Expression of arylhydrocarbon hydroxylase, epoxide hydrolases, glutathione S-transferase and UDP-glucuronosyltransferases in H5-6 hepatoma cells.
1. The presence of arylhydrocarbon hydroxylase (cytochrome P-450 IA1 dependent), glutathione S-transferase, two distinct forms of epoxide hydrolases and UDP-glucuronosyltransferases was detected in H5-6 hepatoma cell homogenates using model substrates, selective inhibitors and specific antibodies. 2. The activity of arylhydrocarbon hydroxylase decreased strongly at the first days after plating and remained at a minimal value (1.5 pmol/min per mg) after 5 days of culture. 3. The hydratation of trans-stilbene oxide catalyzed by the soluble form of epoxide hydrolase was very low (11.0 pmol/min per mg), whereas the hepatoma cells contained appreciable amounts of the membrane-bound epoxide hydrolase and glutathione S-transferase measured with cis-stilbene oxide as substrate (maximal specific activity: 1.46 and 2.73 nmol/min per mg, respectively). 4. These cells also glucuronidated 1-naphthol efficiently (6 nmol/min per mg) and, at a lower extent, bilirubin (12 pmol/min per mg). 5. Addition of fenofibrate (70 microM) into the culture medium for 1-3 days failed to significantly stimulate the activity of cytosolic epoxide hydrolase. Only bilirubin glucuronidation increased 2-fold after 2 days of presence of the drug.
Roques
M
M
Centre du Médicament, U.R.A. CNRS No. 597, Faculté des Sciences Pharmaceutiques et Biologiques, Nancy, France.
Bagrel
D
D
Magdalou
J
J
Siest
G
G
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D002460:Cell Line; D004851:Epoxide Hydrolases / Q000378:metabolism; D011345:Fenofibrate / Q000494:pharmacology; D014453:Glucuronosyltransferase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D008114:Liver Neoplasms, Experimental / Q000201:enzymology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology
D001189:Aryl Hydrocarbon Hydroxylases; D014453:Glucuronosyltransferase; D005982:Glutathione Transferase; D004851:Epoxide Hydrolases; D011345:Fenofibrate