Green tea ingredient may target protein to kill oral cancer cells

January 28, 2015, Pennsylvania State University
Green tea. Credit: Wikimedia Commons

A compound found in green tea may trigger a cycle that kills oral cancer cells while leaving healthy cells alone, according to Penn State food scientists. The research could lead to treatments for oral cancer, as well as other types of cancer.

Earlier studies had shown that epigallocatechin-3-gallate—EGCG—a compound found in green tea, killed cells without harming normal cells, but researchers did not understand the reasons for its ability to target the cancer cells, said Joshua Lambert, associate professor of food science and co-director of Penn State's Center for Plant and Mushroom Foods for Health. The current study shows that EGCG may trigger a process in the mitochondria that leads to .

"EGCG is doing something to damage the mitochondria and that mitochondrial damage sets up a cycle causing more damage and it spirals out, until the cell undergoes programmed cell death," said Lambert. "It looks like EGCG causes the formation of in cancer cells, which damages the mitochondria, and the mitochondria responds by making more reactive oxygen species."

As this mitochondrial demise continues, the cancer cell also reduces the expression of anti-oxidant genes, further lowering its defenses.

"So, it's turning off its mechanism of protection at the same time that EGCG is causing this oxidative stress," Lambert added.

The EGCG did not cause this reaction in normal cells. In fact, it appeared to increase the protective capabilities of the cell, according to the researchers, who report their findings in the online issue of Molecular Nutrition and Food Research.

The researchers studied normal human oral cells side-by-side with human oral cancer cells to determine how EGCG was affecting cancer cells differently than normal cells. They grew the normal and cancer cells on petri dishes and then exposed them to EGCG, the major polyphenol found in green tea, at concentrations typically found in the saliva after chewing green-tea chewing gum. At various times, the researchers would collect the cells and check for oxidative stress and signs of antioxidant response.

"We also took a lot of pictures, so we could use fluorescent dyes that measure mitochondrial function and and actually see these things develop," said Lambert, who worked with Jong-Yung Park, a research technician and Ling Tao, a doctoral candidate in .

The researchers said that a protein called sirtuin 3—SIRT3—is critical to the process.

"It plays an important role in and in anti-oxidant response in lots of tissues in the body, so the idea that EGCG might selectively affect the activity of sirtuin 3 in cancer cells—to turn it off—and in —to turn it on—is probably applicable in multiple kinds of cancers," Lambert said.

The study builds on earlier research on how EGCG affected oral cancer, a disease that is expected to kill more than 8,000 people in the United States this year.

"We've published one paper previously just looking at the effect of these green tea polyphenols on oral cancer cells in cultures, and there have been other papers published using oral and at least a couple of animal model studies that have looked at oral cancer and prevention of oral cancer," said Lambert.

He said the next step would be to study the mechanism in animals. If those tests and human trials are successful, the researchers then hope to create anti-cancer treatments that are as effective as current treatments without the harmful side effects.

"The problem with a lot of chemotherapy drugs—especially early chemotherapy drugs—is that they really just target rapidly dividing cells, so cancer divides rapidly, but so do cells in your hair follicles and cells in your intestines, so you have a lot of side effects," said Lambert. "But you don't see these sorts of side effects with consumption."

Explore further: A new role for milk: Delivering polyphenols with anti-cancer activity

Related Stories

A new role for milk: Delivering polyphenols with anti-cancer activity

December 19, 2013
Polyphenols found in tea manifest anti-cancer effects but their use is limited by poor bioavailability and disagreeable taste. A new study in the Journal of Dairy Science finds that when epigallocatechin gallate (EGCG), the ...

Study explains how green tea could reduce pancreatic cancer risk

May 30, 2014
Green tea and its extracts have been widely touted as potential treatments for cancer, as well as several other diseases. But scientists have struggled to explain how the green tea and its extracts may work to reduce the ...

Researchers develop green tea-based 'missiles' to kill cancer cells more effectively

October 6, 2014
Green tea has long been known for its anti-oxidant, anti-cancer, anti-aging and anti-microbial properties. A group of researchers from the Institute of Bioengineering and Nanotechnology (IBN) of A*STAR has taken the health ...

Green tea helps mice keep off extra pounds

October 4, 2011
Green tea may slow down weight gain and serve as another tool in the fight against obesity, according to Penn State food scientists.

Drinking green tea with starchy food may help lower blood sugar spikes

November 9, 2012
An ingredient in green tea that helps reduce blood sugar spikes in mice may lead to new diet strategies for people, according to Penn State food scientists.

Scientists pinpoint a new line of defence used by cancer cells

December 8, 2014
Cancer Research UK scientists have discovered a new line of defence used by cancer cells to evade cell death, according to research published in Nature Communications today.

Recommended for you

Fusion hybrids: A newly discovered population of tumor cells

September 24, 2018
In a recent study published in Science Advances, Charles E. Gast and co-workers detail the spontaneous process of cancer cell fusion with white blood cells to produce heterogenous hybrid clones in multiple biological systems, ...

Cancer cells evade immunotherapy by hiding telltale marker, suggesting how to stop relapse

September 24, 2018
Harnessing the immune system to treat cancer shows great promise in some patients, but for many, the response does not last long-term. In an effort to find out why, Fred Hutchinson Cancer Research Center scientists are using ...

In zebrafish, a way to find new cancer therapies, targeting tumor modulators

September 21, 2018
The lab of Leonard Zon, MD, at Boston Children's Hospital has long been interested in making blood stem cells in quantity for therapeutic purposes. Looking for a way to test for their presence in zebrafish, their go-to research ...

What can salad dressing tell us about cancer? Think oil and vinegar

September 20, 2018
Researchers led by St. Jude Children's Research Hospital scientists have identified another way the process that causes oil to form droplets in water may contribute to solid tumors, such as prostate and breast cancer. The ...

Novel biomarker found in ovarian cancer patients can predict response to therapy

September 20, 2018
Despite months of aggressive treatment involving surgery and chemotherapy, about 85 percent of women with high-grade wide-spread ovarian cancer will have a recurrence of their disease. This leads to further treatment, but ...

Testing fluorescent tracers used to help surgeons determine edges of breast cancer tumors

September 20, 2018
A team of researchers with members from institutions in The Netherlands and China has conducted a test of fluorescent tracers meant to aid surgeons performing tumor removal in breast cancer patients. In their paper published ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

210
1 / 5 (1) Jan 28, 2015
Have you ever tried green tea ice cream....shockingly good.

word-

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.