Mixed function oxidase and UDP-glucuronyltransferase activities in the human Hep G2 hepatoma cell line.
In cultured human hepatoma cells phenolphthalein glucuronidation was increased 3-fold by 2 mM phenobarbitone (PB) in the culture medium but not by 25 microM benz(a)anthracene (BA), while 1-naphthol glucuronidation was not increased by either PB or BA. Ethoxyresorufin O-deethylation (EROD) was increased 15-fold by BA but not by PB, while the O-dealkylations of pentoxyresorufin (PROD) and benzyloxyresorufin (BROD) were increased by either PB or BA. The BROD activity increased by BA was sensitive to inhibition by alpha-naphthoflavone whereas that induced by PB was not. This suggests induction of different cytochrome P-450 isoenzymes. Control Hep G2 cells had similar glucuronide conjugation and cytochrome reductase activities to freshly isolated human adult hepatocytes, but had lower O-dealkylation and elevated microsomal epoxide hydrolase activities.
Grant
M H
MH
Department of Medicine and Therapeutics, University of Aberdeen, Foresterhill, U.K.
Duthie
S J
SJ
Gray
A G
AG
Burke
M D
MD
D006528:Carcinoma, Hepatocellular / Q000201:enzymology*; D019362:Cytochrome P-450 CYP2B1; D004851:Epoxide Hydrolases / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000201:enzymology; D008113:Liver Neoplasms; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010078:Oxazines / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D014407:Tumor Cells, Cultured
D010078:Oxazines; C007649:ethoxyresorufin; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D019362:Cytochrome P-450 CYP2B1; D014453:Glucuronosyltransferase; D004851:Epoxide Hydrolases