Synergistic induction of drug-metabolizing enzymes in co-cultures of bovine hepatocytic and sinusoidal cell lines.

Hepatocyte-derived cell lines provide useful experimental systems for studying liver metabolism. Unlike human and rodents, few hepatocyte-derived cell lines have been generated from cattle. Here, we established two immortalized bovine hepatocyte-derived cell lines (BH4 and BH5) via transfection with a SV40 large T-antigen construct. Morphological and immunocytochemical analyses revealed that BH4 and BH5 originated from hepatocytes and biliary-epithelial cells, respectively. A potent carcinogen, 3-methylcholanthrene (3-MC), upregulated gene expression of cytochrome P450 (CYP)1A1, CYP1A2, and CYP1B1 in BH4 and BH5, but only to levels less than one-fifteenth of those in primary cultured bovine hepatocytes. Phenobarbital (PB) also increased expression levels of CYP2B6, CYP2C18, and CYP3A4 in BH4 and BH, but at a lower level than 3-MC. By contrast, when BH4 or BH5 was co-cultured with previously established bovine liver sinusoidal cell lines and treated with 3-MC, the gene expression levels of CYP1A1, CYP1A2, and CYP1B1 increased by 38~290%, compared with those in BH4 or BH5 cells cultured alone. PB-treated co-cultures of BH4 or BH5 cells and liver sinusoidal cell lines also showed synergistic increases in CYP2B6 and CYP2C18 expression. Together, the results suggest that these co-cultures could provide an in vitro model for investigations into pharmacological and toxicological properties of drugs in cattle liver.