Stat5 protein is particularly plentiful in high histological grade human prostate cancer

Prostate cancer is much more likely to be aggressive if a key protein called Stat5 is found activated and in abundance in the cancer cells, report researchers from Georgetown University's Lombardi Comprehensive Cancer Center.

By inhibiting this protein, called Stat5, doctors are exploring how to develop a new treatment strategy for advanced prostate cancer.

The new findings, reported in the July 15th issue of the journal Cancer Research, show that active Stat5 protein is particularly plentiful in high histological grade human prostate cancer. High histological grade prostate cancers have often already metastasized by the time of diagnosis and are typically more aggressive in growth.

"Currently, there are only few treatment options available for advanced prostate cancer," said Marja Nevalainen, MD, PhD, assistant professor of oncology at Georgetown University Lombardi Comprehensive Cancer Center. "If we can find a way to stop Stat5 from turning on in prostate cancer cells, we may be able to devise a new strategy for treating this disease."

Previous studies by Nevalainen show that when the "telephone line" that sends signals to turn Stat5 on is blocked, human prostate cancer cells die. When the line remains open for communication, allowing Stat5 to send cellular signals, prostate cancer cells stay alive and thrive. Nevalainen's work is focused on finding ways to short-circuit the signals that turn on Stat5, thus killing prostate cells before they flourish.

In this study, human prostate cancer specimens, which are routinely collected during prostate cancer surgeries for analysis of the histological grade of each prostate cancer, were analyzed for activation of Stat5. Activation of Stat5 was then correlated statistically with the histological grade of each specimen.

Nevalainen sees dual possibilities for where the future of Stat 5 research may one day lead: development of potential treatments and identifying whether Stat5 could serve as an effective sign for diagnosing cancer. "We are in the process of determining whether activation of Stat5 in prostate cancer would serve as an effective prognostic biomarker. Development of additional diagnostics, beyond the PSA test, may help physicians on the frontlines of cancer detection."