Hepatocyte cell lines: their use, scope and limitations in drug metabolism studies

Abstract

Gaining knowledge on the metabolism of a drug, the enzymes involved and its inhibition or induction potential is a necessary step in pharmaceutical development of new compounds. Primary human hepatocytes are considered a cellular model of reference, as they express the majority of drug-metabolising enzymes, respond to enzyme inducers and are capable of generating in vitro a metabolic profile similar to what is found in vivo. However, hepatocytes show phenotypic instability and have a restricted accessibility. Different alternatives have been explored in the past recent years to overcome the limitations of primary hepatocytes. These include immortalisation of adult or fetal human hepatic cells by means of transforming tumour virus genes, oncogenes, conditionally immortalised hepatocytes, and cell fusion. New strategies are currently being used to upregulate the expression of drug-metabolising enzymes in cell lines or to derive hepatocytes from progenitor cells. This paper reviews the features of liver-derived cell lines, their suitability for drug metabolism studies as well as the state-of-the-art of the strategies pursued in order to generate metabolically competent hepatic cell lines.

Preapoptotic cell stress response of primary hepatocytes

“…4 Although the metabolic state of isolated hepatocytes is extensively studied, there are no data on modulation of apoptotic machinery after isolation.…”

“…2 As a consequence, the use of primary cultured hepatocytes in drug metabolism studies is confined to the first days in culture. 4 Although the metabolic state of isolated hepatocytes is extensively studied, there are no data on modulation of apoptotic machinery after isolation.…”

CCAAT/Enhancer-binding Protein α (C/EBPα) and Hepatocyte Nuclear Factor 4α (HNF4α) Synergistically Cooperate with Constitutive Androstane Receptor to Transactivate the Human Cytochrome P450 2B6 (CYP2B6) Gene

“…Unfortunately, the human hepatic cell lines available (e.g. HepG2) are not a real alternative because they express only marginal levels of drug-metabolizing CYPs and do not respond to CYP inducers (15). This could result from an altered (mostly repressed) expression of liverenriched transcription factors and co-regulators.…”

“…Human hepatic cell lines could be a suitable model for screening strategies. Unfortunately, commonly used hepatic cell lines have consistently demonstrated a very low or marginal CYP expression, which hinders their use as alternative models for drug metabolism and induction studies (15). A feasible explanation for this lack of CYP expression is that the hepatic-specific transcription factors controlling CYP genes are down-regulated in these cell systems.…”

Approaches for the Development of Antiviral Compounds: The Case of Hepatitis C Virus

“…The duration of exposure of drugs to the hepatocytes may be limited by susceptibility to drug metabolizing enzymes, since hepatocytes are the major site where drug metabolism occurs. Furthermore, drug exposure in hepatocytes may also be limited by the various unidirectional active transport (ATP dependent) proteins, including P-gp, BCRP\ABCG2, and MRP2 (Castell et al 2006;Chandra and Brouwer 2004;Elferink and Groen 2002;Gomez-Lechon et al 2004;Leslie et al 2005;Pauli-Magnus and Meier 2006;Vermeir et al 2005). Although nucleoside analogs are not substrates for P-gp or CYP3A4, most protease inhibitors and NNI are substrates for both the P-gp efflux pump (Aungst 1999;Storch et al 2007) and CYP3A 4 metabolism (Sagir et al 2003;Zhou et al 2005).…”