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Pet Article
DOGS, CATS AND CANCER
A detection technique called TRAP (Telomeric Repeat Amplification Protocol) used
in the early detection of cancer in humans has found its way into the realm of
veterinary medicine. This relatively new method of cancer detection allows veterinarians to
catch cancer earlier, increasing the likelihood of successful treatment.
The test works by detecting the enzyme telomerase, which helps cancer cells
reproduce indefinitely. Telomerase activity seems to be a unique feature of benign tumor
cells that have undergone malignant transformation.
Regular cells and cancer cells have some very basic differences. A normal cell
has a "cap" called a telomere on the end of its DNA. DNA is a substance found in
the nucleus of the cell that contains all of the information about the cell. The
"cap" prevents damage of the DNA sequences during mitosis, which is reproduction
of the cell by division. The telomere sits on the end of the DNA strand and
guards its integrity. After each cell division the telomere erodes a bit until
it can no longer protect the cell from errors during cell division (replication).
At this point a normal cell will be signaled to stop replicating or will die of
apoptosis, which is pre-programmed cell death.
Cancerous cells have the unique characteristic of being "immortal," which means
that they do not die when they are supposed to and they have unlimited ability
to reproduce themselves. Cancer cells achieve this through several different
mechanisms, one of which is the production of an enzyme called telomerase.
Telomerase acts by adding on to the end of the telomere that caps the DNA.
Because the telomere does not get shorter over time as it normally should, the
cell is not triggered to stop replicating. This is one of the reasons that
malignant cancer cells keep growing.
Because normal cells do not usually produce the enzyme telomerase, presence of
this enzyme can indicate the presence of cancer. Based on findings to date, it is believed
that this tool may prove to be useful to help in rapidly diagnose malignancies.
In a recent study of telomerase activity in cats, published in the American
Journal of Veterinary Research, telomerase activity was present in 29 of 31
malignant tumors and only 1 of 22 benign tumors examined over a two year period.
Dr Kitchell believes that the two malignant tumors were found to be negative of
telomerase activity due to errors in tissue processing.
In addition to early detection, this enzyme is also under investigation as a
possible tool to use in the future as a target in the treatment of cancer. Dr.
Kitchell says, "If the thing proves to be really useful in larger clinical
studies, then I would anticipate a snap style ELISA kit for the early detection
of cancer could be available at your neighborhood clinic some time in the
future."
If you have any questions about cancer in pets, please contact your local
veterinarian.
Mark Woodcock
1 Flea Control
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