Antenatal glucocorticoid administration is used in cases of fetuses at risk to be born prematurely to enhance fetal pulmonary surfactant production and prevent infant respiratory distress syndrome. The CYP1A1 is the most important xenobiotic-metabolizing cytochrome P450 enzyme in the human placenta. Importantly, CYP1A1 generates reactive species and its placental activity is elevated in smoking women. CYP1A1 expression is mainly controlled by aryl hydrocarbon receptor (AHR) ligands. Glucocorticoid co-regulation of CYP1A1 has been described in various cell types but has not been systematically examined in the human placental trophoblast. We studied the effects of the glucocorticoids dexamethasone and betamethasone on inducibility of CYP1A1 and other AHR target genes CYP1A2, CYP1B1, UGT1A1 (UDP-glucuronosyltransferase 1A1) and BCRP (Breast cancer resistance protein) by prototype AHR ligand 3-methylcholanthrene (3MC) in isolated human placental trophoblast culture. We show that glucocorticoids alone had no effect on activity and protein/mRNA expression of CYP1A1 and little effect on mRNA expression of other AHR target genes. However, glucocorticoids significantly stimulated CYP1A1 mRNA, but not CYP1A2, CYP1B1, UGT1A1 and BCRP mRNAs, induction mediated by the AHR ligand. Consistently, glucocorticoids significantly augmented 7-ethoxyresorufin- O -deethylation (EROD) enzymatic activity in primary human placental trophoblast. Dexamethasone did not influence AHR and ARNT (Aryl hydrocarbon receptor nuclear translocator) mRNAs, suggesting that this phenomenon is not due to AHR or ARNT up-regulation by glucocorticoids in human trophoblast. In conclusion, our data suggest that glucocorticoids have no effect on AHR target genes expression per se , but they may potentiate CYP1A1 induction in human term placental trophoblast.
- MeSH
- aktivace transkripce genetika účinky léků MeSH
- betamethason farmakologie MeSH
- cytochrom P-450 CYP1A1 * genetika metabolismus MeSH
- dexamethason farmakologie MeSH
- exprese genu genetika účinky léků MeSH
- glukokortikoidy * farmakologie MeSH
- kultivované buňky MeSH
- lidé MeSH
- messenger RNA genetika MeSH
- methylcholanthren farmakologie MeSH
- placenta * cytologie metabolismus účinky léků MeSH
- receptory aromatických uhlovodíků genetika MeSH
- techniky in vitro MeSH
- transport proteinů genetika účinky léků MeSH
- trofoblasty cytologie metabolismus účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
AIMS: The aim was develop stable human cell line stable over-expressing transcription co-activator peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α) with restored hepatospecific functions and increased expression of major xenobiotic metabolizing enzymes. METHODS: Six clones of HepG2-PGC-1α and one control clone HepG2-pcDNA3 were isolated and analyzed for secretion of hepatospecific markers, fibrinogen, albumin and alpha1-antitrypsin. Expression levels of protein and mRNA of hepatocyte nuclear factor (HNF4α), pregnane X receptor (PXR) and aryl hydrocarbon receptor (AhR) were determined. We measured basal and ligand inducible expression of CYP1A1 and CYP3A4. RESULTS: Stably transfected cell line HepG2-PGC-1α derived from HepG2 cells over-expressing PGC-1α displayed increased secretion of fibrinogen, but not albumin or alpha1-antitrypsin compared to parent HepG2 cells. We found increased levels of HNF4α, PXR and AhR proteins but not their mRNAs in HepG2-PGC1 cells. Basal expression of CYP3A4 protein in HepG2-PGC-1α cells was increased but rifampicin-inducible expression of CYP3A4 protein was lowered in comparison with parent HepG2 cells. Induction of CYP3A4 mRNA varied between 1.3 - 1.9 fold in individual clones. Expression of TCDD-inducible CYP1A1 protein was lower in HepG2-PGC-1α cells than in parent HepG2 cells. Induction of CYP1A1 mRNA by TCDD in HepG2-PGC-1α cells was comparable with that in parent HepG2 cells and ranged between 103 - 198 fold. CONCLUSION: Stable expression of PGC-1α in HepG2 cells restores several hepatospecific functions, such as secretion of fibrinogen, expression of HNF4α1 and xenoreceptors PXR and AhR. However, the expression and induction of key drug-metabolizing enzymes (CYP1A1 and CYP3A4) were not improved.
- MeSH
- buňky Hep G2 MeSH
- cytochrom P-450 CYP1A1 metabolismus MeSH
- cytochrom P-450 CYP3A metabolismus MeSH
- fibrinogen sekrece MeSH
- gentamiciny farmakologie MeSH
- hepatocytární jaderný faktor 4 metabolismus MeSH
- hepatocyty metabolismus MeSH
- lidé MeSH
- nádorové biomarkery metabolismus MeSH
- polychlorované dibenzodioxiny farmakologie MeSH
- PPAR gama metabolismus MeSH
- receptory aromatických uhlovodíků metabolismus MeSH
- steroidní receptory metabolismus MeSH
- teratogeny farmakologie MeSH
- transfekce metody MeSH
- transkripční faktory bHLH metabolismus MeSH
- transkripční faktory metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
