PMID- 7083159
OWN - NLM
STAT- MEDLINE
DCOM- 19820814
LR  - 20151119
IS  - 0008-5472 (Print)
IS  - 0008-5472 (Linking)
VI  - 42
IP  - 7
DP  - 1982 Jul
TI  - Cytochrome P-450- and flavin-containing monooxygenase-catalyzed formation of the 
      carcinogen N-hydroxy-2-aminofluorene and its covalent binding to nuclear DNA.
PG  - 2671-7
AB  - The metabolic N-oxidation of the carcinogen 2-aminofluorene was examined in vitro 
      using fortified hepatic microsomes from a variety of species. Rat, dog, human, 
      and pig liver microsomes catalyzed the formation of N-hydroxy-2-aminofluorene 
      (N-OH-AF) from AF at rates of 1.6, 1.0, 1.2, and 3.5 nmol/min/mg protein, 
      respectively. The involvement of both cytochrome P-450 and the flavin-containing 
      monooxygenase was demonstrated with hepatic microsomes and with purified enzymes 
      by using specific enzyme inhibitors. 
      2-[(2,4-Dichloro-6-phenyl)phenoxy]ethylamine, a potent cytochrome P-450 
      inhibitor, decreased microsomal N-OH-AF formation by 96, 83, 70, and 46% in the 
      rat, dog, human, and pig, respectively; and further addition of methimazole, a 
      high-affinity flavin-containing monooxygenase substrate, abolished the residual 
      N-hydroxylating activity. Using the purified porcine flavin-containing 
      monooxygenase, metabolic formation of N-OH-AF occurred at a rate of 4.9 
      nmol/min/nmol flavin adenine nucleotide and was insensitive to 
      2-[(2,4-dichloro-6-phenyl)phenoxy]ethylamine inhibitor. In addition, purified rat 
      liver cytochrome P-450 (isolated from 5,6-naphthoflavone-induced animals) 
      N-hydroxylated AF (1.1 nmol/min/nmol P-450) and was completely inhibited by 
      2-[(2,4-dichloro-6-phenyl)-phenoxy]ethylamine, but the reaction was insensitive 
      for methimazole. To determine whether or not the metabolic formation of N-OH-AF 
      could lead directly to covalently bound adduct(s) with DNA under these incubation 
      conditions (30 min, pH 7.5), the binding of synthetic and metabolically formed 
      [3H]-N-OH-AF to added calf thymus DNA and to DNA in isolated rat liver nuclei was 
      investigated. In all cases, the amount of DNA-bound carcinogen accounted for 0.08 
      to 0.15% of the N-OH-AF present in the incubation mixtures. These data, when 
      compared to the levels of AF bound to hepatic nuclear DNA reported in vivo, 
      suggest that the nonenzymatic reaction of N-OH-AF with nuclear DNA may be 
      sufficient to account for a substantial portion of the observed in vivo binding 
      of this carcinogen.
FAU - Frederick, C B
AU  - Frederick CB
FAU - Mays, J B
AU  - Mays JB
FAU - Ziegler, D M
AU  - Ziegler DM
FAU - Guengerich, F P
AU  - Guengerich FP
FAU - Kadlubar, F F
AU  - Kadlubar FF
LA  - eng
GR  - ES 01590/ES/NIEHS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Cancer Res
JT  - Cancer research
JID - 2984705R
RN  - 0 (Carcinogens)
RN  - 0 (Fluorenes)
RN  - 3A69OS195N (2-aminofluorene)
RN  - 61M94X4V24 (N-hydroxy-2-aminofluorene)
RN  - 9007-49-2 (DNA)
RN  - 9035-51-2 (Cytochrome P-450 Enzyme System)
RN  - EC 1.13.- (Oxygenases)
RN  - EC 1.14.13.8 (dimethylaniline monooxygenase (N-oxide forming))
SB  - IM
MH  - Animals
MH  - Carcinogens/*metabolism
MH  - Cattle
MH  - Cell Nucleus/*metabolism
MH  - Cytochrome P-450 Enzyme System/*metabolism
MH  - DNA/*metabolism
MH  - Dogs
MH  - Fluorenes/*metabolism
MH  - Humans
MH  - Liver/metabolism/ultrastructure
MH  - Microsomes, Liver/enzymology
MH  - Oxygenases/*metabolism
MH  - Rats
MH  - Rats, Inbred Strains
MH  - Swine
MH  - Thymus Gland/ultrastructure
EDAT- 1982/07/01 00:00
MHDA- 1982/07/01 00:01
CRDT- 1982/07/01 00:00
PHST- 1982/07/01 00:00 [pubmed]
PHST- 1982/07/01 00:01 [medline]
PHST- 1982/07/01 00:00 [entrez]
PST - ppublish
SO  - Cancer Res. 1982 Jul;42(7):2671-7.