A study published by Penn State food scientists revealed that a green tea compound kills oral cancer cells. Oral cancer kills an estimated 8,000 people in the United States annually. The green tea compound called (EGCG) epigallocatechin-3-gallate interferes with cancer metabolism by damaging the cell mitochondria while health cells are untouched.
“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 Joshua Lambert, associate professor of food science and co-director of Penn State’s Center for Plant and Mushroom Foods for Health. “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 cell death continues, the cancer cell reacts by reducing the expression of anti-oxidant genes, further lowering its defenses.
This reaction does not occur in normal cells. Instead EGCG increases the protective capabilities of the cell. Mitochondria are often referred to as the powerhouses of the cells. They generate the energy that our cells need to do their jobs.
The study consisted of growing normal human oral cells and human oral cancer cells and exposing both sets of ECGC at concentrations found in the saliva after chewing green tea gum. At various intervals, 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, who worked with Jong-Yung Park, a research technician and Ling Tao, a doctoral candidate in food science.
The researchers identified a protein called sirtuin 3 (SIRT3) as critical to the process. “It 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 sirtuin 3 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.
Ling Tao1, Jong-Yung Park1 andJoshua D. Lambert. Differential prooxidative effects of the green tea polyphenol, (–)-epigallocatechin-3-gallate, in normal and oral cancer cells are related to differences in sirtuin 3 signaling. Molecular Nutrition and Food Research. DOI: 10.1002/mnfr.201400485