Document Detail


Essential role of caspases in epigallocatechin-3-gallate-mediated inhibition of nuclear factor kappa B and induction of apoptosis.
MedLine Citation:
PMID:  14676829     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Green tea constituent (-) epigallocatechin-3-gallate (EGCG) has shown remarkable cancer-preventive and some cancer-therapeutic effects. This is partially because of its ability to induce apoptosis in cancer cells without affecting normal cells. Previous studies from our laboratory have shown the involvement of NF-kappa B pathway in EGCG-mediated cell-cycle deregulation and apoptosis of human epidermoid carcinoma A431 cells. Here we show the essential role of caspases in EGCG-mediated inhibition of NF-kappa B and its subsequent apoptosis. Treatment of A431 cells with EGCG (10-40 microg/ml) resulted in dose-dependent inhibition of NF-kappa B/p65, induction of DNA breaks, cleavage of poly(ADP-ribose) polymerase (PARP) and morphological changes consistent with apoptosis. EGCG treatment of cells also resulted in significant activation of caspases, as shown by the dose- and time-dependent increase in DEVDase activity, and protein expression of caspase-3, -8 and -9. EGCG-mediated caspase activation induces proteolytic cleavage of NF-kappa B/p65 subunit, leading to the loss of transactivation domains, and driving the cells towards apoptosis. EGCG-mediated induction of apoptosis was significantly blocked by the caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (Z-VAD-FMK), and moderately blocked by the specific caspase-3 inhibitor Z-DEVD-FMK. Further, pretreatment of cells with Z-VAD-FMK was found to suppress the cleavage of NF-kappa B/p65 subunit, thereby increasing nuclear translocation, DNA binding and transcriptional activity, thus protecting the cells from EGCG-induced apoptosis. Taken together, these studies for the first time demonstrate that EGCG-mediated activation of caspases is critical, at least in part, for inhibition of NF-kappa B and subsequent apoptosis.
Authors:
Sanjay Gupta; Kedar Hastak; Farrukh Afaq; Nihal Ahmad; Hasan Mukhtar
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Oncogene     Volume:  23     ISSN:  0950-9232     ISO Abbreviation:  Oncogene     Publication Date:  2004 Apr 
Date Detail:
Created Date:  2004-04-01     Completed Date:  2004-04-27     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8711562     Medline TA:  Oncogene     Country:  England    
Other Details:
Languages:  eng     Pagination:  2507-22     Citation Subset:  IM    
Affiliation:
Department of Urology, Case Western Reserve University, Cleveland, OH 44106, USA.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Chloromethyl Ketones / pharmacology
Apoptosis / drug effects*
Carcinoma, Squamous Cell
Caspases / antagonists & inhibitors,  metabolism*
Catechin / analogs & derivatives*,  pharmacology*
Cell Line, Tumor
Cell Nucleus / metabolism
Cell Survival
DNA / metabolism
Dose-Response Relationship, Drug
Enzyme Activation
Humans
Male
Models, Biological
NF-kappa B / antagonists & inhibitors*,  chemistry,  metabolism
Oligopeptides / pharmacology
Poly(ADP-ribose) Polymerases / drug effects
Prostatic Neoplasms
Protein Structure, Tertiary / drug effects
Time Factors
Transcription, Genetic
Grant Support
ID/Acronym/Agency:
R01 CA 78809/CA/NCI NIH HHS
Chemical
Reg. No./Substance:
0/Amino Acid Chloromethyl Ketones; 0/NF-kappa B; 0/Oligopeptides; 0/benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; 0/benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; 154-23-4/Catechin; 9007-49-2/DNA; 989-51-5/epigallocatechin gallate; EC 2.4.2.30/Poly(ADP-ribose) Polymerases; EC 3.4.22.-/Caspases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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