title: Molecular and morphologic correlates of the alternative lengthening of telomeres phenotype in high-grade astrocytomas.
abstract: Recent studies suggest that the telomere maintenance mechanism known as alternative lengthening of telomeres (ALT) is relatively more common in specific glioma subsets and strongly associated with ATRX mutations. We retrospectively examined 116 high-grade astrocytomas (32 pediatric glioblastomas, 65 adult glioblastomas, 19 anaplastic astrocytomas) with known ALT status using tissue microarrays to identify associations with molecular and phenotypic features. Immunohistochemistry was performed using antibodies against ATRX, DAXX, p53 and IDH1(R132H) mutant protein. EGFR amplification was evaluated by fluorescence in situ hybridization (FISH). Almost half of fibrillary and gemistocytic astrocytomas (44%) demonstrated ALT. Conversely all gliosarcomas (n = 4), epithelioid (n = 2), giant cell (n = 2) and adult small cell astrocytomas (n = 7) were ALT negative. The ALT phenotype was positively correlated with the presence of round cells (P = 0.002), microcysts (P < 0.0002), IDH1 mutant protein (P < 0.0001), ATRX protein loss (P < 0.0001), strong P53 immunostaining (P < 0.0001) and absence of EGFR amplification (P = 0.004). There was no significant correlation with DAXX expression. We conclude that ALT represents a specific phenotype in high-grade astrocytomas with distinctive pathologic and molecular features. Future studies are required to clarify the clinical and biological significance of ALT in high-grade astrocytomas.
authors.affiliation: Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Doreen N
authors.initials: DN
authors.lastname: Nguyen
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Heaphy
authors.forename: Roeland F
authors.initials: RF
authors.lastname: de Wilde
authors.forename: Brent A
authors.initials: BA
authors.lastname: Orr
authors.forename: Yazmin
authors.initials: Y
authors.lastname: Odia
authors.forename: Charles G
authors.initials: CG
authors.lastname: Eberhart
authors.forename: Alan K
authors.initials: AK
authors.lastname: Meeker
authors.forename: Fausto J
authors.initials: FJ
authors.lastname: Rodriguez
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001254:Astrocytoma / Q000473:pathology* / Q000648:ultrastructure; D001932:Brain Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D002648:Child; D002675:Child, Preschool; D056970:Co-Repressor Proteins; D004265:DNA Helicases / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D053208:Kaplan-Meier Estimate; D008297:Male; D046228:Microarray Analysis; D008875:Middle Aged; D018832:Molecular Chaperones; D009687:Nuclear Proteins / Q000378:metabolism; D010641:Phenotype; D016019:Survival Analysis; D016615:Telomere / Q000473:pathology* / Q000648:ultrastructure; 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