title: MicroRNA Profiling Implies New Markers of Gemcitabine Chemoresistance in Mutant p53 Pancreatic Ductal Adenocarcinoma.
abstract: BACKGROUND
  No reliable predictors of susceptibility to gemcitabine chemotherapy exist in pancreatic ductal adenocarcinoma (PDAC). MicroRNAs (miR) are epigenetic gene regulators with tumorsuppressive or oncogenic roles in various carcinomas. This study assesses chemoresistant PDAC for its specific miR expression pattern.
  
  
  METHODS
  Gemcitabine-resistant variants of two mutant p53 human PDAC cell lines were established. Survival rates were analyzed by cytotoxicity and apoptosis assays. Expression of 1733 human miRs was investigated by microarray and validated by qRT-PCR. After in-silico analysis of specific target genes and proteins of dysregulated miRs, expression of MRP-1, Bcl-2, mutant p53, and CDK1 was quantified by Western blot.
  
  
  RESULTS
  Both established PDAC clones showed a significant resistance to gemcitabine (p<0.02) with low apoptosis rate (p<0.001) vs. parental cells. MiR-screening revealed significantly upregulated (miR-21, miR-99a, miR-100, miR-125b, miR-138, miR-210) and downregulated miRs (miR-31*, miR-330, miR-378) in chemoresistant PDAC (p<0.05). Bioinformatic analysis suggested involvement of these miRs in pathways controlling cell death and cycle. MRP-1 (p<0.02) and Bcl-2 (p<0.003) were significantly overexpressed in both resistant cell clones and mutant p53 (p = 0.023) in one clone.
  
  
  CONCLUSIONS
  Consistent miR expression profiles, in part regulated by mutant TP53 gene, were identified in gemcitabine-resistant PDAC with significant MRP-1 and Bcl-2 overexpression. These results provide a basis for further elucidation of chemoresistance mechanisms and therapeutic approaches to overcome chemoresistance in PDAC.
authors.affiliation: Department of General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
authors.forename: Sameer A
authors.initials: SA
authors.lastname: Dhayat
authors.affiliation: Department of General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
authors.forename: Wolf Arif
authors.initials: WA
authors.lastname: Mardin
authors.affiliation: Integrated Functional Genomics, Interdisciplinary Center for Clinical Research, Medical Faculty of the University of Muenster, Muenster, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Seggewiß
authors.affiliation: Comprehensive Cancer Center Muenster, University Hospital Muenster, Muenster, Germany.
authors.forename: Anda Jana
authors.initials: AJ
authors.lastname: Ströse
authors.affiliation: Department of General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Matuszcak
authors.affiliation: Department of General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Hummel
authors.affiliation: Department of General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Senninger
authors.affiliation: Department of General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
authors.forename: Sören Torge
authors.initials: ST
authors.lastname: Mees
authors.affiliation: Comprehensive Cancer Center Muenster, University Hospital Muenster, Muenster, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Haier
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D020869:Gene Expression Profiling; D016158:Genes, p53; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D009154:Mutation; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D015203:Reproducibility of Results; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D035683:MicroRNAs; D012333:RNA, Messenger; D003841:Deoxycytidine; D000093542:Gemcitabine