Defining the Contributions of Pancreatic Ductal and Acinar Cells to Tumorigenesis

描述（由申请人提供）：胰腺癌是美国癌症死亡的第四大原因。5%的五年生存率表明需要改进治疗方法。为了满足这一需求，我们需要更好地了解胰腺癌发生的机制。可能决定肿瘤表型的几个因素包括：1)肿瘤起源的细胞类型，2)转化细胞获得的总体基因突变，以及3)获得基因突变的序列。基于以往的研究和我们的初步数据，我的假设是细胞起源是决定胰腺肿瘤表型的重要因素。虽然胰腺导管腺癌（PDA）是最常见的胰腺癌，但我们仍然不知道是哪种细胞类型引起的。对其他类型的胰腺肿瘤也是如此。我的目标是研究特异性表达于成年胰腺腺泡细胞（AC）或导管细胞（DC）的突变的致瘤作用。我将使用两个鼠标模型。第一种通过k-ras和Trp53的同时突变繁殖PDA；第二种是我们实验室最近开发的一种新型实体假乳头状瘤（SPT）模型，该模型基于外源激活的¿-catenin，通过Cre重组-切除外显子3（¿-catex3）。我的第一个目标是只针对成年小鼠的AC突变。我将携带条件表达突变k-ras和Trp53等位基因（k-rasG12D/Trp53R172H）或-catenin （-catex3）的小鼠与携带他莫昔芬激活的Cre的小鼠进行杂交，Cre通过源自弹性酶基因的启动子表达为AC。肿瘤将通过组织学和免疫组织化学进行表征。基因表达谱将通过定量PCR分析。我的第二个目标是评估k-rasG12D/Trp53R172H或¿-catex3在DC中的作用。目前，没有启动子将Cre引导到导管上皮。相反，我将从成年krasG12D/Trp53R172H或¿-catex3小鼠中分离和培养DC，并用慢病毒递送的Cre在体外激活它们。荧光素酶将同时引入，允许通过发光在体内监测肿瘤生长。我们将这些细胞重新植入裸鼠体内，并以与Aim 1相同的方式表征形成的肿瘤。公共卫生相关性：确定引起胰腺肿瘤的细胞类型具有几个重要意义。首先，我们将能够集中更多的研究工作，针对特定的细胞类型，并对胰腺肿瘤发生背后的机制进行更详细的研究。其次，我们也许能够提供更有针对性的治疗，提高疗效，减少副作用。

DESCRIPTION (provided by applicant): Pancreatic cancer is the fourth-leading cause of cancer deaths in the United States. The 5% five-year survival rate demonstrates the need for improved treatments. To address that need, a better understanding of the mechanisms of pancreatic carcinogenesis is needed. Several factors that may determine tumor phenotype include: 1) cell type of tumor origin, 2) aggregate genetic mutations acquired by transformed cells, and 3) sequence by which genetic mutations are acquired. Based on previous studies and our preliminary data, my hypothesis is that cellular origin is an important factor in determining pancreatic tumor phenotype. Although pancreatic ductal adenocarcinoma (PDA) is the most common form of pancreatic cancer, we still do not know which cell type gives rise to it. This lack of insight is also true for other types of pancreatic tumors. My objectives are to study the tumorigenic effects of mutations expressed specifically to adult pancreatic acinar cells (AC) or ductal cells (DC). I will use two mouse models. The first reproduces PDA via concurrent mutations in k-ras and Trp53; the second is a novel model for solid pseudopapillary tumor (SPT) that our laboratory recently developed and is based on exogenously activated ¿-catenin via Cre recombination-excision of exon 3 (¿-catex3). My first aim is to target mutations to only AC in adult mice. I will cross mice carrying conditionally expressed alleles of mutated k-ras and Trp53 (k-rasG12D/Trp53R172H) or ¿-catenin (¿-catex3) to mice carrying tamoxifen-activated Cre that are expressed to AC via a promoter derived from the elastase gene. Tumors will be characterized with histology and immunohistochemistry. Gene expression profiles will be analyzed by quantitative PCR. My second aim is to evaluate the effects of k-rasG12D/Trp53R172H or ¿-catex3 in DC. Currently, there is no promoter to direct Cre to only ductal epithelium. Instead, I will isolate and culture DC from adult krasG12D/Trp53R172H or ¿-catex3 mice and activate them in vitro with lentiviral delivered Cre. Luciferase will be concurrently introduced to allow in vivo monitoring of tumor growth via luminescence. We will re-implant these cells into nude mice and characterize formed tumors in the same manner as in Aim 1. PUBLIC HEALTH RELEVANCE: Identifying the types of cells that give rise to pancreatic tumors has several important implications. First, we will be able to focus additional research efforts towards that particular cell type and pursue more detailed studies into the mechanisms behind pancreatic tumorigenesis. Secondly, we may be able to deliver more targeted therapy that has increased efficacy and reduced side effects.