Telomerase and Cancer: The Chemical Fountain of Youth?

Telomerase is an enzyme in the human body. You can always tell if something is an enzyme if it ends in "ase." But telomerase is a very interesting enzyme due to its function. Although telomerase presents an opportunity to be instrumental in reversing the aging process, it also has been implicated in causing cancer if used for such a purpose.

Telomerase functions in DNA replication, adding specific nucleotide sequences to a replicating strand of DNA. It adds these sequences to the end of the DNA strand which is designated as the 3' (three prime) end of the chromosome. To those who haven't studied biology since high school, chromosomes are found in human cells and contain all of our genetic information. Telomerase belongs to a class of enzymes known as the reverse transcriptases, and uses a strand of RNA as a template to create new segments of DNA on the existing DNA strand. Telomerase is needed because in order for cells to divide and replicated, the genetic material must also be replicated exactly. Telomerase's potential at reducing aging derives from its action on special chromosomal regions called telomeres.

Telomeres are the ends of DNA strands, and after each subsequent DNA replication, they shorten to a certain degree. To explain the full mechanism of telomerase and DNA replication would be time-consuming and difficult to explain to those who are not versed in intermediate biology, so I will refrain. Telomeres are like ticking age clocks. When they shorten, cells become less hardy, and effects of aging begin to manifest themselves increasingly. Although it is unknown to what extent telomere shortening causes aging, the correlation has been supported with clinical data. Since telomerase works by adding new segments of DNA to shortened telomeres, one would think that people could prolong their life indefinitely with it. Is it that simple?

Unfortunately, the idea of telomerase as a kind of "fountain of youth" is not very sound. This is why pharmaceutical companies have not been battling over patents on telomerase as an effective drug or supplement. The reason behind this is telomerase's ability to produce cancer. If telomerase is used too much, then telomeres can become abnormally long and cells can interpret this length as genetic mutation. The cell will then undertake measures to correct the damage, which can leave the genetic material more damaged or even mutated to a large extent. Mutated DNA from outside sources such as heat or radiation often causes cells to divide at an unchecked rate, which we call cancer. Telomerase can potentially prolong a cell's life indefinitely, but that is a death warrant if the cell in question is a cancer cell. If a cancer cell is allowed to divide and reproduce indefinitely, then malignant tumors can form in a person's body.

Unfortunately, much of the study into telomerase causing cancer has been performed in bacterial cultures and not human bodies. The FDA sort of limits that. At this point it is unclear what the deciding factor is between whether or not a cell with increased telomerase will divide into benign cells or cancerous cells. The point to take away is that many more trials must be performed and clinical data collected on this enzyme and cancer before any kind of treatment for aging using telomerase becomes a viable option.

Cancer is not something that pharmaceutical companies want to deal with if it's caused by their products. So, it will likely be a long time before a genetic solution to aging manifests itself in the form of telomerase.