Alternative lengthening of telomeres (ALT) and chromatin: Is there a connection?

Thalia Nittis, Lionel Guittat, Sheila A. Stewart

Research output: Contribution to journalReview articlepeer-review

29 Scopus citations

Abstract

The acquisition of cellular immortality is a critical step in the tumorigenic process that requires stabilization of the telomeres, nucleoprotein structures at the termini of chromosomes. While the majority of human tumors stabilize their telomeres through activation of telomerase (hTERT), a significant portion (10-15%) utilize a poorly understood alternative mechanism of telomere maintenance referred to as ALT (Alternative Lengthening of Telomeres). Strikingly, the ALT mechanism is more prevalent in tumors arising from tissues of mesenchymal origin than in those of epithelial origin. This observation suggests that cell type specific mechanisms favor the activation of the ALT mechanism versus telomerase in human tumorigenesis. In addition, the presence of an alternative mechanism of telomere maintenance raises the possibility that telomerase-positive tumors undergoing anti-telomerase therapies might escape by activating the ALT pathway. For these reasons, delineating the ALT mechanism is critical for our understanding of the tumorigenic process and the development of ALT-specific anti-neoplastic therapies. Recent studies have demonstrated that epigenetic modifications at telomeres have a profound effect on telomere length, and may also be linked to the ALT mechanism. In this review we focus on these recent advances and their implications in telomere maintenance.

Original languageEnglish
Pages (from-to)5-12
Number of pages8
JournalBiochimie
Volume90
Issue number1
DOIs
StatePublished - Jan 1 2008

Keywords

  • Alternative lengthening of telomeres
  • DNA methylation
  • Epigenetic modifications
  • Histone methylation
  • Telomere

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