title: Loss of ATRX or DAXX expression and concomitant acquisition of the alternative lengthening of telomeres phenotype are late events in a small subset of MEN-1 syndrome pancreatic neuroendocrine tumors.
abstract: Approximately 45% of sporadic well-differentiated pancreatic neuroendocrine tumors harbor mutations in either ATRX (alpha thalassemia/mental retardation X-linked) or DAXX (death domain-associated protein). These novel tumor suppressor genes encode nuclear proteins that interact with one another and function in chromatin remodeling at telomeric and peri-centromeric regions. Mutations in these genes are associated with loss of their protein expression and correlate with the alternative lengthening of telomeres phenotype. Patients with multiple endocrine neoplasia-1 (MEN-1) syndrome, genetically defined by a germ line mutation in the MEN1 gene, are predisposed to developing pancreatic neuroendocrine tumors and thus represent a unique model for studying the timing of ATRX and DAXX inactivation in pancreatic neuroendocrine tumor development. We characterized ATRX and DAXX protein expression by immunohistochemistry and telomere status by telomere-specific fluorescence in situ hybridization in 109 well-differentiated pancreatic neuroendocrine lesions from 28 MEN-1 syndrome patients. The study consisted of 47 neuroendocrine microadenomas (<0.5 cm), 50 pancreatic neuroendocrine tumors (≥0.5 cm), and 12 pancreatic neuroendocrine tumor lymph node metastases. Expression of ATRX and DAXX was intact in all 47 microadenomas, and none showed the alternative lengthening of telomeres phenotype. ATRX and/or DAXX expression was lost in 3 of 50 (6%) pancreatic neuroendocrine tumors. In all three of these, tumor size was ≥3 cm, and loss of ATRX and/or DAXX expression correlated with the alternative lengthening of telomeres phenotype. Concurrent lymph node metastases were present for two of the three tumors, and each metastasis displayed the same changes as the primary tumor. These findings establish the existence of ATRX and DAXX defects and the alternative lengthening of telomeres phenotype in pancreatic neuroendocrine tumors in the context of MEN-1 syndrome. The observation that ATRX and DAXX defects and the alternative lengthening of telomeres phenotype occurred only in pancreatic neuroendocrine tumors measuring ≥3 cm and their lymph node metastases suggests that these changes are late events in pancreatic neuroendocrine tumor development.
authors.affiliation: Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Roeland F
authors.initials: RF
authors.lastname: de Wilde
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Heaphy
authors.forename: Anirban
authors.initials: A
authors.lastname: Maitra
authors.forename: Alan K
authors.initials: AK
authors.lastname: Meeker
authors.forename: Barish H
authors.initials: BH
authors.lastname: Edil
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Wolfgang
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Ellison
authors.forename: Richard D
authors.initials: RD
authors.lastname: Schulick
authors.forename: I Quintus
authors.initials: IQ
authors.lastname: Molenaar
authors.forename: Gerlof D
authors.initials: GD
authors.lastname: Valk
authors.forename: Menno R
authors.initials: MR
authors.lastname: Vriens
authors.forename: Inne H M
authors.initials: IH
authors.lastname: Borel Rinkes
authors.forename: G Johan A
authors.initials: GJ
authors.lastname: Offerhaus
authors.forename: Ralph H
authors.initials: RH
authors.lastname: Hruban
authors.forename: Karen E
authors.initials: KE
authors.lastname: Matsukuma
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis*; D000236:Adenoma / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018278:Carcinoma, Neuroendocrine / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D056970:Co-Repressor Proteins; D004265:DNA Helicases / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D018832:Molecular Chaperones; D018761:Multiple Endocrine Neoplasia Type 1 / Q000150:complications; D009687:Nuclear Proteins / Q000096:biosynthesis*; D010190:Pancreatic Neoplasms / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D016615:Telomere / Q000378:metabolism / Q000473:pathology*; D000075924:X-linked Nuclear Protein; D055815:Young Adult
chemical_list: D048868:Adaptor Proteins, Signal Transducing; 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