Assessment of metabolic capabilities of PLHC-1 and RTL-W1 fish liver cell lines

摘要

Metabolic capabilities of PLHC-1 and RTL-W1 cell lines were investigated since to date, cytochrome P450 (CYP) 1A and glutathione-S-transferase have been almost the unique biotransformation enzymes reported in these cells. Functionality of CYP3A-, CYP2M- and CYP2K-like enzymes was assessed by studying the hydroxylation of testosterone (T) and lauric acid (LA), and glucuronidation and sulfation capacity was assessed by looking at 1-naphthol (1-N) and T conjugation. Only PLHC-1 cells showed the ability to hydroxylate T at 6o-position (a CYP3A-like catalysed pathway) and LA at (s-1)-position (a CYP2K-like catalysed pathway). Hydroxysteroid dehydrogenase and steroid reductase enzymes showed comparatively higher activities than CYPs: 5l-dihydrotestosterone, androstenedione and 3o-androstanediol were the major metabolites of T detected in both cell lines. Regarding phase II activities, both cell lines metabolised 1-N to glucuronide and sulfate conjugates. In contrast, when using T as substrate, RTL-W1 formed the glucuronide, whilst PLHC-1 formed the corresponding sulfate. Overall, the observed enzymatic activities are much lower (up to 17.5c10pd times) than those reported in primary cultures of fish hepatocytes. The present study highlights the need of developing new fish cell lines that could be used as alternative in vitro tools for studying xenobiotic metabolism and toxicity in fish.