Telomerase Activity in Cancer Cells

Telomerase is a ribonucleoprotein complex, which is made of a reverse transcriptase enzyme subunit and a long non-coding RNA which contains the template sequence for telomere synthesis. Telomeres are specialized DNA-protein complexes found at the end of all linear chromosomes. These telomeres in human somatic cells are slowly cut off and shortened after each replication cycle due to, in which some experts believe is oxidative stress of the telomeres. Telomerase is the enzyme responsible for lengthening/maintaining the telomeres that are shortening after each replication. Telomeres are there to protect chromosome ends from being recognized as damaged DNA by DNA damage responses (DDRs). There are certain lengths to where the telomere is too short and it is known as the "critical length". At this critical length most cells become "replicative" senescence cells.