Extract of green tea has potential as an anti-cancer agent, U.S. scientists said in a study on bladder cancer cells.

The study, published in the February 15 issue of the journal Clinical Cancer Research, proved for the first time that green tea extract is able to target cancer cells while leaving healthy cells alone.

It also uncovered more about how the extract works to counteract the development of cancer, said researchers at the University of California in Los Angeles (UCLA).

Sipping a cup of this traditional Chinese beverage daily may help prevent cancer, said JianYu Rao, an associate professor at UCLA who led the research group.

"Unlike earlier researches, the extract in our study is very similar to the component in the tea you drink daily; that means you can at least boost up the resistance against cancer by tea drinking," Rao said.

"Our study adds a new dimension in understanding the mechanisms of green tea extract," he added. "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, 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. When actin remodeling is activated, the cancer cells can move and invade other healthy cells and eventually other organs.

The green tea extract can make 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.

Bladder cancer is the fifth most common cancer in the U.S., with about 56,000 new cases diagnosed each year.