Sterol metabolism and oral epithelial cell growth |
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Authors: | Gretchen B Caughman George S Schuster Thomas R Dirksen |
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Institution: | (1) Department of Oral Biology, School of Dentistry, Medical College of Georgia, 30912 Augusta, Georgia |
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Abstract: | Previous studies have demonstrated that as the density of cultured oral epithelial cells increases, there is a concomitant
increase in phospholipids and cholesterol ester synthesis and a decrease in that of cholesterol and sterol precursors. Other
studies have suggested that the effects of exogenous cholesterol sulfate may be similar to growth responses and influence
metabolic steps related to cell density. To further examine this possibility, in the present study lipid synthesis was monitored
in hamster cheek pouch epithelial cells in cultures established at different cells densities and in the presence of varying
amounts of exogenous cholesterol sulfate. Cell 14C]acetate incorporation into lipids was measured in cultures established at four densities ranging from very subconfluent
to very dense (postconfluent) in two media, Dulbecco’s modified Eagle’s medium (DMEM) with 5% fetal bovine serum and KSFM,
a non-serum containing keratinocyte medium. Results indicated that the relative proportion of radiolabel incorporated into
different lipid classes changed with cell density. In DMEM, the percentage of radiolabel incorporated into total phospholipids
and fatty acids increased significantly with increasing cell density whereas percent incorporation into cholesterol, sterol
precursors, and cholesterol esters significantly decreased. In KSFM cultures, proportionate phospholipids labeling was significantly
increased in more dense cultures whereas cholesterol and cholesterol esters labeling was significantly decreased. In subconfluent
and confluent cultures exposed to 10 or 25μM cholesterol sulfate, the relative proportions of phospholipid labeling also increased significantly compared to dimethyl
sulfoxide (solvent) controls, whereas sterol precursors, fatty acids, and cholesterol esters labeling was signifcantly decreased.
These results indicate that cholesterol sulfate can affect cellular lipid synthesis in a manner similar to that which occurs
with increasing cell density, and strengthen the hypothesis that cholesterol sulfate may regulate lipid metabolic pathways
related to growth and differentiation. |
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Keywords: | lipids cholesterol sulfate cell density epithelium |
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