Study reveals how cancer-causing protein activates
to the development of cancers, particularly breast and prostate
cancer, the most commonly diagnosed cancers in the United States.
In a study published in the magazine Science, Brown Medical School researchers show that STAT3, a cause of breast and prostate cancers, is turned on inside cells not one, but two, ways. Drug makers can use the findings to try and inhibit this deadly "oncoprotein" more effectively.
The team discovered a new chemical modification that activates STAT3. This protein is important for embryonic growth and development, helping cells grow, duplicate and migrate. In adulthood, STAT3 presumably falls dormant, but its unexpected and continuous activation causes breast and prostate cells to develop and move through the body.
Eugene Chin, assistant professor of surgery at Brown Medical School said experts suspect that environmental factors, such as a diet rich in animal fat and hormones, may activate STAT3.
One known trigger that turns on the protein inside cells is phosphorylation, which modifies some of the tyro-sine and serine amino acids that make up the STAT3 protein. One other trigger is acetylation, another chemical process that modifies amino acids, such as lysine.
These findings might explain why drugs that only block STAT3 phosphorylation cannot completely stop cancer cells from growing and invading other parts of the body.
"Both tyrosine phosphorylation and lysine acetylation modifications are important events for STAT3 to stimulate cancer cell growth and metastasis," Chin said. "That's why the finding is so exciting. Now that we know more about STAT3 activation, we can create better drugs."
This latest piece of research provides an important target for drugs in treating breast and prostate cancers that are common in the United States. According to the American Cancer Society, an estimated 217,440 Americans were diagnosed with breast cancer and 230,110 were diagnosed with prostate cancer in 2004.
"Finding a drug to block both tyrosine phosphorylation and lysine acetylation of STAT3 protein should be a more effective cancer treatment," Chin explained.
