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Green tea extract helps fight cancer, researchers find

Posted Feb. 16, 2005
Courtesy the University of California at Los Angeles
and World Science staff

Green tea extract may help fight bladder cancer by snarling up tiny “skeletons” within cells, which cancer cells use to move around, according to researchers.

The findings appear in a study published in the Feb. 15 issue of the scientific journal Clinical Cancer Research.

The researchers who conducted the study, from the University of California at Los Angeles, examined how the substance affected bladder cancer cells in laboratory tests. Their results were consistent with suggestions from previous studies that the extract fights several cancers, and showed how it might do so, said the university’s JianYu Rao, the study’s senior author. 

It found the extract targets cancer cells while leaving healthy cells alone, the researchers said.

“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.”

Previous studies had suggested the extract might work by killing cancer cells and hampering the development of a blood supply that feeds them. 

The UCLA scientists said they showed that green tea extract affects a process, called actin remodeling, in which cells’ internal “skeleton” changes its shape. This rearrangement, not unlike the movements of our own skeletons, allows the cancer cells to move, and thus migrate out of the bladder to invade new areas of the body.

“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.”

The green tea extract influenced this remodeling by making cells stick together, preventing the skeletons from moving around very much, the researchers said.

The extract also had a second effect, they found: it changed the cells into slightly different types of cells. 

This finding is consistent with a growing number of studies that have shown that forcing a cell into a particular shape or skeletal configuration can change the type of cell it is, often turning it into one of the types of cells that normally lives in that configuration. 

These shape-shifting changes often switch a cell from an immature type—a stem cell, which potentially can become one of a number of specific kinds of cell, such as bone or fat—into one of those particular types. 

Researchers have been working to exploit this shape-related change in cell type to create new cells that could help cure certain medical conditions. For instance, some researchers hope to use similar processes to grow new cartilage cells to replace those lost in arthritis.

But the new findings might represent the first time shape-related changes in cells are being harnessed to fight bladder cancer. The disease is the fifth most common cancer in the United States, with about 56,000 new cases diagnosed each year, according to the researchers. About half of all bladder cancers are believed to be related to cigarette smoking. 

The cancer can be hard to detect in the early, most treatable stages, the researchers added. When not found early, the tumors can be aggressive, and more than half of patients with advanced cancers experience recurrences. 

UCLA researchers currently are seeking hundreds of former smokers who have had bladder cancer for a clinical trial studying whether green tea extract prevents recurrence—one of the first studies in the country to test the agent on cancer patients. The university is asking volunteers interested in participating to call (310) 825-4415.

Rao cautioned that his study was conducted in a carefully controlled environment and that more research needs to be done to discover exactly how green tea extract functions as a cancer fighter. The next phase of his research will analyze urine from bladder cancer patients to determine which patients would benefit most from taking green tea extract. 

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