Telomeres, telomerase and cancer: an up-date

In the mid 1990s, the hypothesis emerged that the upregulation or re-expres sion of a telomere-synthesising ribonucleoprotein, called telomerase, is a critical event responsible for continuous tumour cell growth. In contrast t o normal cells, in which gradual mitosis-related erosion of telomeres event ually limits replicative life span, tumour cells have telomerase and show n o loss of these chromosomal ends. These data suggest that telomere stabilis ation may be required for cells to escape replicative senescence and to pro liferate indefinitely. Because of the close association between telomerase and malignancy, both pathologists and clinicians expect this molecule to be a useful malignancy-marker and a new therapeutic target. This review focus es on the components of the human telomere and of the human telomerase enzy me. A synopsis of reports studying the clinical-diagnostic value of telomer e length measurements, of telomerase activity analyses and of the in situ t elomerase detection is given. Finally, a summary of recent experimental wor k that sheds new light on the biological role of this fascinating molecule is presented.