Title
Differences in metabolism and isomerization of all-trans-retinoic acid and 9-cis-retinoic acid between human endothelial cells and hepatocytes
Author
Lansink, M.
van Bennekum, A.M.
Blaner, W.S.
Kooistra, T.
TNO Preventie en Gezondheid
Publication year
1997
Abstract
Retinoic acid stimulates the expression of tissue-type plasminogen activator (t-PA) in vascular endothelial cells in vitro and enhances t-PA levels in plasma and tissues in vivo. Compared with the in vivo situation, high retinoic acid concentrations are required to induce optimally t-PA expression in vitro. These findings led us to study retinoic acid metabolism in cultured human endothelial cells. For comparison, these studies were also performed in the human hepatoma cell line, HepG2, and key experiments were repeated with human primary hepatocytes. Both hepatocyte cultures gave very similar results. Human endothelial cells were shown to possess an active retinoic acid metabolizing capacity, which is quantitatively comparable to that of hepatocytes, but different from that of hepatocytes in several qualitative aspects. Our results demonstrate that all-trans-retinoic acid is quickly metabolized by both endothelial cells and hepatocytes. All trans-retinoic acid induces its own metabolism in endothelial cells but not in hepatocytes. 9-cis-Retinoic acid is degraded slowly by endothelial cells. whereas hepatocytes metabolize 9-cis-retinoic acid very quickly. Furthermore, our data show that hepatocytes, but not endothelial cells, detectably isomerise all-trans-retinoic acid to 9-cis-retinoic acid and vice versa. In both endothelial cells and hepatocytes all-trans-retinoic acid metabolism was inhibitable by the cytochrome P-450 inhibitors liarozole (10 μM) and ketoconazole (10 μM), albeit to different extents and with different specificities. In the presence of the most potent retinoic acid metabolism inhibitor in endothelial cells, liarozole, at least 10-fold lower all trans-retinoic acid concentrations were required than in the absence of the inhibitor to obtain the same induction of t-PA. In conclusion, our results clearly demonstrate that all-trans-retinoic acid and 9-cis retinoic acid are actively but differently metabolized and isomerised by human endothelial cells and hepatocytes. The rapid metabolism of retinoic acid explains the relatively high concentrations of retinoic acid required to induce t-PA in cultured endothelial cells. Chemicals/CAS: alitretinoin, 5300-03-8; Tretinoin, 302-79-4
Subject
Health
Human endothelial cell
Human hepatocyte
Isomerization
Metabolism
Liarozole
Plasminogen activator
Retinoic acid
Cell culture
Controlled study
Drug metabolism
Endothelium cell
High performance liquid chromatography
Human cell
In vitro study
Isomerism
Isotope labeling
Liver cell culture
Lliver metabolism
Biotransformation
Cells, Cultured
Chromatography, High Pressure Liquid
Endothelium, Vascular
Humans
Isomerism
Kinetics
Liver
Tretinoin
Umbilical Veins
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http://resolver.tudelft.nl/uuid:cef4ff6c-4fa7-405e-9750-2a7964ba40ad
TNO identifier
234002
ISSN
0014-2956
Source
European Journal of Biochemistry, 247 (2), 596-604
Document type
article