Pomegranate juice packs a punch on prostate cancer that prolongs post-surgery PSA doubling time, drives down cancer cell proliferation and causes prostate cancer cells to die, according to a study published in the July 1 issue of Clinical Cancer Research.

Researchers at the Jonsson Cancer Center at UCLA reported that patients with recurrent prostate cancer who drank pomegranate after surgery or radiation treatment saw their PSA blood content levels double after about 54 months. By comparison, PSA levels in the same patients prior to drinking the daily doses of eight-ounce pomegranate juice accelerated more quickly, doubling their PSA levels in only 15 months.

PSA, or prostate specific antigen, is a protein marker for prostate cancer. The faster PSA levels increase in the blood of men after treatment, the greater their potential for dying of prostate cancer.

“The velocity of the increase in PSA is decreased by 35 percent among those who drank the pomegranate juice,” said Allan Pantuck, M.D., associate professor, Department of Urology, David Geffen School of Medicine, UCLA, and lead author of the paper.

“We are hoping that pomegranate juice offers a novel strategy for prolonging the doubling time in men who have been treated for prostate cancer,” Dr. Pantuck added.

According to the study, sera from patients after treatment yielded a net decrease of almost 30 percent in the numbers of prostate cancer cells raised in culture. Similarly, cultured sera from these patients decreased cell proliferation by 12 percent, compared to cells grown with sera from the men taken prior to initiation of the pomegranate treatment program. In addition, treated sera induced 17 percent more programmed cell death, or apoptosis, than sera from the men prior to treatment.

Additional exploratory experiments conducted by Dr. Pantuck and his colleagues examined antioxidant characteristics of the fruit juice.

“Pomegranate is high in antioxidants, and there is good evidence that inflammation plays an important role in prostate cancer,” he said.

Dr. Pantuck and his colleagues detected a 23 percent increase in nitric oxide sera content from patients after they began their daily pomegranate regimen. These studies were conducted in the UCLA laboratory of Louis Ignarro, Ph.D., the Nobel laureate who contributed key scientific findings to define the role of nitric oxide in health and disease.

As with vitamin C and other antioxidants, ellagic acid -  a primary antioxidant in pomegranate juice -  works to quench molecules that oxidate, or add oxygen, to cellular and circulatory proteins and fats, altering their biological function.

“By quenching oxidative species with antioxidants, you are basically preserving circulating nitric oxide, so it can have a greater biologic effect,” Dr. Pantuck said. “By decreasing the amount of free radicals, you are probably decreasing the circulating factors that are destroying nitric oxide.”

While their findings on nitric oxide, cell proliferation and apoptosis served as exploratory endpoints, Dr. Pantuck stressed that clinical trials with more precise design are necessary to confirm the biological role the fruit plays in prolonging or preventing recurrence of prostate cancer in men.

“We don’t believe we are curing anyone from prostate cancer,” he said. “In our initial trial, although a third of patients experienced a decrease in their PSA during the study, nobody’s PSA went to zero.

“The PSA doubling time, however, was longer. For many men, this may extend the years after surgery or radiation that they remain recurrence free and their life expectancy is extended. They may be able to prevent the need to undergo additional therapies, such as radiation, hormonal or chemotherapies.”

Dr. Pantuck’s colleagues who contributed to this study included Ignarro, John Leppert, Nazy Zomarodian, William Aronson, Jenny Hong, James Bernard, Navindra Seeram, Harley Liker, Hejing Wang, Robert Elashoff, David Heber, and Arie Belldegrun from the departments of Urology, Medicine, Physiologic Science or Biomathematics at the David Geffen School of Medicine, UCLA. Michael Aviram from the Technion Faculty of Medicine, the Rambam Medical Center, Bat -  Galim, Haifa, Israel, also contributed to these studies.

Funding to support these studies came from the Lynda and Stewart Resnick Revocable Trust. The Resnicks are the owners of the POM Wonderful Company. Additional NIH funding (P50CA92131 and IR01CA100938) supported portions of the science conducted in the course of these experiments.

American Association for Cancer Research (AACR)