[Telomeres, telomerase and cancer].

The chromosome ends are specialized nucleoprotein structures called telomeres, which length predicts replicative capacity of cells. Activation of telomerase, the DNA polymerase that synthesizes telomeric repeats, seems to be necessary for cells to become immortal. Methods of measuring telomerase activity, now reliable and semiquantitative, have shown that telomerase is expressed in most human cancers, but not in normal somatic tissues. Research about regulation of telomere length and telomerase activity, highlights connexions between senescence and cancer. This article details diagnosis, prognosis and therapeutic prospects linked to the study of telomerase activity.