这一假设，本文提出了三个目标。目的1：确定调节Ref-1‘S氧化还原活性在肿瘤细胞和间质成纤维细胞中的生物学效应；目标2和3：利用 建立原位小鼠胰腺癌模型(Aim 2)和遗传性小鼠胰腺癌模型(Aim 3)，以确定单独阻断Ref-1的氧化还原功能以及联合应用吉西他滨的效果。在该项目成功完成后，我们将建立Ref-1抑制对胰腺肿瘤生长和转移的影响，以及Ref-1的调节如何影响缺氧信号通路和胰腺癌的进展。这一新知识有望产生一种新的策略，在胰腺肿瘤的异质环境中消除多种生存机制。此外，评估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彻底评估抑制Ref-1产生治疗PDAC的新方法的潜力。

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.