Magazine article Science News

Finding a Missing Link: Scientists Show a New Connection between Inflammation and Cancer

Magazine article Science News

Finding a Missing Link: Scientists Show a New Connection between Inflammation and Cancer

Article excerpt

For more than 100 years, researchers have sought links between inflammation and cancer. Now, a team of scientists studying gastrointestinal cancer in mice presents powerful evidence of a molecular connection between those conditions.

In two experiments, researchers at the University of California, San Diego showed that deactivating a protein called I-kappa-B kinase beta (IKK-beta) inside cells stops cancer progression in its tracks.

IKK-beta normally plays a role in healing. During infection or injury, immune system molecules activate IKK-beta. Once stimulated, this protein keeps cells alive and growing, despite the insult. IKK-beta also promotes inflammation in damaged tissues.

These effects could be a double-edged sword in the presence of carcinogens, says molecular biologist Michael Karin. Before the experiments, he speculated that, by preventing programmed cell death and encouraging inflammation, IKK-beta also promotes the emergence and growth of tumors.

"This hypothesis was a no-brainer, but it's hard to prove it," Karin says.

To show the protein's role in tumor development, Karin and his team genetically engineered mice to lack the gene for IKK-beta in specific parts of their bodies. In the first experiment, the researchers deleted the gene in cells lining the intestines of 12 mice. They injected these mice, as well as 12 normal mice, with an irritant to injure the intestines and provoke an immune response. Simultaneously, the mice received a chemical that typically triggers tumor growth in the gastrointestinal tract.

After 12 weeks, all 24 mice had intestinal tumors, but the researchers saw a dramatic difference between the two groups, says Karin. The mice without intestinal IKK-beta had one-fourth as many tumors as did the normal mice, the researchers report in the Aug. 6 Cell. Without the cell-preserving actions of IKK-beta, pre-cancerous cells died before tumors were even initiated, Karin speculates. …

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