Researchers from Penn State's University's Center for Plant and Mushroom Foods for Health said they hoped the in vitro findings would contribute to the development of alternative treatments for oral and other types of cancer.
Previous studies suggested such a cancer-fighting capacity for polyphenols, but the mechanism was not determined.
According to the paper published in the journal Molecular Nutrition and Food Research, this beneficial effect may be due to an interaction in the mitochondria, the so-called powerhouse of the cell.
They said that EGCG caused oxidative damage in the cancer cell mitochondria, which then spread to the rest of the cell causing it to die by attacking its antioxidant gene defences.
However, it did not damage normal cells and could even increase their protective abilities.
The researchers studied the process in both normal human oral cells and human oral cancer cells in Petri dishes.
Key proteins
An important part of this process was the expression of vascular endothelial growth factor (VEGF) – a signal protein which, when over-expressed, could help contribute to disease like cancer by blood and oxygen supply and increased growth of tumours.
“These data demonstrate for the first time that VEGF is a key molecular target for specific polyphenols found in tea, apples and cocoa which potently inhibit VEGF signalling and angiogenesis [the creation of new blood vessels from existing] at physiological concentrations,” the researchers wrote.
They found that the EGCG “strongly inhibited” the binding of the signal protein to cells.
Tea as a treatment?
Professor Joshua Lambert, one of the study’s authors, said they were now looking to test the findings in animals, something which could lead to the development of alternative cancer treatments.
"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," he said.
"But you don't see these sorts of side effects with green tea consumption."
Source: Molecular Nutrition and Food Research
Published online ahead of print, doi: 10.1002/mnfr.201400478
“Potent inhibition of VEGFR-2 activation by tight binding of green tea epigallocatechin gallate and apple procyanidins to VEGF: Relevance to angiogenesis”
Authors: C. W. A. Moyle, A. B. Cerezo, M. S. Winterbone, W. J. Hollands, Y. Alexeev, P. W. Needs and P. A. Kroon