title: High-throughput microRNA (miRNAs) arrays unravel the prognostic role of MiR-211 in pancreatic cancer.
abstract: BACKGROUND
  Only a subset of radically resected pancreatic ductal adenocarcinoma (PDAC) patients benefit from chemotherapy, and identification of prognostic factors is warranted. Recently miRNAs emerged as diagnostic biomarkers and innovative therapeutic targets, while high-throughput arrays are opening new opportunities to evaluate whether they can predict clinical outcome. The present study evaluated whether comprehensive miRNA expression profiling correlated with overall survival (OS) in resected PDAC patients.
  
  
  RESULTS
  High-resolution miRNA profiles were obtained with the Toray's 3D-Gene™-miRNA-chip, detecting more than 1200 human miRNAs. RNA was successfully isolated from paraffin-embedded primary tumors of 19 out of 26 stage-pT3N1 homogeneously treated patients (adjuvant gemcitabine 1000 mg/m(2)/day, days-1/8/15, every 28 days), carefully selected according to their outcome (OS<12 (N = 13) vs. OS>30 months (N = 6), i.e. short/long-OS). Highly stringent statistics included t-test, distance matrix with Spearman-ranked correlation, and iterative approaches. Unsupervised hierarchical analysis revealed that PDACs clustered according to their short/long-OS classification, while the feature selection algorithm RELIEF identified the top 4 discriminating miRNAs between the two groups. These miRNAs target more than 1500 transcripts, including 169 targeted by two or more. MiR-211 emerged as the best discriminating miRNA, with significantly higher expression in long- vs. short-OS patients. The expression of this miRNA was subsequently assessed by quantitative-PCR in an independent cohort of laser-microdissected PDACs from 60 resected patients treated with the same gemcitabine regimen. Patients with low miR-211 expression according to median value had a significantly shorter median OS (14.8, 95%CI = 13.1-16.5, vs. 25.7 months, 95%CI = 16.2-35.1, log-rank-P = 0.004). Multivariate analysis demonstrated that low miR-211 expression was an independent factor of poor prognosis (hazard ratio 2.3, P = 0.03) after adjusting for all the factors influencing outcome.
  
  
  CONCLUSIONS
  Through comprehensive microarray analysis and PCR validation we identified miR-211 as a prognostic factor in resected PDAC. These results prompt further prospective studies and research on the biological role of miR-211 in PDAC.
authors.affiliation: Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands. elisa.giovannetti@gmail.com
authors.forename: Elisa
authors.initials: E
authors.lastname: Giovannetti
authors.forename: Arjan
authors.initials: A
authors.lastname: van der Velde
authors.forename: Niccola
authors.initials: N
authors.lastname: Funel
authors.forename: Enrico
authors.initials: E
authors.lastname: Vasile
authors.forename: Vittorio
authors.initials: V
authors.lastname: Perrone
authors.forename: Leticia G
authors.initials: LG
authors.lastname: Leon
authors.forename: Nelide
authors.initials: N
authors.lastname: De Lio
authors.forename: Amir
authors.initials: A
authors.lastname: Avan
authors.forename: Sara
authors.initials: S
authors.lastname: Caponi
authors.forename: Luca E
authors.initials: LE
authors.lastname: Pollina
authors.forename: Valentina
authors.initials: V
authors.lastname: Gallá
authors.forename: Hiroko
authors.initials: H
authors.lastname: Sudo
authors.forename: Alfredo
authors.initials: A
authors.lastname: Falcone
authors.forename: Daniela
authors.initials: D
authors.lastname: Campani
authors.forename: Ugo
authors.initials: U
authors.lastname: Boggi
authors.forename: Godefridus J
authors.initials: GJ
authors.lastname: Peters
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics* / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000032:analysis* / Q000235:genetics; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies
chemical_list: D014408:Biomarkers, Tumor; C549405:MIRN211 microRNA, human; D035683:MicroRNAs