Expression of xenobiotic-metabolizing cytochrome P450 Forms in human full-term placenta
Department of Pharmacology and Toxicology, University of Oulu, 90220 Oulu, Finland Biochemical Pharmacology
(Impact Factor: 5.01).
03/1996; 51(4):403-411. DOI: 10.1016/0006-2952(95)02184-1
The expression of individual xenobiotic-metabolizing cytochrome P450 (CYP) genes in human placenta was studied at the mRNA level by reverse transcriptase-polymerase chain reaction (RT-PCR). mRNAs of CYP1A1, CYP2E1, CYP2F1, CYP3A3/4, CYP3A5, and CYP4B1 were detected by RT-PCR, and CYP1A2, CYP2A6/7, CYP2B6/7, CYP2C8-19, CYP2D6, and CYP3A7 were not detected. Several enzyme activity assays and immunoblots were used to further characterize expression of forms producing detectable mRNA transcripts. The catalytic activities of 7-ethoxycoumarin O-deethylase (ECOD), 7-ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxylase (AHH) were substantially increased in response to maternal cigarette smoking, and paralleled the amount of CYP1A1 mRNA and protein. Aromatase activities were slightly lower in placentas exposed to cigarette smoke compared with nonexposed placentas. These data show that several xenobiotic-metabolizing CYP genes are expressed in human placenta at a low level. The significance of such low-level expression is unknown, but it may have local physiological or toxic consequences.
Available from: PubMed Central
- "Finally, the reaction was terminated at 72°C for 10 minutes. The sequence of primer pairs was shown in Table 1
–. The amplified DNA products were loaded into a 1.8% of agarose gel in 1× of Tris/Borate/EDTA (TBE) buffer for electrophoresis. "
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Chewing of betel quid (BQ) increases the risk of oral cancer and oral submucous fibrosis (OSF), possibly by BQ-induced toxicity and induction of inflammatory response in oral mucosa.
Primary gingival keratinocytes (GK cells) were exposed to areca nut (AN) components with/without inhibitors. Cytotoxicity was measured by 3-(4,5-dimethyl- thiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. mRNA and protein expression was evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting. PGE2/PGF2α production was measured by enzyme-linked immunosorbent assays.
Areca nut extract (ANE) stimulated PGE2/PGF2α production, and upregulated the expression of cyclooxygenase-2 (COX-2), cytochrome P450 1A1 (CYP1A1) and hemeoxygenase-1 (HO-1), but inhibited expression of keratin 5/14, cyclinB1 and cdc25C in GK cells. ANE also activated epidermal growth factor receptor (EGFR), Src and Ras signaling pathways. ANE-induced COX-2, keratin 5, keratin 14 and cdc25C expression as well as PGE2 production were differentially regulated by α–naphthoflavone (a CYP 1A1/1A2 inhibitor), PD153035 (EGFR inhibitor), pp2 (Src inhibitor), and manumycin A (a Ras inhibitor). ANE-induced PGE2 production was suppressed by piper betle leaf (PBL) extract and hydroxychavicol (two major BQ components), dicoumarol (a NAD(P)H:Quinone Oxidoreductase - NQO1 inhibitor) and curcumin. ANE-induced cytotoxicity was inhibited by catalase and enhanced by dicoumarol, suggesting that AN components may contribute to the pathogenesis of OSF and oral cancer via induction of aberrant differentiation, cytotoxicity, COX-2 expression, and PGE2/PGF2αproduction.
CYP4501A1, reactive oxygen species (ROS), EGFR, Src and Ras signaling pathways could all play a role in ANE-induced pathogenesis of oral cancer. Addition of PBL into BQ and curcumin consumption could inhibit the ANE-induced inflammatory response.
Available from: Alice Nova
- "Cytochrome CYP1A1 is an enzyme significantly expressed in the human placenta during the entire pregnancy (Stejskalova and Pavek, 2011). Its expression and activity have been detected in the first and third trimesters at both mRNA and protein levels (Hakkola et al., 1996a,b; Czekaj et al., 2005; Stejskalova and Pavek, 2011). CYP1A1 is an important enzyme for metabolism of both endogenous substrates, such as estrogens (Parl et al., 2009), and exogenous substances such as PAHs. "
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ABSTRACT: The JEG-3 choriocarcinoma cell line has been proposed as a model cell line of human placental trophoblast for induction studies via aryl hydrocarbon receptor (AHR). We examined whether glucocorticoid dexamethasone influences AHR-mediated induction of CYP1A1 enzyme in the JEG-3 cell line. We found that dexamethasone dose- and time-dependently suppresses CYP1A1 transactivation in gene reporter assays, CYP1A1 mRNA induction, and upregulation of 7-ethoxyresorufin-O-deethylase (EROD) activity by 3-methylcholanthrene (MC) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in JEG-3 cells. Co-transfection of JEG-3 cells with glucocorticoid receptor (GR) expression construct and treatment with dexamethasone abolished the effect of MC on CYP1A1 promoter construct in transient transfection gene reporter assays. RU486, a GR antagonist, suppressed the effect of dexamethasone on MC-induced transactivation of AHR responsive reporter constructs. We also found that dexamethasone stimulates both ligand-dependent and ligand-independent degradation of AHR but not of aryl hydrocarbon receptor nuclear translocator (ARNT) protein in JEG-3 cells. In experiments with proteasome inhibitors MG132 and bortezomib, we found that the degradation is not sensitive to proteasome inhibition in JEG-3. We can conclude that dexamethasone suppresses AHR-mediated CYP1A1 induction in JEG-3 cells through the unique mechanism of AHR-GR crosstalk, which involves accelerated degradation of AHR.
Available from: Ewa L Gregoraszczuk
- "OH-PBDEs are also present in human plasma (Athanasiadou et al., 2008; Qiu et al., 2009) and breast milk (Lacorte and Ikonomou, 2009). Metabolic enzymes have been characterized mainly in liver but have also been detected in extrahepatic tissue such as lung, prostate gland, uterus, adrenal gland, placenta, kidney, brain, and testis (Hakkola et al., 1996; Nishimura et al., 2003). Our recent studies have shown that BDE-47 activates the first phase of metabolism in the ovary by stimulating CYP2B1/2 activity. "
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