New anti-inflammatory strategy for cancer therapy identified by UCSD r...( Luo said. The study builds upon...)

The study builds upon previous work in the Karin lab recently featured as the cover article in the August 6, 2004 issue of the journal Cell*. In that study, the researchers provided the first evidence of the molecular link between inflammation and cancer. They determined that an enzyme called I-kappa-B kinase beta (IKKβ) is required for the activation of NF-kB, which acts as a master switch to turn on inflammation in response to bacterial or viral infections. In turn, NF-kB sets off a chain of reactions that lead to cancer.

Mice used in the new study were given colon or breast tumor cells which metastasized to the lung. Some of these cancer cells served as "controls," while other cells were given a protein that specifically inhibited activation of NF-kB, only in cancer cells. The different cells were injected into mice and all were able to establish metastatic growth in the lung, regardless of their ability or inability to activate NF-kB. After a week, all mice were injected with bacterial lipopolysaccchide (LPS), which induced inflammation. A post-mortum inspection of the mice showed that following inflammation, the control cells formed more numerous and larger tumor nodules, while the tumors formed by cells in which NF-kB was inhibited, had shrunk or partially disappeared after the LPS injection. As a result, mice injected with cancer cells lacking NF-kB activity exhibited much better survival than mice inoculated with control cells.

In further tests to determine how NF-kB activation mediates inflammation-induced tumor growth, the team studied mouse lung tissue as well as tumor nodules for expression of specific proteins known to modulate the body's normal cell-killing process. Death-inhibiting proteins were abundant in tumors formed by cancer cells with normal NF-kB, but were absent in the tumors formed by cancer cells where NF-kB was inhibited.

While NF-kB is known to convert inflammatory st
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Contact: Sue Pondrom
spondrom@ucsd.edu
619-543-6163
University of California - San Diego
20-Sep-2004