Green Tea Extract Shows
Promise As An Anti-Cancer Agent
A study on bladder cancer cells lines showed that green tea extract
has potential as an anti-cancer agent, proving for the first time
that it is able to target cancer cells while leaving healthy cells
The study, published in the Feb. 15, 2005 issue of the peer-reviewed
journal Clinical Cancer Research, also uncovered more about how
green tea extract works to counteract the development of cancer,
said JianYu Rao, a Jonsson Cancer Center member, an associate
professor of pathology and laboratory medicine and the study's
"Our study adds a new dimension in understanding the mechanisms
of green tea extract," Rao said. "If we knew exactly how it works
to inhibit the development of cancer, we could figure out more
precisely which bladder cancer patients might benefit from taking
Numerous epidemiologic and animal studies have suggested that
green tea extract provides strong anti-cancer effects in several
human cancers, including bladder cancer. It has been shown to
induce death in cancer cells, as well as inhibiting the development
of an independent blood supply that cancers develop so they can
grow and spread.
In the UCLA study, which brought together researchers from UCLA's
Jonsson Cancer Center, School of Public Health, Center for Human
Nutrition and the departments of Pathology and Laboratory Medicine,
Surgery, Urology and Epidemiology, scientists were able to show
that green tea extract interrupts a process that is crucial in
allowing bladder cancer to become invasive and spread to other
areas of the body.
Green tea extract affects actin remodeling, an event associated
with cell movement. When a human moves, the muscles and skeletal
structure operate together to facilitate that movement. For cancer
to grow and spread, the malignant cells must be able to move.
The cell movement depends on actin remodeling, which is carefully
regulated by complex signaling pathways, including the Rho pathway.
When actin remodeling is activated, the cancer cells can move
and invade other healthy cells and eventually other organs. By
inducing Rho signaling, the green tea extract made the cancer
cells more mature and made them bind together more closely - a
process called cell adhesion. Both the maturity of the cells and
the adhesion inhibited the mobility of the cancer cells, Rao said.
"In effect, the green tea extract may keep the cancer cells
confined and localized, where they are easier to treat and the
prognosis is better," Rao said. "Cancer cells are invasive and
green tea extract interrupts the invasive process of the cancer."
Bladder cancer is the fifth most common cancer in the United
States, with about 56,000 new cases diagnosed each year. About
half of all bladder cancers are believed to be related to cigarette
smoking. Without a reliable, non-invasive way to diagnose the
disease, bladder cancer can be difficult to detect in the early,
most treatable stages. When not found early, the tumors can be
aggressive, and more than half of patients with advanced cancers
UCLA researchers currently are seeking hundreds of former smokers
who have had bladder cancer for a clinical trial studying whether
green tea extract prevents recurrence - one of the first studies
in the country to test the agent on cancer patients. The study
is part of a comprehensive program funded by the National Cancer
Institute and designed to prevent the recurrence and progression
of smoking-related bladder cancer. In addition to the trial, the
program seeks to develop new biomarker tests to help predict who
will get bladder cancer, discover the molecular profile of the
disease to identify those most at risk and create a tumor bank
to aid research. Volunteers interested in participating in the
study should call (310) 825-4415.
Rao cautioned that his study was conducted in a carefully controlled
cell line environment and that more research needs to be done
to discover exactly how green tea extract functions as a cancer
fighter. The next phase of his research will analyze urine from
bladder cancer patients to determine which subset of patients
would benefit most from taking green tea extract. Researchers
will be looking for specific biomarkers associated with actin
remodeling and activation of the Rho signaling pathway.
"We're hoping the results from these studies will tell us who
will best benefit from the agent," Rao said, adding that the basic
research he is doing and the clinical trial on bladder cancer
patients will provide scientists with vital information from both
ends the research continuum, an example of bench-to-bedside-and-back-again
"I think this publication further supports the potential role
of green tea in the prevention and treatment of bladder cancer,"
said Dr. Robert Figlin, a UCLA professor of hematology/oncology
and urology and a principal investigator for the human studies.
"In the end, both studies will help us achieve our goal - to decrease
bladder cancer occurrence and develop molecular profiles that
tell us who is most at risk."
Reference Source 125
February 17, 2005