Constitutive and inducible expression of CYP enzymes in immortal hepatocytes derived from SV40 transgenic mice

Abstract

1. The expression of liver-specific transcription factors and cytochrome P450 (CYP) enzymes have been studied in three new hepatocyte-like cell lines derived from SV ▵ 202 transgenic mice: AMH- ▵ 202 (adult mouse hepatocytes), TAMH- ▵ 202 (tumour-derived adult mouse hepatocytes) and NMH- ▵ 202 (newborn mouse hepatocytes). 2. mRNA levels of liver-enriched transcription factors such as D-element binding protein (DBP), liver-enriched transcription activating protein (LAP) and the hepatic nuclear factors (HNF) 1, 2 and 3 in all ▵ 202 transgenic hepatocyte lines were similar to those in the wild-type liver and in primary mouse hepatocytes. 3. Analysis of basal CYP activities and testosterone metabolism revealed that ▵ 202 cells showed higher similarities to mouse hepatocytes than Hepa 1c1c7 hepatoma cells. All three ▵ 202 cell lines exhibited substantial active CYP1A1/2, CYP2A4/5 and CYP3A11 activities and lower levels of CYP2B, CYP2C and CYP2E1 activities. 4. The ▵ 202 cells also responded to model inducers. 3-Methylcholanthrene induced CYP1A1/2 (7-ethoxyresorufin O- deethylation); phenobarbital induced CYP2B (7-benzoxyresorufin O- debenzylation), CYP2A4/5 (testosterone 7 α -hydroxylation) and CYP3A11 (testosterone 6 β -hydroxylation); and rifampicin and dexamethasone induced CYP3A11 activities in the three ▵ 202 cell lines, whereas only AMH- ▵ 202 cells reproduced to a limited extent the response of CYP2E1 to ethanol observed in hepatocytes. 5. The results suggest that generation of hepatocyte lines from transgenic animals constitutes a successful approach to obtain in vitro models alternative to primary hepatocytes for drug metabolism and CYP inducibility studies.