Telomerase and cancer.

Telomerase is a reverse transcriptase enzyme that can add the hexameric repeats TTAGGG to chromosome ends. So far, telomerase prevents telomere erosion occurring during cell division, because of the semi-conservative DNA replication. The maintenance of telomeres length is necessary for the proliferation of cells and may represent a critical step both in senescence and cancer progression. Telomerase is present in most types of tumors, but usually not in normal somatic cells. This review will focus on the possibility of exploiting telomerase as a marker for cancer diagnosis and prognosis and as an ideal target for cancer therapies based on telomerase inhibitors.