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Regulation of human liver cytochromes P‐450 in family 3A in primary and continuous culture of human hepatocytes
Author(s) -
Schuetz Erin G.,
Schuetz John D.,
Strom Stephen C.,
Thompson Melissa T.,
Fisher Robert A.,
Molowa David T.,
Li Donna,
Guzelian Philip S.
Publication year - 1993
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.1840180535
Subject(s) - phenobarbital , hepatoblastoma , biology , hepatocyte , microbiology and biotechnology , cell culture , messenger rna , cytochrome , cytochrome p450 , lovastatin , hep g2 , isozyme , liver cell , in vitro , biochemistry , medicine , gene , endocrinology , enzyme , genetics , cholesterol
The cytochrome P‐450 3A gene family comprises the dominant forms of cytochrome P‐450 found in human liver. We examined as a possible useful system for studying the regulation of cytochrome P‐450 3A under controlled conditions in vitro , primary monolayer cultures of human hepatocytes and compared the results with those obtained from the study of cytochrome P‐450 3A in the human hepatoblastoma cell line HepG2 or in the human hepatocellular carcinoma cell line TONG/HCC. Using 3A antibodies, 3A cDNAs and 3A3, 3A4, 3A5 and 3A7 isozyme‐specific oligonucleotides as probes, we determined that primary human hepatocyte cultures routinely expressed a 3A3/4 * immunoreactive protein and 3A mRNA. These gene products were well maintained for many days and were induced by treatment of the cultures with dexamethasone, phenobarbital, macrolide antibiotics, the HMG CoA reductase inhibitor lovastatin or an antifungal agent, clotrimazole. Of six donor livers examined, only two contained mRNA or protein for 3A5, a form found in only a few adult human subjects. In cultures prepared from one of these two livers, 3A5 mRNA was detectable for several days. In cultures of hepatocytes from the remaining four human livers that did not contain 3A5 mRNA or protein, we detected neither spontaneous nor inducible 3A5 proteins or mRNAs. HepG2 cells contained only 3A7 protein, a form found in human fetal liver, even after treatment with inducers. Treatment of HepG2 cells with dexamethasone, macrolide antibiotics, phenobarbital and phenobarbital‐like inducers or lovastatin produced dose‐dependent induction of 3A7 mRNA and 3A7 immunoreactive protein. TONG/HCC cells contained 3A3, 3A4 and 3A5 mRNAs, but only 3A5 immunoreactive protein could be detected. Treatment of TONG/HCC cells with dexamethasone, macrolide antibiotics or phenobarbital induced 3A3 and 3A4 mRNAs, as observed in primary cultures, but failed to increase 3A5 mRNA or protein. We conclude that, in addition to primary cultures of human hepatocytes, replicating human hepatic lines HepG2 and TONG/HCC may be useful models for examining regulation of cytochrome P‐450 3A genes polymorphically expressed in the living human being. (HEPATOLOGY 1993;18:1254‐1262).