Inducibility of ethoxyresorufin deethylase and UDP-glucuronosyltransferase activities in two human hepatocarcinoma cell lines KYN-2 and Mz-Hep-1.
Two human hepatoma cell lines, KYN-2 and Mz-Hep-1 were characterized in terms of glucuronidation capacity and inducibility of cytochrome P4501A1/1A2 and several UDP-glucuronosyltransferases (UGTs). Cytochrome P4501A1/1A2 activity was measured using 7-ethoxyresorufin and that of UGTs with 16 different substrates. The effects of dimethyl sulfoxide (DMSO), 3-naphthoflavone, alpha-naphthoflavone, and rifampicin on these drug-metabolizing enzyme activities were studied. DMSO treatment increased in a dose-dependent manner the ethoxyresorufin O-deethylase (EROD) activity in KYN-2 cells, while an opposite effect was observed in Mz-Hep-1 cells. In KYN-2 cells, EROD was more responsive toward beta-naphthoflavone treatment in combination with DMSO. This activity was enhanced in Mz-Hep-1 cells more than 83 times by beta-naphthoflavone. The enhancement of EROD activity by DMSO and beta-naphthoflavone treatments of KYN-2 cells was abolished by alpha-naphthoflavone treatment. In Mz-Hep-1, only the inducing effect of beta-naphthoflavone was abolished by alpha-naphthoflavone treatment. Rifampicin treatment of KYN-2 cells reversed both the DMSO and beta-naphthoflavone effects on the EROD activity. Glucuronidation of steroids, bile acids, fatty acids and drugs was effective in KYN-2 and Mz-Hep-1 cells. Both 1-naphthol glucuronidation and the level of UGT1*6 protein detected by immunoblot and supporting this activity were lowered by DMSO treatment and increased by beta-naphthoflavone treatment in KYN-2 cells. In Mz-Hep-1 cells, DMSO and beta-naphthoflavone had no effect on 1-naphthol glucuronidation activity. DMSO, beta-naphthoflavone and rifampicin also affected the glucuronidation of various substrates supported by different UGT isoforms. These results indicate that KYN-2 and Mz-Hep-1 cells can be used as new in vitro models for the studies of drug metabolism and the regulation of the corresponding enzymes.
Abid
A
A
Centre du Medicament, URA CNRS 597, Nancy, France.
Sabolovic
N
N
Magdalou
J
J
D000904:Antibiotics, Antitubercular / Q000494:pharmacology; D001571:Benzoflavones / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular; D019363:Cytochrome P-450 CYP1A1; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004789:Enzyme Activation; D004790:Enzyme Induction; D014453:Glucuronosyltransferase / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007536:Isomerism; D010088:Oxidoreductases / Q000378:metabolism*; D012293:Rifampin / Q000494:pharmacology; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D014530:Uridine Diphosphate / Q000378:metabolism*; D019324:beta-Naphthoflavone
D000904:Antibiotics, Antitubercular; D001571:Benzoflavones; D014530:Uridine Diphosphate; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D019363:Cytochrome P-450 CYP1A1; D014453:Glucuronosyltransferase; D012293:Rifampin; D004121:Dimethyl Sulfoxide