Astudy on bladder cancer cell lines showed that green tea extract has potentialas an anti‑cancer agent, proving for the first time that it is able totarget cancer cells while leaving healthy cells alone.
Thestudy, published in the Feb. 15 issue of the peer-reviewed journal ClinicalCancer Research, also uncovered more about how green tea extract works tocounteract the development of cancer, said Jian Yu Rao, a Jonsson Cancer Centermember, an associate professor of pathology and laboratory medicine, and thestudy's senior author.
"Our study adds a newdimension in understanding the mechanisms of green tea extract," Rao said. "If we knew exactly how it works to inhibit thedevelopment of cancer, we could figure out more precisely which bladder cancerpatients might benefit from taking it."
Numerous epidemiologicand animal studies have suggested that green tea extract provides stronganti-cancer effects in several human cancers, including bladder cancer. It hasbeen shown to induce death in cancer cells, as well as inhibiting thedevelopment of an independent blood supply that cancers develop so they cangrow and spread.
In the UCLA study — whichbrought together researchers from UCLA's JonssonCancer Center, School of Public Health, Center for Human Nutrition and thedepartments of pathology and laboratory medicine, surgery, urology, and epidemiology — scientists were able to show that green teaextract interrupts a process that is crucial in allowing bladder cancer tobecome 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 tofacilitate that movement. For cancer to grow and spread, the malignant cellsmust be able to move. The cell movement depends on actinremodeling, which is carefully regulated by complex signaling pathways,including the Rho pathway. When actinremodeling is activated, the cancer cells can move and invade other healthycells and eventually other organs.
By inducing Rho signaling, the green tea extract made the cancer cellsmore mature and made them bind together more closely — a process called celladhesion. Both the maturity of the cells and the adhesion inhibited themobility of the cancer cells, Rao said.
"In effect, the green teaextract may keep the cancer cells confined and localized, where they are easierto treat and the prognosis is better," Rao said. "Cancer cells are invasive andgreen tea extract interrupts the invasive process of the cancer."
Bladder cancer is the fifth most commoncancer 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 cigarettesmoking. Without a reliable, noninvasive way to diagnose the disease, bladdercancer can be difficult to detect in the early, most treatable stages. When notfound early, the tumors can be aggressive, and more than half of patients withadvanced cancers experience recurrences.
UCLA researchers currently are seekinghundreds of former smokers who have had bladder cancer for a clinical trialstudying whether green tea extract prevents recurrence — one of the firststudies in the country to test the agent on cancer patients. The study is partof a comprehensive program funded by the National Cancer Institute and designedto prevent the recurrence and progression of smoking-related bladder cancer. Inaddition to the trial, the program seeks to develop new biomarker tests to helppredict who will get bladder cancer, discover the molecular profile of thedisease 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 studywas conducted in a carefully controlled cell line environment and that moreresearch needs to be done to discover exactly how green tea extract functionsas a cancer fighter. The next phase of his research will analyze urine frombladder cancer patients to determine which subset of patients would benefitmost from taking green tea extract. Researchers will be looking for specificbiomarkers associated with actin remodeling andactivation of the Rho signaling pathway.
"We're hoping the resultsfrom these studies will tell us who will best benefit from the agent," Rao said, adding that the basic research he is doing andthe clinical trial on bladder cancer patients will provide scientists withvital information from both ends of the research continuum, an example of bench-to-bedside-and-back-againscience.
"Ithink this publication further supports the potential role of green tea in theprevention and treatment of bladder cancer," said Dr. Robert Figlin, a UCLA professor of hematology/oncology and urologyand a principal investigator for the human studies. "In the end, both studieswill help us achieve our goal — to decrease bladder cancer occurrence anddevelop molecular profiles that tell us who is most at risk."
UCLA'sJonsson Comprehensive Cancer Center is composed ofmore than 240 cancer researchers and clinicians engaged in cancer research,prevention, detection, control and education. One of the nation's largestcomprehensive cancer centers, the JCCC is dedicated to promoting cancerresearch and applying the results to clinical situations. In 2004 the Jonsson Cancer Center was named thebest cancer center in the Western United States by U.S. News & WorldReport, a ranking it has held for five consecutive years.
For more information on the Jonsson Cancer Center, visit the Web site at http://www.cancer.mednet.ucla.edu/.