title: Cytochrome P450 expression profile of the PICM-19H pig liver  cell line: potential application to rapid liver toxicity assays.
abstract: Liver in vitro models are needed to replace animal models for rapid assessment of drug biotransformation and toxicity. The PICM-19 pig liver stem cell line may fulfill this need since these cells have activities associated with xenobiotic phase I and II metabolism lacking in other liver cell lines. The objective of this study was to characterize phase I and II metabolic functions of a PICM-19 derivative cell line, PICM-19H, compared to the tumor-derived human HepG2 C3A cell line and primary cultures of adult porcine hepatocytes. Following exposure of PICM-19H cells to either 3-methylcholanthrene, rifampicin or phenobarbital, the induced activities of cytochrome P450 (CYP450) isozymes CYP-1A, -2, and-3A were assessed. Relative to adult porcine hepatocytes, PICM- 19H cells exhibited 30% and 43%, respectively, of CYP1A and 3A activities, while HepG2 C3A cells exhibited 7% and 0% of those activities. Fluorescent metabolites were extensively conjugated, i.e., 52% and 96% of CYP450-1A and-3A metabolites were released from medium samples following treatment with β-glucuronidase/arylsulfatase. Rifampicin induction of CYP450 isozyme activities was confirmed by conversion of testosterone to 6β-OH-, 2α-OH- and 2β-OH-testosterone, as determined by mass spectrometry. Susceptibility of PICM-19H cells to acetaminophen toxicity was determined; CD50 was calculated to be 14.9±0.9 mM. Toxicity and bioactivation of aflatoxin B1 was determined in 3-methylcholanthrenetreated cultures and untreated controls; CD50 were 1.59 μM and 31 μM, respectively. These results demonstrate the potential use of PICM-19H cells in drug biotransformation and toxicity testing and further support their use in extracorporeal artificial liver device technology.
authors.affiliation: USDA, ARS, Animal and Natural Resources Institute, Animal Biosciences and Biotechnology Laboratory, Beltsville Agricultural Research Center, Bldg. 200, Rm. 13, BARC-East, Beltsville, MD 20705, USA.
authors.forename: Ryan R
authors.initials: RR
authors.lastname: Willard
authors.forename: Nancy W
authors.initials: NW
authors.lastname: Shappell
authors.forename: John H
authors.initials: JH
authors.lastname: Meekin
authors.forename: Neil C
authors.initials: NC
authors.lastname: Talbot
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Caperna
mesh_terms: D000082:Acetaminophen / Q000633:toxicity; D016604:Aflatoxin B1 / Q000633:toxicity; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000378:metabolism*; D004790:Enzyme Induction / Q000187:drug effects; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D050216:Metabolic Detoxication, Phase I; D050217:Metabolic Detoxication, Phase II; D034421:Sus scrofa; D013739:Testosterone / Q000378:metabolism; D018675:Toxicity Tests / Q000379:methods*
chemical_list: D007527:Isoenzymes; D000082:Acetaminophen; D013739:Testosterone; D003577:Cytochrome P-450 Enzyme System; D016604:Aflatoxin B1