Targeting tumor-stromal interaction for pancreatic cancer therapy

描述(申请人提供)：胰腺癌患者的五年生存率在过去30年里一直保持在3-6%。如此糟糕的预后很大程度上是由于胰腺癌对目前可用的治疗方法产生了抵抗力。因此，迫切需要开发一种新的、基于机制的精细化治疗方法来治疗胰腺癌。新的数据表明，肿瘤-间质相互作用在胰腺癌的病理生物学和化疗耐药中起着重要作用。在这方面，我们最近发现，趋化因子CXCL12，主要来自于基质细胞，通过增强CXCR4介导的生存机制而对胰腺癌细胞产生耐药性。在其他新的发现中，我们证明了CXCL12/CXCR4信号轴在胰腺癌细胞中Hedgehog配体(Sonic Hedgehog，SHH)上调中的作用。此外，我们还发现，刺激的胰腺癌细胞的条件培养液(CM)部分地通过Hedgehog依赖的机制促进了胰腺星状细胞(PSCs)产生CXCL12。更重要的是，我们证明了PSCs在共培养实验中诱导的胰腺癌细胞的化疗耐药涉及CXCL12/CXCR4的支持作用和Hedgehog信号机制。基于这些新的发现，我们假设CXCL12/CXCR4和Hedgehog通路进入恶性循环，协同促进胰腺癌生长和化疗耐药，联合靶向这些信号节点将产生更好的治疗结果。为了检验这些假设，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CXCL12/CXCR4和Hedgehog串扰的潜在机制。我们还将研究这些途径是否主要通过旁分泌机制促进胰腺癌细胞的生长和化疗耐药，或者它们也涉及细胞内信号重叠和/或合作。在目标2中，我们将确定CXCL12/CXCR4和Hedgehog相互作用在胰腺癌中的临床相关性。我们将评估CXCL12、CXCR4和SHH在胰腺癌中的发生率、强度和相关表达，并探讨它们与肿瘤分级、分期和患者生存的联合临床相关性。在目标3中，我们将评估针对CXCL12/CXCR4和Hedgehog通路的联合治疗在两种互补的胰腺癌模型(原位异种移植和基因工程小鼠)中的疗效。治疗反应将通过非侵入性成像、肿瘤测量和分子标志物分析来评估。这些拟议研究的完成将为我们提供关于CXCL12/CXCR4和Hedgehog通路在胰腺癌中的集体(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一种新的、有效的治疗致命胰腺癌的方法。

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.