New transgenic animal model to study pancreatic cancer

描述（申请人提供）：胰腺癌是一种侵袭性疾病，目前尚无有效的治疗方法，且预后较差。为这种致命疾病开发改进疗法的能力将大大受益于动物模型，这些动物模型可以重现患者的疾病，并允许非侵入性监测和跟踪胰腺导管腺癌（PDAC）的发展和进展。研究 PDAC 生物学和治疗的研究人员广泛使用 KPC 转基因小鼠，该小鼠含有激活的 K-ras 癌基因，并且在胰腺中删除了一个或两个 p53 肿瘤抑制基因。该动物模型遵循人类疾病的进程，从而为评估治疗干预提供了有用且潜在的预测系统。然而，与人类患者一样，这种小鼠在肿瘤发展的时间和动力学方面表现出很大的变异性，有效监测肿瘤和转移性生长具有挑战性。我们的研究旨在纠正这种情况，并开发一种 PDAC 模型，与现有的 KPC 小鼠模型相比，该模型能够更准确地进行治疗分期和评估。我们测试了这样的假设：在转基因小鼠的所有组织中整合驱动荧光素酶报告基因（CCN1-Luc 基因构建体）的癌症选择性启动子，可以作为 CCN1-Luc 小鼠与 KPC 小鼠杂交后通过生物发光成像（BLI）对原发性肿瘤和转移瘤进行非侵入性成像的手段。已经在几种双转基因动物（CCN1-Luc-KPC 小鼠）中获得了原理验证，表明施用荧光素可以通过 BLI 检测原发性肿瘤和转移瘤，这已通过离体器官中的荧光和免疫组织化学 (IHC) 证实。这些结果具有创新性且意义重大，支持使用这种独特的双转基因小鼠模型（称为“PanMetView”或 PMV 小鼠）进行进一步研究，以评估 PDAC 的发育和转移进展，以及治疗影响这些过程的潜力。 PMV 小鼠模型的特征研究将在我们资助的具体目标 1 中进行。为了证实 PMV 小鼠在评估治疗干预方面的效用，我们选择了一种新的治疗方法，该方法涉及递送聚肌苷-聚胞苷酸 (pIC)，这是一种合成的 dsRNA，可以激活免疫系统，当使用聚乙烯亚胺 (PEI)、[pIC]PEI 施用到癌细胞的细胞质中时，会引起细胞凋亡和毒性自噬。初步研究表明，[pIC]PEI 在体外以及体内多种免疫缺陷动物模型中显示出有效的胰腺抗肿瘤作用，包括异种移植和人胰腺癌细胞的准原位给药。 [pIC]PEI 对 PMV 小鼠的治疗功效的原理验证将在我们资助的具体目标 2 中进行测试。我们的研究的成功完成将彻底改变如何使用转基因小鼠来研究 PDAC，该转基因小鼠作为一种全球性技术，用于产生双转基因小鼠，以跟踪其他癌症模型的发育、进展和治疗，具有广泛的应用。

DESCRIPTION (provided by applicant): Pancreatic cancer is an aggressive disease without currently effective therapies and with poor prognosis. The ability to develop improved therapies for this invariably fatal disease would benefit significantly from animal models that recapitulate the disease in patients and allow for non-invasively monitoring and following pancreatic ductal adenocarcinoma (PDAC) development and progression. Investigators studying PDAC biology and therapy extensively use the KPC transgenic mouse, which contains an activated K-ras oncogene and deletion of one or both p53 tumor suppressor genes in the pancreas. This animal model follows the course of the human disease and thereby provides a useful and potentially predictive system for evaluating therapeutic intervention. However, as with human patients, this mouse shows great variability in the timing and kinetics of tumor development and effectively monitoring tumor and metastatic growth is challenging. Our research seeks to remedy this situation and develop a PDAC model permitting more accurate staging and evaluation of therapy than the existing KPC mouse model. We tested the hypothesis that integrating a cancer-selective promoter driving the luciferase reporter gene, a CCN1-Luc gene construct, in all tissue of a transgenic mouse could serve as a means of imaging primary tumors and metastases non-invasively by bioluminescence imaging (BLI) following crossing of the CCN1-Luc mouse with the KPC mouse. Proof-of-principle has been obtained with several double transgenic animals, CCN1-Luc-KPC mice, indicating that administering luciferin allows for detection of primary tumors and metastases by BLI, as confirmed by fluorescence in isolated organs and immunohistochemistry (IHC). These results are innovative and significant, supporting further studies using this unique double transgenic mouse model, called "PanMetView" or PMV mice, to evaluate PDAC development and progression to metastasis, and the potential of therapy to impact on these processes. Studies characterizing the PMV mouse model will be performed in Specific Aim 1 of our grant. To confirm utility of the PMV mice for evaluating therapeutic intervention, we have chosen a novel therapeutic approach that involves delivery of polyinosinic-polycytidylic acid (pIC), a synthetic dsRNA that activates the immune system and when administered into the cytosol of cancer cells, using polyethyleneimine (PEI), [pIC]PEI, causes apoptosis and toxic autophagy. Preliminary studies indicate that [pIC]PEI displays potent pancreatic antitumor effects in vitro as well as in multiple immune deficient animal models in vivo, including xenografts and quasi-orthotopic administration of human pancreatic cancer cells. Proof-of-principle for therapeutic efficacy of [pIC]PEI in the PMV mice will be tested in Specific Aim 2 of our grant. Successful completion of our studies will be transformative in how PDAC is studied using transgenic mice with wide applications as a global technique for generating double transgenic mice to follow development, progression and therapy in other cancer models.