COMPARISON OF PRIMARY HUMAN HEPATOCYTES AND HEPATOMA CELL LINE HEPG2 WITH REGARD TO THEIR BIOTRANSFORMATION PROPERTIES
Cultures of primary hepatocytes and hepatoma cell line HepG2 are frequently used in in vitro models for human biotransformation studies. In this study, we characterized and compared the capacity of these model systems to indicate the presence of different classes of promutagens. Genotoxic sensitivit...
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Published in | Drug metabolism and disposition Vol. 31; no. 8; pp. 1035 - 1042 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Pharmacology and Experimental Therapeutics
01.08.2003
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Subjects | |
Online Access | Get full text |
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Summary: | Cultures of primary hepatocytes and hepatoma cell line HepG2 are frequently
used in in vitro models for human biotransformation studies. In this study, we
characterized and compared the capacity of these model systems to indicate the
presence of different classes of promutagens. Genotoxic sensitivity, enzyme
activity, and gene expression were monitored in response to treatment with
food promutagens benzo[ a ]pyrene, dimethylnitrosamine (DMN), and
2-amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine (PhIP). DNA damage
could be detected reliably with the comet assay in primary human hepatocytes,
which were maintained in sandwich culture. All three promutagens caused DNA
damage in primary cells, but in HepG2 no genotoxic effects of DMN and PhIP
could be detected. We supposed that the lack of specific enzymes accounts for
their inability to process these promutagens. Therefore, we quantified the
expression of a broad range of genes coding for drug-metabolizing enzymes with
real-time reverse transcription-polymerase chain reaction. The genes code for
cytochromes P450 and, in addition, for a series of important phase II enzymes.
The expression level of these genes in human hepatocytes was similar to those
previously reported for human liver samples. On the other hand, expression
levels in HepG2 differed significantly from that in human. Activity and
expression, especially of phase I enzymes, were demonstrated to be extremely
low in HepG2 cells. Up-regulation of specific genes by test substances was
similar in both cell types. In conclusion, human hepatocytes are the preferred
model for biotransformation in human liver, whereas HepG2 cells may be useful
to study regulation of drug-metabolizing enzymes. |
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ISSN: | 0090-9556 1521-009X |
DOI: | 10.1124/dmd.31.8.1035 |