Study Shows How Green
Tea May Fight Bladder Cancer
Green tea extract may interfere with
a process that helps early bladder cancer to spread throughout
the body, new laboratory research suggests.
The findings, say researchers,
bolster ongoing studies into green tea extract as a cancer treatment
-- and may give green tea drinkers more reason to savor every
The investigators found that when
they exposed human bladder cells to both a cancer-causing chemical
and green tea extract, the extract interfered with a particular
process by which early cancer cells become invasive and spread
throughout body tissue.
This process involves the "remodeling"
of actin, a structural protein in cells that is essential for
cell movement. Actin remodeling allows cancer cells to move and
invade nearby healthy tissue.
Based on the new findings, green
tea extract may get in the way of this process by activating a
protein known as Rho, which helps regulate actin's organization
in cells and has been implicated in tumor development and progression.
Dr. JianYu Rao and his colleagues
at the University of California Los Angeles report the findings
in the journal Clinical Cancer Research.
A number of studies have suggested
that green tea and extracts of the beverage may have cancer-preventing
abilities, possibly due to the tea's concentration of certain
antioxidants -- compounds that help ward off cell damage that
can lead to cancer, heart disease and other ills.
But exactly how green tea may act
in the body to fight cancer is not clear. Lab research has suggested
it can act in several ways -- from hindering tumors from forming
their own blood supply to forcing abnormal cells to commit suicide.
The current study points to an
entirely new mechanism, Rao stated in an interview.
Green tea extract, he explained,
appears to diminish cancer cells' invasiveness -- suggesting that
it could be used in the early stages of cancer treatment.
One recent study found that green
tea extract brought no benefit to men with advanced prostate cancer.
But Rao said that any effects of the extract on cancer would probably
occur in the early stages.
He and his colleagues are now conducting
a clinical trial to see whether green tea extract can reduce the
risk of bladder cancer recurrence in patients with a history of
smoking, which is a risk factor for the disease.
Uncovering the details of how green
tea may stymie cancer could help doctors figure out which patients
are likely to benefit from treatment with extracts, Rao said.
It may be possible to look for specific markers of actin remodeling
and Rho activation in patients' urine to determine who is best
suited for such therapy.
It's also possible, Rao said, that
drinking green tea could reduce the risk of developing bladder
cancer in the first place -- though no one knows how many cups
a person would have to sip over a lifetime.
SOURCE: Clinical Cancer Research,
February 15, 2005.
Reference Source 89
February 24, 2005