Abstract
Green tea has long been thought to possess anticancer properties. Additionally, the polyphenol components of green tea have demonstrated ability to inhibit 26S proteasome function. As there have been reports describing varied responses of gastric carcinoma cells to green tea treatment, the role of green tea treatment on proteasome function in the gastric carcinoma cell line AGS was investigated. Presented here are findings demonstrating that green tea extract is capable of inhibiting proteasome function of AGS cells. Furthermore, treatment of AGS cells with the green tea polyphenol (-)-Epigallocatechin-3-gallate resulted in a similar level of proteasome inhibition. It was also discovered in this study that proteasome inhibition in AGS cells resulted in a buildup of Kip1/p27 and IκBα, proteins that are involved in the progression through the G1/S checkpoint during cell division. Proteasome inhibition by (-)-Epigallocatechin- 3-gallate led to induction of apoptosis of AGS cells. Our results described here strongly suggest that green tea consumption is capable of inducing programmed cell death in gastric carcinoma cells through inhibition of proteasome activity. It should be noted, however, that consumption of green tea during anti-cancer protocols has been reported to reduce the effectiveness of a specific subset of chemotherapeutic compounds. In summary, consumption of green tea in gastric carcinoma patients may be effective in targeting cancer cells and slowing the progression of gastric cancers. Future studies of these natural products may provide some structural information which will allow for the development of the next generation of anti-cancer chemotherapeutics.
Highlights
Green tea has long been consumed worldwide, and numerous reports have provided evidence of the beneficial nutritional aspects of green tea [1]
There was no significant proteasome inhibition in cells treated with 20 μg/ml green tea extract, exposure of AGS cells to 80 μg/ml green tea extract resulted in approximately a 90% inhibition of 26S proteasome activity
Presented here is experimental evidence to support the longstanding idea that the chemical components of green tea possess anti-cancer cell properties
Summary
Green tea has long been consumed worldwide, and numerous reports have provided evidence of the beneficial nutritional aspects of green tea [1]. Epidemiological studies have provided correlative evidence that consumption of green tea reduces cancer development [2]. Effects on tumors and cancer cells have been attributed to the polyphenol compounds contained within green tea extracts [5,6,7]. The catechin (-)-Epigallocatechin-3-gallate (EGCG) is thought to be the most potent of the polyphenol components, and has been shown to mediate an induction of an apoptotic cascade in certain tumor cells [8,9,10]. Varying degrees of tumor cell inhibition have been reported, depending both on cell lines studied [11] and which catechins were used as inhibitors [12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
