Cytochrome b5 and epoxide hydrolase contribute to benzo[a]pyrene-DNA adduct formation catalyzed by cytochrome P450 1A1 under low NADPH:P450 oxidoreductase conditions
Jazyk angličtina Země Irsko Médium print-electronic
Typ dokumentu časopisecké články, práce podpořená grantem
Grantová podpora
14329
Cancer Research UK - United Kingdom
PubMed
24530354
DOI
10.1016/j.tox.2014.02.002
PII: S0300-483X(14)00021-3
Knihovny.cz E-zdroje
- Klíčová slova
- Benzo[a]pyrene, Cytochrome P450 1A1, Cytochrome b(5), Epoxide hydrolase, NADPH:cytochrome P450 oxidoreductase,
- MeSH
- adukty DNA metabolismus MeSH
- benzopyren metabolismus toxicita MeSH
- cytochrom P-450 CYP1A1 metabolismus MeSH
- cytochromy b5 metabolismus MeSH
- epoxid hydrolasy metabolismus MeSH
- geneticky modifikovaná zvířata MeSH
- jaterní mikrozomy účinky léků metabolismus MeSH
- karcinogeny metabolismus toxicita MeSH
- kultivované buňky metabolismus MeSH
- myši knockoutované MeSH
- myši MeSH
- NADPH-cytochrom c-reduktasa metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- adukty DNA MeSH
- benzo(a)pyrene-DNA adduct MeSH Prohlížeč
- benzopyren MeSH
- cytochrom P-450 CYP1A1 MeSH
- cytochromy b5 MeSH
- epoxid hydrolasy MeSH
- karcinogeny MeSH
- NADPH-cytochrom c-reduktasa MeSH
In previous studies we had administered benzo[a]pyrene (BaP) to genetically engineered mice (HRN) which do not express NADPH:cytochrome P450 oxidoreductase (POR) in hepatocytes and observed higher DNA adduct levels in livers of these mice than in wild-type mice. To elucidate the reason for this unexpected finding we have used two different settings for in vitro incubations; hepatic microsomes from control and BaP-pretreated HRN mice and reconstituted systems with cytochrome P450 1A1 (CYP1A1), POR, cytochrome b5, and epoxide hydrolase (mEH) in different ratios. In microsomes from BaP-pretreated mice, in which Cyp1a1 was induced, higher levels of BaP metabolites were formed, mainly of BaP-7,8-dihydrodiol. At a low POR:CYP1A1 ratio of 0.05:1 in the reconstituted system, the amounts of BaP diones and BaP-9-ol formed were essentially the same as at an equimolar ratio, but formation of BaP-3-ol was ∼ 1.6-fold higher. Only after addition of mEH were BaP dihydrodiols found. Two BaP-DNA adducts were formed in the presence of mEH, but only one when CYP1A1 and POR were present alone. At a ratio of POR:CYP1A1 of 0.05:1, addition of cytochrome b5 increased CYP1A1-mediated BaP oxidation to most of its metabolites indicating that cytochrome b5 participates in the electron transfer from NADPH to CYP1A1 required for enzyme activity of this CYP. BaP-9-ol was formed even by CYP1A1 reconstituted with cytochrome b5 without POR. Our results suggest that in livers of HRN mice Cyp1a1, cytochrome b5 and mEH can effectively activate BaP to DNA binding species, even in the presence of very low amounts of POR.
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