Washington, DC -- Cancer researchers at Georgetown University Medical Center have taken a step towards understanding how and why a widely used chemotherapy drug works in patients with breast cancer.

In laboratory studies, the researchers isolated a protein, caveolin-1, showing that in breast cancer cells this protein can enhance cell death in response to the use of Taxol, one of two taxane chemotherapy drugs used to treat advanced breast and ovarian cancer. But in order to work, they found the protein needs to be "switched on," or phosphorylated. The results were reported in the current (February 23) issue of the Journal of Biological Chemistry.

Their finding suggests it may eventually be possible to test individual breast cancer patients for the status of such molecular markers as caveolin-1 in their tumors to determine the efficacy-to-toxicity ratio for Taxol, said the studys first author, postdoctoral fellow Ayesha Shajahan, Ph.D., of Lombardi Comprehensive Cancer Center at Georgetown.

"Because breast tumors are not all the same, it is important to know the cancers molecular makeup in order to increase the efficiency, and lower the toxicity, of chemotherapy drugs, and this work takes us some steps forward in this goal," she said. "It also offers insights into why some breast cancer cells can become resistant to therapeutic drugs."

Additionally, the study identifies caveolin-1 as a new molecular target for increasing the efficacy of taxanes, according to the studys lead investigator, Robert Clarke, Ph.D., D.Sc., a Professor of Oncology and Physiology & Biophysics. "This is important because the taxanes are active drugs in breast cancer, so now that we know caveolin-1 is a new mechanism to explain how these drugs kill breast cancer cells, we can potentially take advantage of that fact to improve these agents."

The taxanes are Taxol (also known as paclitaxel) and Taxotere (docetaxel). Taxol was originally deriv
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Contact: Laura Cavender
lsc6@georgetown.edu
202-687-5100
Georgetown University Medical Center
21-Feb-2007