Scientists find gene that may regulate colon cancer

CHICAGO (Reuters) - 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 on 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 percent 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, 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.