Regulation of cytochrome P450 cholesterol side-chain cleavage, 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase type 1 and estradiol-17 beta-hydroxysteroid dehydrogenase mRNA levels by calcium in human choriocarcinoma JEG-3 cells.
In human placenta the cytochrome P450 side-chain cleavage (P450scc) and 3 beta-hydroxysteroid dehydrogenase type 1 (3 beta-HSD-1) convert cholesterol and pregnenolone producing progesterone, whereas 17 beta-hydroxysteroid dehydrogenase type 1 (17 beta-HSD-1) mediates the interconversion of estrone and estradiol. We have examined the effects of calcium on phorbol ester- and cAMP-induced P450scc, 3 beta-HSD-1 and 17 beta-HSD-1 mRNAs in human JEG-3 cells. A23187 increased in a dose-dependent fashion in the 1.3 kb 17 beta-HSD-1 mRNA whereas a weaker increase followed by a gradual depletion effect of A23187 was observed on 3 beta-HSD-1 mRNA. No significant effect of A23187 on P450scc mRNA was observed. Using 0.50 microM of A23187 the induction of 3 beta-HSD-1 and 17 beta-HSD-1 mRNAs was maximum within about 6 h whereas P450scc mRNA levels stayed unaffected throughout the time-course period. The action of A23187 was synergistic on cAMP-stimulated 17 beta-HSD-1 mRNA levels, while in a dose-dependent manner A23187 progressively depleted 3 beta-HSD-1 and P450scc mRNA abundance probably by activation of a calcium-/calmodulin-dependent phosphodiesterase. On the phorbol 12-myristate, 13-acetate (PMA)-stimulated 3 beta-HSD-1, 17beta-HSD-1 and P450scc mRNA levels only the lowest concentration of A23187 potentialized the PMA effect on the 17 beta-HSD-1 mRNA levels. Using thapsigargin (TG), a cell-permeable sesquiterpene lactone that releases calcium by inhibiting sarco/endoplasmic reticular calcium-ATPase, our data indicated the presence in JEG-3 cells of TG-sensitive and TG-insensitive calcium-ATPases regulating 3 beta-HSD-1 and 17 beta-HSD-1 mRNA levels. These results emphasized the complexity of calcium contribution with the protein kinase A and C pathways in the regulation of P450scc, 3 beta-HSD-1 and 17 beta-HSD-1 mRNA levels. In addition, the different sensitivity of these genes to calcium suggest they could be activated by different subclasses of PKCs.
Beaudoin
C
C
Molecular Endocrinology Laboratory, CHUQ, CHUL Research Center, Laval, Quebec, Canada.
Bonenfant
M
M
Tremblay
Y
Y
D015067:17-Hydroxysteroid Dehydrogenases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D002784:Cholesterol / Q000378:metabolism*; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000187:drug effects / Q000378:metabolism*; D002822:Choriocarcinoma / Q000201:enzymology* / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D009097:Multienzyme Complexes / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011375:Progesterone Reductase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D013251:Steroid Isomerases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000201:enzymology* / Q000235:genetics
C021425:3 beta-hydroxysteroid oxidoreductase-delta(5) 3-ketosteroid isomerase; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D002784:Cholesterol; D015067:17-Hydroxysteroid Dehydrogenases; D011375:Progesterone Reductase; C044256:3 (or 17)-beta-hydroxysteroid dehydrogenase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D013251:Steroid Isomerases; D002118:Calcium