Telomeres are tandem repeats of the noncoding DNA structures at the end of human chromosomes that protect the coding DNA and the integrity of the genome (Blackburn, 1991). The ability to sustain telomere length confers unlimited proliferative capacity to cancer cells. In most cancers telomere length is maintained by the activity of the enzyme telomerase (Kim et al., 1994), whose catalytic subunit is encoded by the telomerase reverse transcriptase (TERT) gene. However, until recently, the underlying mechanisms for telomerase activation in cancer cells were largely unknown.
