Effects of prototypical microsomal enzyme inducers on cytochrome P450 expression in cultured human hepatocytes.
Cultured human hepatocytes are a valuable in vitro system for evaluating new molecular entities as inducers of cytochrome P450 (P450) enzymes. The present study summarizes data obtained from 62 preparations of cultured human hepatocytes that were treated with vehicles (saline or dimethylsulfoxide, 0.1%), beta-naphthoflavone (33 microM), phenobarbital (100 or 250 microM), isoniazid (100 microM) and/or rifampin (20 or 50 microM), and examined for the expression of P450 enzymes based on microsomal activity toward marker substrates, or in the case of CYP2C8, the level of immunoreactive protein. The results show that CYP1A2 activity was markedly induced by beta-naphthoflavone (on average 13-fold, n = 28 preparations), and weakly induced by phenobarbital (1.9-fold, n = 25) and rifampin (2.3-fold, n = 22); CYP2A6 activity tended to be increased with phenobarbital (n = 7) and rifampin (n = 3) treatments, but the effects were not statistically significant; CYP2B6 was induced by phenobarbital (6.5-fold, n = 13) and rifampin (13-fold, n = 14); CYP2C8 was induced by phenobarbital (4.0-fold, n = 4) and rifampin (5.2-fold, n = 4); CYP2C9 was induced by phenobarbital (1.8-fold, n = 14) and rifampin (3.5-fold, n = 10); CYP2C19 was markedly induced by rifampin (37-fold, n = 10), but relatively modestly by phenobarbital (7-fold, n = 9); CYP2D6 was not significantly induced by phenobarbital (n = 5) or rifampin (n = 5); CYP2E1 was induced by phenobarbital (1.7-fold, n = 5), rifampin (2.2-fold, n = 5), and isoniazid (2.3-fold, n = 5); and, CYP3A4 was induced by phenobarbital (3.3-fold, n = 42) and rifampin (10-fold, n = 61), but not by beta-naphthoflavone. Based on these observations, we generalize that beta-naphthoflavone induces CYP1A2 and isoniazid induces CYP2E1, whereas rifampin and, to a lesser extent phenobarbital, tend to significantly and consistently induce enzymes of the CYP2A, CYP2B, CYP2C, CYP2E, and CYP3A subfamilies but not the 2D subfamily.
Madan
Ajay
A
XenoTech, LLC, 16825 West 116th Street, Lenexa, KS 66219, USA.
Graham
Richard A
RA
Carroll
Kathleen M
KM
Mudra
Daniel R
DR
Burton
L Alayne
LA
Krueger
Linda A
LA
Downey
April D
AD
Czerwinski
Maciej
M
Forster
Jameson
J
Ribadeneira
Maria D
MD
Gan
Liang-Shang
LS
LeCluyse
Edward L
EL
Zech
Karl
K
Robertson
Philmore
P
Koch
Patrick
P
Antonian
Lida
L
Wagner
Greg
G
Yu
Li
L
Parkinson
Andrew
A
D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D065637:Cytochrome P-450 CYP2A6; D065702:Cytochrome P-450 CYP2B6; D065731:Cytochrome P-450 CYP2C19; D065727:Cytochrome P-450 CYP2C8; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000145:classification / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology*; D019324:beta-Naphthoflavone / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; C585599:CYP2B6 protein, human; C045793:CYP2C19 protein, human; C450259:CYP2C8 protein, human; C104464:CYP3A protein, human; D019388:Cytochrome P-450 CYP1A2; D065637:Cytochrome P-450 CYP2A6; D065702:Cytochrome P-450 CYP2B6; D065731:Cytochrome P-450 CYP2C19; D065727:Cytochrome P-450 CYP2C8; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D010089:Oxidoreductases, N-Demethylating; D007538:Isoniazid; D012293:Rifampin; D010634:Phenobarbital