Telomere dynamics and telomerase activity in in vitro immortalised human cells

https://doi.org/10.1016/S0959-8049(97)00065-8Get rights and content

This article reviews the current understanding of the involvement of telomerase in in vitro immortalisation of human cells. In vitro immortalisation with DNA tumour viruses or chemicals usually occurs in two phases. The first stage is an extension of lifespan beyond that at which cells would normally senesce, after which the culture enters a period of crisis. The second stage involves the escape from crisis of a rare cell in the culture, which goes on to proliferate indefinitely. The hypothesis that telomere shortening acts as a signal for senescence and crisis, and that cells need to activate telomerase to survive these states, gained support from early studies examining telomere behaviour and telomerase activity in immortalised cell lines. In many cases, telomeres were found to continue to shorten during the phase of extended lifespan, and no telomerase was detectable. Cells which survived crisis had activated telomerase and had stable or lengthened telomeres. However, it is now clear that this model does not apply to all cell lines. Approximately a quarter of in vitro immortalised cell lines so far examined have no detectable telomerase activity, yet have very long and heterogeneous telomeres. These cell lines have acquired a novel mechanism for lengthening their telomeres, named ALT (Alternative Lengthening of Telomeres). The nature of ALT is not yet understood, but may involve non-reciprocal recombination between telomeres. ALT is not merely a phenomenon of in vitro immortalised cell lines, but has also been found in tumours and tumour-derived cell lines. Furthermore, there are a number of cell lines which have been shown to have low levels of telomerase prior to crisis while telomere shortening is still occurring, and the function of these low levels of telomerase activity is unknown.

References (60)

  • HaytlickL et al.

    The serial cultivation of human diploid cell strains

    Exp Cell Res

    (1961)
  • BryanTM et al.

    SV40-induced immortalization of human cells

    Crit Rev Oncogenesis

    (1994)
  • SerranoM et al.

    A new regulatory motif in cellcycle control causing specific inhibition of cyclin DCDK4

    Nature

    (1993)
  • LiY et al.

    Transcnptional repression of the D-type cyclindependent kinase inhibitor p16 by the retinoblastoma susceptibility gene product pRb

    Cancer Res

    (1994)
  • OkamotoA et al.

    Mutations and altered expression of p16INK4 in human cancer

  • OttersonGA et al.

    Absence of p16INK4 protein is restricted to the subset of lung cancer lines that retains wildtype RB

    Oncogcne

    (1994)
  • AagaardL et al.

    Aberrations of p16INK4 and retinoblastoma tumoursuppressor genes occur in distinct subsets of human cancer cell lines

    Int J Cancer

    (1995)
  • ParryD et al.

    Lack of cyclin D-Cdk complexes in Rb-negative cells correlates with high levels of p16INK4MTS1 tumour suppressor gene product

    EMBO J

    (1995)
  • ShapiroGI et al.

    Reciprocal Rb inactivation and p16INK4 expression in primary lung cancers and cell lines

    Cancer Res

    (1995)
  • WhitakerXJ et al.

    Involvement of RB-1, p53, p16INK4 and telomerase in immortalisation of human cells

    Oncogene

    (1995)
  • YeagerT et al.

    Increased p16 levels correlate with pRB alterations in human urothelial cells

    Cancer Res

    (1995)
  • RoganEM et al.

    Alterations in p53 and p16INK4 expression and telomere length during spontaneous immortalization of Li-Fraumem syndrome fibroblasts

    Mol Cell Biol

    (1995)
  • NobleJR et al.

    Association of extended in vitro proliferative potential with loss of p16INK4 expression

    Oncogen

    (1996)
  • GirardiAJ et al.

    SV40-induced transformation of human diploid cells: crisis and recovery

    J Cell Comp Physiol

    (1965)
  • ShayJW et al.

    The frequency of immortalization of human fibroblasts and mammary epithelial cells transfected with SV40 large T-antigen

    Exp Cell Res

    (1993)
  • BlackburnEH

    Structure and function of telomeres

    Nature

    (1991)
  • HarleyCB et al.

    Telomeres shorten during ageing of human fibroblasts

    Nature

    (1990)
  • HastieND et al.

    Telomere reduction in human colorectal carcinoma and with ageing

    Nature

    (1990)
  • LindseyJ et al.

    In vivo loss of telomeric repeats with age in humans

    Mutat Res

    (1991)
  • VaziriH et al.

    Loss of telomeric DXA during aging of normal and trisomy 21 human lymphocytes

    Am J Hum Genet

    (1993)
  • OlovnikovAM

    Principle of marginotomy in template synthesis of polynucleotides

    Doklady Biochem

    (1971)
  • LansdorpPM et al.

    Heterogeneity in telomere length of human chromosomes

    Hum Mol Genet

    (1996)
  • HendersonS et al.

    In situ analysis of changes in telomere size during replicative aging and cell transformation

    J Cell Biol

    (1996)
  • AllsoppRC et al.

    Telomere length predicts replicative capacity of human fibroblasts

  • AllsoppRC et al.

    Evidence for a critical telomere length in senescent human fibroblasts

    Exp Cell Res

    (1995)
  • CookeHJ et al.

    Variability at the telomeres of the human X/Y pseudoautosomal region

  • AllshireRC et al.

    Telomeric repeat from T. thermophila cross hybridizes with human telomeres

    Nature

    (1988)
  • De LangeT et al.

    Structure and variability of human chromosome ends

    Mol Cell Biol

    (1990)
  • GreiderCW et al.

    Identification of a specific telomere terminal transferase activity in Tetrahymena extracts

    Cell

    (1985)
  • HarleyCB

    Telomere loss: mitotic clock or genetic time bomb?

    Mutat Res

    (1991)

    • Cited by (184)

    • Yeast KEOPS complex regulates telomere length independently of its t<sup>6</sup>A modification function

      2018, Journal of Genetics and Genomics
      Citation Excerpt :

      In addition to telomerase, Rad52-mediated homologous recombination (also called alternative lengthening of telomeres, ALT) can replicate telomeres particularly when telomerase is absent (Lundblad and Blackburn, 1993). The yeast cells that use homologous recombination to maintain telomeres are called “survivors” (Bryan and Reddel, 1997; McEachern and Haber, 2006). Type I and type II survivors can be distinguished by their different telomere structures: subtelomeric Y′-element and telomeric TG1-3 repeat amplifications, respectively (Le et al., 1999; McEachern and Haber, 2006).

    • Role of specialized DNA polymerases in the limitation of replicative stress and DNA damage transmission

      2018, Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis

    • HDAC9 regulates the alternative lengthening of telomere (ALT) pathway via the formation of ALT-associated PML bodies

      2016, Biochemical and Biophysical Research Communications
      Citation Excerpt :

      Extreme shortening of telomeres leads to cellular senescence [1]. In contrast, cancer cells overcome this by the activation of a telomere maintenance mechanism (TMM), which can be either through telomerase [2] or the alternative lengthening of telomeres (ALT) [3]. The latter is mostly prevalent in cancer cells [4].

    • KU70 and CAF-1 in Arabidopsis: Divergent roles in rDNA stability and telomere homeostasis

      2024, Plant Journal

    • Effects of p53 and ATRX inhibition on telomeric recombination in aging fibroblasts

      2024, Frontiers in Oncology

    • Establishment of SV40 Large T-Antigen-Immortalized Yak Rumen Fibroblast Cell Line and the Fibroblast Responses to Lipopolysaccharide

      2023, Toxins
    View all citing articles on Scopus
    View full text
    Copyright © 1997 Published by Elsevier Ltd.