Cytochrome P450 3A4 and 1A2 Induction in Immortalized and Primary Cultures of Human Hepatocytes
Cytochrome P450 3A4 and 1A2 Induction in the Immortalized Hepatocyte Line, Fa2N-4, and Comparison with Primary Cultures of Human Hepatocytes
Primary cultures ofHuman hepatocytes are the gold standard for evaluating induction of cytochrome P450 (CYP) enzymes by new molecular entities. Recently, immortalizedHuman hepatocytes, known as Fa2N-4 cells, have been shown to express CYP3A4 and CYP1A2. Additionally, these cells exhibited enzyme induction in response to treatment with agonists of nuclear receptors (Mills et al., 2004). To establish the Fa2N-4 cells as a tool for determining CYP3A4 and CYP1A2 induction, we measured the cells’ response to drugs previously evaluated in multiple primary hepatocyte cultures (Luo et al., 2002). Midazolam 1′-hydroxylase and phenacetin O-dealkylase activity were monitored using LC/MS/MS methods to determine the effects of the drugs on expression of CYP3A4 and CYP1A2, respectively. Toxic Effects of the compounds were monitored with lactate dehydrogenase (LDH) leakage into the culture media. The magnitude of CYP3A4 and CYP1A2 induction in Fa2N-4 cells agrees closely with primary cultures ofHuman hepatocytes. The comparison of the CYP response in the two cell culture systems validates immortalized hepatocytes as a preclinical tool for assessment of CYP3A4 and CYP1A2 induction.