Protein in Body May Stop Cancer

March 31, 2005 - A protein found in the body may act as a natural tumor suppressor by flipping a switch and stopping the growth of cancer cells, according to a new study.

Researchers say the protein, known as PHLPP or "flip," works by deleting parts of a molecule that promotes cell survival. PHLPP stops cancer cell growth by affecting another protein called Akt/protein kinase B, which plays an important role in regulating cell growth and death and has been linked to common cancers.

"A drug that turns on PHLPP, so that it suppresses cell growth caused by Akt, could be a potential cancer therapy," says researcher Alexandra C. Newton, PhD, professor of pharmacology at the University of California, San Diego, in a news release.

Stopping Cancer Growth

In the study, which appears in the April 1 issue of the journal Molecular Cell, researchers looked at ways to turn off Akt once it has been activated.

Previous studies have shown that Akt is locked in the "on" position by the addition of phosphate molecules, so researchers looked at ways to rid Akt of phosphate and flip the growth-triggering protein into the "off" position.

After scanning a database of potential phosphate-stripping candidates, researchers zeroed in on PHLLP, a protein produced throughout the body. Levels of this protein are drastically lower than normal in several colon cancer and other human cell lines with abnormally high levels of Akt.

Laboratory tests showed that adding PHLPP to cancer cell lines caused a significant reduction in tumor growth.

If further tests confirm these results, researchers say drugs may be developed to activate PHLPP and stop cancer cell growth caused by Akt.