Natural Substances In Fruits And Vegetables May Be Potential Treatment For
ROCHESTER, MINN. -- Quercetin (kwer-se-ten), a natural
substance found in apples, onions, tea and red wine, may be a potentially
novel approach for preventing and treating prostate cancer, according to a
laboratory research study conducted at Mayo Clinic in Rochester.
The results of the study were presented today, March 26, at the 92nd
annual meeting of the American Association for Cancer Research (AACR) in New
Orleans. The study also is published in this monthís issue of the cancer
"Our laboratory results showed quercetin blocks the androgen (hormone)
activity in androgen-responsive human prostate cancer cell lines," says
Nianzeng Xing, Ph.D., the Mayo Clinic researcher who presented the results
of the study at AACR.
"By blocking the androgen activity, the growth of prostate cancer cells
can be prevented or stopped," he said. "Our study suggests quercetin may be
a potential non-hormonal approach to accomplishing that goal."
Prostate cancer is the second leading cause of cancer death in men in the
United States. It annually claims about 31,500 men, accounting for about 11
percent of male cancer-related deaths.
The findings may lead to another treatment option for the nearly 200,000
men diagnosed with prostate cancer annually in the United States. It also
may mean that eventually some men may not have to undergo castration, the
current, commonly used treatment for advanced prostate cancer.
However, Dr. Xing cautions, more research is required to determine
whether the preliminary laboratory findings about quercetin translate into
actual benefit for men either at risk or diagnosed with prostate cancer.
Quercetin is an abundant, naturally occurring flavonoid compound. In
addition to apples, onions, black and green tea, and red wine, the compound
is found in green leafy vegetables, beans and citrus fruits.
Quercetin has been studied scientifically for the past 30 years. Itís
documented as safe and having relatively low toxicity.
The compound is currently used in therapeutic treatments for allergic
conditions such as asthma, hay fever, eczema and hives. Itís also used
clinically to treat several inflammatory conditions, including gout,
pancreatitis and prostatitis.
The Mayo Clinic study is the first research indicating quercetin has
significant activity against the androgen receptor in the human prostate
cancer cell lines.
Androgens are male hormones, the most common being testosterone.
Androgens also are involved in the development, progression and growth of
The biological effects of androgens in the prostate are mediated by the
androgen receptor, says Dr. Xing. An activated androgen receptor can turn on
or off critical genes, which affect the biology and pathology of the
"Our laboratory data showed that androgen receptor expression was
inhibited by quercetin and the
rate of response was dose-dependent," says
Dr. Xing. "Our study also delineated the mechanism by which quercetin
reduced the androgen receptor."
Androgen deprivation or suppression therapy by surgery or medication to
remove or reduce the androgens is the cornerstone of current treatment for
advanced prostate cancer.
"Unfortunately, the cancer recurs in about 80 percent of men within one
to two years after undergoing the therapy, and this may be correlated with
mutations in the androgen receptor," says Dr. Xing.
"The androgen receptor may function with either a small of amount of
androgen or independently of androgens," he says. "As a result, the cancer
learns to grow in the prostate with less hormone or even without the need of
In view of that fact, Dr. Xing says, "A more effective strategy in the
fight against prostate cancer may be to minimize or eliminate the amount of
the androgen receptor."
The Mayo Clinic research study indicated that this strategy may be
possible with quercetin.
The next step in the research process is to study the effects of
quercetin in a laboratory mouse model with prostate cancer.
This story has been adapted from a news release issued by Mayo