Pilocytic astrocytomas have telomere-associated promyelocytic leukemia bodies without alternatively lengthened telomeres

Am J Pathol. 2010 Dec;177(6):2694-700. doi: 10.2353/ajpath.2010.100468. Epub 2010 Oct 29.

Abstract

Telomere maintenance by either telomerase activity or the recombination-mediated alternative lengthening of telomeres (ALT) mechanism is a hallmark of cancer. Tumors that use ALT as their telomere maintenance mechanism are characterized by long telomeres of great heterogeneity in length and by specific nuclear structures of co-localized promyelocytic leukemia protein and telomere DNA, called ALT-associated promyelocytic leukemia bodies (APBs). Recent advances have revealed a direct role for APBs in telomere recombination in ALT-positive cells. In this study, we investigated the possibility that APBs could occur before the long 'alternatively' lengthened telomeres arise, particularly in low-grade tumors. We measured APBs, telomere length, and telomerase activity in 64 astrocytomas inclusive of grade 1-4 tumors. Almost all grade 1-3 tumors (93%) were APB-positive using published criteria. Grade 2-3 APB-positive tumors also had long telomeres and were confirmed as ALT positive. However, grade 1 tumors lacked long telomeres and were therefore classified as ALT negative, but positive for telomere-associated promyelocytic leukemia bodies (TPB). This is the first report of a TPB-positive but ALT-negative tumor, and suggests that low-grade tumors have the foundation for recombinational telomere repair, as in ALT. Further work is warranted to characterize the TPB-positive phenotype in other early malignancies, as well as to determine whether TPBs predispose to telomere maintenance by ALT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Astrocytoma / genetics*
  • Astrocytoma / metabolism*
  • Astrocytoma / pathology
  • Brain Neoplasms / genetics*
  • Brain Neoplasms / metabolism*
  • Brain Neoplasms / pathology
  • Child
  • Disease Progression
  • Humans
  • Inclusion Bodies / metabolism
  • Middle Aged
  • Neoplasm Staging
  • Nuclear Proteins / metabolism*
  • Promyelocytic Leukemia Protein
  • Telomere / chemistry
  • Telomere / genetics
  • Telomere / metabolism*
  • Transcription Factors / metabolism*
  • Tumor Suppressor Proteins / metabolism*
  • Young Adult

Substances

  • Nuclear Proteins
  • Promyelocytic Leukemia Protein
  • Transcription Factors
  • Tumor Suppressor Proteins
  • PML protein, human