A new study on bladder cancer cells lines shows 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 alone.
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
A new study on bladder cancer cells lines shows 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 alone.
member, an associate professor of
pathology and laboratory medicine and the study's senior author.
"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 it."
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 experience recurrences.