Scientists have
discovered a genetic mutation linked with colon cancer
that may work like a spigot, controlling the number of
precancerous growths that develop and determining a
person's susceptibility to cancer.
They said the
finding could point to new ways to diagnose, treat, and
possibly even prevent colon cancer, the second-leading cause
of cancer death in the United States after lung
cancer.
In a study
appearing Thursday in the journal Genome Research,
cancer biologists at Thomas Jefferson University in
Philadelphia studied mice that carry a mutation in the
Apc gene, a gene known to cause precancerous growths
or polyps in mice.
Changes in the
human version of the gene are known to start the process
that leads to colon cancer. People who develop large numbers
of polyps are significantly more likely to get colon
cancer.
The researchers
found that the mice that carried only one copy of the
damaged or mutated gene had about 90% fewer polyps in the
small intestine and colon.
Microbiologist
Arthur Buchberg, one of the researchers, described the
finding as a gene "modifier," something that governs the
individual's response to cancer.
"It's kind of
like a rheostat. It's not on or off. It's bad or
better," he said in a telephone interview.
The researchers
believe if a person inherits the colon cancer gene, a
modifier gene can help determine how prone or resistant a
person is to developing polyps, and ultimately tumors.
"A cancer needs
multiple mutations to go from a normal cell to a
cancer cell. It needs multiple modifier genes to determine
the final severity. This is probably one of many
modifier genes," he said.
Buchberg believes
the finding is the first discovery of a mutation on the
Atp5a1 gene, a gene responsible for the cell's energy
production. The discovery gives scientists a new way
to look for potential cancer diagnostic tests and
treatments.
It is the second
colon cancer modifier gene Buchberg and his wife and
colleague Linda Siracusa have found.
"These modifier
genes we think play an important role," Buchberg said.
"It's certainly a piece of the puzzle."
Several genes are
linked to colon cancer. Lifestyle is also an important
factor, with smoking, lack of exercise, and a diet high in
meat and low in fruits and vegetables all associated
with colon cancer.
According to the
American Cancer Society, it will kill 52,000 people this
year in the United States alone. (Julie Steenhuysen,
Reuters)