Document Detail


Beta-sitosterol induces anti-proliferation and apoptosis in human leukemic U937 cells through activation of caspase-3 and induction of Bax/Bcl-2 ratio.
MedLine Citation:
PMID:  17603173     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Beta-sitosterol is the main dietary phytosterol found in plants and has been shown to inhibit proliferation and induce apoptosis in human solid tumors such as colon and breast cancers. However, the mechanism by which beta-sitosterol induces apoptosis is not completely understood in leukemic cells. This study investigated the mechanism of apoptosis induced by beta-sitosterol in human leukemic U937 cells. beta-Sitosterol induced cytotoxicity and apoptosis in U937 cells in a concentration dependent manner, as measured by hemocytometer counts, fluorescence microscopy, agarose gel electrophoresis, and flow cytometry analysis. The increase in apoptosis induced by beta-sitosterol was associated with down-regulation of Bcl-2, degradation of poly-(ADP-ribose) polymerase (PARP) and phospholipase C (PLC)-gamma1 protein, and activation of caspase-3. beta-Sitosterol induced apoptosis was not associated with changes in the expression of Bcl-xL, Bax, or inhibitor of apoptosis proteins (IAPs). z-DEVD-fmk, a caspase-3 specific inhibitor, blocked caspase-3 activation and PARP degradation, and significantly attenuated beta-sitosterol-induced apoptosis. This suggests that caspase-3 activation is partially essential for beta-sitosterol-induced apoptosis. Bcl-2 overexpression also significantly blocked caspase-3 activation and the decrease in PARP cleavage by beta-sitosterol, and effectively attenuated the apoptotic response to beta-sitosterol. These results show that beta-sitosterol potently induces apoptosis in U937 cells and that beta-sitosterol-induced apoptosis is related to the selective activation of caspase-3 and induction of Bax/Bcl-2 ratio.
Authors:
Cheol Park; Dong-Oh Moon; Chung-Ho Rhu; Byung Tae Choi; Won Ho Lee; Gi-Young Kim; Yung Hyun Choi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biological & pharmaceutical bulletin     Volume:  30     ISSN:  0918-6158     ISO Abbreviation:  Biol. Pharm. Bull.     Publication Date:  2007 Jul 
Date Detail:
Created Date:  2007-07-02     Completed Date:  2007-08-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9311984     Medline TA:  Biol Pharm Bull     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  1317-23     Citation Subset:  IM    
Affiliation:
Department of Biochemistry, Dongeui University, College of Oriental Medicine, Busan, South Korea.
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MeSH Terms
Descriptor/Qualifier:
Apoptosis / drug effects*
Caspase 3 / antagonists & inhibitors,  metabolism*
Cell Proliferation / drug effects
Enzyme Activation / drug effects
Humans
Proto-Oncogene Proteins c-bcl-2 / analysis*
Sitosterols / pharmacology*
U937 Cells
bcl-2-Associated X Protein / analysis*
Chemical
Reg. No./Substance:
0/Proto-Oncogene Proteins c-bcl-2; 0/Sitosterols; 0/bcl-2-Associated X Protein; 5779-62-4/sitosterol; EC 3.4.22.-/Caspase 3

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