Document Detail


Protein kinase Cδ and caspase-3 modulate TRAIL-induced apoptosis in breast tumor cells.
MedLine Citation:
PMID:  20665667     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
This report describes that protein kinase C delta (PKCδ) overexpression prevents TRAIL-induced apoptosis in breast tumor cells; however, the regulatory mechanism(s) involved in this phenomenon is(are) incompletely understood. In this study, we have shown that TRAIL-induced apoptosis was significantly inhibited in PKCδ overexpressing MCF-7 (MCF7/PKCδ) cells. Our data reveal that PKCδ inhibits caspase-8 activation, a first step in TRAIL-induced apoptosis, thus preventing TRAIL-induced apoptosis. Inhibition of PKCδ using rottlerin or PKCδ siRNA reverses the inhibitory effect of PKCδ on caspase-8 activation leading to TRAIL-induced apoptosis. To determine if caspase-3-induced PKCδ cleavage reverses its inhibition on caspase-8, we developed stable cell lines that either expresses wild-type PKCδ (MCF-7/cas-3/PKCδ) or caspase-3 cleavage-resistant PKCδ mutant (MCF-7/cas-3/PKCδ mut) utilizing MCF-7 cells expressing caspase-3. Cells that overexpress caspase-3 cleavage-resistant PKCδ mutant (MCF-7/cas-3/PKCδmut) significantly inhibited TRAIL-induced apoptosis when compared to wild-type PKCδ (MCF-7/cas-3/PKCδ) expressing cells. In MCF-7/cas-3/PKCδmut cells, TRAIL-induced caspase-8 activation was blocked leading to inhibition of apoptosis when compared to wild-type PKCδ (MCF-7/cas-3/PKCδ) expressing cells. Together, these results strongly suggest that overexpression of PKCδ inhibits caspase-8 activation leading to inhibition of TRAIL-induced apoptosis and its inhibition by rottlerin, siRNA, or cleavage by caspase-3 sensitizes cells to TRAIL-induced apoptosis. Clinically, PKCδ overexpressing tumors can be treated with a combination of PKCδ inhibitor(s) and TRAIL as a new treatment strategy.
Authors:
Shuping Yin; Seema Sethi; Kaladhar B Reddy
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Journal of cellular biochemistry     Volume:  111     ISSN:  1097-4644     ISO Abbreviation:  J. Cell. Biochem.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8205768     Medline TA:  J Cell Biochem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  979-87     Citation Subset:  IM    
Affiliation:
Department of Pathology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, Michigan 48201, USA.
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Grant Support
ID/Acronym/Agency:
R01 CA 118089/CA/NCI NIH HHS

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