While
naked mole rats may not look like the cute and resourceful sidekick from Kim Possible, new research is showing
that they can also fight crime in the form of cancer. In the article The Anti-Mouse, scientists are shocked to find that when
testing carcinogens on naked mole rats, not only do they fail to form tumors,
but that cancer has never been observed in these rodents. While delving into the question of why,
Dr. Gorbunova from the University of Rochester learns that these mole rats have
a very unique immune system and interesting way of fighting the formation of
malignant tumors.
One of the hallmarks of cancer is
sustaining proliferative signaling, enabling the cancer cells to drastically
and rapidly increase in number.
When cells are grown in a petri dish, there is a phenomenon called
contact inhibition, where the cells will come together to form a single layer
and then stop dividing. When this
goes awry and cells grow out of control, tumors form, but we have tumor
suppressor genes, such as p16 and p27.
When naked mole rat cells were put into a petri, however, the contact
inhibition was so strong that cells that barely touched immediately stopped
growing. These mole rats were
found to have an early acting version of this same tumor suppressing system,
giving them a double layer of protection in comparison to humans and greatly
decreasing the chances of any cells growing out of control. In this way, cancer cells cannot
maintain cell proliferation, an important property of cancer, and naked mole
rats are able to evade this disease.
Telomeres
are very important to cell division, as talked about in class, and can be
simply compared to the little plastic bit on the ends of shoelaces. Telomeres are the ends of chromosomes
that protect them and get continuously shorter as the cells divide and grow. Telomerase, which makes telomeres, is
also unique in naked mole rats as the activity is increased. In humans, telomerase is shut off later
in life, leading to the wear and tear of chromosomes and aging. The reasons for it stopping could possibly
be a defense against cancer, as cancer cells keep telomerase on all the time,
therefore becoming immortal. Since
naked mole rats have an increase in telomerase, their chromosomes can last
longer before becoming damaged by replication. Because their contact inhibition system is an excellent
defense against cancer, it seems they do not need as much telomerase regulation
as do human cells.
Based
on what we’ve learned of the hallmarks of cancer, we can understand why naked
mole rats have such a strong immune system in general, but especially in
regards to cancer. It is possible
that these rodents could help us find ways to better fight off cancer in the
future, but the difficulties of working with them in the lab such as a higher
age of sexual maturity than regular mice, slow the process. Until then, these fascinating creatures
will continue to escape the tragedies of cancer.
