Clues to How Cancer Cells Grow Unchecked

Bacterial enzyme may play role in their survival

THURSDAY, April 24, 2003 (HealthDayNews) -- An explanation for how cancer cells can grow unchecked may be found in an enzyme that helps protect bacteria from attacks by the body's immune system, says a Wake Forest University Baptist Medical Center study.

This enzyme, called peroxiredoxin, is used by bacteria such as salmonella to deactivate hydrogen peroxide coming from the body's white blood cells. Hydrogen peroxide is released by white blood cells to kill invaders.

The study, published in the April 25 issue of Science, outlines how the peroxiredoxin enzyme works differently in mammals and bacteria.

The enzyme, which is a key to human cell survival and growth, acts as a biochemical switch to maintain low levels of hydrogen peroxide in the body. But the enzyme lets those levels increase when hydrogen peroxide is needed for signaling between cells. Those complex signaling pathways are present in mammals, but not in bacteria.

"Because the bacteria don't have the complex signaling pathways present in mammals, they don't need this ability to turn off peroxiredoxin," study author Leslie B. Poole says in a news release.

That means the enzyme is always available to the bacteria to eliminate hydrogen peroxide produced by white blood cells. That helps the bacteria to withstand attacks by a person's immune system.

That finding may provide new information about human diseases. For example, the researchers believe peroxiredoxin-regulated signaling may be related to cancer.

Normally, abnormal cells are programmed to die off. But in some cancer cells, this cell death process stops working and the cancer cells keep multiplying. The cancer cells may not get the signal to die because of the peroxiredoxin enzyme.

The researchers say they found a correlation between too much peroxiredoxin and the failure of cancer cells to receive the signal to die, suggesting the two could be related.

More information

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SOURCE: Wake Forest University Baptist Medical Center, news release, April 24, 2003
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