Uptake of dehydroepiandrosterone-3-sulfate by isolated trophoblasts from human term placenta, JEG-3, BeWo, Jar, BHK cells, and BHK cells transfected with human sterylsulfatase-cDNA.
The human placenta lacks the enzyme 17alpha-hydroxylase/17-20-lyase, and is thus unable to convert cholesterol into estrogens. Therefore estrogen synthesis of trophoblast cells depends on the supply of precursors such as dehydroepiandrosterone-3-sulfate (DHEA-S) and 16alpha-hydroxy-dehydroepiandrosterone-3-sulfate by maternal and fetal blood. To investigate the cellular internalisation of these anionic hydrophilic precursors, the uptake of [(3)H]-/[(35)S]-DHEA-S and [(3)H]-taurocholate by isolated cytotrophoblasts, cells of choriocarcinoma cell lines (JEG-3, BeWo, Jar), BHK and BHK cells transfected with human sterylsulfatase-cDNA (BHK-STS cells) was studied. Furthermore, the activity of sterylsulfatase of these cells in suspension and in corresponding cell homogenate was measured. During the first 5 min of incubation with [(3)H]-DHEA-S or [(35)S]-DHEA-S, radioactivity of cytotrophoblasts increased significantly, while radioactivity of JEG-3, Jar, BHK and BHK-STS cells did not increase. Radioactivity of BeWo cells increased slightly. For all cell types, there was no significant difference for uptake of either substrate. During incubation with [(3)H]-taurocholate, radioactivity of cytotrophoblasts did not increase. Sterylsulfatase activity of cytotrophoblast homogenate was significantly lower than that of cytotrophoblast suspension. Sterylsulfatase activity of BHK-STS, JEG-3 or BeWo cell homogenate was significantly higher than that of the corresponding cell suspension. In BHK and Jar cells sterylsulfatase activity was not detectable. Cytotrophoblasts take up DHEA-S without prior hydrolysis. BHK, BHK-STS, JEG-3, and Jar cells do not take up and BeWo cells slowly take up DHEA-S. In cytotrophoblasts extracellular DHEA-S rapidly gains access to intracellular sterylsulfatase, while in choriocarcinoma and BHK-STS cells access of DHEA-S to sterylsulfatase is limited. Our results indicate, that uptake by cytotrophoblasts is mediated by a carrier which is not expressed in choriocarcinoma or BHK cells and which is different from the known taurocholate-transporting organic anion transporting polypetides.
Ugele
B
B
I. Frauenklinik, Klinikum Innenstadt, Ludwig-Maximilians-Universität München, Maistr. 11, D-80337, Munich, Germany. ugele@lrz.muenchen.de
Simon
S
S
D001192:Arylsulfatases / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D019314:Dehydroepiandrosterone Sulfate / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D010920:Placenta / Q000378:metabolism*; D043266:Steryl-Sulfatase; D013656:Taurocholic Acid / Q000378:metabolism; D014162:Transfection; D014327:Trophoblasts / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D019314:Dehydroepiandrosterone Sulfate; D013656:Taurocholic Acid; D001192:Arylsulfatases; D043266:Steryl-Sulfatase