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| 18th century tea botanical print. |
The good news from Penn State researchers last week is that a powerful catechin found in green tea may lead to new treatments for some cancers.
The better news is that these new treatments might be accomplished without the debilitating side effects of existing chemo-therapies, such as hair loss.
Epigallocatechin-3-gallate, commonly known as EGCG, has been the buzz word for tea and health since the Third International Tea & Health Symposium, held at the USDA in Washington, DC in 2003.
I was in the audience that day and heard scientist after scientist explain their findings concerning EGCG and it’s ability to limit the growth of some cancer cells. Green tea is an excellent source of EGCG, and from that day forward, green tea and good health have become synonymous.
“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. We now know that EGCG may trigger a process in the mitochondria that leads to cell death.
“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 reactive oxygen species 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 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 green tea consumption.”
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| Chinese Lung Ching (Dragonwell) green tea contains high levels of the powerful catechin EGCG. |
EGCG did not cause this reaction in normal cells. In fact, it appeared to increase the protective capabilities of the cell.
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 both normal and cancer cells on Petri dishes and then exposed them to EGCG. 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 oxidative stress and actually see these things develop,” said Lambert.
The researchers went on to say that a protein called sirtuin 3 (SIRT3) is critical to the process.
“SIRT3 plays an important role in mitochondrial function and in anti-oxidant response in lots of tissues in the body, so the idea that EGCG might selectively affect the activity of SIRT3 in cancer cells—to turn it off, and in normal cells, to turn it on—is probably applicable in multiple kinds of cancers,” Lambert said.
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.
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| Green teas may take many shapes but all are best made in water no hotter than 175 degrees F. |
The American Institute for Cancer Research supported this study. Read the entire article in the January 28, 2015 edition of Penn State News.