Cancer Prevention Research MicroRNAs in Plasma of Pancreatic Ductal Adenocarcinoma Patients as Novel Blood-Based Biomarkers of Disease

Development of minimally invasive biomarker assays for early detection and effective clinical management of pancreatic cancer is urgently needed to reduce high morbidity and mortality associated with this malignancy. We hypothesized that if aberrantly expressing microRNAs (miRNA) in pancreatic adenocarcinoma tissues are detected in blood plasma, then plasma profiling of these miRNAs might serve as a minimally invasive early detection biomarker assay for this malignancy. By using a modified protocol to isolate and quantify plasma miRNAs from heparin-treated blood, we show that miRNA profiling in plasma can differentiate pancreatic adenocarcinoma patients from healthy controls. We have profiled four miRNAs, miR-21, miR-210, miR-155, and miR-196a, all implicated in the development of pancreatic cancer with either proven or predicted target genes involved in critical cancerassociated cellular pathways. Of these, miR-155 has recently been identified as a candidate biomarker of early pancreatic neoplasia, whereas elevated expression of miR196a has been shown to parallel progression of disease. The results revealed a sensitivity of 64% and a specificity of 89% with the analyses of plasma levels for this panel of four miRNAs. The area under the receiver operating characteristic curve were estimated at 0.82 and 0.78 without and with leave-one-out cross-validation scheme, respectively. These observations, although a “proof of principle” finding at this time, show the feasibility of developing plasma miRNA profiling as a sensitive and specific blood-based biomarker assay for pancreatic cancer that has the potential of translation to the clinic with additional improvements in the future. Sensitive and specific cancer biomarkers are essential to early detection and diagnosis as well as for undertaking novel therapeutic trials and prevention strategies. Development of blood-based biomarker assays for malignancies such as pancreatic cancer is critical because most patients with this neoplasm remain asymptomatic until they present with locally advanced or distally metastatic and surgically inoperable disease at the time of diagnosis. With pancreatic cancer being the fourth most common cause of cancer-related deaths in the United States (1) and an average 5-year survival rate of <5%, early detection of this malignancy at a surgically resectable stage offers the best curative option for the patients (2). The majority of pancreatic cancers arise from the epithelial lining of the exocrine pancreatic ducts as pancreatic ductal adenocarcinoma (PDAC) through a multistep progression process involving noninvasive precursor lesions (3). The precursor lesions consist of microscopic pancreatic intraepithelial neoplasia within the duct (4) and macroscopic intraductal papillary mucinous neoplasms (IPMN) as cystic lesions connected with the main pancreatic duct or one of its branches (5). In both pancreatic intraepithelial neoplasia and IPMN, the epithelium lining shows varying degrees of histologic atypia ranging form adenoma to carcinoma in situ (4). Interestingly, some of the seminal genetic alterations detected in invasive pancreatic carcinomas, such as mutations in KRAS2, DPC4/ SMAD4, and TP53 are observed in both pancreatic intraepithelial neoplasia (6–8) and IPMN (3, 9), lending support to their roles as bona fide precursor lesions. Despite identification of such common genetic mutation signatures shared between noninvasive and invasive pancreatic lesions, their utility in discriminating between benign and malignant pancreatic disease remain unresolved primarily because minimally invasive diagnostic methods for screening of candidate biomarkers are still not available. It has been reported that even imaging techniques such as computed tomography andmagnetic resonance imaging sometimes fail to differentiate between benign and malignant lesions with up to 6% of the cases suspected as malignant with these methods later found to be benign at surgery with subsequent postsurgical complications developing among a significant number of these patients (10). Endoscopic Authors' Affiliations: Departments of Molecular Pathology, Epidemiology, Gastrointestinal Medical Oncology, and Genetics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas Received 5/6/09; revised 6/12/09; accepted 7/1/09; publishedOnlineFirst 9/1/09. Grant Support: The National Cancer Institute grant UO1CA111302. The National Cancer Institute Cancer Center Support grant CA16672. University Cancer Foundation grant from UTMDACC. Requests for reprints: Subrata Sen, Department of Molecular Pathology, Unit 951, The University of Texas M.D. Anderson Cancer Canter, 7435 Fannin, Houston, Texas, 77054. Phone: 713-834-6040; Fax: 713-834-6083; E-mail: [email protected]. ©2009 American Association for Cancer Research. doi:10.1158/1940-6207.CAPR-09-0094 807 Cancer Prev Res 2009;2(9) September 2009 www.aacrjournals.org Cancer Research. on June 16, 2017. © 2009 American Association for cancerpreventionresearch.aacrjournals.org Downloaded from Published OnlineFirst September 1, 2009; DOI: 10.1158/1940-6207.CAPR-09-0094