Document Detail

Reduced lecithin:retinol acyl transferase activity in cultured squamous cell carcinoma lines results in increased substrate-driven retinoic acid synthesis.
MedLine Citation:
PMID:  9989277     Owner:  NLM     Status:  MEDLINE    
The uptake and metabolism of retinol was compared in squamous cell carcinoma lines, SCC12b and SCC13, and in normal human keratinocytes (NHK). Long chain fatty acid esters of retinol and 3,4-didehydroretinol were the predominant metabolites formed in both cell types. Lesser amounts of unesterified retinol, 3,4-didehydroretinol, and their respective active acid forms were also observed. Despite a qualitatively similar retinoid composition, there were significant quantitative differences between cell types. Most notable was that SCC formed only about one-fourth the retinoid ester as did normal cells. In parallel with this, unesterified retinol and retinoic acid concentrations in SCC were significantly elevated over those in normal cells. This altered pattern of retinoid metabolites in SCC was found to be due to very low lecithin:retinol acyltransferase (LRAT) activity. SCC exhibited less than one-tenth the LRAT activity of normal cells. Acyl-coenzyme A:retinol acyltransferase (ARAT) and retinyl ester hydrolase activities were not different between cell types. Challenging cells with increasing medium retinol concentrations resulted in dose-dependent increases in retinol and retinoic acid within SCC. In contrast, retinol and retinoic acid concentrations in similarly challenged normal cells remained relatively low across a wide retinol concentration range. This was accomplished by the storage of retinol, via LRAT activity, as retinyl ester. Consistent with increased substrate-driven retinoic acid synthesis in SCC, the expression of transglutaminase 1 was suppressed to a greater extent in the SCCs than in NHK, when cells were exposed to equivalent medium concentrations of retinol. The data demonstrate a central role of LRAT in regulating retinoic acid synthesis via its capacity to modulate cellular levels of substrate retinol.
V Jurukovski; M Simon
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1436     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1999 Jan 
Date Detail:
Created Date:  1999-03-04     Completed Date:  1999-03-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  479-90     Citation Subset:  IM    
Department of Oral Biology and Pathology, School of Dental Medicine, State University of New York at Stony Brook 11794-8702, USA.
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MeSH Terms
Acyltransferases / deficiency,  metabolism*
Base Sequence
Carcinoma, Squamous Cell / enzymology*,  metabolism
Cell Line
DNA Primers / genetics
Gene Expression
Keratinocytes / metabolism
Substrate Specificity
Transglutaminases / genetics
Tretinoin / metabolism*
Tumor Cells, Cultured
Vitamin A / metabolism
Reg. No./Substance:
0/DNA Primers; 11103-57-4/Vitamin A; 302-79-4/Tretinoin; EC 2.3.-/Acyltransferases; EC 2.3.1.-/lecithin-retinol acyltransferase; EC; EC 1

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