title: Loss of DAXX and ATRX are associated with chromosome instability and reduced survival of patients with pancreatic neuroendocrine tumors.
abstract: OBJECTIVE
  Sporadic pancreatic neuroendocrine tumors (pNETs) are rare and genetically heterogeneous. Chromosome instability (CIN) has been detected in pNETs from patients with poor outcomes, but no specific genetic factors have been associated with CIN. Mutations in death domain-associated protein gene (DAXX) or ATR-X gene (ATRX) (which both encode proteins involved in chromatin remodeling) have been detected in 40% of pNETs, in association with activation of alternative lengthening of telomeres. We investigated whether loss of DAXX or ATRX, and consequent alternative lengthening of telomeres, are related to CIN in pNETs. We also assessed whether loss of DAXX or ATRX is associated with specific phenotypes of pNETs.
  
  
  METHODS
  We collected well-differentiated primary pNET samples from 142 patients at the University Hospital Zurich and from 101 patients at the University Hospital Bern (both located in Switzerland). Clinical follow-up data were obtained for 149 patients from general practitioners and tumor registries. The tumors were reclassified into 3 groups according to the 2010 World Health Organization classification. Samples were analyzed by immunohistochemistry and telomeric fluorescence in situ hybridization. We correlated loss of DAXX, or ATRX, expression, and activation of alternative lengthening of telomeres with data from comparative genomic hybridization array studies, as well as with clinical and pathological features of the tumors and relapse and survival data.
  
  
  RESULTS
  Loss of DAXX or ATRX protein and alternative lengthening of telomeres were associated with CIN in pNETs. Furthermore, loss of DAXX or ATRX correlated with tumor stage and metastasis, reduced time of relapse-free survival, and decreased time of tumor-associated survival.
  
  
  CONCLUSIONS
  Loss of DAXX or ATRX is associated with CIN in pNETs and shorter survival times of patients. These results support the hypothesis that DAXX- and ATRX-negative tumors are a more aggressive subtype of pNET, and could lead to identification of strategies to target CIN in pancreatic tumors.
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Marinoni
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Anja Schmitt
authors.initials: AS
authors.lastname: Kurrer
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Erik
authors.initials: E
authors.lastname: Vassella
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Dettmer
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rudolph
authors.affiliation: Department of Visceral Surgery and Medicine, Inselspital, University Hospital Bern, Bern, Switzerland.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Banz
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Fabio
authors.initials: F
authors.lastname: Hunger
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Silvan
authors.initials: S
authors.lastname: Pasquinelli
authors.affiliation: Department of Molecular Cell Biology, Institute of Pathology University Medical Center, Maastricht, Holland.
authors.forename: Ernst-Jan
authors.initials: EJ
authors.lastname: Speel
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland. Electronic address: aurel.perren@pathology.unibe.ch.
authors.forename: Aurel
authors.initials: A
authors.lastname: Perren
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency / Q000235:genetics*; D014408:Biomarkers, Tumor / Q000172:deficiency / Q000235:genetics*; D043171:Chromosomal Instability; D056970:Co-Repressor Proteins; D004265:DNA Helicases / Q000172:deficiency / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D018832:Molecular Chaperones; D009154:Mutation; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D018358:Neuroendocrine Tumors / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D010641:Phenotype; D011379:Prognosis; D017422:Sequence Analysis, DNA; D016019:Survival Analysis; D059505:Telomere Homeostasis / Q000235:genetics; D000075924:X-linked Nuclear Protein
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D014408:Biomarkers, Tumor; D056970:Co-Repressor Proteins; C106985:DAXX protein, human; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D004265:DNA Helicases; C092332:ATRX protein, human; D000075924:X-linked Nuclear Protein
keywords: ALT; ATR-X gene; ATRX; CGH; CI; CIN; DAXX; Exp(B); FISH; Human; IHC; Neoplasm ALT; PML; PNA; Pancreas; Prognosis; TMA; alternative lengthening telomeres; chromosomal instability; comparative genomic hybridization; confidence interval; death domain–associated protein gene; fluorescence in situ hybridization; immunohistochemistry; odds ratio; pNET; pancreatic neuroendocrine tumor; peptide nucleic acid; promyelocytic leukemia; tissue microarray