Document Type : Review Article
Typically, the length of the telomeres is shortened at each time of cell division, which can induce chromosomal instability. In many tumor cells, telomere lengths are maintained by an enzyme called telomerase, which is a mechanism for starting and surviving tumors. The human telomerase reverse transcriptase (hTERT) as the main subunit of telomerase enzymes in cancer cells is increased by various genetic and epigenetic mechanisms such as hTERT structural variants, hTERT promoter mutations and epigenetic modifications through hTERT promoter methylation. The hTERT upregulation in cancer cell propose the achievement that requires research into the mechanism of hTERT action in tumor cells.