Question

Activation of the telomerase gene is an indicator of cancer progression. How does the telomerase gene assist in granting cancer cells 'immortality'?

Answer 1

Telomerase is a ribonucleoprotein which consists of RNA which is used as template to add telomere sequence to the 3' end of the DNA. Telomere consists of repeating sequence of the six nucleotides i.e. TTAGGG. These telomeres caps the chromosome ends and protects them from deterioration and also perevent fusion of the chromosomes.

In normal conditions, these telomeres shortens as the cell divides repeatedly due to absence of the telomerase and after around 50-70 cell divisions called Hayflick limit, these telomeres become very short and the cell stops dividing which leads to senesence.

In cancer cells, telomerase is expressed and prevents the shortening of telomeres which maintains the integrity of the chromosomes. There is no hayflick limit for the cancer cells which allows the cancer cells to divide in uncontrolled manner and prevent the cell death. In this way the telomerase makes the cancer cell immortal.