Targeting tumor-stromal interaction for pancreatic cancer therapy

描述（由申请人提供）：在过去的三十年中，胰腺癌患者的五年生存率一直保持在3-6%。这种不良预后在很大程度上是由于胰腺癌对目前可用的治疗方式的抗性。因此，显然迫切需要开发一种新的，基于机制的针对胰腺癌的精细治疗方法。新出现的数据表明肿瘤间质相互作用在胰腺癌病理生物学和化疗耐药性中的重要作用。在这方面，我们最近已经表明，趋化因子CXCL 12，主要来源于基质细胞，赋予胰腺癌细胞通过增强CXCR 4介导的生存机制的耐药性。在另外的新发现中，我们证明了CXCL 12/CXCR 4信号传导轴在胰腺癌细胞中hedgehog配体（sonic hedgehog，SHH）上调中的作用。此外，我们表明，条件培养基（CM）从刺激胰腺癌细胞增强CXCL 12生产的胰腺星状细胞（PSC），在一定程度上，通过刺猬依赖性机制。更重要的是，我们证明了PSC诱导的胰腺癌细胞在共培养试验中的耐药性涉及CXCL 12/CXCR 4和hedgehog信号传导机制的支持作用。基于这些新的发现，我们假设CXCL 12/CXCR 4和hedgehog通路参与恶性循环以协同促进胰腺癌生长和化学抗性，并且这些信号传导节点的组合靶向将产生上级治疗结果。为了验证这些假设，我们提出了三个具体目标。在目标1中，我们将描述胰腺癌中CXCL 12/CXCR 4和hedgehog串扰的机制。我们还将研究这些途径是否通过旁分泌机制促进胰腺癌细胞的生长和化疗耐药性，或者它们还涉及细胞内信号重叠和/或合作。在目标2中，我们将确定CXCL 12/CXCR 4和hedgehog相互作用在胰腺癌中的临床相关性。我们将评估胰腺癌中CXCL 12、CXCR 4和SHH的发生率、强度和相关表达，并研究它们与肿瘤分级、分期和患者生存率的联合临床相关性。在目标3中，我们将评估靶向CXCL 12/CXCR 4和hedgehog通路的组合疗法在胰腺癌的两种互补模型（原位异种移植物和基因工程小鼠）中的功效。将通过非侵入性成像、肿瘤测量和分子标志物分析评价治疗反应。这些研究的完成将为我们提供关于胰腺癌中CXCL 12/CXCR 4和hedgehog通路的集体（机制，临床和治疗）相关性的重要数据。从长远来看，由此产生的信息可能会导致致命的胰腺癌的新的和有效的治疗。

DESCRIPTION (provided by applicant): Five-year survival rate of pancreatic cancer patients has remained at 3-6% for over past three decades. Such a poor prognosis is largely due to the resistance of pancreatic cancer to currently available therapeutic modalities. Hence, there is clearly a pressing need to develop a novel, mechanism-based refined therapeutic approach against pancreatic cancer. Emerging data suggest a major role of tumor-stromal interaction in pancreatic cancer pathobiology and chemoresistance. In this regard, we have recently shown that the chemokine CXCL12, mostly derived from the stromal cells, confers drug-resistance to pancreatic cancer cells through potentiation of CXCR4-mediated survival mechanisms. In additional novel findings, we demonstrate a role of CXCL12/CXCR4 signaling axis in upregulation of hedgehog ligand (sonic hedgehog, SHH) in pancreatic cancer cells. Furthermore, we show that conditioned media (CM) from stimulated pancreatic cancer cells enhances CXCL12 production by pancreatic stellate cells (PSCs), in part, through hedgehog-dependent mechanism. More importantly, we demonstrate that PSCs-induced chemoresistance of pancreatic cancer cells in a co-culture assay involves supportive roles of CXCL12/CXCR4 and hedgehog signaling mechanisms. Based on these novel findings, we hypothesize that CXCL12/CXCR4 and hedgehog pathways engage in a vicious loop to cooperatively promote pancreatic cancer growth and chemoresistance, and combined targeting of these signaling nodes will produce superior therapeutic outcome. To test these hypotheses, we have proposed three specific aims. In aim 1, we will characterize the mechanisms underlying CXCL12/CXCR4 and hedgehog cross-talk in pancreatic cancer. We will also investigate if these pathways promote growth and chemoresistance of pancreatic cancer cells by essentially acting in paracrine mechanisms or they also involve intracellular signaling overlap and/or cooperation. In aim 2, we will determine the clinical relevance of CXCL12/CXCR4 and hedgehog interaction in pancreatic cancer. We will assess the incidence, intensity and correlative expression of CXCL12, CXCR4 and SHH in pancreatic cancer, and examine their joint clinical association with tumor -grade, -stage, and patient's survival. In aim 3, we will evaluate the efficacy of a combination therapy targeting CXCL12/CXCR4 and hedgehog pathways in two complementary models (orthotopic xenograft and genetically-engineered mouse) of pancreatic cancer. Treatment response will be evaluated by non-invasive imaging, tumor measurements and analyses of molecular markers. Completion of these proposed studies will provide us important data on collective (mechanistic, clinical and therapeutic) relevance of CXCL12/CXCR4 and hedgehog pathways in pancreatic cancer. In the long term, the resulting information may lead to a novel and effective treatment for lethal pancreatic cancer.