[Catalyst 2017]

Telomeres
WAYS TO
PROLONG LIFE
B y A n d r e w S t e fa n i
Two hundred years ago, the average life
expectancy oscillated between 30 and 40
years, as it had for centuries before. Medical
knowledge was fairly limited to superstition
and folk cures, and the science behind what
actually caused disease and death was lacking.
Since then, the average lifespan of human
beings has skyrocketed due to scientific
advancements in health care, such as an
understanding of bacteria and infections.
Today, new discoveries are being made
in cellular biology which, in theory, could
lead us to the next revolutionary leap in life
span. Most promising among these recent
discoveries is the manipulation of telomeres
in order to slow the aging process, and the
use of telomerase to identify cancerous cells.
Before understanding how telomeres can be
utilized to increase the average lifespan of
humans, it is essential to understand what
a telomere is. When cells divide, their DNA
must be copied so that all of the cells share
an identical DNA sequence. However, the
DNA cannot be copied all the way to the end
of the strand, resulting in the loss of some
DNA at the end of the sequence with every
single replication. 1 To prevent valuable genetic
code from being cut off during cell division,
our DNA contains telomeres, a meaningless
combination of nucleotides at the end of our
chromosomal sequences that can be cut off
without consequences to the meaningful
part of the DNA. Repeated cell replication
causes these protective telomeres to become
shorter and shorter, until valuable genetic
code is eventually cut off, causing the cell to
malfunction and ultimately die. 1 The enzyme
telomerase functions in cells to rebuild these
constantly degrading telomeres, but its activity
is relatively low in normal cells as compared to
cancer cells. 2
The applications of telomerase manipulation
have only come up fairly recently, with
the discovery of the functionality of both
telomeres and telomerase in the mid 80’s
by Nobel Prize winners Elizabeth Blackburn,
Carol Grieder, and Jack Sjozak. 3 Blackburn
discovered a sequence at the end of
chromosomes that was repeated several
times, but could not determine what the
purpose of this sequence was. At the same
time, Sjozak was observing the degradation of
minichromosomes, chromatin-like structures
which replicated during cell division when
introduced to a yeast cell. Together, they
combined their work by isolating Blackburn’s
repeating DNA sequences, attaching them to
Telomeres
(Protective Caps)
Paired Strands of
DNA
Figure 1: DNA strand with telomere ends
Sjozak’s minichromosomes, and then placing
the minichromosomes back inside yeast cells.
With the new addition to their DNA sequence,
the minichromosomes did not degrade as they
had before, thus proving that the purpose
of the repeating DNA sequence, dubbed the
telomere, was to protect the chromosome and
delay cellular aging.
Because of the relationship between
telomeres and cellular aging, many scientists
theorize that cell longevity could be enhanced
by finding a way to control telomere
degradation and keep protective caps on the
end of cell DNA indefinitely. 1 Were this to
be accomplished, the cells would be able to
divide an infinite number of times before they
started to lose valuable genetic code, which
would theoretically extend the life of the
organism as a whole.
In addition, studies into telomeres have
revealed new ways of combating cancer.
Although there are many subtypes of
cancer, all variations of cancer involve the
uncontrollable, rapid division of cells. Despite
this rapid division, the telomeres of cancer
cells do not shorten like those of a normal
cell upon division, otherwise this rapid
division would be impossible. Cancer cells
are likely able to maintain their telomeres
due to their higher levels of telomerase. 3 This
knowledge allows scientists to use telomerase
levels as an indicator of cancerous cells, and
then proceed to target these cells. Vaccines
that target telomerase production have
the potential to be the newest weapon in
combating cancer. 2 Cancerous cells continue
to proliferate at an uncontrollable rate even
when telomerase production is interrupted.
However, without the telomerase to protect
their telomeres from degradation, these cells
eventually die.
As the scientific community advances
its ability to control telomeres, it comes
closer to controlling the process of cellular
reproduction, one of the many factors
associated with human aging and cancerous
cells. With knowledge in these areas
continuing to develop, the possibility of
completely eradicating cancer and slowing the
aging process is becoming more and more
realistic.
WORKS CITED
[1]Genetic Science Learning Center. “Are Telomeres the
Key to Aging and Cancer.” Learn. Genetics. March 1,
2016. Accessed October 5, 2016.
[2]Shay, Jerry W., and Woodring E. Wright. “Telomerase
Therapeutics for Cancer: Challenges and New ...” Nature
Reviews Drug Discovery. July 2006. Accessed October
16, 2016.
[3]“The 2009 Nobel Prize in Physiology or Medicine -
Press Release.” The 2009 Nobel Prize in Physiology or
Medicine - Press Release. Accessed October 4, 2016.
Images from Veernavya via Freepik
DESIGN BY Albert Han
EDITED BY Katrina Cherk
CATALYST | 11