microRNAs as novel Biomarkers for Pancreatic Ductal Adenocarcinoma

描述(申请人提供)：人胰腺导管腺癌(PDAC)是美国成年人癌症死亡的第四大原因。正如NCI赞助的胰腺癌进展回顾小组的报告所强调的那样，开发新的生物标记物和新的治疗策略是非常必要的。因此，重要的是确定是否有信息丰富的分子生物标记物可以被识别用于诊断目的。这项建议侧重于将microRNAs(MiRNAs)作为PDAC中潜在的生物标记物。MiRNAs是新近发现的一类短小的非编码RNA基因，是基因表达的转录后负调控因子。MiRNAs特定亚群的表达改变与不同类型的白血病和实体瘤有关，它们可能作为早期发现、诊断和/或预后的生物标志物具有潜在的临床价值。此外，与蛋白质编码基因的信使RNA(MRNAs)相比，它们的小尺寸使得它们对降解不那么敏感，这些降解通常与组织的福尔马林固定和石蜡包埋(FFPE)或通过内窥镜超声引导(EUS)细针抽吸(FNA)获得的细胞准备有关。因此，miRNAs可能是比mRNAs更适合于从胰腺获得的档案组织样本和FNA细胞样本的表达特征的生物标志物。我们的初步研究(和/或来自其他小组的报告)已将一小部分miRNAs与PDAC联系起来。此外，我们还实施了miRNA原位杂交(ISH)方案，可以定量检测石蜡包埋的胰腺组织或细胞悬液中单个细胞中miRNA的表达。这项开创性的技术将使我们能够评估miRNA表达的变化是否发生在PDAC中的癌细胞内和/或相邻的间质和实质成分中，以及这些变化是否已经在恶变的早期阶段表现出来，如胰腺上皮内病变。在这里，我们建议进行一项彻底的调查，目的是：1)确定区分PDAC与良性病变和慢性胰腺炎的最佳miRNAs子集；2)评估这个选定子集的临床价值；以及3)实施ISH方法，潜在地将miRNAs作为FNA样本的早期检测或诊断生物标记物应用于临床。公共卫生相关性：胰腺导管腺癌(PDAC)是一种致命的恶性肿瘤，其死亡率与发病率几乎相等，但目前尚无早期诊断标记。MiRNAs是一类新的调控RNA，在癌症生物学中具有重要的作用。我们认为miRNA表达的变化与PDAC的启动和/或进展有关，这些变化的特征将为在临床环境下评估这些miRNAs作为新的生物标志物在PDAC早期检测和诊断中的价值提供基础，当与内窥镜超声联合使用时。

DESCRIPTION (provided by applicant): Human pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death in adults in the United States. As underscored by the NCI-sponsored Report of the Pancreatic Cancer Progress Review Group there is a tremendous need to develop novel biomarkers and novel therapeutic strategies. Thus, it is important to determine whether there are informative molecular biomarkers that can be identified for diagnostic purposes. This proposal focuses on microRNAs (miRNAs) as potential biomarkers in PDAC. miRNAs are a recently- discovered class of short non-coding RNA genes, which act as post-transcriptional negative regulators of gene expression. Altered expression of specific subsets of miRNAs has been linked to different types of leukemias and solid tumors, and they appear to have potential clinical value as biomarkers for early detection, diagnosis and/or prognosis. Moreover, their small size makes them less sensitive than messenger RNAs (mRNAs) of protein-encoding genes to degradation often associated with processing of tissue for formalin-fixation and paraffin-embedding (FFPE) or cell preparation obtained by endoscopic ultrasound-guided (EUS) fine needle aspiration (FNA). Thus, miRNAs may be more suitable biomarkers than mRNAs for expression characterization in archival tissue specimens and FNA cell samples obtained from the pancreas. Our preliminary studies (and/or reports from other groups) have linked a small subset of miRNAs to PDAC. In addition, we have implemented a miRNA in situ hybridization (ISH) protocol that permits the quantification of miRNA expression within individual cells in paraffin-embedded pancreatic tissue or in cell suspension. This pioneering technique will allow us to evaluate whether changes of miRNA expression occur within the cancer cells in PDAC and/or within the ad- joining stromal and parenchymal elements, and whether these changes are already manifested at early stages of malignancy such as pancreatic intraepithelial lesions. Here, we propose to conduct a thorough investigation aimed at: 1) Identifying the best subset of miRNAs to discriminate PDAC from benign lesions and chronic pancreatitis; 2) Assessing the clinical value of this selected subset in a sample of 150 archival patient cases; and 3) Implementing ISH methodology for potential clinical application of miRNAs as early detection or diagnostic biomarkers on FNA samples. PUBLIC HEALTH RELEVANCE: Pancreatic ductal adenocarcinoma (PDAC) is a deadly malignancy in which mortality virtually equals incidence, yet for which there are no early diagnostic markers. miRNAs are a novel class of regulatory RNAs with great importance in cancer biology. We propose that changes in miRNA expression are linked to the initiation and/or progression of PDAC, and that characterization of these changes will provide the basis for assessing in a clinical setting the value of these miRNAs as novel biomarkers for early detection and diagnosis of PDAC when used in conjunction with endoscopic ultrasonography.