Abstract |
Animal studies have demonstrated that a dietary polyphenol known as tannic acid (TA) exhibits anticarcinogenic activity in chemically induced cancers. Most recently, we have reported that TA and ester-bond containing green tea polyphenols are potent proteasome inhibitors in vitro and in vivo. We hypothesize that CellQuest, a patented formula which contains high level of TA obtained from a musaceas (plantain) plant extract, will inhibit the tumor cell proteasome activity. Here, we report that a partially purified CellQuest fraction, S3, potently inhibits the proteasomal chymotrypsin-like activity of Jurkat T cell extracts in a concentration-dependent manner. Inhibition of the proteasome by S3 in leukemia Jurkat T, simian virus 40-transformed and prostate cancer LNCaP cells results in accumulation of ubiquitinated proteins and the natural proteasome substrate p27Kip1, followed by induction of apoptosis. In contrast, non-transformed, immortalized human natural killer cells and normal human fibroblasts are resistant to S3-mediated proteasome inhibition and apoptosis induction. Our present study suggests that CellQuest targets and inhibits the proteasome selectively in tumor cells, which may contribute to the claimed anticancer activity.
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Authors | Aslamuzzaman Kazi, Daniel A Urbizu, Deborah J Kuhn, Abelardo L Acebo, Edward R Jackson, Gail P Greenfelder, Nagi B Kumar, Q Ping Dou |
Journal | International journal of molecular medicine
(Int J Mol Med)
Vol. 12
Issue 6
Pg. 879-87
(Dec 2003)
ISSN: 1107-3756 [Print] Greece |
PMID | 14612961
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Multienzyme Complexes
- Plant Extracts
- Cysteine Endopeptidases
- Proteasome Endopeptidase Complex
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Topics |
- Apoptosis
(drug effects)
- Cell Line, Transformed
- Cysteine Endopeptidases
- Humans
- Jurkat Cells
- Male
- Multienzyme Complexes
(antagonists & inhibitors)
- Musaceae
(metabolism)
- Plant Extracts
(pharmacology)
- Prostatic Neoplasms
(drug therapy)
- Proteasome Endopeptidase Complex
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