Key pathway in end-stage prostate cancer blocked

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Prostate cancer advances when tumors become resistant to hormone treatment, which is the standard therapy for patients, and begin producing their own androgens.

Scientists at UT Southwestern Medical Center have observed that blocking one of the enzymatic steps that allow the tumor to produce androgens could be the key in halting a tumor's growth.

The findings, appearing online and in the recent issue of Endocrinology, suggest that this step might one day provide a new avenue of treatment for patients with end-stage prostate cancer. Health care experts estimate that more than 2 million men in the U.S. have prostate cancer, with more than 27,000 deaths correlation to the disease in 2009.

"We were able to block the androgen response, which is a central pathway for tumor progression," said Dr. Nima Sharifi, assistant professor of internal medicine and the study's senior author.

End-stage prostate tumors typically are treated with hormones that suppress the levels of the androgens, or male hormones like testosterone, that cause prostate cancer cells to grow. Eventually, however, the tumors become resistant to this treatment and resume their growth.

Using prostate cancer cell lines, Dr. Sharifi and colleagues observed that the hormone dehydroepiandrosterone (DHEA) is converted by the tumors into androgens. By blocking the enzyme 3β-hydroxysteroid dehydrogenase (3βHSD), which is responsible for the first enzymatic step that is mandatory to convert DHEA to androgens, scientists were able to shut down the tumors' lifeline.

"Enzymes in general can make great drug targets, so this process conceivably could be targeted for the development of new therapys for end-stage prostate cancer, which has limited therapeutic options right now," said Dr. Sharifi, an investigator in UT Southwestern's Harold C. Simmons Comprehensive Cancer Center. "The goal would be to develop a drug that targets that enzyme to be used for the advanced, incurable stage".

No standard therapys currently target this enzyme, but there is proven clinical evidence that this pathway is central to driving tumor progression.


Posted by: Mark    Source