Study shows how green tea may fight bladder cancer
Last Updated: 2005-02-23 16:05:54 -0400 (Reuters Health)
By Amy Norton
NEW YORK (Reuters Health)
– 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 cup.
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 told Reuters Health 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.