Lupeol, a chemical constituent found in fruits, vegetables and medicinal plants, shows strong potential for being tested in clinical trials to treat prostate cancer, according to a study led by researchers at The Hormel Institute, University of Minnesota-Mayo Clinic.

Dr. Mohammad Saleem, head of the Molecular Chemoprevention and Therapeutics section at The Hormel Institute, and his team recently published a study titled, “Lupeol, a Novel Androgen Receptor Inhibitor: Implications in Prostate Cancer Therapy,” in Clinical Cancer Research, a journal of the American Association for Cancer Research. The journal focuses on innovative clinical and translational cancer research studies that bridge the laboratory and the clinic.

“We suggest that lupeol alone or added to a drug has enormous translational potential to be tested in humans for prostate cancer treatment,” Saleem said.

Dr. Hifzur Siddique and Dr. Shrawan Kumar Mishra — members of Saleem’s team at the Institute — along with Dr. R. Jeffrey Karnes of Mayo Clinic’s Department of Urology are co-authors of the study, which recently has been featured in the The New York Times, The Wall Street Journal and other national media.

According to the American Cancer Society, 217,730 men were diagnosed with prostate cancer and another 32,050 prostate-cancer patients died during 2010 in the United States.

Despite initial efficacy of androgen-deprivation therapy, prostate cancer progresses within a few years from androgen-dependent prostate cancer to castration-resistant prostate cancer in most of the patients, the study says. Accumulating evidence suggests androgen receptor is a critical player in the development of early androgen-dependent prostate cancer as well as late-stage castration-resistant prostate cancer.

There is great interest in identifying agents that are effective inhibitors of androgen-receptor signaling, can act independently of hormonal status and possibly reduce the rates of occurrence and mortality of prostate-cancer patients.

Agents that inhibit androgen-receptor signaling in both ADPC and CRPC conditions could be extremely useful for treating patients with prostate cancer, and lupeol qualifies as such an agent, Saleem says.

“This study shows that lupeol, by adopting several approaches, inhibits androgen receptor signaling in prostate cancer of both androgen-dependent and castration-resistant prostate cancer,” Saleem said.

Lupeol — a nontoxic, diet-derived agent found in foods such as strawberries, olives, grapes, apples and cucumbers — possesses strong antioxidant, anti-inflammatory, antiarthritic, antimutagenic and antimalarial activity in laboratory studies.

This research is clinically relevant, Saleem says, because it shows lupeol sensitizes prostate-cancer cells, which generally do not respond to therapy, to become responsive to clinical therapeutic agents and reduces PSA, the clinical biomarker for prostate cancer diagnosis and prognosis.

The Hormel Institute is a world-renowned medical research center in Austin, Minnesota, specializing in research leading to cancer prevention and control, including by studying how plant-based food chemicals behave inside the body

and how they might be used to fight cancer.

Established in 1942, The Hormel Institute is a research unit of the University of Minnesota and collaborative cancer research partner with Mayo Clinic.