Document Detail


Downregulation of neutral ceramidase by gemcitabine: Implications for cell cycle regulation.
MedLine Citation:
PMID:  19345744     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Gemcitabine (GMZ) is a chemotherapeutic agent with well established effects on cell growth arrest and apoptosis. In this study, we investigated the potential roles of bioactive sphingolipids in mediating the growth suppressing effects of GMZ on a polyoma middle T transformed murine endothelial cell line. After 12-hour GMZ (0.6 microM) treatment, cell growth was arrested at the G(0)/G(1) phase as detected by flow cytometric cell cycle analysis and MTT cell viability analysis, and this was accompanied by dephosphorylation of the retinoblastoma protein (Rb). Furthermore, GMZ treatment resulted in increased levels of specifically the very long chain ceramides as determined by mass spectrometry. Mechanistically, GMZ did not appear to affect the activities of many enzymes of ceramide metabolism; however, GMZ caused a selective reduction in the protein levels of neutral ceramidase (NCDase), as indicated by Western blot analysis, with a concomitant decrease in NCDase activity. The significance of NCDase loss on cell cycle regulation was investigated by specific knockdown of the enzyme using small interfering RNA (siRNA). Interestingly, NCDase siRNA transfection was sufficient to induce a cell cycle arrest at G(0)/G(1) and an increase in total ceramide levels, with significant elevation in very long chain ceramides (C(24:1) and C(24:0)). NCDase siRNA also induced Rb dephosphorylation. These data provide evidence for a novel mechanism of action for GMZ and highlight downregulation of NCDase as a critical step in GMZ-mediated ceramide elevation and cell cycle arrest.
Authors:
Bill X Wu; Youssef H Zeidan; Yusuf A Hannun
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-04-02
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1791     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2009 Aug 
Date Detail:
Created Date:  2009-07-20     Completed Date:  2009-09-23     Revised Date:  2010-12-03    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  730-9     Citation Subset:  IM    
Affiliation:
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, 29425, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cell Cycle / drug effects*
Cell Line
Ceramides / metabolism
Deoxycytidine / analogs & derivatives*,  pharmacology
Down-Regulation / drug effects*
Endothelial Cells / cytology*,  drug effects,  enzymology*
Gene Knockdown Techniques
Mice
Neutral Ceramidase / metabolism*
Phosphorylation / drug effects
RNA, Small Interfering / metabolism
Retinoblastoma Protein / metabolism
Sphingomyelin Phosphodiesterase / metabolism
Grant Support
ID/Acronym/Agency:
CA87584/CA/NCI NIH HHS; GM43825/GM/NIGMS NIH HHS; P01 CA097132-06/CA/NCI NIH HHS; R01 CA087584-09/CA/NCI NIH HHS
Chemical
Reg. No./Substance:
0/Ceramides; 0/RNA, Small Interfering; 0/Retinoblastoma Protein; 103882-84-4/gemcitabine; 951-77-9/Deoxycytidine; EC 3.1.4.12/Sphingomyelin Phosphodiesterase; EC 3.5.1.23/Neutral Ceramidase
Comments/Corrections

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