Phenotyping pain in a mouse model of pancreatic cancer

描述（由申请人提供）：胰腺癌，特别是胰腺导管腺癌（PDAC），是包括美国在内的西方国家癌症死亡的五大主要原因之一。尽管诊断成像和手术技术取得了进步，但死亡率仍然接近发病率，因为非特异性且往往是晚期症状使早期检测变得复杂，而且频繁的传播限制了治愈的机会。胰腺癌的重要临床表现之一是疼痛。通常剧烈的疼痛被认为是由肿瘤细胞侵入胰腺神经引起的。这种神经与癌症的相互作用也可能导致胰腺肿瘤的侵袭行为。这些发现共同表明，周围神经系统与胰腺癌之间存在密切关系，其中肿瘤产生的生长因子诱导神经萌芽和肥大，增加神经与癌症的相互作用，进而促进癌症的生长和侵袭。我们已经开始培育一种转基因小鼠模型，该模型表达人类胰腺癌中最常见的遗传病变（Kras 功能获得性突变和 p53 肿瘤抑制基因的缺失），并产生几乎具有人类疾病中所有特征的肿瘤。但在我们开发一个综合计划来利用这些小鼠来研究癌症疼痛之前，我们需要确定它们实际上是否表现出可量化的疼痛行为，以及这些行为是否与人类周围感觉神经系统的变化相关。我们的假设是，Kras/p53 小鼠的胰腺癌会产生与肿瘤生长和神经营养因子的产生相关的疼痛行为，这些神经营养因子已被证明可以调节成年伤害感受器的解剖结构和功能（例如 NGF 和 artemin）。为了检验这一假设，我们将完成以下目标： SA1：PDAC 进展期间 Kras/p53 小鼠的表型疼痛行为。 a) 使用 Kras/p53 和对照小鼠，我们将对受持续疼痛影响的行为进行纵向研究，包括旷场行为、步态分析和驼背，以及测试相关超敏反应（例如，对腹部皮肤）的发展。 SA2：检验 PDAC 增加神经营养因子（例如 NGF、artemin、GDNF）并诱导内脏传入神经肥大的假设。该假设将通过以下方式检验：a) 确定胰腺肿瘤中生长因子和生长因子受体表达的变化（通过实时 PCR、蛋白质印迹）。 b) 记录 PDAC 过程中生长因子依赖性传入纤维的胰腺神经支配变化。 公共卫生相关性：胰腺癌仍然是一种常见且极其痛苦的疾病，每年影响美国约 40,000 人。这项提议将确定胰腺癌小鼠模型是否也经历持续的疼痛，这种小鼠模型具有人类疾病的许多遗传、解剖和生化特征。这些研究有可能为未来的实验奠定基础，阐明引起胰腺癌疼痛的机制，目标是开发治疗癌痛的新疗法。

DESCRIPTION (provided by applicant): Pancreatic cancer, and specifically pancreatic ductal adenocarcinoma (PDAC), is among the five leading causes of cancer death in Western countries including the United States. Despite advances in diagnostic imaging and surgical techniques, mortality still approaches incidence as non-specific and often late symptoms complicate early detection and the frequent spread limit chances of cure. One of the important clinical manifestations of pancreatic cancer is pain. The often intense pain is thought to arise from invasion of tumor cells into the pancreatic nerves. This nerve-cancer interaction may also contribute to the aggressive behavior of pancreatic neoplasms. Together these findings suggest an intimate relationship between the peripheral nervous system and pancreatic cancer, wherein tumor-produced growth factors induce nerve sprouting and hypertrophy, increasing nerve-cancer interactions, which in turn promote cancer growth and invasion. We have begun to breed a transgenic mouse model that expresses the most common genetic lesions seen in human pancreatic cancer (a gain-of-function Kras mutations and loss of the p53 tumor suppressor gene) and develop tumors with virtually all of the features seen in the human disease. But before we develop a comprehensive program to exploit these mice for the study of cancer pain we need to determine if in fact they exhibit quantifiable pain behaviors, and whether these behaviors are correlated with changes in the peripheral sensory nervous system as has been seen in humans. Our hypothesis is that pancreatic cancer in Kras/p53 mice will produce pain behaviors that are correlated with tumor growth and the production of neurotrophic factors that have been shown to regulate anatomy and function of adult nociceptors (e.g., NGF and artemin). To test this hypothesis we will complete the following aims: SA1: Phenotype pain behaviors in Kras/p53 mice during progression of PDAC. a) Using Kras/p53 and control mice, we will conduct longitudinal studies of behaviors that should be affected by ongoing pain, including open field behavior, gait analysis, and hunching, as well as testing for the development of referred hypersensitivity (e.g., to abdominal skin). SA2: Test the hypothesis that PDAC increases neurotrophic factors (e.g. NGF, artemin, GDNF) and induces hypertrophy of visceral afferents . This hypothesis will be examined by: a) Determining changes in growth factor and growth factor receptor expression in pancreatic tumors (via real- time PCR, Western blots). b) Documenting changes in pancreatic innervation for growth factor dependent afferent fibers during the course of PDAC. PUBLIC HEALTH RELEVANCE: Pancreatic cancer remains a common and extremely painful disease, affecting about 40,000 individuals in the United States each year. This proposal will determine if a mouse model of pancreatic cancer, one that has many of the genetic, anatomical and biochemical features of the human disease, also experiences ongoing pain. These studies have to potential to lay the foundation for future experiments that will elucidate the mechanisms that cause pancreatic cancer pain, with the goal of developing novel therapies for cancer pain.